Collaborative Research on 

Road Weather Observations and 

Predictions by Universities, 

State Departments of Transportation,

and National Weather Service 

Forecast Offices

Publication No. FHWA-HRT-04-109 OCTOBER 2004

Research, Development, and Technology

Turner-Fairbank Highway Research Center

6300 Georgetown Pike

McLean, VA 22101-2296
FOREWORD 

This report documents the results of five research projects to improve the sensing, 

predictions and use of weather-related road conditions in road maintenance and 

operations. 

 The primary purpose for these projects was to evaluate the use of weather observations 

and modeling systems to improve highway safety and to support effective decisions made 

by the various jurisdictions that manage the highway system. In particular, the research 

evaluated how environmental sensor station data, particularly Road Weather Information 

System (RWIS) data, could best be used for both road condition forecasting and weather 

forecasting. The collaborative efforts also included building better relations for training 

and sharing information between the meteorological and transportation agencies. 

 

These projects are unique because they each involved collaborated partnerships between 

National Weather Service (NWS) Weather Forecast Offices (WFOs), State departments 

of transportation (DOTs), and universities. Lessons learned from these projects can help 

all State DOTs improve how they manage RWIS networks and achieve maximum utility 

from RWIS investments. Sufficient copies are being distributed to provide one copy to 

each Federal Highway Administration (FHWA) Resource Center, two copies to each 

FHWA Division, and one copy to each State highway agency. Direct distribution is being 

made to the FHWA Divisions Offices. Additional copies may be purchased from the 

National Technical Information Service (NTIS), 5285 Port Royal Road, Springfield, VA 

22161. 

 

 Toni Wilbur 

 Director, Office of Operations 

 Research and Development 

 

Notice 

 

This document is disseminated under the sponsorship of the U.S. Department of 

Transportation in the interest of information exchange. The U.S. Government assumes no 

liability for the use of the information contained in this document. 

 

The U.S. Government does not endorse products or manufactures. Trademarks or 

manufacturers' names appear in this report only because they are considered essential to 

the objective of the document. 

 

Quality Assurance Statement 

 

The Federal Highway Administration (FHWA) provides high-quality information to 

serve Government, industry, and the public in a manner that promotes public 

understanding. Standards and policies are used to ensure and maximize the quality, 

objectivity, utility, and integrity of its information. FHWA periodically reviews quality 

issues and adjusts its programs and processes to ensure continuous quality improvement. 
Technical Report Documentation Page 

1. Report No.

FHWA-HRT-04-109 

2. Government Accession No. 

 

3. Recipient’s Catalog No.

 

5. Report Date 

September 2004 

4. Title and Subtitle 

Collaborative Research on Road Weather Observations and Predictions 

by Universities, State DOTs and National Weather Service Forecast 

Offices 

6. Performing Organization Code

 

7. Author(s) 

Dr. Victoria Johnson, Dr. Darko Koracin, William Gallus, David R. 

Fitzjarrald, Paul Knight, and John Horel 

8. Performing Organization Report No. 

 

10. Work Unit No. 

 

9. Performing Organization Name and Address 

Desert Research Insitute Iowa State University SUNY-Albany 

2215 Raggio Parkway 3025 Agronomy Hall 215 Fuller Road 

Reno, NV 89512 Ames, IA 50011 Albany, NY 12203 

 

Pennsylvania State University University of Utah 

110 Technology Center 819 William C. Browning Bldg. 

University Park, PA 16802 Salt Lake City, UT 84112 

Cooperative Program for Operational Meteorology, 

Education and Training 

(COMET®) 

PO Box 3000 

Boulder, CO 80307

11. Contract or Grant No. 

DTFH61-00-Y-30095 

13. Type of Report and Period Covered 

Final Report 

2001-2003 

12. Sponsoring Agency Name and Address 

Office of Operations National Science Foundation 

Federal Highway Administration 4201 Wilson Blvd, Rm 775 

400 7th Street, SW Arlington, VA 22230 

Washington, DC 20590 14. Sponsoring Agency Code 

 

15. Supplementary Notes 

This report is a part of a study for FHWA titled, "Collabortative research on road weather observation and predictions." FHWA 

Contracting Officer's Technical Representatives (COTRs) are Paul Pisano HOTO and Rudy Persaud HRDO. 

16. Abstract 

The Federal Highway Administration (FHWA) Road Weather Management program partnered with the National Weather 

Service (NWS) to sponsor five research projects through the Cooperative Program for Operational Meterology, Education, and 

Training (COMET). The goal was to create teams of personel from State departments of transportation (DOT), NWS Weather 

Forecast Offices (WFO), and universities to foster collaborative and productive relationships between meterological and 

transportation agencies. These teams were to use data from Road Weather Information Systems (RWIS) to improve the 

utilization of these data in both weather and transportation operations and to create new predictive algorithms for use in road

maintenance activities. Such advances in road weather management ultimately will improve mobility on the roads, and DOT 

productively in operations. 

17. Key Words 

Mesonet, Artificial Neural Network, IceCast pavement 

model, Integrated Weather Data Network, MesoWest 

meso-meterological network 

18. Distribution Statement 

No restrictions. This document is available to the public through 

the National Technical Information Service, Springfield, VA 

22161. 

19. Security Classif. (of this report) 

Unclassified 

20. Security Classif. (of this page) 

Unclassified 

21. No of Pages

70 

22. Price 

 

Form DOT F 1700.7 (8-72) Reproduction of completed pages authorized 
ii 

SI* (MODERN METRIC) CONVERSION FACTORS 

APPROXIMATE CONVERSIONS TO SI UNITS

Symbol When You Know Multiply By To Find Symbol 

LENGTH 

in inches 25.4 millimeters mm 

ft feet 0.305 meters m 

yd yards 0.914 meters m 

mi miles 1.61 kilometers km 

AREA 

in2 square inches 645.2 square millimeters mm2

ft2 square feet 0.093 square meters m2

yd2 square yard 0.836 square meters m2

ac acres 0.405 hectares ha 

mi2 square miles 2.59 square kilometers km2

VOLUME 

fl oz fluid ounces 29.57 milliliters mL 

gal gallons 3.785 liters L 

ft3 cubic feet 0.028 cubic meters m3 

yd3 cubic yards 0.765 cubic meters m3 

NOTE: volumes greater than 1000 L shall be shown in m3

MASS 

oz ounces 28.35 grams g

lb pounds 0.454 kilograms kg

T short tons (2000 lb) 0.907 megagrams (or "metric ton") Mg (or "t") 

TEMPERATURE (exact degrees) o

F Fahrenheit 5 (F-32)/9 Celsius oC 

or (F-32)/1.8 

ILLUMINATION 

fc foot-candles 10.76 lux lx 

fl foot-Lamberts 3.426 candela/m2 cd/m2

FORCE and PRESSURE or STRESS 

lbf poundforce 4.45 newtons N 

lbf/in2 poundforce per square inch 6.89 kilopascals kPa 

APPROXIMATE CONVERSIONS FROM SI UNITS 

Symbol When You Know Multiply By To Find Symbol 

LENGTH

mm millimeters 0.039 inches in 

m meters 3.28 feet ft 

m meters 1.09 yards yd 

km kilometers 0.621 miles mi 

AREA mm2

 square millimeters 0.0016 square inches in2 

m2 square meters 10.764 square feet ft2 

m2 square meters 1.195 square yards yd2 

ha hectares 2.47 acres ac 

km2 square kilometers 0.386 square miles mi2 

VOLUME 

mL milliliters 0.034 fluid ounces fl oz 

L liters 0.264 gallons gal 

m3 cubic meters 35.314 cubic feet ft3 

m3 cubic meters 1.307 cubic yards yd3 

MASS 

g grams 0.035 ounces oz

kg kilograms 2.202 pounds lb

Mg (or "t") megagrams (or "metric ton") 1.103 short tons (2000 lb) T 

TEMPERATURE (exact degrees) o

C Celsius 1.8C+32 Fahrenheit oF 

ILLUMINATION 

lx lux 0.0929 foot-candles fc 

cd/m2 candela/m2 0.2919 foot-Lamberts fl

FORCE and PRESSURE or STRESS 

N newtons 0.225 poundforce lbf 

kPa kilopascals 0.145 poundforce per square inch lbf/in2

*SI is the symbol for th International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E e 380. 

(Revised March 2003)
iii 

TABLE OF CONTENTS 

Executive Summary 1

Developing an Interactive Mesonet for PennDOT 10

 Summary of Original Proposed Scope of Work 10

 Work Accomplished 10

 Changes to Scope 16

Problems Encountered 17

 Division of Labor 17

 Recommendations 17

 

Improved Frost Forecasting Through Coupled Artificial Neural Network TimeSeries Prediction Techniques and a Frost Deposition Model 19

 Summary of Original Proposed Scope of Work 19

 Work Accomplished 19

 Changes to Scope 25

Problems Encountered 25

 Division of Labor 25

 Recommendations for Future Work Related to this Project 26

 Broader Recommendations 26

 

Use of Road Weather Information Systems in the Improvement of Nevada 

Department of Transportation Operations and National Weather Service 

Forecasts in the Complex Terrain of Western Nevada 27

 Summary of Original Proposed Scope of Work 27

 Work Accomplished 28

 Changes to Scope 42

Problems Encountered 43

 Division of Labor 43

 Recommendations for Future Work Related to This Project 44

 Broader Recommendations 44

 

The New York Integrated Weather Data Network 47

 Summary of Original Proposed Scope of Work 47

 Work Accomplished, Problems Encountered, Changes to Scope 47

 Division of Labor 52

 Recommendations for Future Work Related to This Project 53

 Broader Recommendations 53

 
iv 

Application of Local Data Assimilation in Complex Terrain 55

 Summary of Original Proposed Scope of Work 55

 Work Accomplished 55

 Problems Encountered 59

Division of Labor 59

 Recommendations 59

 

References 61

Additional Publications and Conference Presentations 63
v 

LIST OF FIGURES 

Figure 1. Stations included in the Pennsylvania mesonet. 11

Figure 2. Contours of temperature lines. 13

Figure 3. Frequency of observations taken by RWIS network during 1 month. 13

Figure 4. Early example of a quality assurance report on RWIS data. Clicking 

on the station designation provides facility details. 14

Figure 5. Sample metadata page for an RWIS site. 15

Figure 6. Tabletop exercise from roadway managers training session. 16

Figure 7. Comparison of RWIS temperatures with ASOS temperatures as a 

function of RWIS wind speed for 12 stations. 22

Figure 8. Comparison of ASOS-RWIS wind speeds as a function of direction 

for four stations. 23

Figure 9. Comparison of RWIS dewpoint temperatures with ASOS dewpoint 

temperatures as a function of RWIS wind speed for 12 stations. 24

Figure 10. Locations of the NDOT stations that are available for analysis on 

the DRI Web site. 29

Figure 11. A schematic of the DRI-developed real-time forecasting system that 

assimilates NDOT data in the first 12 hours of the pre-forecasting time. 31

Figure 12. Geographical setup of the real-time MM5 forecasting domains. 33

Figure 13. Time series of wind speeds measured at NDOT Washoe Valley 

station and simulated with MM5 without FDDA, with Run A FDDA options, 

and with Run C FDDA options. 34

Figure 14. Vertical profiles of temperature, dewpoint temperature, and winds 

measured by radiosonde in Reno, NV, on March 31, 2003 at 00 UTC (4 p.m. 

local time) (left panel) and on April 1, 2003 at 12 UTC (4 a.m. local time) 

(right panel). 35

Figure 15. Time series of temperature (upper panel) and wind speed (lower 

panel) at the Reno, NV, station for the period from April 1–2, 2003. 36

Figure 16. A schematic of the NDOT pavement temperature model with its 

major physical components. 37

Figure 17. Computer screen with a menu for predicted meteorological 

parameters to be input for the pavement temperature model run. 38
vi 

LIST OF FIGURES (CONTINUED)

Figure 18. Computer menu screen with a list of stations for which the 

pavement temperature forecast can be obtained. 39

Figure 19. A time series of the forecasted pavement temperature at the Incline 

Village station for the test case for the period of 3 a.m. on October 31, 2002, to 

3 a.m. on November 1, 2002. 40

Figure 20. Time series of the pavement temperature predicted by the NDOT 

IceCast Pavement Model for various changes in meteorological input 

parameters with respect to the baseline run. 41

Figure 21. Change of the predicted minimum pavement temperature as a 

function of changing meteorological inputs by step units. 42

Figure 22. NYSDOT RWIS stations for which manually downloaded data have 

been analyzed. 48

Figure 23. Panoramic views of three of the weather stations studied. 50

Figure 24. Wind roses and transmission factors for surface weather stations. 51

Figure 25. Locations of MesoWest stations (plus symbols), RWIS stations 

(green triangles), and Union Pacific Railroad stations (yellow diamonds). 56

Figure 26. Summary of current weather and road state in Utah available in 

MesoWest. 58
vii 

LIST OF TABLES 

Table 1. Program participants and projects. 1

Table 2. Parameters collected on an hourly basis. 13

Table 3. Details of the intercomparison regression statistics (RWIS sites 

i88, rt5, and rt29) compared with NWS sensor at the Albany, NY airport. 

49
1 

EXECUTIVE SUMMARY 

From 2001 to 2003, the Road Weather Management Program of the Federal Highway 

Administration (FHWA) Office of Operations partnered with the National Weather Service 

(NWS) to sponsor five research projects to improve the sensing, prediction, and use of 

weather-related road conditions in road maintenance and operations. These projects are 

unique because they each involved collaborative partnerships between NWS Weather 

Forecast Offices (WFOs), State departments of transportation (DOTs), and universities. 

Participants and their project titles are listed in the table below: 

Table 1. Program participants and projects. 

