# Presentation: 587148

## NWSRFS International Workshop October 23, 2003

*River Forecasting Operations*
*by*
*Robert S. Cox**1*
*Missouri Basin River Forecast Center*
*National Weather Service*
*Pleasant Hill, MO*
*1**bob.cox@noaa.gov*

**Notes:**
Good morning.  My name is Bob Cox and I’m from the Missouri Basin River Forecast Center.

## Our Mission 

- NWS Policy Directive 10-9 ...
*“ **The Objectives of the NWS Hydrologic Services Program are to provide river and flood forecasts and warnings for the protection of life and property and to provide hydrologic information for the Nation’s economic well-being.”*

**Notes:**
I’ll do my best to describe how we operate at the RFCs, or more specifically how we use NWSRFS to fulfill our mission.  And you can read our mission statement here as well as I can read it to you.  If you are from a similar agency in another country, your mission statement is probably very similar.  Some of what I will mention you have probably already heard about during your workshop.  Hopefully, I won’t be too redundant.  And please, if you have questions as we go along or need more explanation, don’t hesitate to interrupt.

## Hydro Program Responsibilities 

**Notes:**
To accomplish our mission, we distribute responsibilities to various offices in the weather service.

## Regional / RFC Delineation

**Notes:**
In the NWS, the contiguous US is divided into 4 regions along state boundaries.  (We also have Alaska and Pacific Regions that are not shown on this map)  Along with that, we have a total of 13 River Forecast Centers, divided along major river basins ... 4 in SR, 3 in both WR and ER, one that covers the Alaska and Pacific Regions, and in the CR we have two ... North Central RFC who handles the Upper Mississippi basin and our office, the Missouri Basin RFC.  

## WFOs Served by MBRFC

- Aberdeen, SD
- Billings, MT
- Bismarck, ND
- Cheyenne, WY
- Denver, CO
- Des Moines, IA
- Dodge City, KS
- Glasgow, MT
- Goodland, KS
- Great Falls, MT
- Hastings, NE
- North Platte, NE
- Omaha, NE
- Pleasant Hill, MO
- Rapid City, SD
- Riverton, WY
- St. Louis, MO
- Sioux Falls, SD
- Springfield, MO
- Topeka, KS
- Wichita, KS

**Notes:**
Each RFC serves the Weather Forecast Offices in its area of responsibility.  MBRFC serves a total of 21 WFOs in 10 states.  Again, the RFCs do not typically serve the public directly, however we do interact extensively with other water resources agencies ... the USACE, USBR, NRCS, USGS, for example.

## Staffing

**Notes:**
RFCs have a total staff of 15-20 people.  MBRFC has a total staff of 19, counting the secretary ... so we are one of the larger RFCs.  The supervisor for the office is called the Hydrologist-in-Charge or HIC.  Each RFC also has 6 senior hydrologists and a number of journeyman hydrologists ... we have 11.  Although we all wear the title “hydrologist”, half of us come from engineering backgrounds, one-third have backgrounds in meteorology, and two of us are geologists.  Given the broad spectrum of tasks we are expected to perform these days, diversity is a good thing.

## Hours of Operation

- 365 days a year
- Nominal 16 hour days (6:30AM – 10:00PM)
- Extended hours / overtime as situation dictates
- Two people on weekends / holidays
- One-person evening shift

**Notes:**
Our office is staffed every day of the year, but unlike the WFOs we typically only staff two shifts per day unless there is a need for critical forecasts during the off-hours.  We cover weekends and holidays with two people typically and one person on the evening shift.

