Page 1 GAO-13-559R Post-Storm Assessments

441 G St. N.W.

Washington, DC 20548

July 11, 2013

Congressional Committees

NOAA: Initial Response to Post-Storm Assessment Requirements

After a hurricane, assessing damage caused by different perils, such as high winds or flooding, 

is especially challenging when all that is left after the storm is a structure’s foundation. For these 

properties, there may not be enough physical evidence to determine the extent to which 

damage was caused by wind versus flooding. Private property-casualty insurers typically cover 

wind damage but exclude coverage for flood damage. The National Flood Insurance Program, 

administered by the Department of Homeland Security’s Federal Emergency Management 

Agency (FEMA), provides federally backed coverage for flood damage. After the hurricane 

season in 2005, legal disputes arose between private property-casualty insurers and 

policyholders over interpretation of policy language that excluded coverage of damage caused 

concurrently or sequentially by a covered peril—wind—and an excluded peril—flooding.

The Consumer Option for an Alternative System to Allocate Losses Act of 2012 (COASTAL 

Act)1 addresses the compilation and use of scientific data to help FEMA allocate losses related 

to wind and flooding after major storms for certain properties. The act requires the Department 

of Commerce's National Oceanic and Atmospheric Administration (NOAA) to generate poststorm assessments within 90 days of certain tropical storms or hurricanes for FEMA’s use in a 

standard formula for allocating such losses.

2 To generate the post-storm assessments, NOAA is 

required by the COASTAL Act to develop a post-storm model by regulation by December 28, 

2013, that replicates wind speeds, storm surge heights, and other measurements for these 

storms. The act requires a certain degree of accuracy for both the post-storm assessment and 

post-storm model. For example, the post-storm model must be designed to generate post-storm 

assessments that have a degree of accuracy of not less than 90 percent for every specific 

property loss for which it is utilized. The act does not define 90 percent accuracy and does not 

specify how to measure it.

 1

Pub. L. No. 112-141, Div. F, Tit. II, Subtit. B, 126 Stat. 405, 969 (2012).

2

Specifically, the act requires NOAA to generate these assessments for “named” storms that the NOAA 

Administrator, in consultation with the Secretary of Homeland Security, determines may reasonably constitute a 

threat to any portion of a coastal state. The act defines a named storm as any organized weather system with a 

defined surface circulation and maximum winds of at least 39 miles per hour that NOAA’s National Weather Service 

names a tropical storm or hurricane. According to NOAA officials, the act did not fully capture the official NOAA 

criteria used when categorizing and naming tropical storms and hurricanes (i.e., tropical cyclones), which requires 

maximum sustained winds of 39 miles per hour or greater. NOAA officials told us that the agency will continue to 

follow its criteria in naming these types of storms. A coastal state is defined as a U.S. state in, or bordering on, the 

Atlantic, Pacific, or Arctic Ocean, the Gulf of Mexico, Long Island Sound, or one or more of the Great Lakes and 

includes the U.S. territories.
Page 2 GAO-13-559R Post-Storm Assessments

NOAA, in consultation with the Office of the Federal Coordinator for Meteorology (OFCM),3 also 

is to identify federal and state efforts, as well as domestic private and academic efforts, that are 

capable of collecting the weather data (i.e., covered data) necessary to develop the post-storm 

model and assessment, evaluate their coverage gaps, and report to Congress a plan for 

collecting the covered data.4

The act mandates GAO to audit federal efforts to collect covered data.5 During our review,

NOAA was in the process of developing the post-storm model and determining which data 

collection efforts would be required. Based on discussions with the relevant committees, we 

determined our objectives were to examine (1) storm data collection efforts that NOAA has 

identified that may provide the covered data for the COASTAL Act storm model and (2) the 

extent to which selected federal agencies collect cost information on their storm data collection 

efforts. On May 29, 2013, we briefed you (see encl. I) on our overall findings, which are also 

reflected in this report, concerning federal efforts to collect covered data to address the 

mandate.

To examine storm data collection efforts that NOAA has identified, we reviewed COASTAL Act 

planning documents from an interagency work group that included NOAA and other agencies—

the Department of the Interior’s U.S. Geological Survey (USGS), the U.S. Army Corps of 

Engineers (the Corps), the National Aeronautics and Space Administration (NASA), and FEMA.

We interviewed officials from NOAA and these other agencies, as well as the Department of 

Homeland Security’s U.S. Coast Guard and OFCM. We also interviewed representatives from a 

university, a nonprofit organization, and a private company about their storm data collection 

efforts because they were identified in the COASTAL Act planning documents and during 

interviews with the federal agencies.