Partners Project Title 

Pennsylvania State University, Pennsylvania 

Department of Transportation (PennDOT), and the 

State College, PA NWS WFO 

“Developing an Interactive Mesonet for 

PennDOT” 

Iowa State University, Iowa DOT, and the Des 

Moines, IA NWS WFO 

“Improved Frost Forecasting through 

Artificial Neural Networks” 

University of Nevada (Desert Research Institute), 

Nevada DOT, and the Reno, NV NWS WFO 

“Use of Road Weather Information Systems 

in the Improvement of Transportation 

Operations in the Complex Terrain of 

Western Nevada” 

State University of New York at Albany, New 

York State DOT (NYSDOT), and the Albany, NY 

NWS WFO 

“The New York Integrated Weather Data 

Network” 

University of Utah, Utah DOT, and the Salt Lake 

City, UT NWS WFO 

“Applications of Local Data Assimilation in 

Complex Terrain” 

The primary purpose for these projects was to evaluate the use of weather observations and 

modeling systems to improve highway safety and to support effective decisions made by the 

various jurisdictions that manage the highway system. In particular, the research evaluated 

how environmental sensor station data, particularly Road Weather Information System 

(RWIS) data, could best be used for both road condition forecasting and weather forecasting. 

The collaborative efforts also included building better relations for training and sharing 

information between the meteorological and transportation agencies. 

The Cooperative Program for Operational Meteorology, Education and Training (COMET®), 

an organization funded primarily by the NWS, received project funding from the Road 

Weather Management Program. The awards, made in early 2001, were for 2-year projects 

and primarily supported university researchers, with matching efforts from local NWS WFOs 

and State DOTs. 

COMET solicited proposals, conducted the review process, and managed the project 

contracts. This was the first time that the COMET Program had extended its usual university-
2 

NWS collaborations to the transportation community, an important step in building 

institutional relations for further research and operations. 

The project reports, written by the project participants, make up the main body of this report. 

Below is a summary of each project and its accomplishments. 

PENNSYLVANIA STATE UNIVERSITY: “DEVELOPING AN INTERACTIVE 

MESONET FOR PENNDOT” 

Both the NWS and FHWA are interested in evaluating use of RWIS data for road condition 

forecasting and broader weather forecasting. For example, the NWS is interested in creating 

mesoscale networks (mesonets) that include RWIS sites, while FHWA would like to 

establish guidelines that define the optimal density for a network of RWIS sites in different 

seasons and various locations. For both parties, the usefulness of RWIS observations depends 

on several factors including site considerations and data quality, which varies according to 

performance specifications for equipment and maintenance practices. 

One of the main goals of this project was to construct a mesonet of hourly weather reporting 

sites across Pennsylvania. These sites include 32 Automated Surface Observing Systems 

(ASOS) and a few Automated Weather Observing Systems (AWOS), both operated by the 

Federal Aviation Administration (FAA), 82 RWIS operated by PennDOT, and 47 

Commonwealth of Pennsylvania Air Monitoring System (COPAMS) sites maintained by the 

Pennsylvania Department of Environmental Protection (PADEP). In addition, the State’s 

approximately 200 hourly precipitation gauges of the Integrated Flood Observing and 

Warning Systems (I-FLOWS) are also being incorporated in the network. More than 300 

daily observations will be available when the NWS’s cooperative weather stations (about 125 

sites) submit their data on a daily basis, including their reports of maximum temperature, 

minimum temperature, and 24-hour precipitation. 

The data from these sites are stored in a database and processed each hour for real-time 

information (http://pasc.met.psu.edu/MESONET) of weather-derived parameters and time 

series displays from each site. Streamlines are overlaid on a topographic map to help identify 

patterns over the complex terrain in the State.

Developing the mesonet was particularly challenging because PennDOT contracted with 

three different manufacturers to provide, install, and maintain the sensors in various regions 

of the State. The result is data in three different formats within this single network. In 

addition, ground-based network connections and limited server capacities posed a serious 

challenge to including the RWIS data in the mesonet, and irregular polling times added 

difficulty to developing an automated quality control system. Delays in reporting the 

observations also hampered production of real-time products that are useful in “nowcasting” 

hazardous weather and highway conditions. Another problem in managing the data flow 

resulted from lower reliability in RWIS data during the seasons when the DOT has a reduced 

need for the observations. 

All the RWIS data were converted to network Common Data Form (netCDF), a machineindependent format for representing scientific data. Once decisions were made regarding how 

to handle the data collection issues, a quality control system was designed using the 

Oklahoma mesonet standards. Concerns about instrument siting and calibration still exist, 
3 

which can add further errors to the quality control process. Once the data quality is assured, 

the plan is to make the observations available to all involved parties, including the PennDOT 

Technology Division and the District offices. 

Another major goal of the project was to include near real-time RWIS and other mesonet 

data sets into the NWS Advanced Weather Interactive Processing System (AWIPS) data 

display and the Pennsylvania State Climate Office database. This initially required both 

management and quality control of the data feed. Parameters to collect from the different 

networks were determined. To be chosen, a parameter had to contribute to augmenting or 

improving general surface observations, climatology, forecast verification, modeling, or the 

welfare of the general public. Nineteen parameters met these criteria and are collected in the 

database. 

An additional task arose when researchers found there was little or no station history—

records of movement due to construction or other reasons—for the RWIS and COPAMS 

sites. Assimilating the data into NWS system and the State Climate database requires precise 

geospatial information that was not readily available from PennDOT. As a result, State 

Climate personnel visited each of the 82 sites with a global positioning system (GPS) device 

and digital camera and created comprehensive metadata files for all RWIS sites. Images of 

the station (and GPS records) are a relatively new but increasingly important part of station 

history and metadata. 

Preparing and delivering 3 training sessions for more than 160 roadway weather managers 

was the last task in this project. The NWS Warning Coordination Meteorologist (WCM) 

taught the fundamentals of weather and products available from the NWS WFOs. The State 

climatologist (the principal investigator on this project) taught forecasting techniques using 

RWIS data and winter weather and conducted a desktop exercise for all participants. The 

training occurred during the week of October 7, 2002. 

The following summarizes the findings of this project: 

• The State of Pennsylvania has hundreds of observational systems that, if integrated, can 

provide a powerful tool for monitoring and forecasting road conditions and improving 

general weather forecasts. 

• Integration is difficult because different manufacturers use different data formats. 

Similarly, there are instrument siting and maintenance issues related to data from various 

sources in various formats. Data need to be converted to a common format for the 

broadest possible usage. 

• Communication problems also inhibit integration, including unreliable transmission via 

phone lines and polling procedures that delay data transmissions. 

• Quality control (including having complete station metadata) must be addressed for the 

data to have maximum utility. 

• Providing a good training program on weather forecasts and using weather data is 

important to road weather managers. 
4 

IOWA STATE UNIVERSITY: “IMPROVED FROST FORECASTING THROUGH 

ARTIFICIAL NEURAL NETWORKS” 

Frost is one of the least predictable weather parameters requiring anti-icing or deicing 

treatment of road surfaces. It often occurs in localized regions under generally quiescent 

weather conditions. Ice deposition onto road surfaces can occur if road surface temperatures 

drop below the dewpoint temperature of the nearby air. A previous collaboration between the 

Iowa DOT and Iowa State University (ISU) produced a frost prediction model, which is 

currently being tested. Inputs required for the model include predictions of road surface 

temperature, air temperature, dewpoint temperature, and wind speeds. These predictions 

could come from raw or statistically post-processed numerical weather model output, such as 

Model Output Statistics (MOS) derived from the NWS Nested Grid Model (NGM). 

However, output from these weather models is typically limited to every 3 or 6 hours, and 

therefore is not available at the high temporal frequency required for good frost predictions. 

In addition, these models do not normally predict road temperatures. Statistical methods, 

such as artificial intelligence, can be used to overcome these problems. 

Artificial Neural Networks (ANN) are one type of artificial intelligence technique, patterned 

loosely after the human brain. Different weightings are assigned to different relationships in a 

training set of data to create a system that can predict one variable based on a range of other 

variables. These techniques are potentially better than the sole use of forecast model data 

because the training technique should allow biases in the model data to be corrected. For 

instance, if the NGM model is always too cold in its forecasts of air temperature (compared 

to RWIS observations), the neural network will likely determine that the air temperature is 

going to be equal to the model prediction plus a small correction term. 

This project used ANN data to develop a time series prediction system that could be coupled 

with the frost prediction model to improve roadway frost forecasting. NGM MOS data and 

RWIS data were collected for 3 years from 1996–98 and used to train and test the system. 

Results of the project indicated that in general, ANN-derived weather data compared better 

with RWIS observations than with the NGM-MOS forecasts alone. However, in some 

circumstances, the ANN predictions were only better than MOS for the first 6 to 9 hours of 

the prediction period. Nonetheless, the use of ANN data to predict roadway temperature, air 

temperature, dewpoint, and wind speed appears promising. 

A second part of the study used the ANN data in the ISU frost deposition model; “yes” frost 

predicted and “no” frost predicted results were compared with observations of roadway frost. 

For the winters of 1996–98, the ANN-based predictions were not particularly good. The 

poor results may have been due in part to frost observations obtained by maintenance 

personnel looking out the windows of their vehicles on the way to work, perhaps not a very 

accurate method. Poor agreement was also attributed to ANN system’s physically impossible 

predictions of a dewpoint exceeding the air temperature. 

In the winter of 2001–2002, ISU students closely monitored conditions on one bridge during 

the early morning hours, likely a more accurate verification technique. During this period, 

frost predictions using the ANN data were very accurate, nearly matching the forecasts made 

after the fact when RWIS data were fed into the frost deposition model. However, during the 
5 

winter of 2002–2003 when students monitored three bridges, the performance was worse 

with relatively high false alarm rates and low probabilities of detection. 

The third part of the project determined if data from the NWS and FAA observation systems, 

RWIS and AWOS/ASOS respectively, are comparable. The comparisons suggest that RWIS 

temperature readings have a high bias when wind speeds are light. The behavior is attributed 

to the fact that, unlike AWOS/ASOS sensors, RWIS temperature and dewpoint sensors are 

not aspirated. In addition, wind speed data from the RWIS stations was typically a few knots 

lower than the AWOS/ASOS sensors, probably due to siting differences. Other parameters 

(such as dewpoint) showed systematic differences that could be quantified and taken into 

account when using the data. A Web site was developed to allow direct comparisons between 

the different measuring systems in real time (http://mesonet.agron.iastate.edu/compare/). The 

NWS found the results particularly useful because data from these sensors have been 

combined into a mesonet (as part of another, earlier project), providing valuable information 

for monitoring conditions and validating forecasts. 

The final task extended the ANN application to an NWS problem forecasting precipitation 

amounts during the warm season. As was the case with the ANN data for the frost 

predictions, results for this study were mixed, but generally suggest that ANN data can 

provide an improvement compared to model forecasts. Further work needs to be done in this 

area. 

The conclusions of the principal investigators are as follows: 

• ANN data used in the frost prediction model (as well as in precipitation forecasting) 

appears promising, but more testing and validation is needed. The ANN was initially 

trained on 3 years of data. Additional data collected since that time would likely improve 

forecast skill if the system were trained with the larger data record. 

• Preliminary work from another project suggests that the use of weather parameters 

predicted by a mesoscale model such as Mesoscale Model 5 (MM5), may provide 

significant improvement, and further investigations might reveal whether ANN data 

trained on the mesoscale predictions provides the best results. 

• Some calibration of data contained in the mesonet is probably necessary to account for 

differences in RWIS and AWOS/ASOS sensors and siting. 

• Finding a project topic that benefits both the DOT and NWS partners equally is 

challenging. Both partners have a need for quality data, and both have mutually 

beneficial data sets. However, the NWS did not have a need for a frost prediction 

technique, so their participation in the project was more limited. 
6 

UNIVERSITY OF NEVADA (DESERT RESEARCH INSTITUTE): “USE OF ROAD 

WEATHER INFORMATION SYSTEMS IN THE IMPROVEMENT OF 

TRANSPORTATION OPERATIONS IN THE COMPLEX TERRAIN OF WESTERN 

NEVADA” 

The complex terrain of western Nevada presents a challenge to both weather forecasters and 

transportation managers, particularly when winter snows cause road closures and delays. The 

economic impacts of winter storms can be significant. On a typical winter weekend, as many 

as 1.5 million people travel into the Sierra Nevada to Lake Tahoe and Reno, NV, bringing 

about $2 million into the economy. A winter storm warning by the NWS on a Thursday for a 

weekend in the Sierra Nevada can result in an estimated $800,000 decrease in potential 

revenue due to cancelled room reservations alone. Snow removal operations for road 

management and public safety are also costly. These impacts highlight the need for improved 

road-related forecasts that to date are hampered by limited weather observations and 

imperfect model guidance. 

Predicting local weather features, such as high winds and heavy snow, is extremely difficult 

due to small-scale terrain features and hence large variations in weather over small distances. 

Forecasters and transportation managers need a dense network of weather observations to 

better “see” these small-scale features. Critical data is provided by additional State DOT 

weather stations to the NWS network and weather stations already available for forecasting. 

The first task in this project was to develop programs to automatically access and download 

the data from Nevada Department of Transportation (NDOT) computers and to integrate and 

archive the data in the database of the Western Regional Climate Center at the Desert 

Research Institute (DRI). At the same time, NDOT was upgrading 11 mesonet sites and 

installing 5 new sites. A Web site on the DRI server was established to provide interactive 

graphical displays of the data once it was acquired (http://www.ndot.dri.edu). The site is still 

active, but some of the NDOT stations are not currently operational, transmission software in 

some have changed, and some stations simply do not transfer data to DRI. 

A related task was to establish a data assimilation system to transfer data from NDOT to the 

NWS. The task was difficult due to slow models and frequent computer crashes at the 

beginning of the project. By the second year, better file transfer procedures were established, 

and faster computers were installed at both the NWS and NDOT. The collection of this data 

continues and has been expanded to other areas of the State outside of the local Reno, NV 

mesonet area. The collection of these additional sites was not part of the original scope of 

work for this project. 

The second goal was to improve NWS operational forecasts through better model guidance 

and knowledge. The NWS is in the process of implementing a National Digital Forecast 

Database (NDFD) to give the NWS forecaster the ability to predict weather at spatial and 

temporal resolutions far greater than previously possible. The high resolution forecast model 

used by the Reno NWS WFO and the NDFD rely on a dense network of surface data, 

including the NDOT sites. Verification of high wind warnings and improvement to fire 

weather forecasts occurred as a direct result of having these data. 
7 

One of the main goals of this study was to establish a data assimilation system for the MM5 

at DRI. The model was used both with and without the enhanced data set that included 

NDOT sites for two winter storm case studies. In the first case, the model successfully 

simulated a frontal system passing through Reno, NV, on March 8, 2002. One finding was 

that it is important to use an optimum set of data stations. However, each of the surface 

stations has micro location characteristics and generally is not representative for the larger 

area that needs to be captured by the model. Nonetheless, additional data from the NDOT 

stations significantly improved model results. 