## Basin Management (fgroups)

- Upper Missouri
- Bighorn
- Yellowstone
- Milk
- Upper Dakota Tribs
- Middle Dakota Tribs
- Lower Dakota Tribs
- North Platte
- South Platte
- James/Vermillion
- Big/Little Sioux
- Loup
- Elkhorn/Platte
- Upper Missouri Tribs
- Upper Republican
- Upper Smoky Hill
- Lower Republican
- Lower Smoky Hill
- Big Blue
- Kansas
- Marais des Cygnes
- Osage
- Lower Missouri Tribs
- Grand/Chariton
- Missouri Mainstem

**Notes:**
With the exception of the HIC and secretary, each member of our staff has daily forecast responsibilities.  Because the Missouri is such a large basin, we sub-divide these responsibilities by forecast groups or fgroups.  (I’m sure you’ve already learned about these.)  We currently have a total of 25 fgroups defined in NWSRFS, so you can see that some forecasters are assigned more than one group.  We each have primary, secondary, and tertiary responsibilities.  We rotate through these assignments every few months, except that we retain the same primary and secondary forecasters during the flood season each year.  This varies considerably from RFC to RFC.

## Forecast Points Blue River Basin

**Notes:**
If we take a closer look at one of these fgroups, in this case the Big Blue basin, you can see the typical resolution of our modeling.  This particular forecast group contains 16 locations for which we issue river forecasts, and one federal reservoir operated by the Corps of Engineers.  As you can see, the basin has been divided into 39 sub-basins for modeling purposes, with an average area of about 250 sqmi.

## Services Provided

- Deterministic forecasts
-  5 to 28 days
- Time series and crests
- Outlooks – spring snowmelt (90 days)
- Probabilistic forecasts/outlooks –                        several months
- Contingency forecasts

**Notes:**
A quick look at the types of information we provide ...

## The System

**Notes:**
I am sure you have seen a diagram similar to this already.  NWSRFS is the system of software that allows us not only to generate our forecasts and guidance on a routine basis, but it also contains the tools to develop those models in the first place.  The basic systems-within-the-system are the calibration system, the operational forecast system, the ensemble streamflow prediction system, and the flash flood guidance system.  IFP, then, is the forecaster’s interface to the operational forecast system, if you will.

## The Process

*Development*
*Operations*

**Notes:**
If we think in terms of processes, rather than systems, we have certain processes that are required to develop and implement our models (which are shown in blue here) and we have processes that utilize those models to provide forecast information for our customers (shown in yellow).  Developmentally, we acquire historical data, check that data for consistency, and generate historical mean-areal time series from it.  We then use those time series to calibrate our models against historical streamflow data.  Once those models are calibrated we define them in the operational forecast system.  Operationally, then, we acquire real-time data ( both observed and forecast), we execute our models, generate and issue forecast products to our customers.  That’s the general flow of things for both our development efforts and forecast operations.

## Model Calibration

*hydrograph analysis, statistics*
*each parameter serving its purpose*
*remove systematic biases*

**Notes:**
As you implement NWSRFS, you will find that the most time-consuming tasks you are confronted with are data analysis and model calibration.  We are never finished calibrating our models it seems.  The advent of the Interactive Calibration Program (ICP) has sped up this process considerably, however.  Your goals in calibration are essentially to remove systematic biases as much as possible and to ensure that each model parameter is serving the purpose for which it is intended.

## OFS Initialization & Maintenance

- Involves two initialization programs
- Preprocessor parametric initialization (PPINIT)
- Forecast component initialization (FCINIT)
- Changes/additions to station network
- Enhanced modeling
- New calibrations
- Stage-discharge relationships
- AHPS implementation

**Notes:**
Of course, once you have calibrated your models, you must define them in the forecast system.  Maintaining OFS is a never-ending task, as you can imagine.  Anytime a gage location changes or a new gage is added, anytime new models are developed, or a rating curve changes, etc., we must ensure that those changes are reflected in OFS as well.  We actually spend more of our time developing models and maintaining the forecast system than we do operating the system and making forecasts.