To examine the extent to which selected agencies collect cost information on their storm data 

collection efforts, we selected NOAA and USGS to focus on because these agencies had 

certain data collection efforts that agency officials told us would likely be an important source of 

covered data. We reviewed budget and financial documentation for fiscal years 2012 and 2013

provided by NOAA and USGS for their storm data collection efforts. We also interviewed agency 

officials from these two agencies to identify the type of cost information available for these 

agencies’ storm data collection efforts.

We conducted this performance audit from September 2012 to July 2013 in accordance with 

generally accepted government auditing standards. Those standards require that we plan and 

perform the audit to obtain sufficient, appropriate evidence to provide a reasonable basis for our 

findings and conclusions based on our audit objectives. We believe that the evidence obtained 

provides a reasonable basis for our findings and conclusions based on our audit objectives.

 3

OFCM is an interdepartmental office, within the Department of Commerce, established in 1964 to coordinate federal 

meteorological activities among various agencies.

4

Covered data are defined by the act as data collected before, during, or after named storms and necessary to 

determine magnitude and timing of wind speeds, rainfall, barometric pressure, and river flows; the extent, height, and 

timing of storm surge; topographic (land shape) and bathymetric (ocean depth) data; and other measures.

5

Pub. L. No. 112-141, Div. F, Tit. II, Subtit. B, § 100252, 126 Stat. 405, 974 (2012). The act requires GAO to submit a 

report on its audit findings by July 6, 2013 (1 year after enactment of the act).
Page 3 GAO-13-559R Post-Storm Assessments

In summary, NOAA, in consultation with OFCM and other agencies, has identified federal and 

nonfederal storm data collection efforts that may provide the covered data for the COASTAL Act 

storm model. However, NOAA officials told us they will not know which specific efforts will be 

used until they develop the post-storm model. According to agency officials and representatives 

from nonfederal entities, efforts that can collect surface level water, wave, and wind 

measurements over land will likely provide important sources of data for the model. NOAA and 

USGS, as well as some nonfederal entities such as universities and private companies, 

currently collect some surface level data on wind and water. However, these officials and 

representatives said current efforts may not be sufficient for the model to achieve the highly 

accurate estimates needed for individual structures in all locations. For example, USGS officials

said they may not have enough mobile, temporary water level sensors to deploy in locations 

along the Atlantic Coast for measuring storm tide.

6 Moreover, officials from NOAA, USGS, and 

the Corps told us that current efforts do not measure certain types of data that likely will be 

needed to model wind and water impacts on individual structures. These officials said that, in 

particular, data on waves that occur over land on top of the storm surge are critical for 

assessing water damage to structures from tropical storms and hurricanes but are not currently 

collected. NOAA officials told us that, among their next steps in planning for meeting the 

requirements of the COASTAL Act, the agency will be examining how to fill the gaps they 

identified in current storm data collection efforts.

The selected agencies we reviewed—NOAA and USGS—do not typically collect cost 

information on specific types of storm or weather data, such as wind speed, that reflects the 

expense for all activities involved in collecting and using the data. Officials from NOAA and 

USGS told us that their storm data collection efforts typically collect multiple types of storm or 

weather data and that the costs for processing, analyzing, and storing the data are calculated 

for all data types rather than a single one. Agencies then incorporate the cost information they 

do collect on their storm data collection efforts into the costs of major programs and projects, 

such as responding to a major hurricane. For example, one NOAA official said cost information 

is collected under the agency’s Tides and Currents program for all data collected by the 

National Water Level Observation Network (NWLON) and another effort called the Physical 

Oceanographic Real-Time System (PORTS). NWLON collects water level data at the U.S. 

coastline and PORTS collects water and weather data in some U.S. ports and harbors. In 

addition, USGS officials told us they collected detailed cost information on activities related to 

collecting data on storm tide, barometric pressure, and high water mark levels during Hurricane 

Sandy. NOAA officials said that, as a next step in its COASTAL Act planning, the agency plans 

to prepare a resource analysis that is to, in part, identify some of the additional resources 

needed to fill gaps in storm data collection efforts. At the time of our review, a NOAA official told 

us that the agency did not know when the resource analysis would be completed because the 

agency officials involved in COASTAL Act planning were still deliberating on the post-storm 

model and the data collection efforts that will be required for this model.

We are not making any recommendations in this report.

 6

USGS installs these sensors along the shoreline and a short distance inland to supplement permanent water level 

sensors. According to USGS officials, there are 300 sensors distributed among USGS offices in most of the coastal 

states to facilitate rapid deployment 48 to 24 hours prior to a major storm’s landfall. Storm tide is water level rise due 

to the combination of storm surge and the normal high tide.
Page 4 GAO-13-559R Post-Storm Assessments

Agency Comments

We provided a draft of this report to officials from the Departments of Commerce, Defense, 

Homeland Security, and the Interior; NASA; and OFCM for their review and comment.

Commerce and the Interior provided technical comments, which we incorporated as 

appropriate. The other agencies we reviewed had no comments.