The second winter storm study looked at a storm that occurred in March of the next year. 

Again, the results indicated that the model runs that used assimilated NDOT data compared 

better with measurements for both temperature and wind speed when compared to model 

runs that did not include NDOT data. 

From an NDOT perspective, improving weather forecasts is a benefit, but another important 

challenge is forecasting whether ice will form on roads. To evaluate how sensitive minimum 

pavement temperature forecasts are to meteorological inputs, DRI researchers tested NDOT’s 

IceCastTM pavement model using the MM5 model results from the first case study as the 

baseline simulation. They then changed each of the input meteorological parameters by a 

certain value and ran the pavement model again for each case. These tests resulted in a large 

variation in the minimum pavement temperature, ranging from –7 to –12 °C. Researchers 

learned that predicted pavement minimum temperature appears to be mostly sensitive to air 

temperature changes and to the total cloud cover and precipitation. Inaccuracies in the air 

temperature of 1 and 2 °C cause a change in the minimum pavement temperature of more 

than 0.5 and 1 °C, respectively. Significant underestimation of precipitation can yield a 

change in the minimum pavement temperature of about 2 °C; inaccurate predictions of 

cloudiness can yield a change in the predicted minimum pavement temperature of more than 

3 °C. 

The last project goal—to create a travelers’ forecast Web site as one source of all information 

on road and traffic conditions—was not realized. The researchers plan to continue to work 

with NDOT to achieve this goal. 

The conclusions of the principal investigators can be summarized as follows: 

• A Web site that provides interactive graphical and statistical displays is a useful tool after 

the complexities of handling data streams are resolved. 

• Expanding the data available for NWS analyses and weather forecasts by including 

NDOT data in the mesonet database is valuable for a variety of operational forecasts. 

• Model results improved in two cases that included NDOT data as part of the set used to 

initialize a mesoscale model that can better capture the small-scale weather features. 

• Pavement model forecasts are highly sensitive to air temperature, precipitation, and cloud 

cover forecasts. Improving model predictions of these parameters (which is related to the 

previous bullet) should greatly help improve predictions of icy conditions on roads. 
8 

• Having additional upper air measurements would probably provide stronger guidance to 

the models, which could then improve both NWS mesoscale forecasts and NDOT 

pavement temperature forecasts. 

• In addition to creating the travelers’ forecast, another component that should be 

completed is to fully integrate the MM5 model with the pavement temperature model, 

creating a fully operational tool. Verification of model results should also be carried out. 

• A quality assurance system that would continuously report the status of all NDOT 

stations in real or near-real time is needed. 

• Future projects should ensure that NDOT collaborators (whose main priority is to work 

on direct NDOT operations) have dedicated time to accomplish projected objectives. 

STATE UNIVERSITY OF NEW YORK AT ALBANY: “THE NEW YORK 

INTEGRATED WEATHER DATA NETWORK” 

As was the case with the Nevada and Pennsylvania projects, the main objective of the State 

University of New York at Albany (SUNYA) project was to create a mesonet by integrating 

the data from the New York State DOT (NYSDOT) RWIS systems with other data sources. 

Other project goals included: 

Assessing the quality of the RWIS data. 

• Making the data available to the NWS to improve local forecasting skill. 

• Archiving the data for climatological analyses. 

• Assisting NYSDOT in evaluating various automatic weather stations for secondary road 

monitoring sites. 

• Evaluating how local obstacles can change the near-road environment. 

• Testing a road surface forecasting model. 

Good progress was made on some of the objectives, but others had to be abandoned, partly 

because of the loss of personnel at NYSDOT and partly because of difficulties that arose in 

dealing with the RWIS data. These difficulties included delays in the installation of new 

RWIS sites and problems downloading data from sites that use proprietary software. As a 

result, the major focus of the project shifted to an effort to download data from a few sample 

NYSDOT RWIS sites and to audit data quality from the RWIS sites by comparing them to 

nearby NWS sites. 

Data quality for the RWIS stations proved to be a large problem. For example, data from one 

station indicated an apparent change in calibration and resolution in the wind sensor occurred 

midway through 2002, but the contractor indicated that there was no reason to question the 

data. Nonetheless, the data appears to be suspect, at least for part of the year. These kinds of 

issues still need to be resolved. 

The program to establish a network of secondary road monitoring sites was delayed 

indefinitely. SUNYA tested one system, but this general objective was not achievable during 

the span of this project. 
9 

SUNYA completed a one-dimensional energy balance model for curing concrete bridge 

decks (the SUNY/Local Atmosphere Bridge Simulation (SLABS) model), which they 

intended to adapt to predict the state of road surfaces. However, for this task and the one to 

evaluate local obstacles, a data archive from the stations was needed. Because the data 

acquisition step required more time than expected, not enough time was available to develop 

a database for a large number of stations. 

UNIVERSITY OF UTAH: “APPLICATIONS OF LOCAL DATA ASSIMILATION IN 

COMPLEX TERRAIN” 

Three of the projects described above sought to build mesonets. The University of Utah 

project could be characterized as constructing a “mega-mesonetwork.” The efforts funded by 

FHWA built on a project that began several years ago when the University of Utah began 

developing one of the first mesonets in the country. At the time this project began, the 

mesonet (called MesoWest) accessed data from approximately 2500 observing stations in the 

western United States. In 2001, most of the RWIS stations in the database were located in 

Montana, with a few along major interstates in Wyoming, Utah, and the Lake Tahoe area of 

California and Nevada. Over the course of this project, the network expanded considerably to 

more than 6000 stations with many sites (including RWIS stations) added from Colorado, 

Idaho, Oregon, and Washington. 

Another important addition to the MesoWest database is weather information at 264 

locations along the major Union Pacific rail corridors in the West. Most of the stations report 

temperature only; however, wind conditions are reported at many critical locations. 

A specialized Web interface to the MesoWest database (www.met.utah.edu/mesowest) was 

developed and maintained for use by Utah Department of Transportation (UDOT) personnel. 

This interface has been used extensively for winter road maintenance as well as road 

construction and summer paving projects. 

High resolution forecast models used in complex terrain will resolve the weather in adjacent 

valleys independently. However, observation corrections to the initial background field 

obtained from a model can bleed laterally through the terrain. To deal with this problem, 

which has affected the suitability of the analyses along some transportation corridors, a 

graduate student developed anisotropic weighting functions for the Advanced Regional 

Prediction System (ARPS) Data Analysis System (ADAS), a data assimilation system. These 

anisotropic weights are critical to resolving a systematic source of error in the analyses where 

weather observations in one valley affect the analysis in adjacent valleys. 

An additional benefit of the relationships between the NWS, UDOT, and University of Utah 

was that all three groups worked closely to provide weather and road state information, as 

well as forecasts, to Olympic organizers, public safety personnel, and the public for the 2002 

Winter Olympics and Paralympics. These efforts were judged to be highly successful by 

representatives of many different organizations involved in the Olympics. 
10 

DEVELOPING AN INTERACTIVE MESONET FOR PENNDOT 

University: Pennsylvania State University (PSU) 

Name of University Researchers Preparing Report: Paul G. Knight and Brian B. Ayers 

NWS WFO: State College, PA 

Name of Primary NWS Collaborator: David Ondrejik 

DOT Office: Pennsylvania Department of Transportation (PennDOT) 

Name of Primary DOT Collaborators: Alfred Uzowke, and formerly Douglas Schmitt 

Cooperative Project, UCAR Award No. S01-32792 

SUMMARY OF ORIGINAL PROPOSED SCOPE OF WORK

The original proposal called for collaboration between PennDOT, the NWS WFO for Central 

Pennsylvania, and the State Climate Office at Pennsylvania State University. The plan had 

several components, including assuring the quality of and validating the Roadway Weather 

Information System (RWIS) network, training PennDOT roadway weather managers, 

incorporating the RWIS data into both NWS forecasts and warnings, developing a mesoscale 

climatology, and testing the utility of RWIS data to enhance initial conditions for regional 

mesoscale models. Many of these goals were met. A few unplanned projects developed, 

specifically the design of a metadata system for the fledgling mesonet. The final goal of the 

project was not addressed for several reasons that will be discussed in the recommendation 

section. 

WORK ACCOMPLISHED 

The final project had four focal points. The first was to integrate the various data sets into a 

cohesive mesonet and to create methods to easily retrieve archived mesonet data. The second 

was to incorporate quality controlled RWIS data into the local NWS forecasts and the State 

Climate Office database. In the process of tackling the first two tasks, it became clear that the 

RWIS and COPAMS sites lacked important station information, and so a third task was 

added to create this station metadata. The NWS and State Climate Office staff trained 

PennDOT roadway weather managers in the final task. Each of the main components of the 

project is described in more detail below. 

Mesonet Observations System 

One of the main accomplishments of this project was the construction of a network of hourly 

weather reporting sites across Pennsylvania. These sites include: 

• Thirty-two ASOS operated by the FAA. 

• A handful of new AWOS operated and maintained by the FAA and the Aviation Division 

of PennDOT. 

• Eighty-two RWIS operated by PennDOT. 

• Forty-seven COPAMS sites, maintained by PADEP. 

All reporting stations measure hourly temperature, wind direction, and wind speed. In 

addition, the Climate Office is incorporating the State’s approximately 200 hourly 
11 

precipitation gauges of the Integrated Flood Observing and Warning System (I-FLOWS) in 

the network (see figure 1). When the NWS cooperative weather stations’ (about 125 sites) 

daily submissions are included with their reports of maximum temperature, minimum 

temperature, and 24-hour precipitation, the network will provide more than 300 daily 

observations for the Commonwealth of Pennsylvania. 

Figure 1. Stations included in the Pennsylvania mesonet. 

These reports are being stored in a 

MySQL database and are processed 

each hour for real-time display 

(http://pasc.met.psu.edu/MESONET) 

of weather-derived parameters, 

including wind streamlines, 

temperatures (see figure 2), dewpoint 

contours, and time series displays 

from each site. The streamlines are 

overlaid on a topographic map to 

discern channeling and air motions 

over the complex mountain-valley 

system of the State. 

Assembling data from a range of 

agencies to serve the function of a meteorological mesonet presented challenges in handling 

differing data formats that were a function of different priorities for the meteorological 

parameters measured within each individual network. These factors are related to the primary 

purpose of the stations within each individual network. 

Figure 2. Contours of isotherms (temperature lines). 
12 

Another complicating factor was the fact that, in an effort to maximize the benefit of 

competition in the RWIS market, PennDOT selected three different manufacturers to 

provide, install, and maintain 82 RWIS stations along various highways across the State. All 

three types serve the primary objective to monitor roadway surface conditions and 

secondarily to monitor atmospheric conditions. Most of the sensors that are used on an ASOS 

are also present on the RWIS stations. However, variables vital to a surface weather 

observation mesonet, such as air pressure and rainfall accumulation, are not available from 

these 82 hourly stations. Nonetheless, the absence of these two parameters is compensated by 

an abundance of roadway surface and subsurface parameters, such as temperature, condition 

of ground (snow cover, icy, wet), and average speed of vehicles. The data can be applied to 

conduct research on the effects of adverse weather on public transportation. This large 

volume of information obtained from each RWIS observation (and the proprietary nature of 

the output by each RWIS manufacturer), such as number of highway lanes at each station, 

units of visibility, wind variables, and methods of reporting weather phenomena, lead to three 

varying formats of data output within this single network. 

Ground-based network connections and limited server capacities also posed a serious 

challenge for including the RWIS data into the mesonet. In addition, irregular polling times 

complicated the development of an automated quality control system. 

Incorporation of Data into NWS Forecast Office System and State Climate Office 

Database 

Another aim of the project was the inclusion of near real-time RWIS and other mesonet data 

sets into the NWS AWIPS1

 data display and the Pennsylvania State Climate Office database. 

This initially required both management and quality control of the data feed. After 

deciphering the unique formats from each data source, Perl scripts were written to transfer 

the data from a flat file into a MySQL relational database on an hourly and even half-hourly 

basis. Most recent efforts have focused on access to RWIS five-minute data streams. 

One issue that arose was determining which parameters to collect from the different 

networks. First, it was necessary to confirm the routine collection of the parameter by all of 

the instruments within a network. This allowed for an adequate spatial representation of the 

data across Pennsylvania and provided enough of a database to perform quality control using 

neighboring sites within the network. For a parameter to be chosen, it needed to augment 

general surface observations, climatology, forecast verification, modeling, or the welfare of 

the general public. Nineteen parameters met these criteria (see table 2) and are collected in 

the database as frequently as available to the State Climate Office.

 

 1 AWIPS: An integrated suite of automated data-processing equipment that supports complex analysis, 

interactive processing, display of hydrometeorological data, and the rapid dissemination of warnings and 

forecasts in a highly reliable manner. 
13 

Table 2. Parameters collected on an hourly basis. 

Weather Wind Direction

Accumulated 

Precipitation 

Roadway Surface 

Temperature 

Temperature Wind speed Precipitation rate Roadway surface conditions 

Dewpoint Wind gust Snow depth Roadway average speed 

Relative 

humidity Ceiling Cloud cover 

Subgrade (at 17 inches or 43.2 

centimeter- depth) temperature 

Air pressure Visibility Solar radiation 

Data flow quality proved more challenging than expected. The primary difficulty was the 

means of communication of the data from the sensor to a central location. The observations 

taken at the COPAMS and RWIS sites use external modems to communicate with their 

respective control centers, leading to delays in the observations. COPAMS reports arrive 90 

minutes after the observation is taken, and the RWIS stations average a 30-minute to 1-hour 

delay depending on the time the call was made. This hampers production of real-time 

products that are useful in “nowcasting” hazardous weather and highway conditions. It also 

prevents many reports from being included in the AWIPS Statewide surface analysis fields. 

Another drawback to using modems and traditional telephone lines is their lack of reliability 

in hazardous conditions when the observations are in highest demand. 