## OFS Building Blocks

- Stations
- Basins
- Areas
- Rating Curves
- Operations
- Segments
- Fgroups
- Cgroups

- PPINIT
- FCINIT

**Notes:**
You have already learned about what I refer to as the “building blocks” of NWSRFS.  You probably know that those shown in pink here are maintained using a program called PPINIT (which stands for PreProcessor Parametric Initialization).  Those shown in green apply to the FCINIT program (which stands for Forecast Component Initialization).  I’m going to spend a little time describing how we are utilizing each of these building blocks at MBRFC.  As you begin working with NWSRFS, you will find that, although it is a complex system, it is extremely modular ... meaning that you have a great deal of flexibility in how you configure it to meet your specific needs.

## Station Network

- Missouri Basin – 530,000 mi2 (m/l)
- 1.4 million km2
- 85,800 grid bins
- 3800 precipitation stations
- 700 observed temperature stations
- 160 forecast temperature stations
- 800 river and reservoir stations

**Notes:**
Just to give you an idea of the magnitude of the modeling system that OFS can accommodate ... the Missouri basin encompasses around 530,000 sqmi or 1.4 million sqkm if my math serves me.
You can see the number of stations we have defined in our network.
These numbers have steadily increased over time, essentially doubling over the past ten years.  More enhancements are on the way.  There is no replacement for good data.  All the modeling in the world is of little value if you don’t have good data driving it.

## Basins / Areas

- Definitions include lat/lon pairs, computation method, station weights, centroids, etc.
- 1260 MAPs
- 1200 MATs (excludes Rain-on-Res)
- 1100 basins, MAPXs, FMAPs
- Mountainous basins have more than one MAP/MAT by elevation zone

**Notes:**
In terms of the basins and areas that we have defined, and again these are maintained using PPINIT, you can see that we have roughly 11 to 12 hundred areas in our system.  The reason that we have more MAPs and MATs than Basins is that in mountainous areas the basins need to be sub-divided into two or more elevation zones due to the variability of precip and temperature with elevation.

## Forecast Component

- 900 segments ...
- in 25 forecast groups ...
- in 4 carryover groups
- Approx. 800 segments include a rating curve
- Vast majority provided by USGS
- Frequent updates
- A few provided by other entities or derived synthetically.

**Notes:**
Now in the forecast component of OFS, again we use FCINIT to maintain these definitions, we have ...
So this just gives you an idea of the scope of the system that we have implemented and it’s growing all the time.  In OFS, you actually size your files to accommodate everything that needs to be modeled.  So if you are like us and you’re continually adding to your forecast system, then from time to time the files need to be resized as well.  This isn’t a big deal, but something we need to keep an eye on.

## A Simple Operations Table RIFM7  (local area 1719)

- MERGE-TS  1719
- LAG/K  JRMM7RTD
- SNOW-17  1719
- SAC-SMA  1719
- FFG  1719
- UNIT-HG  1719
- ADD/SUB  1719
- ADD/SUB  JRMM7RTD
- STAGE-Q  RIFM7
- ADJUST-Q  RIFM7
- STAGE-Q  SSTG
- ADD/SUB  RIFM7FTS
- LIST-FTW  RIFM7
- PLOT-TUL  RIFM7

**Notes:**
To give you an idea of what a typical segment might look like, here is an example of the list of operations for a very simple segment.  This is a segment that includes streamflow routed from an upstream segment, hence the Lag/K routing operation.  We have one local area in this segment (shown in yellow), so we have a snow model, runoff model, and unit hydrograph for that area.  We have add/sub operations to add the various contributions together.  Stage-Q operations to convert stage to flow and vice-versa using the rating curve for RIFM7.  And we have operations to display the computed time series.

## Forecast Operations

- Day-in / day-out, regardless of hydrometeorological conditions
- First priority every day
- Typical AM Sequence –
- 6:30-7:30: QPF and MPE processing (HAS)
- 6:30-10:00: Manage river models (iterative), data Q/C
- 9:00-10:00: Issue river forecasts (30 locations routinely)
- 10:00-11:00: Final model runs, FFG, other products (FOD)
- Critical forecasts typically updated at 6-hour intervals

**Notes:**
Hydrologists at RFCs wear many hats, but first and foremost we are forecasters.  We may be expected to spend much of our time on development work, calibrating models, writing computer software, maintaining databases, etc., but our daily forecast responsibilities always get top priority.  It’s the first thing we do each morning.  A typical morning would consist of ...