--- --- --- --- ---

We are sending copies of this report to the Secretaries of Commerce, Defense, Homeland 

Security, and the Interior; the Administrator of NASA; the Federal Coordinator for Meteorology;

the appropriate congressional committees; and other interested parties. In addition, the report is 

available at no charge on the GAO website at http://www.gao.gov.

If you or your staff members have any questions concerning this report, please contact me at 

(202) 512-3841 or fennella@gao.gov. Contact points for our Offices of Congressional Relations 

and Public Affairs may be found on the last page of this report. GAO staff who made key 

contributions to this report are listed in enclosure II.

Anne-Marie Fennell

Director, Natural Resources and Environment

Enclosures—II
Page 5 GAO-13-559R Post-Storm Assessments

List of Committees

The Honorable Tim Johnson

Chairman

The Honorable Mike Crapo

Ranking Member

Committee on Banking, Housing, and Urban Affairs

United States Senate

The Honorable Jay Rockefeller

Chairman

The Honorable John Thune

Ranking Member

Committee on Commerce, Science, and Transportation

United States Senate

The Honorable Jeb Hensarling

Chairman

The Honorable Maxine Waters

Ranking Member

Committee on Financial Services

House of Representatives

The Honorable Lamar Smith

Chairman

The Honorable Eddie Bernice Johnson

Ranking Member

Committee on Science, Space, and Technology

House of Representatives
Page 6 GAO-13-559R Post-Storm Assessments

Enclosure I

Briefing on NOAA: Initial Response to Post-Storm Assessment Requirements

NOAA: Initial Response to Post-Storm 

Assessment Requirements

Briefing for Congressional Committees

May 29, 2013, revised June 28, 2013

Page 1
Page 7 GAO-13-559R Post-Storm Assessments

Introduction

• Hurricanes pose challenges for insurers and property owners because they cause 

damage from multiple perils, such as high winds and flooding. Assessing such damage 

is especially challenging when all that is left after the storm is a structure’s foundation. 

For these properties, there may not be enough physical evidence to determine the 

extent to which damage was caused by wind versus flooding.

• Private property-casualty insurers typically cover wind damage but exclude coverage 

for flood damage. The National Flood Insurance Program (NFIP), administered by the 

Federal Emergency Management Agency (FEMA), provides federally backed coverage 

for flood damage.

• After the hurricane season in 2005, legal disputes arose between private propertycasualty insurers and policyholders over interpretation of policy language that 

excluded coverage of damage caused concurrently or sequentially by a covered 

peril—wind—and an excluded peril—flooding.

Page 2
Page 8 GAO-13-559R Post-Storm Assessments

Introduction

(Continued)

• The Consumer Option for an Alternative System to Allocate Losses Act of 2012 

(COASTAL Act)1 addresses the compilation and use of scientific data to help FEMA 

allocate losses related to wind and flooding after major storms for certain properties 

(i.e., indeterminate losses). 

• Under the act, indeterminate losses are those arising from flooding and wind 

associated with a named storm where an adjuster certified under the NFIP,2 in 

consultation with an engineer, as appropriate, determines for that specific property 

there (1) are no material remnants except the building foundation and (2) is insufficient 

or no tangible evidence as a result of the named storm. 

Page 3

1The act was enacted along with other provisions reauthorizing and reforming the NFIP within the Moving Ahead for Progress in the 21st Century 

Act. Pub. L. No. 112-141, Div. F, Tit. II, Subtit. B, 126 Stat. 405, 969 (2012).

2Specifically, the act defines a “named storm” as any organized weather system with a defined surface circulation and maximum winds of at least 

39 miles per hour that the National Weather Service of the National Oceanic and Atmospheric Administration (NOAA) names a tropical storm or 

hurricane. According to NOAA officials, the act did not fully capture the official NOAA criteria used when categorizing and naming tropical storms 

and hurricanes (i.e., tropical cyclones), which requires maximum sustained winds of 39 miles per hour or greater. NOAA officials told us that the 

agency will continue to follow its criteria in naming these types of storms.
Page 9 GAO-13-559R Post-Storm Assessments

Introduction

(Continued)

• The act requires that the Department of Commerce's National Oceanic and 

Atmospheric Administration (NOAA) generate post-storm assessments within 90 days 

of a named tropical storm or hurricane that the NOAA Administrator, in consultation 

with the Secretary of Homeland Security, determines may reasonably constitute a 

threat to any portion of a coastal state, including U.S. territories.3 

• Under the act, NOAA must ensure, to the greatest extent practicable, that each poststorm assessment has a degree of accuracy of not less than 90 percent. In addition, 

the NOAA Administrator is to certify the degree of accuracy for each post-storm 

assessment, including specific reference to any segments or geographic areas for 

which the assessment is less than 90 percent accurate.