Yet another challenge of the RWIS network was that each of the three manufacturers 

transmits their data through a different method to a central computer at PennDOT. Adding 

this link between the observing station and the State Climate Office database increases the 

risk of communication failure. Figure 3 shows the large difference in the number of 

observations taken by each RWIS station during a late autumn month. More than 750 

observations indicate approximately one report per hour during that 30-day period. The 

uncertainty of the frequency and timing of RWIS observations curtailed attempts to refine 

mesoscale model initial conditions based on RWIS reports. 

0

200

400

600

800

1000

1200

Stations

Frequency

Figure 3. Frequency of observations taken by RWIS network during 1 month. The horizontal 

axis represents one vertical bar per RWIS station. 
14 

Another data flow issue is the RWIS stations’ reliability during the seasons when PennDOT 

has less of a need for frequent observations. A gradual increase in the number of reporting 

stations and frequency of reports was noticed from the summer of 2001 through late winter 

2003, at which time nearly 82 stations were regularly reporting data. 

After the data flow issues were addressed, a quality control system was designed to the same 

standards as the Oklahoma mesonet. A conversion to netCDF was undertaken to facilitate 

storing all RWIS data and help retrieve archived mesonet data sets. The RWIS conversion 

was completed during the late autumn 2003. A robust quality assurance of the RWIS data is 

under development with a user-friendly interface being tested for both internal and external 

users. Figure 4 shows an early example of the quality assurance interface. 

Figure 4. Early example of a quality assurance report on RWIS data. Clicking on the station 

designation provides facility details. 
15 

In addition to these issues, there are still concerns about instrument siting and calibration that 

add errors to the quality control process. 

After the data quality is assured, the goal is to make the data available for all involved 

parties, including PennDOT’s Technology Division and the District offices. Early 

applications include plotting critical isotherms for PennDOT, tracking airborne pollutants in 

wind streamlines for DEP, developing a microclimate database in the Office of the State 

Climatologist, and verifying warnings for the NWS in Pennsylvania. 

Mesonet Metadata 

As the data networks were being assembled, it became obvious that there was little or no 

station history for the RWIS and COPAMS sites. In fact, assimilating the data into AWIPS 

and the State Climate database required precise geospatial information that was not readily 

available from PennDOT. Therefore, the State Climate Office endeavored to create 

comprehensive metadata files for all RWIS sites. A State Climate Office staff member 

traveled to each site with a GPS device and digital camera. This was a substantial 

commitment of personnel time, since there were 82 sites to visit. 

The specific metadata parameters were discussed with the local Data Acquisition Program 

Manager and the National Cooperative Program Manager. Because a modernization of the 

NWS cooperative network is imminent, it was decided to acquire and display the site 

information that will best match the new network. Figure 5 shows a sample metadata page 

for an RWIS site along U.S. Interstate 80 in Pennsylvania. The metadata for other RWIS sites 

can be found at http://pasc.met.psu.edu/MESONET/metadata/. Site maintenance records will 

be added later, and the COPAMS network metadata is nearing completion. 

Figure 5. Sample metadata page for an RWIS site. 
16 

Road Manager Training 

PennDOT’s Bureau of Maintenance and Operations scheduled three consecutive training 

sessions for more than 160 roadway weather managers on their staff. Each PennDOT district 

sent representatives to a central location. At the request of the winter-storm project manager, 

a four-part training plan was drafted and submitted for PennDOT’s approval. This was betatested at a local district office, and adjustments were made based on important feedback from 

PennDOT personnel. In the first and second part, the NWS Warning Coordination 

Meteorologist (WCM) taught the fundamentals of weather and products available from the 

NWS WFOs. The State climatologist taught the third and fourth parts that centered on 

utilizing RWIS data and winter weather forecasting techniques, including a desktop exercise 

for all participants. The training occurred during the week of October 7, 2002. 

A group of roadway weather managers arrived midday for 4 hours of training, followed by a 

session of the same length the next morning. At midday of the second day, the first group 

departed and was replaced by another set of roadway weather managers. This process 

continued through three cycles. 

Approximately 1 hour of the course 

was devoted to essentials of 

atmospheric circulations. Another 

hour covered the climatology of 

winter weather in Pennsylvania. 

Time was also committed to 

reviewing the forecast products 

available from local NWS WFOs. 

The second half of the training 

focused on interpreting radar, 

reading numerical model forecasts, 

and connecting RWIS observations 

to local forecasts. Figure 6 

illustrates a component of the 

training sessions from a sample 

Microsoft® PowerPoint® slide. A 

month after the initial sessions, 

another smaller group of managers 

was also trained, and the WCM 

spent a day at a District office in western Pennsylvania conducting further training. 

CHANGES TO SCOPE 

As mentioned above, researchers intended to use the RWIS to refine mesoscale model initial 

conditions to improve weather forecasts. However, a large amount of time was spent 

resolving the uncertainty of the frequency and timing of RWIS observations and other issues 

related to the variety of data formats required. Researchers also determined that the lack of 

station history and precise location information was critical. A major effort was expended to 

Figure 6. Tabletop exercise from roadway managers 

training session.
17 

provide this documentation, something not initially planned for in the proposal. Additionally, 

it is debatable whether RWIS data would enhance mesoscale model initial conditions in light 

of recent sensitivity studies that indicate the need for a denser upper air, rather than surface, 

network of observations. Therefore, this part of the project was postponed. 

PROBLEMS ENCOUNTERED 

As indicated, most of the problems encountered revolved around data transmission and data 

format issues. 

DIVISION OF LABOR 

The State Climate Office was responsible for creating the database and its reports, 

developing quality assurance procedures, visiting the RWIS sites to obtain station metadata, 

and conducting part of the road managers training. 

The NWS wrote some of the programs to capture the RWIS data and helped design the 

forecast Web page that links to all pertinent NWS WFO zone forecasts within PennDOT. 

PennDOT amended software so NWS and the State Climate Office could receive RWIS 

reports, and provided valuable guidance to training session designs and finances for all RWIS 

managers to attend. They also sought advice on siting two new RWIS sites and sought PSU’s 

assistance in designing the quality assurance for all RWIS sites. They made their field offices 

available to NWS and the State Climate Office to test receiving 5-minute data. 

RECOMMENDATIONS 

In retrospect, communication with PennDOT personnel is critical to the success of the 

collaboration. Awareness of the different infrastructures within PennDOT would be useful 

for future endeavors, especially in light of the various hierarchies within State agencies. A 

designated staff member within PennDOT is needed for continuity of the project. It is 

strongly recommended that all State DOTs move toward wireless technology for their RWIS 

networks. Future partnerships must also include a comprehensive metadata of the RWIS 

networks for ready inclusion into the National Oceanic and Atmospheric Administration’s 

(NOAA) plans for a national mesonet and modernization of their cooperative network. 

19

IMPROVED FROST FORECASTING THROUGH COUPLED 

ARTIFICIAL NEURAL NETWORK TIME-SERIES 

PREDICTION TECHNIQUES 

AND A FROST DEPOSITION MODEL 

University: Iowa State University (ISU) 

Name of University Researcher Preparing Report: William A. Gallus, Jr. 

NWS WFO: Des Moines, IA 

Name of Primary NWS Collaborator: Karl A. Jungbluth 

DOT Office: Iowa Department of Transportation 

Name of Primary DOT Collaborator: Dennis Burkheimer 

Cooperative Project, UCAR Award No. S01-32791 

SUMMARY OF ORIGINAL PROPOSED SCOPE OF WORK 

The project originally proposed to develop a time-series prediction system for parameters 

needed as input by a frost deposition model (road surface and air temperatures, air dewpoint, 

winds) by training an artificial neural network (ANN) on meteorological observations and 

model output. The project’s objectives also included comparing RWIS observations with 

those of standard ASOS/AWOS instruments to determine the quality of the data. In addition, 

plans included working with the NWS WFO so that they could use the neural network 

system to improve forecasting of other parameters. 

WORK ACCOMPLISHED 

ANN Forecasting System 

MOS data were gathered from the NWS NGM model for the 3-year period (1996–1998) that 

matched the frost observation record period. Researchers also collected an appropriate data 

set of RWIS measurements. They accessed the RWIS archive valid over this time period, 

interpolated the data to a standard 20-minute time interval, performed some quality control of 

the data, and flagged those time periods when gaps between observations exceeded 4 hours 

or could interfere with important time periods when frost was possible. 

The corrected and usable data from both MOS and RWIS observations were organized into a 

very large database, which was used to train the ANN. The training set used 85 percent of all 

of the data, with the remaining 15 percent saved as a test set; 181 possible inputs to the 

model were tested. It was decided that the best approach would be to limit the inputs to the 

8–10 found to be most important for each parameter. Programs were developed to collect the 

data automatically in real-time with a regular 20-minute resolution for future applications. 

Staff tested several different neural network configurations to predict the four variables 

needed as inputs for the frost prediction model—roadway surface temperature, air 

temperature, dewpoint, and wind speed. Despite the ANN’s ability to predict multiple 

outputs with one model, it can only predict at one point in time. Therefore, researchers 

determined that the best way to predict the necessary parameters with a time frequency of 20 
20

minutes was to create separate neural network models for each weather parameter. 

Consequently, 288 neural network models were needed for the 4 weather parameters. Many 

configurations were tested to determine the best one for each parameter at each time. 

When validation was done over the entire training and test set, the ANN predictions 

correlated well with the RWIS observations and generally performed better than the NGM 

MOS output alone. However, for the test set, the ANN predictions of temperature and wind 

speed were better than MOS only for the first few hours of the prediction period 

(corresponding to forecasts 6–9 hours in the future). MOS forecasts had smaller root mean 

square errors (RMSE) later in time. The ANN had smaller RMSEs for wind speed, but the 

smaller average errors were achieved by always forecasting light winds, even when strong 

winds occurred. MOS does not include a forecast for roadway temperature. Thus, the ANN 

system provided much better forecasts during daylight hours when compared to the 2-meter 

MOS air temperature as a proxy for road temperature. At nighttime, the ANN showed a small 

improvement over the crude estimate based on MOS. In general, the errors with the ANN 

system were smaller than those obtained from three mesoscale models. The mesoscale 

models ran with two different sets of initial conditions for the Maintenance Decision Support 

System (MDSS) project1

 in Iowa during the winter of 2003. As in that project, dewpoint 

errors are much larger than temperature errors. 

The ANN output was then tested in the frost deposition model for the winters of 1996–1998, 

2001–2002 and 2002–2003. The verification statistics for the winters of 1996–1998 were 

provided by the Iowa DOT. During this time, “yes” and “no” observations of frost were 

made by maintenance personal looking out the windows of their vehicles on the way into 

work. Therefore, great uncertainty is present about the quality of the verification statistics. 

The ANN-based predictions of frost for this period were not particularly good. False alarm 

rates were very high—generally .90 to .98 at most stations tested. Probability of detection 

tended to be in the .2 to .6 range. Although the lack of skill in the forecasts was likely partly 

related to poor verification data, it was observed that the ANN system often predicted a 

dewpoint exceeding the air temperature. This is a physically impossible condition, and it 

stems from the independent nature of the ANN models forecasting each parameter. 

For the winter of 2001–2002, frost verification data was available from an Iowa DOTsponsored project in Ames, IA, where Iowa State University (ISU) students closely 

monitored a bridge in the region during the early morning hours. These “yes” and “no” frost 

observations are believed to be highly accurate, although frost is a very microscale 

phenomena, again complicating interpretation of verification data. For this period, the ANN 

predictions were very accurate, nearly matching the forecasts made after the fact when RWIS 

data from Ames, IA, were fed to the frost deposition model. Thus, for this period, the ANN 

forecast approached the “best” value that might be expected. False alarm rates (FAR),2

though still high, were around 0.56. The probability of detection (POD)3

 was 0.57. Even 

more promising, the forecasts were much more skillful than those of the private forecasting 

firm that had been contracted by the Iowa DOT to forecast frost during this winter. 

 

 1 MDSS: A large, multiagency project that began with a prototype experiment in Iowa in winter 2002-03. The 

goal was an automated system that uses weather data as accurately as possible and that is easy to read and 

understand, and that recommends courses of action for road maintenance. 

 2

 FAR: A measure of how often an event is forecast and fails to materialize; lower numbers are desirable. 

 3

 POD: A measure of how often an event is forecast and does occur; higher numbers are desirable. 
21

In the winter of 2002–2003, the Ames, IA, frost verification project was expanded using 

Aurora4

 funding, so that three bridges were monitored. This again complicated verification. 

Data for verification were not available until the end of the COMET project, and thus 

verification statistics are preliminary. It appeared that forecast skill was much less in 2002–

03 than in the previous winter, with the FAR rising to 0.79, and the POD falling to 0.30. 

Nonetheless, the threat score, a combined measure of skill, was still comparable to that of the 

private firm the previous winter. At the time of this report, no other verification data was 

available from 2002–2003 for comparison to the ANN. 

In summary, the ANN forecasting system showed promise, and the performance during the 

2001–2002 winter was very encouraging. The fact the system earned much better scores than 

a contracted forecasting agency also was considered a success. However, some other winters 

exhibited much worse performance of the ANN system. The independent nature of the 

predictions for different parameters allows for some nonphysical situations to be predicted. 

An improved ANN system in the future could predict the dewpoint depression instead of 

temperature and dewpoint as separate quantities. This would avoid the problem of unrealistic 

forecasts and may help improve performance. 

RWIS-ASOS Comparison 

Detailed comparisons of RWIS and AWOS/ASOS observations were performed. During the 

COMET project, a separate initiative was established at ISU to combine all mesoscale data 

into one convenient mesonetwork, known as the Iowa Environmental Mesonet (IEM). 

Several meetings occurred at ISU that included NWS Des Moines personnel, Iowa DOT 

personnel, and other interested parties from State agencies. Establishing the IEM enhanced 

the ability to compare RWIS observations to more standard meteorological observations of 

surface conditions, particularly ASOS readings. 

A thorough comparison was performed for several weather parameters by averaging RWIS 

and ASOS or AWOS data over an entire year. The comparisons suggest that RWIS 

temperature readings have a high bias when wind speeds are light, with the worst problem at 

the lightest wind (figure 7). This behavior is expected because RWIS sensors are not 

aspirated, while ASOS and AWOS are aspirated. 