## Data Ingest (observed and forecast)

- Data Ingest (observed and forecast)

- Vast majority of data arrive coded in SHEF (Standard Hydrometeorological Exchange Format)
- Automated gage networks – communicated via satellite, meteor burst
- Still rely heavily on cooperative observers for precip and some stage data.
- Precip, temperature, river, reservoir, (snow)
- Temperature forecasts provided by WFOs and NCEP.
- Posted into the forecast system every 15 minutes

**Notes:**
Data flows into our forecast system throughout the day.  Primarily, the input data we are talking about is ...

## SHEF Messages

**RR3MCI**
**.A  LVNK1  1003  C  DH07 / PP  0.00 / TX  66 / TN  41 / TA  56 / SF  0.0**

**RR1SGF**
**.B  SGF  1003  C  DH07 / HP / DH00 / HP / QID / QTD**
**: LAKE OF THE OZARKS**
**:           7AM POOL   /  MDT POOL   / INFLOW (KCFS)  / OUTFLOW (KCFS)**
**LKSM7       659.32    /        659.26    /          1.400           /       1.100**
**.END**
**.B  SGF  1003  C  DH07  /  DC0310030824**
**.B1   DRD+1 / QTDF / DRD+2 / QTDF / DRD+3 / QTDF**
**:   OUTFLOW FORECAST NEXT THREE DAYS (KCFS)**
**LKSM7        0.800   /   1.200   /   1.500**
**.END**

**Notes:**
Here are a couple of examples of SHEF messages.  The first one is from a cooperative observer who is reporting 24-hr precip, max, min and current air temperatures, and in this case zero snowfall.  This is all reported via a touch-tone telephone.  The second is an example of reservoir information collected by a WFO and transmitted to the RFC.  It includes pool elevations, inflow and outflow information as well as forecast outflows for the next three days.

## Precip Processing

- Multi-sensor Precipitation Estimator (MPE)
- Merge estimates from 26 radars with ground-truth (hourly reports)
- Quality-control as part of HAS function
- Gridded fields are converted to mean-areal values by the MAPX pre-processor
- Hourly time series

**Notes:**
I mentioned earlier that one of the first things we do each morning is the precip processing.  This is performed as part of the HAS function using a program called MPE.  You have already learned about MPE have you not?  MPE allows us to combine radar estimates of precipitation with gage reports to derive the best gridded field possible.   The gridded estimates are converted into 1-hr mean-areal values by the MAPX pre-processor of OFS.  This all needs to be completed as early as possible each morning because every river forecaster is depending on it.

## QPF

- NMAP program run as part of HAS function
- Gridded fields provided by HPC at 6-hour intervals
- HAS forecaster has ability to accept or modify HPC input
- Routinely run for 48 hours
- However, only 12 or 24 hours is used in the models, depending on season
- NMAP produces QPF mods for each area which FMAP converts into 6-hour time series
- MAPX pre-processor merges radar estimates with FMAPs

**Notes:**
Has anyone talked about QPF to this point?  QPF stands for Quantitative Precipitation Forecast.  This is the second function performed by the HAS forecasters early each morning ... to decide on the QPF that should go into our models.  This is accomplished using the NMAP application and also involves the FMAP and MAPX pre-processors of OFS.  The HAS forecasters make a determination of how much precipitation to expect over the basin during the next 48 hours.  However, we routinely include only 12 hours of QPF in our forecasts during the convective season and 24 hours of QPF the rest of the year.