Page 4

3Specifically, a coastal state is defined as a U.S. state in, or bordering on, the Atlantic, Pacific, or Arctic Ocean, the Gulf of Mexico, Long Island 

Sound, or one or more of the Great Lakes. In addition, the definition of a coastal state includes Puerto Rico and the other U.S. territories. 
Page 10 GAO-13-559R Post-Storm Assessments

Introduction

(Continued)

• To generate post-storm assessments, the act requires NOAA to develop by regulation 

a post-storm model that replicates wind speeds, storm surge heights, and other 

measurements for the designated named storm. The post-storm model must be 

designed to generate post-storm assessments that have a degree of accuracy of not 

less than 90 percent for every indeterminate loss for which it is utilized. 

• NOAA also is to identify federal and state efforts, as well as domestic private and 

academic efforts, that are capable of collecting the weather data (i.e., covered data) 

necessary to develop the post-storm model and assessment, evaluate their coverage 

gaps, and report to Congress a plan for collecting the covered data.

• The act further requires FEMA, in consultation with NOAA, to establish by rule a 

standard formula to determine and allocate wind losses and flood losses for claims 

involving indeterminate losses that uses NOAA’s post-storm assessment; however, 

FEMA can only use the post-storm assessment if NOAA certifies that it has a degree of 

accuracy of not less than 90 percent in connection with the specific indeterminate loss 

for which the assessment and formula are used. 

Page 5
Page 11 GAO-13-559R Post-Storm Assessments

Objectives

• The COASTAL Act mandates GAO to audit federal efforts to collect covered data. 

• The act mandates GAO to submit a report on its audit findings by July 6, 2013, to the 

Committees on Banking, Housing, and Urban Affairs and on Commerce, Science, and 

Transportation of the U.S. Senate; and the Committees on Financial Services and on 

Science, Space, and Technology of the House of Representatives. 

• During the course of our work, NOAA was still in the process of developing the poststorm model and determining which data collection efforts would be required. Based 

on discussions with the cognizant congressional committees, we determined our 

objectives were to examine

• storm data collection efforts that NOAA has identified that may provide the covered 

data for the COASTAL Act storm model, and 

• the extent to which selected federal agencies collect cost information on their storm 

data collection efforts.

Page 6
Page 12 GAO-13-559R Post-Storm Assessments

Scope and Methodology

To examine storm data collection efforts that NOAA has identified that may provide 

the covered data for the COASTAL Act storm model:

• We reviewed COASTAL Act planning documents from an interagency work group that 

included NOAA and other agencies—the U.S. Geological Survey (USGS), U.S. Army 

Corps of Engineers (the Corps), and National Aeronautics and Space Administration 

(NASA)—with which the act required NOAA to consult. Among the documents we 

reviewed were descriptions that officials compiled on the agencies’ observing systems 

(referred to in this review as data collection efforts).

• We interviewed officials from NOAA and the other agencies identified above, as well as 

FEMA, the U.S. Coast Guard, and the Office of the Federal Coordinator for 

Meteorology (OFCM), with which the act also required NOAA to consult.4 In addition to 

the agencies identified in the COASTAL Act, we interviewed representatives from a 

university, a nonprofit organization, and a private company about their storm data 

collection efforts because they were identified in the COASTAL Act planning 

documents and during interviews with the federal agencies. 

Page 7

4OFCM is an interdepartmental office, within the Department of Commerce, established in 1964 to coordinate federal meteorological activities among 

various agencies. 
Page 13 GAO-13-559R Post-Storm Assessments

Scope and Methodology

(Continued)

To examine the extent to which selected agencies collect cost information on their 

storm data collection efforts: 

• We selected NOAA and USGS to focus on because in examining objective 1, we found 

that these agencies had certain data collection efforts that agency officials told us 

would likely be an important source of covered data. 

• We reviewed budget and financial documentation for fiscal years 2012 and 2013 

provided by NOAA and USGS for these storm data collection efforts.

• We interviewed agency officials from NOAA and USGS to identify the type of cost 

information available for these agencies’ storm data collection efforts.

Page 8
Page 14 GAO-13-559R Post-Storm Assessments

Scope and Methodology

(Continued)

• Officials from the Departments of Commerce, Defense, Homeland Security, and the 

Interior; NASA; and OFCM reviewed a draft version of this presentation for factual 

accuracy. Commerce and the Interior provided technical clarifications, which we 

incorporated as appropriate.

Page 9
Page 15 GAO-13-559R Post-Storm Assessments

Summary of Findings

• NOAA, in consultation with OFCM and other agencies, has identified federal and 

nonfederal storm data collection efforts that may provide the covered data for the 

COASTAL Act storm model. However, NOAA officials told us they will not know which 

specific efforts will be used until they develop the model. According to agency officials 

and representatives from nonfederal entities, efforts that can collect surface level water, 

wave, and wind measurements over land will likely provide important sources of data 

for the model. However, these officials and representatives said current surface level 

data collection efforts may not be sufficient for the model to achieve the highly accurate 

estimates needed for individual structures in all locations. For example, data are not 

currently collected on waves that occur over land on top of the storm surge.