 

 4 Aurora is an international program of collaborative research, development and deployment in the field of 

road weather information systems (RWIS), serving the interests and needs of public agencies. 
22

 Figure 7. Comparison of RWIS temperatures with ASOS temperatures as a function of 

RWIS wind speed for 12 stations. 

RWIS winds also typically read a few knots less than AWOS/ASOS (figure 8) at the stations 

where RWIS sensors were within 8.7 nautical miles (nm) (16.1 kilometers (km)) of AWOS 

or ASOS sensors. Although both platforms are designed to record wind at the same elevation 

(32.8 feet (ft) or 10 meters (m)), many RWIS platforms are sited in ditches that may 

somewhat shelter the instruments. Average wind speeds were computed for RWIS and ASOS 

instruments as a function of wind direction (octants) at 12 stations. The impact of siting 

clearly can be seen when average wind speed differences vary from around zero at a 

particular site for a given wind direction to roughly 3 knots for other directions, a roughly 40 

percent decrease in magnitude from the ASOS values. The RWIS values are less than the 

ASOS for most directions at all sites. 
23

Figure 8. Comparison of ASOS-RWIS wind speeds as a function of direction 

for four stations. 

Comparisons of other parameters as a function of hour of the day or of wind speed also were 

performed. See figure 9 for the comparison of dewpoints. It appears that systematic 

differences can be quantified; this should allow for calibration to improve use of the 

combined data set. At the time of this report, a paper on the comparison was being 

developed. Some of the results were discussed at COMET/FHWA meetings in Washington, 

DC, in September 2002 and in Albany, NY, in August 2003. 
24

Figure 9. Comparison of RWIS dewpoint temperatures with ASOS dewpoint temperatures as 

a function of RWIS wind speed for 12 stations. 

In addition to the detailed comparisons discussed above, researchers established a Web site 

that allows direct comparisons between the different measuring systems in real time. It can 

be accessed at http://mesonet.agron.iastate.edu/compare/. Some results from these 

comparisons were published in the preprints of the 18th International Conference on 

Interactive Information and Processing Systems (IIPS) in Orlando, FL, January 2002. 

Extension of ANN Applications to the NWS 

The graduate student also explored an additional use of neural networks designed to assist the 

NWS Des Moines office in forecasting. A neural network predictive system for warm season 

quantitative precipitation forecasting (QPF) was designed. For this neural network system, 

the technique of Hall et al. was followed.(1) A neural network was trained on data collected 

from the NWS Eta model and soundings valid for both Omaha, NE, and Davenport, IA, 

(DVN) over the warm seasons of 1998–2001. More than 30 variables were used as input 

parameters in the model. Results using just the Omaha (OMA) data were very encouraging, 

so more than 400 cases from Davenport (DVN) were added to expand the number of patterns 
25

used by the neural network. The expansion was necessary because early results implied some 

memorization or over parameterization might have been occurring. Results using the OMA 

and DVN data together indicated that the neural network system still performed better than 

either the operational Eta model, or 10-km meso-Eta simulations in predicting 24-hour 

rainfall, particularly for heavier amounts that are generally unpredictable in grid point 

models. However, combining the data seemed to harm the results, because errors were larger 

than using OMA alone. 

Results from the Omaha, NE, training were presented at the 18th International Conference on 

IIPS in Orlando, FL, in January 2002. A discussion of all results was given at the U.S. 

Weather Research Program Science Symposium in Boulder, CO, in April 2002 and at the 

World Weather Research Programme’s QPF Conference held in September 2002 in Reading, 

United Kingdom. The neural network system based on the combined data was run in real 

time during summer 2002, and results were made available to the NWS via a Web page. In 

this real-time test period, the system was altered to allow inputs directly from the Eta model 

instead of a mixture of model and rawinsonde output. This allowed forecasts to be made at 

grid points across Iowa. This output was also made available via the Web page. The summer 

2002 test, however, indicated a high bias in the neural network predictions. It appears that 

some calibration would be necessary to improve the forecasts. 

CHANGES TO SCOPE 

There were no changes to scope of this project. Researchers benefited from a running start on 

the neural network modeling and by the fact the IEM project allowed for easier-thanexpected comparison of RWIS observations to ASOS and AWOS. 

PROBLEMS ENCOUNTERED 

No serious problems were encountered in conducting the research, apart from some 

Microsoft Windows® operating system-related computer crashes that occasionally caused 

data losses. 

DIVISION OF LABOR 

The primary method of interaction during this project occurred through occasional meetings, 

phone calls, and e-mails with the NWS Des Moines office and the Iowa DOT. The vast 

majority of the work, because it involved very site-specific neural network software, 

occurred at ISU. The Iowa DOT’s involvement extended beyond the 2.5 years of this project, 

because they provided the 1996–1998 frost observations before the start of the COMET 

project. 
26

RECOMMENDATIONS FOR FUTURE WORK RELATED TO THIS PROJECT 

Creating a neural network forecasting system is very labor intensive. Much of the project 

period was used to gather all necessary data, quality control the data, and enter it into the 

appropriately formatted input tables required by the ANN software. Although extensive 

testing was performed to find the best neural network models for each parameter, there are 

enough degrees of freedom to the problem that additional improvements would be likely if 

more experimenting could be done with the ANN software. 

A future project evaluating the forecasting skill of a combined MOS-ANN system could 

benefit both the Iowa DOT and NWS. In addition, it may be possible to run an ensemble of 

MOS and ANN systems. The mean would likely provide the most valuable input to the frost 

deposition model. Also, an ongoing project at ISU has hinted that a mesoscale model such as 

MM5 may have more skill than the NGM-MOS that was used to train this project’s ANN. It 

would be very interesting to test the performance of an ANN system that used MM5 output 

for training instead of NGM-MOS. When this project began, there were only 3 years of 

RWIS data useful for training. That period has now nearly doubled. With all ANN systems, 

the more data to train on, the better the forecast skill. In summary, this project clearly showed 

that with more study, artificial intelligence systems such as neural networks may offer 

valuable improvements in forecasting. 

BROADER RECOMMENDATIONS 

Although researchers were able to follow the original scope of work closely without major 

problems, it was still difficult to emphasize one core project of significant benefit to both the 

Iowa DOT and NWS partners. In fact, of the five groups that received funding, this was the 

only group whose main focus was not primarily to create a mesonet (merger of DOT data 

with NWS and other data sources). The creation of the mesonet is perhaps the only project 

that seems to benefit both partners roughly equally. Even this project included a task 

involving mesonet applications—the comparison of RWIS data with ASOS and AWOS. This 

project may have differed from the others, because the Iowa DOT has a long history of being 

at the cutting edge of initiatives. Researchers had access to the Iowa DOT RWIS data before 

the COMET request for proposal, and the establishment of the Iowa mesonet was likely the 

furthest along of any such effort in the Nation. It is possible that future combined 

COMET/FHWA projects will primarily assist the Iowa DOT or the NWS, but not both, 

unless the project simply manipulates multiple data sources. Traditional COMET projects 

benefit the NWS. Future FHWA collaborations may yield very little interaction and direct 

benefit to the NWS. For this project, the data comparison was believed to help the NWS, and 

they were welcome to use the ANN system. However, the system was designed to forecast 

road frost, which is something the NWS is not permitted to do. Thus, at best, the NWS would 

only be able to use the software system secondarily. 
27

USE OF ROAD WEATHER INFORMATION SYSTEMS IN THE 

IMPROVEMENT OF NEVADA DEPARTMENT OF 

TRANSPORTATION OPERATIONS AND NATIONAL WEATHER 

SERVICE FORECASTS IN THE COMPLEX TERRAIN OF WESTERN 

NEVADA 

University: Desert Research Instate (DRI), University of Nevada System 

Name of University Researcher Preparing Report: Darko Koracin, Ph.D. 

NWS WFO: Reno, NV 

Name of Primary NWS Collaborators: Mr. Jim Fischer, and formerly by Ms. Mary Cairns 

DOT Office: Nevada Department of Transportation (NDOT) 

Name of Primary DOT Collaborators: Mr. Richard Nelson, Ms. Inda Denise, and Ms. Pamela 

Klessig 

Cooperative Project, UCAR Award No. S01-32790 

SUMMARY OF ORIGINAL PROPOSED SCOPE OF WORK 

Prediction of mesoscale weather features is extremely difficult where small-scale terrain 

features create large variations in weather over small distances. Locally high winds and 

heavy snow induced by the orographic features, and flash floods that occur in small drainage 

basins are examples of mesoscale weather features in the Western United States. To better 

evaluate these small-scale features, a dense network of weather observations is desirable. The 

addition of reliable and good quality State DOT weather stations that report at temporal 

resolutions of typically one hour provides data in areas critical to the protection of life and 

property. 

According to our proposal, the primary goals of this project were to: 

• Improve pavement forecasts through improved model input. 

• Improve NWS operational forecasts through better model guidance. 

• Improve operational decisions regarding snow and control operations. 

• Develop an NDOT public travelers’ forecast. 

The proposed project was originally divided into the following main tasks. Partners with 

primary responsibility for each task are indicated in parentheses: 

• Acquire and organize relevant data sets (NDOT, DRI, and NWS). 

• Assimilate the NDOT data into MM5 (DRI and NWS). 

• Test improved pavement forecasts (DRI and NDOT). 

• Implement data assimilation techniques into local NWS MM5 model (NWS and DRI). 

• Test real-time MM5 model output for pavement temperature model (DRI and NDOT). 

• Develop pavement travelers’ forecasts (NDOT and DRI). 

• Write project reports, participate in seminars and workshops, and use project results for 

thesis (DRI, NWS, and NDOT). 
28

WORK ACCOMPLISHED 

This multidisciplinary project was a valuable experience for the collaborating partners: 

NDOT, the NWS WFO in Reno, NV, and the DRI. The project resulted in significant 

advancements by accomplishing the following proposed main objectives: 

NDOT Perspective: RWIS Network 

• Provide high quality meteorological data from the operational network of NDOT RWIS 

stations. 

• Integrate the data from the NDOT station network to improve NDOT operations and for a 

possible larger community use. 

• Understand the input uncertainties and provide guidance on improving NDOT pavement 

temperature forecasts. 

NWS Perspective: Using NDOT Data to Improve Mesoscale Forecasts in Complex Terrain 

• Improve the operational mesoscale/regional scale forecasts at the NWS WFO in Reno, 

NV. 

• Use the NDOT operational network for model evaluation and weather warnings. 

DRI Perspective: Using NDOT Data to Improve Mesoscale Forecasts in Complex Terrain 

• Integrate NDOT data into the DRI-Western Regional Climate Center data network. 

• Improve mesoscale forecasts of weather in the complex terrain of northern Nevada by 

using data from the operational network of NDOT stations. 

• Develop an optimum Four-Dimensional Data Assimilation (FDDA) system to improve 

MM5. 

DRI Perspective: Testing and Improving the NDOT Pavement Temperature Model 

• Study the sensitivity of pavement temperature model predictions to input meteorological 

parameters. 

NDOT: Road Weather Information System Network 

There is a significant need to improve road-related weather forecasts from the point of view 

of NDOT operations, and from a traffic and economic perspective. To address this issue, 

NDOT has implemented a variety of snow and ice control strategies, including developing a 

RWIS. The system includes a network of remotely located environmental sensor stations that 

collect, process, and disseminate information on road and weather conditions relevant to 

highway transportation. 

Several major questions arise: 

• What is the main use of these data for NDOT, NWS, other institutions, and the 

community? 

• Can this system be a part of other networks? 

• What is the quality of the collected data? 
29

In the beginning of the project, researchers established the links and a data stream from the 

NDOT weather stations network to DRI and NWS. Programs were developed at DRI to 

automatically access and download the data from NDOT computers and integrate the data 

into the database of the Western Regional Climate Center at DRI. The operational Web site 

has been developed on the DRI server computer at http://www.ndot.dri.edu. 

This site provides an interactive graphical display of the data. It is in continuous operation 

and receives all available NDOT data in two different formats and sampling intervals (10 and 

15 minutes). Incoming data is archived. Researchers have been working with the NDOT staff 

to ensure a continuous stream of information and to include the newly established NDOT 

stations in DRI’s Western Regional Climate Center information system. However, at the 

current time, some stations are not operational, some have changed their transmission 

software, some have not been transferred to DRI, and some are still reporting. 

The DRI Web site provides access to statistical and graphical analyses of current and past 

data, including time series, wind roses, monthly and daily statistics, and the ability to 

download data of interest. Figure 10 shows the main page of the Web site with stations that 

are available for statistical and graphical analysis. 

Figure 10. Locations of the NDOT stations that are available for analysis 

on the DRI Web site. 

Recently, NDOT has undertaken major steps to reorganize their network of operational 

stations. Eleven sites have been upgraded, and five new sites have been installed. The 

Remote Processing Unit (RPU) type was upgraded from the Zeno® or Vaisala Milos models 
30

to the Vailsala ROSA Weather Station RPU. The Zeno® RPUs were used with the now 

defunct coastal system. 

 

The Milos system will soon be obsolete, and replacement parts will be unavailable. However, 

parts salvaged from the upgraded sites will be available for troubleshooting the remaining 

sites operating on the Milos RPUs. 

The 11 Nevada sites that were upgraded cover the following: Black Springs, Cave Rock, 

Diamond Peak, Gardnerville, Holbrook Junction, Kahle Drive, Mount Rose, Secret Creek, 

Spooner Summit, Tracy Clark, and the U.S. I-395/U.S. I-50 junction. The five new sites that 

are now functional include Highland Flats, U.S. I-580 at the NDOT Reno, NV, yard, 

Moundhouse, Toulon, and Walker Lake. With these sites, there are now 21 operational sites 

in District II. Eight sites are operational in District III, and work continues to bring additional 

sites online. 

A new server has been installed to provide a redundant backup in the event of a major failure. 

In addition, the new server will provide an increased hard drive memory capacity and will 

operate at higher speeds. 

NWS: Using NDOT Data to Improve Mesoscale Forecasts in Complex Terrain 

The first goal was to establish a data assimilation system. This was the most difficult goal 

because of the state of technology when the project began. Frequent computer crashes and 

the use of dial-up modems between the NWS and NDOT challenged the information 

technology (IT) staff of both NWS and NDOT. By the second year of the project, file transfer 

protocol (FTP) procedures were set up, and faster computers were installed at both NWS and 

NDOT, which improved the reliability of data assimilation. Both NWS and DRI archived the 

data at the Western Region Climate center. 