## Pre-Processors

- Essentially convert point observations and forecasts into evenly-spaced time series
- MAP, MAT, and RRS pre-processors run automatically every 15 minutes, immediately following data ingest
- FMAP run manually as part of QPF process
- MAPX run automatically each hour, but also manually by HAS forecasters

**Notes:**
As you know, we have other pre-processors in OFS besides FMAP and MAPX.  The job of these pre-processors is essentially to convert all of the point observations and forecasts that are provided to us from various sources into evenly-spaced, usually mean-areal, time series.  These time series, then, are the input to our models.  Any data we receive are not available to our forecast models until the pre-processors have executed.  Consequently, we run the MAP, MAT, and RRS pre-processors every 15-minutes immediately following data ingest.

## OFS / IFP

- Operational Forecast System (OFS)
- Interactive Forecast Program (IFP)
- User Interface to OFS
- Each forecaster executes IFP on at least a daily basis by forecast group
- Models typically operate on 6-hour time steps
- Forecaster can choose between MAP and MAPX as input

**Notes:**
Once all the input time series are available to the models, the river forecasters access the forecast system via IFP.  Each forecaster will run IFP as often as necessary each morning to adjust the models in his/her forecast groups based on the stage data that’s available.  During a period of hydrologic activity, this can be an iterative process.

## Model Adjustments

- The goal of model adjustments is to ensure that simulated model states reflect current conditions
- Soil moisture
- Snow pack
- Reservoir inflow, outflow, pool
- Streamflow
- Stage (may be ignored in some cases)
- The forecaster should gather as much information as possible before deciding on the proper adjustment

**Notes:**
Even well-calibrated models frequently need adjustment.  So the goal of the forecaster is to gather as much information as possible, then select the proper adjustments to ensure that the simulated model states reflect current conditions.

## Model Adjustments

**Notes:**
When it’s all said and done, the forecaster has hopefully chosen the proper adjustments to convert an over-simulation such as this ...

## Model Adjustments

**Notes:**
Into a simulation that looks more like this, with the ultimate result of an accurate forecast.  IFP allows us to make these adjustments fairly efficiently.

## Model Adjustments (Run-time mods)

- Forecasters have the ability to adjust ...
- Any value(s) in any time series (TSCHNG)
- Timing/magnitude of rain-melt time series (RRICHNG, RRIMULT)
- Timing/magnitude of runoff time series (ROCHNG, ROMULT)
- Condition of snow pack (AESCCHNG, WEADD, WECHNG, MFC)
- SAC-SMA model states (SACCO, SACBASEF)
- Typing of precip (RAINSNOW)
- Unit hydrograph ordinates (UHGCHNG)
- Etc.

**Notes:**
Just a few of the run-time modifications at our disposal ...

## Communication / Collaboration

- We depend on one another – communication is important.
- Each forecaster is responsible for a basin that is either upstream or downstream of another.
- Many RFCs either accept input from or provide model output to another RFC.
- Reservoir operations affect forecasts and vice-versa.

**Notes:**
We cannot over-stress the importance of communication to the forecast process.  Within the office, the river forecasters depend on the HAS forecasters to provide accurate input.  Also, each river forecaster is managing models that affect another forecaster downstream or vice-versa.  Some RFCs also depend on other RFCs ... for instance we have 5 RFCs handling portions of the Mississippi basin.  We depend on information provided by agencies operating reservoirs like USBR and USACE and they depend on our forecasts to decide how they will operate their reservoirs.  We also rely on the USGS for streamflow and rating curve information and they use our forecasts to decide where to take measurements.  So communication is extremely important.

## Forecast Services Provided

- Short-term or long-range
- Deterministic or probabilistic
- Text or graphical
- Coded or narrative

**Notes:**
Some examples of the types of forecast services we provide.  To re-iterate, our products fall into the following categories ...