• The selected agencies we reviewed—NOAA and USGS—do not collect cost 

information on specific types of storm data, such as wind speed or storm surge. Agency 

officials said their data collection efforts typically collect multiple types of storm or 

weather data, and cost information on these efforts is calculated for all data collected. 

The agencies then incorporate the cost information they collect on these efforts into the 

costs of major programs and projects, such as responding to a major hurricane. 

Page 10
Page 16 GAO-13-559R Post-Storm Assessments

Background

• As shown in figure 1, the COASTAL Act contains a number of requirements and 

deliverables for NOAA and FEMA to help FEMA establish a standardized loss 

allocation system for evaluating wind and water losses. 

• NOAA’s post-storm model (Named Storm Event Model) is a key requirement because 

it will be used to generate the post-storm assessments. 

• The post-storm model must be designed to generate post-storm assessments that 

have a degree of accuracy of not less than 90 percent for every indeterminate loss for 

which it is utilized. The act does not define 90 percent accuracy and does not specify 

how to measure it.

• According to NOAA officials, developing a model that can replicate storm 

measurements for an individual structure with not less than 90 percent accuracy 

represents a scientific and technical challenge because the agency does not currently 

possess the capability to model with this level of detail.

Page 11
Page 17 GAO-13-559R Post-Storm Assessments

PRELIMINARY

The Consumer Option for an Alternative System to Allocate Losses Act of 2012 (COASTAL Act) 

was enacted, along with other provisions reauthorizing and reforming, the National Flood 

Insurance Program within the Moving Ahead for Progress in the 21st Century Act.

Page 12

The National Oceanic and Atmospheric Administration (NOAA), in consultation with the Office of the 

Federal Coordinator for Meteorology (OFCM), must identify all federal and state efforts and systems 

as well as domestic private and academic systems that are capable of collecting covered data (not 

later than 180 days after enactment).

NOAA must establish a database—called the Coastal Wind and Water Event Database—for the 

collection and compilation of covered data (not later than 1 year after enactment).

NOAA, in consultation with OFCM, must submit to Congress a plan for collecting the covered data 

necessary to develop the storm model and post-storm assessment, including any coverage gaps in 

the identified systems (not later than 270 days after enactment).

NOAA must develop a post-storm model—called the Named Storm Event Model—by regulation and 

a protocol for collecting and assembling the covered data (not later than 540 days after enactment).

The Federal Emergency Management Agency (FEMA), in consultation with NOAA, must establish 

by rule a standard formula—called the COASTAL Formula—to determine and allocate wind losses 

and flood losses for claims involving indeterminate loss properties. Along with other information, the 

COASTAL Formula must use NOAA’s post-storm assessment, if NOAA certifies that it has a degree 

of accuracy of not less than 90 percent in connection with the specific indeterminate loss for which 

the assessment and formula are used (not later than 180 days after NOAA establishes the protocol 

for collecting and assembling the covered data for the database).

July 6, 2012

January 2, 2013

April 2, 2013

July 6, 2013

December 28, 2013

June 26, 2014

FEMA must submit the COASTAL Formula to the National Academy of Sciences for evaluation; the 

National Academy will submit a report on this evaluation to congressional committees (upon 

issuance of the rule establishing the COASTAL Formula and any subsequent amendments).

Note: After FEMA establishes the COASTAL Formula, by rule, the NOAA Administrator, in consultation with the Secretary of Homeland Security, is required to identify named storms that may reasonably constitute a threat to any portion of a coastal state, as defined in the act (which includes U.S. territories). In addition, not later than 90 days after the identification of a named storm, NOAA must submit the post-storm assessment to the Secretary of Homeland Security.

Source: GAO analysis of the COASTAL Act.

Background (continued)

Figure 1: Timeline of COASTAL Act Requirements
Page 18 GAO-13-559R Post-Storm Assessments

Background

(Continued)

• Under the act, NOAA’s post-storm model must use covered data to replicate the 

condition of winds and water for a designated named tropical storm or hurricane.

• Covered data are specified in the act as data collected before, during, or after 

designated named storms and necessary to determine magnitude and timing of wind 

speeds, rainfall, barometric pressure, and river flows; the extent, height, and timing of 

storm surge; topographic (land shape) and bathymetric (ocean depth) data; and other 

measures.

• In addition to NOAA, a number of federal agencies collect weather data for diverse 

agency purposes. The act directs NOAA to consult with certain of these agencies—

including USGS, the Corps, and NASA, among others—to coordinate the collection 

and maintenance of covered data and establish a process to share information 

regarding the covered data. 