Data collection continues today and has been expanded to other areas of the State outside of 

the local Reno, NV, mesonet area. This change in scope to this project was not anticipated 

when the project was started. 

The second goal was to improve NWS operational forecasts through better model guidance 

and knowledge. As mentioned in the proposal, NWS is in the process of implementing an 

NDFD. The proposal mentioned the resolution of this database would be less than 5.4 nm (10 

km) and, indeed at this time it is at 1.3 nm (2.5 km) and will be reduced to 0.67 nm (1.25 km) 

some time in the future. This gives the NWS forecaster the ability to forecast weather at 

spatial and temporal resolutions far greater than previously possible. However, high 

resolution forecast models are necessary for guidance. Initialization of these models and the 

NDFD relies on a dense network of surface data, including the NDOT sites. 

The NWS in Reno is using a local model at 4.9 nm (9 km) resolution and hourly time steps 

for some of the sensible weather elements in the NDFD, including wind and temperatures. 

The University of Utah’s ADAS model has become a starting point for verifying the NDFD 

data, and a side benefit of the project is that NDOT data is entered into this model through 

Utah’s MesoWest database. 
31

Verification of high wind warnings and improved fire weather forecasts came as a direct 

result of this data. As an example, on June 30, 2000, a wildfire near Reno, NV, started near 

the Mt. Rose highway, where several of the NDOT sensors are located. Weather forecasters 

used the NDOT data to support fire weather forecasts for that fire. Also, several high wind 

warnings were verified using the Washoe Valley NDOT sensor. This sensor is sited in a 

particularly windy area, and several times a year trucks overturn due to high winds along this 

stretch of highway. 

DRI: Using NDOT Data to Improve Mesoscale Forecasts in Complex Terrain 

One of the main goals of this proposed study was to establish a data assimilation system for 

the MM5 at DRI. Figure 11 shows a schematic of the data assimilation and the weather 

forecasting system that uses NDOT data to improve model initial conditions. The improved 

weather forecasts were then used to improve results from the NDOT Pavement Temperature 

Model. 

MM5 Four

Dimensional Data

Assimilation

MM5 FourDimensional Data

Assimilation

12 hrs 36 hrs

Real time access

DRI-WRCC

Real-Time Access

DRI-WRCC

NDOT

Operational

Mesonetwork

23 stations

Western Nevada

NDOT

Operational

Mesonetwork

23 stations

western Nevada

Boundary Conditions

ETA model - 48 km

NCEP/NCAR

DRI automatic link

Boundary Conditions

ETA model—48 km

NCEP/NCAR

DRI automatic link

MM5 Forecast MM5 Forecast

MM5

Output

MM5

Output

NDOT

Pavement

Temperature Model

NDOT

Pavement

Temperature Model

NWS

- Mesoscale

forecasts

- National Digital

Forecast Database

NWS

- Mesoscale

forecasts

- National Digital

Forecast Database

RealTime

MM5

RealTime

MM5

Applications

- Air Quality

- Regional

Transport

- Wind energy

- Coupling with

oceanic models

- Coupling with

hydrological

models

- Cloud seeding

simulations

- Real-time

forecasting (US

West Coast)

Applications

- Air quality

- Regional

transport

- Wind energy

- Coupling with

oceanic models

- Coupling with

hydrological

models

- Cloud seeding

simulations

- Real-time

forecasting (U.S.

West Coast)

Structure and applications of the MM5 real-time forecasting system

DRI—Division of Atmospheric Sciences—Atmospheric and Dispersion Modeling Program

Initial conditions

NCEP global

observational network

DRI automatic link

Initial Conditions

NCEP global

observational network

DRI automatic link

Computer: SGI Origin 2000 (16) 

)

Figure 11. A schematic of the DRI-developed real-time forecasting system that assimilates 

NDOT data in the first 12 hours of the pre-forecasting time. (NCEP is the National Centers 

for Environmental Prediction, NCAR is the National Center for Atmospheric Research, and 

SGI® represents Silicon Graphics Incorporated) 
32

To achieve the proposed objectives of the study, we applied our developed system shown in 

figure 11 to two winter storm cases. The forecasting periods were: 

• March 7–9, 2002. 

• April 1–2, 2003. 

Case 1: Mesoscale modeling using NDOT data for March 7–9, 2002 

Since the reporting and quality of data improved in the beginning of 2002, FDDA tests 

focused on a case study of a significant snowstorm that occurred during March 7–9, 2002. 

During that time, 11 stations were reporting. During the same period, the National Center for 

Atmospheric Research (NCAR) in Boulder, CO, and DRI were conducting the Integrated 

Sounding System field program in the Reno, NV, and Washoe, NV, basins. Surface and 

upper air measurements were collected at two locations from February 26 to March 26, 2002. 

A heavy snowstorm occurred in the Sierra Nevada Mountains during March 6–8, 2002, with 

a maximum snow-water equivalent of 77.97 centimeters (cm) measured on March 8 at the 

Central Sierra Snow Lab in the Donner Pass area near Truckee, CA. A frontal system passed 

over the Reno area on March 8 at 02:00 universal time coordinated (UTC) with measured 

rain amounts of 5 to 10 millimeters (mm). The system was associated with a strong southerly 

flow preceding the front. It appears that this frontal system was merging with the significant 

moisture advection from southern California and over the Central California Valley. Radar 

images showed wide areas of convective precipitation moving from the valley over the 

Sierras. The precipitation started over the Sierras on March 6 and propagated into the Reno 

area later on March 7. Severe driving conditions on I-80 due to gusty winds and snow were 

reported in the area, especially east of Reno near Fallon, NV. 

This snowstorm event has been simulated with the DRI MM5 real-time operational model 

using a coarse grid with 18-km horizontal resolution (133 x 121 x 28 grid points) and a 

nested grid with a horizontal resolution of 6 km (148 x 169 x 28 grid points). The setup of the 

MM5 modeling domains is shown in figure 12. 
33

Figure 12. Geographical setup of the real-time MM5 forecasting domains. 

The model was able to forecast a frontal system passing through Reno, NV, on March 8, 

2002 between 00:00 and 02:00 UTC. The main objective of the study in this period was to 

use FDDA to improve the accuracy of the MM5 forecasts. Results indicate that the two major 

FDDA parameters are the nudging coefficient and the radius of influence of the data that is 

being assimilated into the model.5

 In addition, it is important to use an optimum set of 

stations; however, it should be emphasized that each of the surface stations has micro 

location specifics and generally is not representative for the larger area that needs to be 

captured by the model. Figure 13 shows a wind speed time series comparing NDOT Station 

13 data (Washoe Valley, 39° 16’ 26.28” N, 119° 49’ 7.90”W) with the model results without 

data assimilation (base case) and with several FDDA runs with varied nudging coefficients, 

radii of influence1

, and a number of selected stations entered into the FDDA system. 

 

 5 FDDA is a method of including present and past data in a numerical model. The data incorporated in the 

model continuously correct (nudge) model results toward measured data at the point where the measurements 

took place and also for model results within a certain radius (the radius of influence) of the measurement point. 1

The model corrects its results strongest at the measurement point and weaker as it goes further from the point 

within the radius of influence. 
34

 

Run A: radius of influence = 240 km, nudging coefficient = 4e-3. 

Run C: radius of influence = 50 km, nudging coefficient = 4e-2. 

Figure 13. Time series of wind speeds measured at NDOT Washoe Valley station and 

simulated with MM5 without FDDA, with Run A FDDA options, 

and with Run C FDDA options. 

The figure clearly shows the efficiency of using NDOT data in the FDDA mode to improve 

the accuracy of forecasts. Both the A and C FDDA tests agree better with measurements than 

the MM5 run without data assimilation (baseline simulation). The correlation coefficient is 

significantly greater in the FDDA cases (0.71 and 0.75) compared to the baseline case 

without data assimilation (0.47). 

Case 2: Mesoscale Modeling Using NDOT Data for March 1–2, 2003 

The system was also tested on a case from winter 2002/2003. An unusually late winter storm 

occurred in western Nevada in the beginning of April 2003. The storm was characterized by 

an intense frontal system, high winds, a significant drop in temperature, and snow showers. 

The severity of the weather conditions can be illustrated by the radiosonde observation taken 

before and during the storm (Figure 14). 
35

Figure 14. Vertical profiles of temperature, dewpoint temperature, and winds measured by 

radiosonde in Reno, NV, on March 31, 2003 at 00 UTC (4 p.m. local time) (left panel) and 

on April 1, 2003 at 12 UTC (4 a.m. local time) (right panel). 

The figure shows a large temperature drop below 500 millibars (mb) during the storm as 

compared to the pre-frontal sounding. There was a significant increase of moisture in all 

tropospheric layers and consequent increase of atmospheric instability, clouds, and 

precipitation. The westerly winds increased significantly in the atmospheric boundary layer 

and at all elevations, with peaks to about 80–90 knots aloft. 

Figure 15 shows a time series of measured and simulated air temperature and wind speeds for 

the April 2003 case. The figure shows the MM5 simulations for a baseline run and an FDDA 

run. The simulations were able to reproduce the observed strong, almost monotonic drop, in 

temperature of about 20 °C within 36 hours. The model runs that used assimilated NDOT 

data compared better with measurements for both temperature and wind speed. 
36

Figure 15. Time series of temperature (upper panel) and wind speed (lower panel) at the 

Reno, NV, station for the period from April 1–2, 2003. 
37

DRI: Testing and Improving the NDOT Pavement Temperature Model 

In the later phase of the study, researchers obtained the code for the pavement temperature 

forecast model. The model was installed and setup on a computer. For the remaining time on 

the project, researchers tested the code and examined various input data options. In 

particular, they focused on meteorological input parameters such as air temperature, 

dewpoint temperature, humidity, cloudiness, radiation, and precipitation. 

NDOT has been using an IceCasttmi 6 Pavement Model to coordinate its winter operations. 

IceCast is a numerical model of surface pavement temperature and surface conditions. This is 

essentially a surface-heat balance model, in which the surface temperature responds to 

changes in the various heat fluxes that affect the pavement. A schematic of the basic 

components of the model is shown in figure 16. 

Short wave

radiation

Long wave

radiation

Conduction

from ground

Sensible

heat

Latent

heat

Traffic

Heat Fluxes of Pavement Energy Budget 

Figure 16. A schematic of the NDOT pavement temperature model with 

its major physical components. 

The main inputs to the pavement temperature model are technological and meteorological 

parameters. To the authors’ knowledge, the sensitivity of the forecasted pavement 

temperature on the meteorological inputs is not known or documented. Consequently, 

researchers examined the effects of changes in the meteorological input parameters on the 

forecasted pavement temperature obtained by IceCast. In particular, they examined how the 

minimum pavement temperature would change if each of the meteorological parameters was 

changed. 

 

 6 IceCasttmi is a pavement temperature model of the Vaisala Corporation 
38

Figure 17 displays an image of a computer screen with a menu showing the main 

meteorological inputs to be inserted for the pavement temperature model run. The 

meteorological input consists of air temperature, dewpoint temperature, wind speed, cloud 

cover, cloud type, and precipitation intensity. These parameters must be predicted for the 

desired period of the pavement temperature forecasts. 

Figure 17. Computer screen with a menu for predicted meteorological parameters to be input 

for the pavement temperature model run. 

These necessary meteorological inputs have been extracted from the MM5 real-time 

forecasts for the period of interest at all locations at which the pavement model will generate 

forecasts. Figure 18 shows the stations for which the NDOT data exist for the test case. 
39

Figure 18. Computer menu screen with a list of stations for which the pavement temperature 

forecast can be obtained. 

After all data are input, the model computes the predicted pavement temperature at each of 

the considered stations. An example of a time series of the pavement temperature at the 

Incline Village station is shown in Figure 19. 
40

Figure 19. A time series of the forecasted pavement temperature at the Incline Village station 

for the test case for the period of 3 a.m. on October 31, 2002, to 3 a.m. on November 1, 2002. 

The first step of testing the effects of the meteorological input on the pavement temperature 

model took the MM5 results for the first case study (March 7–9, 2002) as a baseline 

simulation. Then researchers changed each of the input meteorological parameters by a 

certain value and ran the pavement model for each of these cases. The final results are shown 

in figure 20. Various line colors and symbols indicate sensitivity tests in which 

meteorological variables were changed with respect to the baseline run. The specific change 

for each test is shown in the legend on the right side of figure 20. These tests resulted in a 

large variation in the minimum pavement temperature, ranging from –7 to –12 °C. 
41

Forecasted temperature for the base run -- 7 March 2002

-12

-7

-2

3

8

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Hours after model start (12 LST)

Temp (deg C)

BASE

T+2

T+1

T-1

T-2

TD+2

TD+1

TD-1

TD-2

WS+2

WS+1

WS-1

WS-2

TCA+4

TCA+8

PPB+1

PPB+2

ST1+1

ST1+2

ST1-1

ST1-2

BT1+1

Figure 20. Time series of the pavement temperature predicted by the NDOT IceCast

Pavement Model for various changes in meteorological input parameters with respect to the 

baseline run. 

Because the minimum temperature is a crucial parameter for road conditions, researchers 

analyzed the effects of each input parameter on the minimum pavement temperature. Figure 

21 shows results from the sensitivity tests that can be used to identify the most important 

meteorological inputs for the pavement temperature model. 
42

Minimum temperature difference

-2

-1

0

1

2

3

4

T+2T+1

T-1T-2

TD+2TD+1

TD-1TD-2

WS+2WS+1

WS-1WS-2

TCA+4TCA+8

PPB+1PPB+2

ST1+1ST1+2

ST1-1ST1-2

BT1+1BT1+2

BT1-1BT1-2

Test run

Temperature (deg C)

T = temperature; TD = dewpoint; WS = wind speed; TCA = total cloud cover; 

PPB = precipitation; ST = surface temperature; and BT= depth temperature (-25 cm).

Figure 21. Change of the predicted minimum pavement temperature as a function of 

changing meteorological inputs by step units. 