## Short-term forecasts  

**RIVER FORECAST**
** ****NATIONAL WEATHER SERVICE**
** ****MISSOURI BASIN RFC - PLEASANT HILL, MO**
** ****2116Z Thu Feb  6 2003**
** **
** ****==> This forecast includes obsd precip & 24 hours of QPF <==**
** **
** **
** ****RIVER/STATION            FS     TDY     F O R E C A S T**
** **
** ****LITTLE BLUE R       **
** ****LAKE CITY MO           18.0    3.9    CREST NR 20.5 FT 2/7 NOON**
** **
** **
** ****LAKE CITY MO         LITTLE BLUE R         EAX  FS 18.0 FT    FIS 16.0 FT **
** **
** ****.E  LKCM7    0206 DH00/HGIRX/DIH06/  :6-hour observed stages (ft)**
** ****.E1    3.9/  3.9/  3.9/  3.9 **
** ****.A  LKCM7    0207 DC02062116/DM020718/HGIFFX 20.5 FT  :crest forecast (ft)**
** ****.E  LKCM7    0207 DC02062116/DH00/HGIFF/DIH06/  :6-hour forecast stages (ft)**
** ****.E1    3.9/  6.0/ 15.0/  20.5/ 16.0/  9.9/  4.8/  4.2/  4.0/  3.9**
** ****.E1 /  3.9/  3.9/  3.9/  3.9/  3.9/  3.9/  3.9/  3.9/  3.9/  3.9**
** **
** ****$$**
** **
** ****Forecaster:  Cox **

**Notes:**
Here is an example of a short-term forecast, in this case 5 days.  Again, I’m not sure if you can read this.  It includes a narrative portion and a SHEF-coded portion, forecast time series and crest forecast.  We use a program outside of OFS to generate forecasts such as this that reads information from the processed database of OFS, but still allows intervention by the forecaster.

## Reservoir inflow forecasts

-  **UPPER MISSOURI BASIN FORECAST**
** ****NWS/MISSOURI BASIN RFC - PLEASANT HILL, MO**
** ****1509Z Fri Jul 12 2002**
** **
** ****==> This forecast includes obsd precip & 12 hours of QPF <==**
** **
** ****NOTE:  Last routine 5-day inflow forecasts for this season**
** **
** **
** ****CANYON FERRY RES MT            MISSOURI R**
** ****.E  CYNM8    0711 /DH18/QIIRX/DIH6/   2.75 /   2.70 /   2.70 /   2.72 :observed**
** ****.E  CYNM8    0712 DC07121509/DH18/QIIFF/DIH6/        :forecast inflows in kcfs:**
** ****.E1     2.79/  2.84/  2.89/  2.90/  2.93/  2.94/  2.93/  2.91/  2.89/  2.88**
** ****.E1  /  2.86/  2.85/  2.84/  2.82/  2.81/  2.80/  2.79/  2.77/  2.76/  2.75**
** **
** **
** ****TIBER RES MT                   MARIAS R**
** ****.E  TBRM8    0711 /DH18/QIIRX/DIH6/   2.41 /   2.38 /   2.34 /   2.30 :observed**
** ****.E  TBRM8    0712 DC07121509/DH18/QIIFF/DIH6/        :forecast inflows in kcfs:**
** ****.E1     2.30/  2.27/  2.21/  2.14/  2.08/  2.02/  1.96/  1.93/  1.91/  1.89**
** ****.E1  /  1.87/  1.85/  1.83/  1.81/  1.79/  1.77/  1.75/  1.73/  1.72/  1.70**
** **
** ****Forecaster:  Meyer**

**Notes:**
Here are examples of inflow forecasts for two reservoirs in Montana, in this case going out 5 days into the future.  6-hourly SHEF-coded time series are provided with units are in KCFS.  These forecasts are provided to the operating agencies such as the USBR and USACE for their decision-making process.