Page 13
Page 19 GAO-13-559R Post-Storm Assessments

Background

(Continued)

• In September 2012, OFCM established an interagency work group, co-chaired by 

NOAA, USGS, and the Corps, to help NOAA identify federal and nonfederal data 

collection efforts for purposes of the COASTAL Act. NOAA also solicited input from 

academic, state, and private entities. 

• In consultation with the interagency work group, NOAA and OFCM developed a 

COASTAL Act Capabilities Development Plan to describe NOAA’s approach for 

addressing the requirements of the act. At the time of our review, NOAA officials told us 

that the agency’s senior leadership was reviewing the plan and the agency had not yet 

submitted the plan to Congress. Because it is unknown how long the entire clearance 

process will take, program officials do not know when the plan will be submitted to 

Congress.

• The plan identifies, among other things, the types of data it may need for its post-storm 

model. It also provides an inventory of federal and nonfederal weather data collection 

efforts that currently may collect the covered data at various levels of detail. 

Page 14
Page 20 GAO-13-559R Post-Storm Assessments

Objective 1: Storm Data Collection Efforts

NOAA has identified storm data collection efforts that may provide the covered data 

for the post-storm model.

• NOAA, in consultation with OFCM and the other agencies in the interagency work 

group, identified a range of data collection efforts that may provide the covered data. 

• These included data collection efforts by at least six federal agencies, as well as 

nonfederal entities. These efforts collect weather data on the ground and in water, as 

well as from sensors dropped from airplanes and positioned on satellites. For example, 

some NOAA airplanes fly into the eye of a hurricane and drop sensors to collect wind 

and other types of weather data.

• NOAA officials told us that the agency will not know which specific data collection 

efforts will be used or whether additional efforts would be needed until the agency 

develops the post-storm model. However, according to NOAA officials, there will be 

gaps in current data collection efforts. These gaps are discussed in more detail later in 

these slides.

Page 15
Page 21 GAO-13-559R Post-Storm Assessments

Objective 1: Storm Data Collection Efforts

(Continued)

Surface Level Data Collection Efforts 

• According to agency officials and representatives from nonfederal entities we spoke 

with, data collection efforts that can provide surface level water, wave, and wind 

measurements over land will likely provide important data for the post-storm model. 

• These efforts will be important because the post-storm model will require 

measurements of water, wave, and wind data analyzed at regularly spaced time 

intervals (i.e., time series) as near as possible to the location of indeterminate loss 

structures. 

• NOAA and USGS, as well as some nonfederal entities, such as universities and 

private companies, currently collect some surface level data on wind and water. 

• The following two slides provide examples of surface level data collection efforts. 

Page 16
Page 22 GAO-13-559R Post-Storm Assessments

Objective 1: Storm Data Collection Efforts

(Continued)

• NOAA National Water Level Observation 

Network (NWLON): These are permanent 

observing stations that, among other things, 

collect water level data at the coastline (see 

fig. 2). There are currently 210 NWLON 

stations nationwide, and 91 of these are 

located in states along the Gulf or East 

Coasts, as well as Puerto Rico and the U.S. 

Virgin Islands.

• USGS Mobile Storm Tide Networks: 

These are mobile, temporary water level 

sensors that are installed along the shore 

line and a short distance inland (see fig. 3). 

There are 300 sensors distributed among 

USGS offices in most of the coastal states 

to facilitate rapid deployment 48 to 24 hours 

prior to a major storm’s landfall. These 

sensors supplement permanent water level 

sensors.

Page 17

Figure 2: National Water 

Level Observation 

Network Station

Figure 3: U.S. 

Geological Survey 

(USGS) Storm Tide 

Sensor Deployed Prior 

to Hurricane Irene

Source: National Oceanic and 

Atmospheric Administration/

National Ocean Service/Center 

for Operational Oceanographic 

Products and Services.

Source: USGS/Photographer 

Kristen McSwain.
Page 23 GAO-13-559R Post-Storm Assessments

Objective 1: Storm Data Collection Efforts

(Continued)

• NOAA Automated Surface Observing 

Systems (ASOS): This is a network of 

about 1,000 permanent stations located 

primarily at airports and operated jointly with 

the Federal Aviation Administration and 

Department of Defense (see fig. 4). ASOS 

stations measure wind speed and other 

weather data. There are about 145 stations 

located in coastal counties in the states 

along the Gulf and East Coasts, as well as 

Puerto Rico and U.S. Virgin Islands.

• Digital Hurricane Consortium Deployable 

Sensors: This is a network of mobile, 

temporary sensors, such as tripods called 

“StickNets,” that collect wind speed and 

other weather data (see fig. 5). They are 

operated by a group of universities primarily 

in the Gulf Coast and Florida. These 

sensors are deployed on land at the 

expected location of a storm’s landfall and 

aim to collect the highest wind speed. 