Figure 21 indicates several important features. Predicted pavement minimum temperature 

appears to be mostly sensitive to a change in air temperature, as well as to the total cloud 

cover and precipitation. Inaccuracies in the air temperature of 1 and 2 °C induce a change of 

the minimum pavement temperature of more than 0.5 and 1 °C, respectively. Significant 

underestimation of precipitation can yield a change of the minimum pavement temperature of 

about 2 °C, while inaccurate prediction of cloudiness can yield the change of the minimum 

pavement temperature of more than 3 °C. 

The project results were presented at meetings in Washington, DC (September 17, 2002), 

Albany, NY (Aurora Board Meeting, August 26, 2003), and at the 10th Annual Workshop on 

Weather Prediction in the Intermountain West.(2)

CHANGES TO SCOPE 

Researchers completed all major components of the proposed study as stated in Section 1 and 

elaborated above, but did not have an opportunity to work with the NDOT to develop a 

travelers’ forecast system. Instead, researchers developed a dedicated Web site that can be 

used to catalog and access the data and process them numerically and graphically. 
43

PROBLEMS ENCOUNTERED 

The main problems of establishing the NDOT data network and incorporating data into the 

information network were solved during the first year. However, there are still problems with 

data recovery, data reliability, nonexistent detailed quality check controls, and interrupted 

communications. 

Regarding the NWS partner, the main problem was that the co-primary investigator left NWS 

in the summer of 2002, and the collaboration with the NWS Reno, NV, office was 

interrupted after her departure. Fortunately, the new Science Operations Officer at the NWS 

Reno, NV, office was helpful in completing the project. 

Regarding DRI, the main problem was computational resources. To solve this problem, 

computers that run the Linux operating system will be used in the future. Researchers learned 

that the MM5 real-time model setup (forced by the available computer resources) with a 

horizontal resolution of 18 km and 6 km is not sufficient to resolve details of the mesoscale 

weather. Resolutions of less than 3–4 km are needed for more accurate mesoscale forecasts. 

Researchers demonstrated that assimilating the NDOT data can improve MM5 real-time 

forecasts and consequently improve the predicted pavement temperature. However, they 

believe that the use of upper-air measurements such as remote sensing would provide 

stronger guidance to the model in improving mesoscale forecasts. Even one or two remote 

sensing instruments (such as wind profilers and acoustic sounders) in the mesoscale area 

would provide data that would most likely improve the meteorological performance. An 

additional benefit would be the use of the vertical profile data from these remote sensing 

instruments to improve NWS operational forecasts. 

Links with DRI/NWS/NDOT regarding inputs and use of the NDOT pavement model for 

sensitivity tests using actual forecast data from the MM5 model were resolved in the final 

stage of the project. The pavement temperature model was obtained and sensitivity tests were 

performed as promised in the proposal. 

Because operations is the primary line of work for NDOT and NWS, a research component 

that improves operations is still an additional (secondary) effort. 

DIVISION OF LABOR 

NDOT’s primary role was to provide access to the RWIS meteorological stations, perform 

and improve necessary sensors and communication protocols, and establish computer links 

between the DRI’s Western Regional Climate Center and NDOT. NDOT has improved the 

monitoring network significantly and, jointly with DRI, improved data acquisition, data 

processing, communication software, and the Web-based data presentation. 

The NWS was responsible for assimilating data and using it in it the forecast process. This 

was done and continues to this day. NWS also distributes this data to other interested parties, 

including the University of Utah and the Western Region Climate Center. This data, when 

used for verification of high winds, is also archived in the Storm Prediction Center’s database 
44

as a severe weather report. NWS has gained more experience running local mesoscale 

models by installing the workstation Eta and MM5 on local Linux machines. 

In addition to coordinating the overall project, DRI’s primary role was to develop methods of 

using NDOT data to improve mesoscale forecasts and, consequently, the pavement 

temperature predictions. DRI managed to operationally incorporate and archive data from the 

NDOT stations into the database of the DRI Western Regional Climate Center. NDOT data is 

being included in the University of Utah’s MesoWest database, which includes over 3000 

automated sites in the western United States. This database has a wide range of uses, 

including initialization of local mesoscale models such as the MM5 and Meso Eta. 

In addition, DRI provided guidance and assistance in designing the sampling times, 

requirements, and software analysis for the NDOT network data. DRI set up a dedicated Web 

site for NDOT data access, statistical evaluation, and graphical representation. 

DRI gained significant experience and expertise in using the MM5 FDDA technique and 

demonstrated that the use of the NDOT data improves the accuracy of the mesoscale 

forecasts in complex terrain. 

RECOMMENDATIONS FOR FUTURE WORK RELATED TO THIS PROJECT 

Due to delays caused by some problems encountered during the execution of the projects (as 

described in the previous section), there are several issues remaining that should be 

addressed, if the funding and time are available. The main component to be completed would 

be to integrate the pavement temperature model with the MM5 real-time operational forecast 

into the unique forecasting system. 

A travelers’ forecast, including all aspects of road and traffic conditions, has not been 

realized. NDOT, NWS, and the community in general would use this forecast. Researchers 

will continue to work with NDOT to complete the project, which supports the NWS goal of 

creating new and innovative products. A Web site should be established with all relevant 

information on weather and road and traffic conditions. This information should be shared 

with broadcasting companies. 

BROADER RECOMMENDATIONS 

This project was a very valuable experience and provided great benefits in linking the NDOT 

operations, NWS forecasting, and university (DRI) research and applications. The 

partnerships formed for this project will be lasting and will go beyond the scope of this 

particular project. For future projects, it would be valuable to ensure some dedicated time to 

the NDOT collaborators (whose main priority is to work on direct NDOT operations) to 

accomplish projected objectives. 

Regarding possible future projects, it would be essential to evaluate the quality of the NDOT 

station data and write detailed quality assurance software that continuously would report the 

status of all stations in real or near-real time. 
45

A comprehensive evaluation of the use of the NDOT data and a plan for additional possible 

use should be conducted. 

It also would be valuable to perform a comprehensive study to verify mesoscale weather 

forecasts and actual predictions of the pavement temperature. The particular pavement 

temperature model used by NDOT should be analyzed critically and compared with other 

pavement temperature models used worldwide. New techniques such as artificial neural 

networks (ANNs) should be tested as possible options and improvements. 

47

THE NEW YORK INTEGRATED WEATHER DATA NETWORK 

University: University at Albany, State University of New York (SUNYA) 

Name of University Researcher Preparing Report: David R. Fitzjarrald, Atmospheric 

Sciences Research Center, SUNYA 

NWS WFO: Albany, NY 

DOT Office: New York State Department of Transportation (NYSDOT) 

Name of Primary DOT Collaborators: Joe Doherty, formerly Anthony Sambuca 

UCAR Award No.: S01-24243 

SUMMARY OF ORIGINAL PROPOSED SCOPE OF WORK 

The objectives of the project were to: 

• Integrate data from NYSDOT RWIS. 

• Make these data available to the NWS to improve local forecasting skill. Develop initial 

codes to import RWIS data into standard NWS processing packages. 

• Archive data for climatological purposes and to determine significant local variations in 

microclimate from the regional airport standard. 

• Assess the quality of RWIS data to facilitate integration of surface station data from 

disparate sources. Establish an independent procedure for assessing data obtained by 

commercial RWIS stations and analyzed using proprietary software. 

• Assist the NYSDOT in evaluating different low cost automatic weather stations to serve 

as the basis for a network of secondary road-monitoring sites. 

• Understand how local obstacles can change the near-road environment. 

• Identify local terrain influences on local weather. 

• Exercise the State University of New York (SUNY)/National Institute of Standards and 

Technology (NIST)/Local Atmosphere Bridge Simulation (SLABS) model to make road 

surface forecasts using NWS forecast output products after a network of data are 

obtained. 

WORK ACCOMPLISHED, PROBLEMS ENCOUNTERED, CHANGES TO SCOPE 

Useful progress was made on some of the original objectives. Though the team members at 

NYSDOT provided steady encouragement and goodwill, they became understaffed during 

the course of this project. As a result, the major focus of the project shifted from the points 

listed above to an effort to download data from a few sample NYSDOT RWIS sites. 

Researchers attempted to audit data quality from the RWIS sites by comparison with nearby 

NWS sites (the forth objective listed). The process was done manually for the most part; 

details were outlined in an earlier interim report. The three stations identified in figure 22 

were analyzed, and their regression statistics are shown in table 23. 
48

Notes: Stations P1 through P9 are NCAR weather stations deployed during October 2003 as part of the SUNYA 

Hudson Valley Ambient Meteorological Study. Red arrows indicate stations that were compared to NWS sites. 

Figure 22. NYSDOT RWIS stations for which manually downloaded data 

have been analyzed. 
49

Table 3. Details of the intercomparison regression statistics (RWIS sites i88, rt5, and rt29) 

compared with NWS sensor at the Albany, NY airport. 

Station Period Temperature Humidity Wind Speed 

 Intercept Slope Intercept Slope Intercept Slope 

1- 95, 2002 -1.2 1.00 0.5 0.79 3.1 0.88

i88 195-366, 2002 -1.2 1.00 0.2 0.88 1.7 0.30

1-100, 2003 -1.0 0.97 0.1 0.97 1.8 0.38

1-195, 2002 0.4 0.92 0.4 0.85 2.6 0.50

rt5 195-366, 2002 0.3 0.93 0.3 0.87 2.1 0.14

1-200, 2003 -0.2 0.94 0.2 0.91 2.2 0.19

1-195, 2002 -1.4 0.99 0.2 0.89 2.1 0.55

rt29 195-366, 2002 -1.2 0.98 0.1 0.89 1.5 0.18

1-200, 2003 -1.2 0.98 0.1 0.89 1.5 0.22

State University of New York (SUNY) 

Progress was made in determining how individual RWIS station reports differ from those 

regularly reported by the NWS at the Albany, NY, airport. This comparison is important, 

because forecasters currently rely on such “Class 1” stations for information. In a companion 

project, the Hudson Valley Ambient Meteorological Study (HVAMS), SUNYA deployed 

five HOBO® weather stations and nine sophisticated surface meteorological stations on loan 

from NCAR (at P1–P9 in figure 22). 

RWIS stations are not sited ideally for capturing wind and temperature characteristics of the 

wider region; in fact, they were not designed to do so. The stations are often in locations near 

obstacles that affect wind and temperature measurements (such as foliage, structures or 

terrain) (figure 23). 
50

Figure 23. Panoramic views of three of the weather stations studied. 

Figure 24 illustrates the kinds of analyses researchers attempted with the Statewide network 

of RWIS sites (the sixth and seventh objectives). Each station is illustrated by the 

“transmission factor” in gray (essentially the degree of blockage compared to an 

unobstructed station, the circle) and a “wind rose” (the solid bars) that shows the observed 

distribution of wind speed and direction. The key point is to illustrate the two competing 

ambitions inherent in this type of project. On one hand, NWS wants surface information that 

is as representative as possible of the area for it to be relevant to understanding the wider 

weather event. On the other hand, the State DOT wants to know the conditions directly at the 

road surface. Researchers will continue this work even though the COMET project is 

complete. 
51

Notes: Stations P1 through P9 correspond to the stations depicted in figure 22. The thin gray polygon represents the 

transmission for wind coming from the given direction. The circle represents an ideal, representative station. The wind 

rose gives frequency and intensity of wind from the designated direction. Changes of line thickness indicate break 

points of 3 m/s. 

Figure 24. Wind roses and transmission factors for surface weather stations. 

One obstacle to creating the New York Integrated Weather Data Network (related to the first 

three objectives) is continued delays in installing new RWIS sites and issues with the older 

RWIS sites that remain under the proprietary SCAN® software. For 2 years, SUNYA 

researchers acquired data through a tedious manual process, and data quality is still not up to 

standard. NYSDOT personnel are aware of the problems and are working with SCAN®

manufacturers as they can, in an environment of drastically reduced resources. The details of 

these problems were described in the COMET project interim report of August 2003. 

Researchers encountered a number of difficulties dealing with the contractor for the 

NYSDOT RWIS sites, as detailed in the interim report. The authors believe that data 

acquisition glitches are not fundamental; the glitches could be resolved eventually if State 

DOT personnel worked more diligently with the RWIS contractor. However, this work could 

not be completed by the end of this COMET project. Data assembled up to this point will be 

folded into the other surface data obtained during HVAMS. Thus, though the project with 
52

COMET is now over, certain aspects of the effort will continue. Data gathered to date, along 

with the NOAA’s ASOS station reports, have been collated and are available at the 

researchers’ anonymous file transfer protocol (ftp) site for public access. 

Though NYSDOT’s program to establish the network of low cost stations has been delayed 

indefinitely (fifth objective), making this task unachievable, researchers will continue to 

explore this possibility after the end of this particular grant. 

In regard to the eighth objective, the plan was for SUNYA to begin research related to 

natural and artificial surface state prediction for the local area when the data were available 

in real time. SUNYA would have sought input from NWS staff in developing onedimensional energy balance models that predict surface temperatures and state (i.e., wet, dry, 

icy, snowy) by determining the exchange of energy between the surface, the atmosphere 

above it, and the ground below it. The idea was to apply the models to both natural surfaces 

such as fields, and artificial surfaces such as roads, gaining valuable insight into the 

differences between the energy balances of different surfaces. 

This work was postponed when researchers realized that the RWIS data downloads did not 

include information about the road surface temperature. The road temperature sensors are 

installed, and the observations appear in certain graphical displays. However, road 

temperature information did not survive the “exporting” command to the SUNYA database. 

With the publication of the SUNY SLABS model paper, researchers are now in a position to 

apply this work to road surface state modeling.(3) However, for this and the remaining tasks 

not detailed, researchers cannot reasonably proceed until an archive of data from many 

stations is available. It was not anticipated that the major effort would be the initial data 

acquisition step; therefore, researchers have not been able to develop a database from a large 

number of stations. 

DIVISION OF LABOR 

In this study, the team of students and staff from the SUNYA Atmospheric Sciences 

Research Center (ASRC) did most of the data acquisition and analysis work. Throughout the 

project, NYSDOT personnel were very cooperative. In November 2002, NYSDOT 

contracted consultants to facilitate data availability. These consultants visited ASRC/SUNYA 

and the NWS WFO in Albany, NY; there was a subsequent meeting to solidify data requests. 

