All three RFCs were involved in the coordination of hydrologic services prior to and
during the event. Coordination was performed between the HAS/Hydrologist staff and WFOs
using three methods: Hydrometeorological Discussions (HMDs). Hydrometeorological
Coordination Me: s (HCMs), and the telephone. The HMD product was used to coordinate
hydrometeorological issues (i.e., QPF changes, rainfall estimates, flood threats). Numerous and
timely HMDs were issued by all RFCs. The HCM product was used to coordinate RFC
operational issues (i.e.. extended hours of operations, requests for additional or extended QPFs.
and Flash Flood Guidance [FFG] issues). These products were issued in a timely manner.
Telephone calls were also initiated by both the WFOs and HAS to coordinate QPF changes. The
improvement in outreach by the MARFC during this event was especially noted by one WFO.
All three RFCs participated in the Hurricane Hotline calls between the WFOs and TPC and in
several FEMA conference calls. This coordination ensured effective communication on QPF and
river forecasts for the effected areas.

The SERFC was very proactive in relaying information to the internal and external user
community before and during the warning period. Some examples include:

° Daily conference calls, initiated by the SERFC, brought together WFOs. USACE.
USGS, FEMA Hurricane Liaison Team, and Divisions of Emergency
Management in Virginia, North Carolina and South Carolina.

. In an attempt to focus additional attention on the major inland flood threat, the
SERFC contacted CNN, The Weather Channel, NWS Eastern and Southern
Region Headquarters, and the FEMA Hurricane Liaison Team.

. The SERFC provided flood potential information through the use of Geographic
Information System (GIS) graphics. Up to 50 graphics were disseminated, via a
SERFC Hurricane Floyd Web site, pin-pointing the threat of “widespread and
major flooding” days in advance of heavy rains. These products were well
received by customers, especially FEMA.

. The SERFC issued a product called the Excessive Streamflow Discussion (ESD)
to convey flood impact and forecast information to customers. An ESD,
disseminated 3 to 7 days in advance of rivers cresting and even before the rain
started to fall, called for major flooding over the areas impacted the most.

° An SERFC hydrologist was detailed to Conway, South Carolina, where he worked
with city officials to help determine the flood crest and consequences of the severe
flooding.


1800 26.1 77.0 930 110
15/0000 27.1 7717 933 115
0600 28.2 78.5 935 110
1200 29.3 78.9 943 100
1800 30.6 79.1 947 95
16/0000 32.1 78.7 950 90 “
0600 33.7 78.0 956 90
1200 35.7 76.8 967 70
1800 38.0 75.3 974 60 tropical storm
17/0000 40.6 73.5 980 50 “
17/0600 42.1 72.1 983 50 tropical storm
1200 43.3 70.6 984 45 extratropical
1800 44.2 68.9 985 45 “
18/0000 44.8 67.3 987 40
0600 45.4 65.5 990 35
1200 46.6 63.0 992 35 “
1800 47.7 59.3 992 35 “
19/0000 48.0 56.3 992 35
0600 48.5 52.5 994 35
1200 49.5 48.0 992 40
1800 merged with low
13/1200 23.9 71.4 921 135 minimum pressure
14/1200 25.4 76.3 930 105 landfall near Alice
Town, Eleuthera
14/1900 26.3 771A 932 120 landfall near Cherokee
Sound, Abaco
16/0630 33.8 78.0 956 90 landfall near Cape

Fear, North Carolina

A-2



egg “ae ; Te ‘4

ie
Flooding in Grifton, North Carolina. (Photograph courtesy of J. Jordan,
U.S. Army Corps of Engineers.)

30


Cause County/Parish Gender
<<
9/16/99 Drown in vehicle* Warren, NC M
9/16/99 Drown in vehicle* Warren, NC 55 M
9/16/99 Fatal injury in car/swept away Wayne, NC 51 M
9/16/99 Drown in vehicle* Wayne, NC 42 F

* Fresh water fatality.


Total Precipitation (inches) from Hurricane Floyd 2

September 13 - 17, 1999

OH

2" to 4”
4" to 8”
8" to 12"
12" to 16"
16” to 21"

CLIMATE PREDICTION
CENTER

Based on reports from the River Forecast Centers
and regional Weather Service Offices

Figure 2. Total Precipitation (inches) from Hurricane Floyd, September 13-17, 1999.


At 3:45 p.m. Thursday, September 16, WFO Wakefield lost all phone service. Wakefield
initiated full-service program backup, contacting backup offices on cell phones. Long-fused
backup responsibility transferred to WFO Morehead City, while short-fused backup was split
among WFOs Sterling. Virginia, Morehead City and Raleigh, North Carolina. However, WFO
Morehead City was dealing with severe flooding and hurricane-related products in their own
area. In order to more evenly distribute the workload, public zone forecast and hydrologic
warning responsibility for Wakefield was transferred to WFO Sterling, the secondary backup
office for Wakefield. WFO Morehead City continued to issue all marine-related products and
Hurricane Local Statements for the Wakefield area. WFO Wakefield was able to assume
forecast responsibility at 2 p.m. Friday, September 17. WFOs Morehead City and Sterling are
commended for their extra efforts to provide quality warning and forecast services for the
Wakefield area during this period of service backup.

The WFOs performed admirably during Hurricane Floyd. There were many examples of
outstanding staff dedication under trying circumstances. For example, at WFO Wakefield, staff
spent hours navigating closed or flooded roads trying to report to work. When all access to
Wakefield became cut off, the staff on duty was stranded at the office for up to 36 hours. During
much of this time, WFO Wakefield was without commercial power, phone service and water.
While virtually all communication was cut off, the staff continued to monitor the ongoing event,
via their satellite-received data on the Advanced Weather Interactive Processing System
(AWIPS), and assist the backup WFOs where possible.