Page 18

Figure 5: Texas 

Tech 

University’s 

“StickNet” 

Tripod

Figure 4: 

Automated 

Surface 

Observing

Systems 

Station

Source: National 

Oceanic and 

Atmospheric 

Administration.

Source: Texas Tech 

University.
Page 24 GAO-13-559R Post-Storm Assessments

Objective 1: Storm Data Collection Efforts

(Continued)

Gaps in Surface Level Data Collection Efforts 

• According to agency officials and representatives from nonfederal entities we spoke 

with, current surface data collection efforts may not be sufficient for the post-storm 

model to achieve the highly accurate estimates needed for individual structures in all 

locations. 

• For example, NOAA officials told us that wind speed sensors in ASOS are not 

designed to measure wind speeds greater than 190 miles per hour, which are the 

sustained wind speeds observed in the most severe category of hurricanes (i.e., 

Category 5). In addition, ASOS platforms are sometimes damaged or destroyed in 

major hurricanes. Furthermore, power failures during major storms often result in data 

losses from ASOS platforms. NOAA has been working to provide uninterrupted power 

supplies to a subset of ASOS stations located in hurricane-prone areas.

Page 19
Page 25 GAO-13-559R Post-Storm Assessments

Objective 1: Storm Data Collection Efforts

(Continued)

• In addition, according to USGS officials, they may not have enough mobile storm tide 

sensors to deploy along the Atlantic Coast. Because tracking the location of hurricane 

landfall along the Atlantic Coast is more challenging than for storms approaching the 

Gulf Coast, the officials explained that the agency may need more sensors available in 

more locations along the Atlantic Coast.

• Further, NOAA officials told us storm data collection capabilities in the U.S. territories in 

the Caribbean and Pacific basins are extremely limited. The officials said that some 

locations may have only one or two storm data collection stations, and would need 

additional stations to adequately collect data on named storms in these locations. 

Page 20
Page 26 GAO-13-559R Post-Storm Assessments

Objective 1: Storm Data Collection Efforts

(Continued)

• Officials from NOAA, USGS, and the Corps told us that current surface level data 

collection efforts do not measure certain types of data that likely will be needed to 

model wind and water impacts on individual structures. In particular, data on the action 

of waves that occur over land on top of the storm surge are critical for assessing water 

damage to structures from tropical storms and hurricanes but are not currently 

collected. 

• Figure 6 in the following slide shows the different water level data needed to model 

storm surge, storm tide, and waves over land, according to agency officials. 

• Storm surge: an abnormal rise of water generated by a storm, above and beyond 

the normal high tide (data measured);

• Storm tide: water level rise due to the combination of storm surge and the normal 

high tide (data measured);

• Waves over land on top of storm surge (data not measured).

Page 21
Page 27 GAO-13-559R Post-Storm Assessments

Objective 1: Storm Data Collection Efforts

(Continued)

Figure 6: Data Needed to Model Storm Surge, Storm Tide, and Waves Over Land

Page 22

Source: National Oceanic and Atmospheric Administration.
Page 28 GAO-13-559R Post-Storm Assessments

Objective 1: Storm Data Collection Efforts

(Continued)

Topographic and Bathymetric Data Collection Efforts

• According to NOAA officials, data on land shape and ocean depth (i.e., topographic 

and bathymetric data) will be needed to replicate conditions at an individual structure. 

• NOAA, USGS, and the Corps collect these data for different purposes. For example:

• NOAA collects bathymetric data from coastal and open ocean areas in support of 

mission requirements, including charting, navigation, and hazard mitigation, as well 

as for storm surge forecast models. 

• USGS collects topographic and bathymetric data to study the vulnerability of U.S. 

shorelines to coastal change hazards such as the effects of severe storms. 

• The Corps collects topographic and bathymetric data of U.S. shorelines to support 

design of specific projects, operations, dredging, and regulatory functions.

• According to agency officials, the agencies collect these data through both individual 

and joint efforts.

Page 23
Page 29 GAO-13-559R Post-Storm Assessments

Objective 1: Storm Data Collection Efforts

(Continued)

Gaps in Topographic and Bathymetric Data

• NOAA officials told us that current topographic and bathymetric data of U.S. coastal 

areas may be outdated because of significant coastline changes due to erosion and 

other factors. 

• In addition, NOAA officials also told us that these data must first be processed into a 

digital elevation model in order to be used as input data in storm models; however, 

current high-quality digital elevation models that would likely be needed for the poststorm model are not available for all U.S. coastal areas, in particular the Gulf and East 

Coasts. 