This work is still ongoing. Through the NYSDOT efforts, researchers logged onto NYSDOT 

computers, downloaded data from a small number of stations, and established the protocols 

for possible future work. One NWS partner helped demonstrate how additional surface 

information could be integrated into the NWS standard. 
53

RECOMMENDATIONS FOR FUTURE WORK RELATED TO THIS PROJECT 

The SUNYA team will continue to work with the RWIS data it has. Without explicit 

resources, this will be done as work that can serve several broader goals. After the NYSDOT 

RWIS data network matures and data are readily available, the team will return to this 

problem. 

BROADER RECOMMENDATIONS 

This effort shows that the same data can serve several disparate purposes. Both NYSDOT 

and NWS have mandated responsibilities that require them to maintain a narrowly defined 

view regarding how data are managed. The mandates of weather forecasting and road surface 

treatments lead both institutions to seek real-time displays of information, and they have less 

interest in the history of events. The key element is to identify repeated patterns, such as 

stretches of roads prone to weather-related difficulties, and use this selective 

microclimatology to make generalizable models of road state and local meteorological 

effects that benefit both operational groups. 

55

APPLICATION OF LOCAL DATA ASSIMILATION 

IN COMPLEX TERRAIN 

University: University of Utah, Cooperative Institute for Regional Prediction 

Principal Investigators: John Horel, Mike Splitt, CIRP 

NWS WFO: Salt Lake City, UT 

Name of Primary NWS Collaborator: Larry Dunn 

DOT Office: Utah Department of Transportation 

Name of Primary DOT Collaborators: Ralph Patterson, and formerly Steve Conger 

Cooperative Project, UCAR Award No.: S01-24244 

 

SUMMARY OF ORIGINAL PROPOSED SCOPE OF WORK 

This study expanded work originally funded by the Utah Department of Transportation 

(UDOT), “Implementing Roadway Weather Information Support Management of Winter 

Maintenance,” UDOT Contract No. 98-8298. That project helped coordinate and identify 

weather resources in Utah pertinent to winter road maintenance. Results from that study were 

presented at a special session on the RWIS at the AMS Interactive Information and 

Processing Systems Conference (IIPS).(4) As a result of previous work, researchers began 

this project having worked toward several of the objectives of the FHWA, NWS and 

COMET programs. For example, they had already established cooperative working relations 

between State DOTs, the university community, and WFOs. They also had fostered an open 

repository of RWIS observations that were integrated with other weather observations around 

the West as part of the MesoWest project.(5) 

The specific goals of this project were to: 

• Facilitate and improve access to RWIS observations in Arizona, Idaho, Nevada, 

Montana, Utah, and Wyoming. 

• Evaluate special weather statements for the 2002 Winter Olympics and Paralympics to be 

issued by the Salt Lake City, UT, WFO on hazardous winter weather along major 

transportation corridors in northern Utah. 

• Develop and evaluate RWIS applications of weather data in areas of complex terrain on 

the basis of local data assimilation. 

• Establish guidance on factors that affect the utility of environmental sensor stations (ESS) 

and weather observations for RWIS decision making in complex terrain. 

WORK ACCOMPLISHED 

Access to RWIS Observations 

A major accomplishment of this project was to continue to facilitate and improve access to 

RWIS observations in the western United States. Figure 25 shows the locations of RWIS 

stations from which weather information is obtained routinely (additional road state 

information is available from many of these stations, as well). Researchers currently collect, 
56

archive, and disseminate RWIS information from stations in California, Colorado, Idaho, 

Montana, Nevada, Oregon, Utah, Washington, and Wyoming, for a total of 6,000 stations in 

the West. 

Figure 25. Locations of MesoWest stations (plus symbols), RWIS stations (green triangles), 

and Union Pacific Railroad stations (yellow diamonds). 

The scope of data collection efforts expanded as opportunities to collaborate with State 

DOTs developed. This component of the study represents the largest fraction of effort. The 

following summarizes this ongoing data collection effort. 

California: The Meteorologist-in-Charge at the Eureka, CA, WFO provided the initial contact 

with the California Department of Transportation (CalTrans) representatives in northern 

California to facilitate access to 11 stations along I-5 north of Redding, CA. Updates every 

30 minutes are available via ftp. 

Colorado: NOAA Forecast Systems Laboratory (FSL), as part of the Meteorological 

Assimilation Data Ingest System (MADIS), in cooperation with the Boulder, CO, WFO, 

provides access to Colorado DOT observations from 55 stations. The data are distributed via 

Unidata’s Local Data Manager (LDM). In addition, winter road maintenance observations in 

support of avalanche control work are collected in cooperation with the Grand Junction, CO, 

WFO. As part of this project, researchers helped install software at the Grand Junction WFO 
57

to dial weather stations at several mountain passes, and researchers continue to help the WFO 

troubleshoot problems in data collection as they occur. 

Idaho: Part of this project involved considerable effort to develop software to collect RWIS 

data (weather and road state) from the Idaho Transportation Department (ITD). This initially 

involved writing software and installing that software on an ITD computer. ITD now has 

installed a system to collect the data, which is accessed via ftp. ITD depends on MesoWest 

for access to real-time weather information for its Road Weather Integrated Data System (see 

http://164.165.237.41/RWIDS_Public/default.asp). Activities as part of this project in 

support of ITD were second only to that provided to the UDOT. 

Montana: The Montana Department of Transportation (MDT) and Great Falls, MT, WFO 

have collaborated for years to share weather and road state information. Researchers obtain 

the weather and road state data from 59 stations via LDM and have worked with MDT 

personnel to identify data quality problems as they become evident. 

Nevada: Data from 47 stations in Nevada are obtained via ftp from NDOT. Staff at the DRI 

and the Reno, NV, WFO have facilitated this work. 

Oregon: Staff at the Pendleton, OR, WFO helped facilitate access to weather information at 

28 stations supported by the Oregon Department of Transportation (ODOT). The weather 

information is collected via access to the DOT Web server. 

Utah: Researchers worked closely with UDOT to facilitate access to weather and road state 

information at 53 locations around the State. Information is collected directly via ftp from a 

RWIS server supported by UDOT, as well as through a computer at the Salt Lake City, UT, 

WFO. 

Washington: Weather and road state information are collected from 72 stations maintained 

by the Washington State Department of Transportation (WSDOT). These data are accessible 

as a result of the efforts of staff at the Seattle, WA, WFO and the University of Washington. 

The data is collected via ftp from the University of Washington. 

Access to Union Pacific Railroad Observations 

As shown in figure 25, researchers obtained access to weather information at 264 locations 

along the major Union Pacific rail corridors in the West. Most of the stations report 

temperature only (to detect track contraction/expansion), and wind conditions are reported at 

many critical locations. 

Data Handling Issues 

Because MesoWest was a well-established database, researchers were experienced in 

handling data in a variety of formats and implementing a quality control program. Quality 

control procedures based on three-dimensional linear regression have been implemented to 

assess temperature, dewpoint temperature, and pressure. Researchers improved simple 

checks for wind data (gust to sustained wind ratio, for example) so that poor wind 
58

observations could be identified. Precipitation is the most difficult to manage; this was left to 

the data providers. 

Olympic Weather Support 

The NWS, UDOT, and University of Utah worked closely to provide weather and road state 

information as well as forecasts to Olympic organizers, public safety personnel, and the 

public for the 2002 Winter Olympics and Paralympics.(6) Many different representatives of 

organizations related to the Olympics judged these efforts to be highly successful. Formal 

evaluation of the NWS weather forecasts issued along the transportation corridors was not 

pursued. 

MesoWest RWIS Data Interface 

A specialized Web interface to the MesoWest database (www.met.utah.edu/mesowest) was 

developed and maintained for UDOT personnel to use. This interface has been used 

extensively for winter road maintenance as well as road construction and summer paving 

projects. An example of the summary of current conditions is provided in figure 26. 

Figure 26. Summary of current weather and road state in Utah available in MesoWest. 
59

Local Data Assimilation 

Researchers developed anisotropic weighting functions for the ADAS data assimilation 

system.(7) These anisotropic weights are critical to resolving a systematic source of error in 

the analyses where weather observations in one valley affect the analysis in adjacent 

valleys.(8) This error is particularly problematic because a forecast model at very high 

resolution will resolve the weather in adjacent valleys independently. However, observation 

corrections to the initial background field obtained from a model can bleed laterally through 

the terrain. This affected the suitability of the analyses along some transportation corridors. 

The NWS is interested in data assimilation efforts over complex terrain to initialize and 

validate Integrated Forecast Preparation System (IFPS) gridded forecasts at WFOs around 

the West. The support from COMET helped develop ADAS further for these applications. 

RWIS Decision-making 

In part as a result of the increased data collection efforts, less effort was placed on evaluating 

the utility of RWIS observations in the decisionmaking process. Questionnaires were 

distributed to winter maintenance personnel during the 2001 winter season to collect 

information on the utility of local RWIS data. Preliminary analysis of data collected from 

shed foremen in Idaho, Montana, and Utah during the following spring was inconclusive; 

therefore, this effort was suspended for the 2002 winter season. 

PROBLEMS ENCOUNTERED

Access to RWIS data in some States was difficult to obtain. Researchers were not able to 

develop contacts at the CalTrans district level in many parts of California, waited several 

years to access RWIS data from Arizona, and have not identified an appropriate contact in 

New Mexico. 

DIVISION OF LABOR

The greatest level of interaction between the Salt Lake City, UT, WFO, UDOT, and 

University of Utah took place during the first year of the project as a result of the need for 

preparation and coordination of research, development, and operations for the 2002 Winter 

Olympics and Paralympics. The interaction was very positive and beneficial to all three 

organizations. A major goal of the Olympic weather support effort was to provide a legacy of 

improved understanding of winter storms and enhanced capabilities to predict weather in the 

region. This legacy is in place in part because of projects such as this. 

RECOMMENDATIONS 

The FHWA/NWS COMET program provided a framework to approach State DOTs to share 

weather and road state information. However, support to sustain this effort is unclear. Ways 

to sustain this effort are being explored initially with UDOT and ITD through their 

participation in the Cooperative Institute for Regional Prediction (CIRP) Consortium. CIRP 
60

has developed innovative tools to conduct research and assist government and commercial 

operations that are sensitive to weather around the Nation, in part with funding from research 

and development efforts supported by the NWS, FHWA, and other agencies. These tools 

include MesoWest, which provides real-time monitoring and analysis of environmental 

conditions, and the authors’ data assimilation and modeling efforts. The CIRP Consortium 

was established to further develop and apply these tools for the unique environmental 

problems of the Intermountain West and other regions of the Nation. The consortium is 

intended to provide support for the continued real-time operations of MesoWest and provide 

the foundation for further applied research and development related to real-time weather and 

emergency management operations, air quality, fire weather, winter road maintenance, wind 

power, and water resource management. The CIRP Consortium is modeled after the 

Northwest Regional Modeling Consortium developed at the University of Washington. 

The initial feedback from UDOT and ITD to the Consortium funding approach is favorable. 

However, is it reasonable to expect those States to fund researchers’ efforts to access weather 

and road state information in other regions of the West? There is a clear need for FHWA and 

NWS to support data collection efforts on a national scale that relies, in part, on the local 

partnerships that already exist in some regions of the country. 

Further research is also required to improve the utility of local analysis and forecast grids for 

road weather applications. The NDFD under development by the NWS potentially provides a 

tool to improve road weather decision-making. However, a number of technical issues must 

be resolved regarding how to best to use that information. 
61

REFERENCES 

1. Hall, T., H. Brooks, and C. Doswell, 1999, “Precipitation Forecasting using a Neural 

Network,” Weather and Forecasting, Vol. 14, num 3, pp. 338-345. 

2. Koracin, D., R. Nelson, and J. Fischer, 2003, “Improving Mesoscale Forecasting Using 

Data from the Nevada Department of Transportation Operational Network,” 10th Annual 

Workshop on Weather Prediction in the Intermountain West, November 6, 2003, Reno, 

NV. 

3. Wojcik, G.S., Fitzgerald, D.R., and Plawsky, J.L., 2003, "Modeling the Interaction 

Between the Atmosphere and Curing Concrete Bridge Decks with the SLABS Model," 

Meterol. Appl., 10, 165-186. 

4. Horel, J.D., M. Splitt, and S. Conger, 2001, “RWIS Applications of MesoWest in the 

Western United States,” 17th International Conference on Interactive Information and 

Processing Systems (IIPS) for Meteorology, Oceanography, and Hydrology, American 

Meteorological Society, January 14-18, 2001, Albuquerque, NM. 

5. Horel, J., M. Splitt, L. Dunn, J. Pechmann, B. White, C. Ciliberti, S. Lazarus, J. Slemmer, 

D. Zaff, and J. Burks, 2002, “MesoWest: Cooperative Mesonets in the Western United 

States,” Bulletin of the American Meteorological Society, Vol. 83, pp. 211–226. 

6. Horel, J., T. Potter, L. Dunn, W.J. Steenburgh, M. Eubank, M. Splitt, and D.J. Onton, 

2002, “Weather Support for the 2002 Winter Olympic and Paralympic Games,” Bulletin 

Of the American Meteorological Society, Vol. 83, pp. 227–240. 

7. Lazarus, S., C. Ciliberti, J. Horel, and K. Brewster, 2002, “Near-Real-Time Applications 

of a Mesoscale Analysis System to Complex Terrain,” Weather and Forecasting, Vol. 17, 

No. 5, pp. 971–1000. 

8. Myrick, D., 2003, An Improvement to Data Assimilation over Complex Terrain, M.S. 

Thesis, University of Utah. 56 pp. 

63

ADDITIONAL PUBLICATIONS AND CONFERENCE 

PRESENTATIONS 

Horel, J., and M. Splitt, “RWIS Applications of MesoWest,” ITS America Annual Meeting, 

Miami, FL. 

Splitt, M., and J. Horel, 2002, “Application of Environmental Sensor Stations in the Western 

United States,” 18th International Conference on Interactive Information and Processing 

Systems (IIPS) for Meteorology, Oceanography, and Hydrology, January 13-17, 2002, 

Orlando, FL.
HRDO-04/10-04(1M)E Recycled

Recyclable