## Extended forecasts & outlooks

- low-flow, spring snowmelt, navigation

**ESGSD**
** **
**                  ****NATIONAL WEATHER SERVICE UPPER MIDWEST **
**                      ****SPRING SNOWMELT FLOOD OUTLOOK**
** **
**                ****SIOUX FALLS, SOUTH DAKOTA     FEB 21, 2001**
** **
**TABLE LEGEND**
** ****/l/ PRESENT WATER IN SNOW AND ASSESSED RUNOFF POTENTIAL.**
** ****/2/ NORMAL PCPN TO NORMAL DATES OF SNOW DISAPPEARANCE IS ADDED TO /1/.**
** **
**                                        ****OUTLOOK CRESTS**
**                              ****FLOOD    W.E.    NORM     PREVIOUS RECORD STAGE**
**STREAM/STATION       HB5ID    STAGE    ONLY    PCPN     STAGE   DATE  COMMENT**
**                                        ****/1/     /2/**
**JAMES R**
** ****HURON SD            HURS2    11.0     16.5    18.5      21.3  040597**
** ****FORESTBURG SD 4SE   FORS2    12.0     16.0    18.5      20.7  040897**
** ****MITCHELL SD         MCHS2    14.0     19.5    20.5      23.1  040797**
** ****SCOTLAND SD         SCOS2    13.0     17.0    19.0      20.5  062384**
**BIG SIOUX R**
** ****BROOKINGS SD LOSE   BRKS2     9.0      6.5    10.0      14.8  040969**
** ****SIOUX FALLS SD 38A  SFLS2    12.O     10.0    12.0      19.8  041069**
** ****HAWARDEN IA         HAWI4    15.0      9.0    16.0      24.9  051093**
** ****AKRON IA 1NW        AKRI4    16.0     10.0    16.5      23.0  051093**
** **
** ****END MBRFC**

**Notes:**
We also provide extended range forecasts and outlooks in various forms.  This is an example of a spring snowmelt outlook product.  These crest estimates are derived utilizing OFS for 90 forecast days.  Now you can only run OFS for up to 31 days at a time, so this requires 3 separate executions for the entire Missouri Basin.  These types of products are slowly being replaced by the probabilistic products generated using the Ensemble Streamflow Prediction (ESP) System.  This is occurring as part of AHPS implementation.

## Long-Range Probabilistic Outlooks (AHPS)

**Notes:**
Speaking of AHPS.  This is an example of a trace ensemble produced by ESP, one hydrograph trace for each year of historical data.  Each of these is a simulated hydrograph assuming current model conditions and driven by the precipitation and temperature patterns that occurred in that given year.  

## Long-Range Probabilistic Outlooks (AHPS)

**Notes:**
Another AHPS product ... this one an exceedance probability graph of stage for the Yellowstone River at Billings, MT. This one spans the entire water supply season from Feb 21 thru the end of Sep.  So what this product represents is the chance that a particular stage will be equaled or exceeded at any time during that period ... Feb thru Sep.

## Flash Flood Guidance

- “The amount of rainfall required over a specified duration to initiate flooding on small streams”
- A by-product of river forecast operations
- Utilizes both OFS and the FFGS (Flash Flood Guidance System)
- Provided twice a day for grids, counties, and specific headwater areas
- Text and Graphical
- Durations of 1, 3, and 6 hours

**Notes:**
Finally, another aspect of NWSRFS is the Flash Flood Guidance System (FFGS).  RFCs provide Flash Flood Guidance to WFOs as a guide to when flash flood watches and warnings should be issued.  It really is a by-product of our forecast operations.  We provide it twice a day in a gridded form, as well as county averages, and for specific headwater areas, for rainfall durations of 1, 3, and 6 hours.

## Gridded FFG

**Notes:**
And here is a sample graphic depicting gridded flash flood guidance over the Missouri basin, in this case for the 3-hour duration.  This gridded guidance is the input to the FFMP program that you saw demonstrated earlier.

## Thank you for your attention.

**Notes:**
Well that’s all I have and I thank you for your attention.  Do we have any questions?  Tomorrow morning you will be visiting our office in Pleasant Hill.  It’s about 50 miles from here.  A lot of this will probably make more sense to you when you see it demonstrated first-hand.