• NOAA officials told us that the agency has produced most of its current high-quality 

digital elevation models to support the agency’s Tsunami Program, primarily on the 

West Coast, Alaska, Hawaii, and the Caribbean. NOAA uses data from federal and 

other sources, and coordinates development of these models with the State-Federal 

National Tsunami Hazard Mitigation Program.

Page 24
Page 30 GAO-13-559R Post-Storm Assessments

Objective 1: Storm Data Collection Efforts

(Continued)

• In addition to topographic and bathymetric data, NOAA officials told us that related 

data on land use and cover (e.g., residential areas or forests) will be needed to 

replicate wind conditions for an individual structure. Specifically, these data are 

converted to “roughness” data which determines how different types of land use and 

cover affect wind speed and direction.

• NOAA officials told us that highly detailed roughness data will be needed for analyzing 

wind for the post-storm model. However, the officials explained that such data are not 

currently available for U.S. coastal areas susceptible to tropical storms and hurricanes.

Page 25
Page 31 GAO-13-559R Post-Storm Assessments

Objective 1: Storm Data Collection Efforts

(Continued)

• Agency officials told us that although their current storm data collection efforts collect 

similar types of data, the data have important differences and supplement each other 

for purposes of measuring storm conditions. For example:

• NOAA’s permanent, fixed NWLON stations, which are located miles apart along the 

U.S. coast, measure water levels at all times for multiple purposes and not solely 

for observing major storms. 

• USGS’s mobile storm tide sensors are typically positioned during major storms to 

supplement data collected by NOAA’s fixed water level sensors to obtain detailed 

measures of the advancing storm surge. 

• NOAA officials told us that, among their next steps in planning for meeting the 

requirements of the COASTAL Act, the agency will be examining how to fill the gaps 

they identified in current storm data collection efforts. 

Page 26
Page 32 GAO-13-559R Post-Storm Assessments

Objective 2: Cost Information 

Agencies do not collect cost information that reflects the costs of all activities in 

collecting and using a specific type of storm data. 

• The selected agencies we reviewed—NOAA and USGS—do not typically collect cost 

information for each type of storm or weather data, such as wind speed or storm 

surge, that reflects the expense for all activities involved in collecting and using the 

data. For example:

• NOAA officials told us that they do not track a cost figure that reflects the costs of 

all activities involved in collecting and using a unit of wind speed data from their 

ASOS stations. 

• Agency officials told us that the following activities involved in collecting storm data 

generate costs: deployment, maintenance, and operation of observing systems; 

communications and processing; analysis; dissemination; and data storage.

Page 27
Page 33 GAO-13-559R Post-Storm Assessments

Objective 2: Cost Information

(Continued)

• Officials from NOAA and USGS told us that their storm data collection efforts generally 

involve more than one type of storm or weather data. 

• The costs for processing, analyzing, and storing the data are calculated for all data 

types rather than a single one. For example:

• NOAA officials told us that their NWLON stations collect data on water levels, wind, 

and barometric pressure. NOAA officials told us that it would be challenging, for 

example, to identify the costs for processing only the water level data because 

agency staff process all data collected by the NWLON stations at the same time. 

• NOAA officials also told us that data storage is a centralized agency activity 

provided by the National Environmental Satellite, Data, and Information Service. 

The costs for the staff and computing resources needed are based on all storm 

data types and not one element of data. 

Page 28
Page 34 GAO-13-559R Post-Storm Assessments

Objective 2: Cost Information

(Continued)

• Agencies incorporate the cost information they collect on their storm data collection 

efforts into the costs of major programs and projects. 

• According to NOAA officials, the agency’s major programs include the costs of multiple 

storm data collection efforts. For example, one official told us that cost information is 

collected for all data from NWLON stations and another effort under one program.

• NOAA and USGS officials told us that they also collect cumulative cost information for 

special projects, such as activities related to responding to a major hurricane. 

• USGS officials collected detailed cost information on storm tide, barometric 

pressure, and high water mark level data collected during Hurricane Sandy.5

USGS reported total costs for all activities, such as deploying and operating 

sensors, and processing and disseminating the data, were about $533,000.

• As a next step in its COASTAL Act planning, NOAA plans to prepare a resource 

analysis that is to, in part, identify some of the additional resources needed to fill gaps 

in storm data collection efforts.

Page 29

5USGS’s storm tide data collection effort for Hurricane Sandy was funded by FEMA. 
Page 35 GAO-13-559R Post-Storm Assessments

Enclosure II

GAO Contact and Staff Acknowledgements

GAO Contact

Anne-Marie Fennell, (202) 512-3841 or fennella@gao.gov

Staff Acknowledgements

In addition to the contact listed above, key contributors to this report were Jeff Malcolm, 

Assistant Director; Cheryl Arvidson; Brian M. Friedman; Cindy Gilbert; Bridget Grimes; Armetha 

Liles; Mehrzad Nadji; and Jeanette Soares.

(361445)
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