As the Tar River was nearing crest in eastern North Carolina, the USGS automated river
gage at Greenville malfunctioned. Realizing the importance of timely observations during an
anticipated record flood, a staff member of WFO Morehead City traveled about 60 miles to the
Greenville forecast point to manually take river observations from the wire-weight gage. The
observations were then taken hourly and forwarded to both the Morehead City WFO, local
emergency officials and the SERFC. He traveled back and forth several days to take readings,
having to avoid numerous flooded highways.

Telemetered river gages were invaluable to RFCs and WFOs. However, at least
15 critical river gages became inoperable during the flood. Gage houses were submerged and
telecommunications were lost. This loss of data made it more difficult to forecast river crests
and to monitor flood levels. Examples where this occurred include the floods at Lodi, New
Jersey, on the Saddle River and Tarboro, North Carolina, on the Tar River.

WFO Raleigh and SERFC coordinated closely with the USGS before and during the
event. The interaction helped the USGS determine which river gages needed to be quickly
restored to support flood forecasting and reduced the amount of time vital stage information was
lost. The USGS made significant efforts to restore high impact gages quickly and passed river
information on to WFOs and SERFC.

16


Appendix B

Saffir-Simpson Hurricane Scale*

Winds 74-95 mph (65-82 kts.): No real damage to building structures.
Damage primarily to unanchored mobile homes, shrubbery, and trees.

Winds 96-110 mph (83-95 kts.): Some roofing material, door, and
window damage of buildings. Considerable damage to vegetation, mobile
homes, etc. Flooding damages piers, and small craft in unprotected

Winds 111-130 mph (96-113 kts.): Some structural damage to small
residences and utility buildings with a minor amount of curtainwall
failures. Mobile homes are destroyed. Flooding near the coast destroys
smaller structures with larger structures damaged by floating debris.

Winds 131-155 mph (114-135 kts.): More extensive curtainwall failures

with some complete roof structure failure on small residences. Major

Category Definition—Likely Effects
ONE
Also, some coastal flooding and minor pier damage.
TWO
anchorages break moorings.
THREE
Terrain may be flooded well inland.
FOUR
erosion of beach areas. Terrain may be flooded well inland.
FIVE

Winds greater than 155 mph (greater than 135 kts.): Complete roof
failure on many residences and industrial buildings. Some complete
building failures with small utility buildings blown over or away.
Flooding causes major damage to lower floors of all structures near the
shoreline. Massive evacuation of residential areas may be required.

Note: A "major" hurricane is one that is classified as a Category 3 or higher.

“In operational use, the scale corresponds to the 1-minute average sustained wind speed as
opposed to gusts which could be 20 percent higher or more.

B-1


Table of Contents

Page

Preface 26... ect etee net e rete eden tee een eens ii
Acronyms and Abbreviations... 0.00... ce een e nee e ene nee iv
Service Assessment Team . 10.0.0... 00.0 e cece ccc e tenet ete n tenn eee eee vi
Service Assessment Summary ..... 00.0... cece eee eee eee tent e teen eee 1
Warning and Forecast Performance .... 2.00.0... o cece cece eee cnet n eens 11
Facts. Findings and Recommendations ........... 0.0.0 cece cece cece eee ence ees 23
Practices to Emulate... 0.2.20 n teen c eee es 27
Completed Actions ...... 00.0.0. n een e eee e ee eeeeee 31
Appendix A National Hurricane Center Best Track, Hurricane Floyd,

September 7-17, 1999.6... e eee A-l
Appendix B Saffir-Simpson Hurricane Scale... 2.0.0.6... eee eee eee B-1
Appendix C Record Floods at NWS Forecast Points for Hurricane Floyd (1999) ..... Cl
Appendix D U.S. Tropical Cyclone Deaths Directly Attributed to

Hurricane Floyd (1999) 2.0.0... cece ec e ec eeee eee eee ee D-1
Appendix E Verification of Selected Record Floods at NWS Forecast Points

for Hurricane Floyd, Mid-Atlantic RFC Area ..........0.05 cee eee eee E-1
Appendix F Verification of Selected Record Floods at NWS Forecast Points

for Hurricane Floyd, Southeast RFC Area ........ 006.02 c cece eee eee Fl

iii


Practices to Emulate

The Service Assessment Team identified practices at some NWS offices that were
particularly effective and other field office managers may wish to emulate.

Innovative Wording to Heighten Awareness: WFO Mt. Holly, New Jersey, realized the
potential problem with their customers becoming “desensitized” to Flash Flood Warnings
(FFWs). When they decided to issue an FFW on the anticipation of major flash flooding due to
extreme rainfall, a decision was made to change the header to read “SEVERE FLASH FLOOD
WARNING.” While unconventional, media and emergency officials liked the idea, stating it
gave them an indication as to just how serious the flooding would be.

Providing Detail in Flash Flood Statements: WFO Raleigh, North Carolina, issued numerous
Flash Flood Warnings for flash flooding and severe urban flooding in central North Carolina. As
a follow-up to these warnings, the WFO issued detailed Flash Flood Statements every 2 to

3 hours. The statements provided details of the specific flash flooding areas, mentioning
flooding problems in numerous cities and towns specifically. These statements also provided
cautionary wording that historic river flooding would follow along mainstem rivers. This detail
was exemplary of the flash flood warning process.

WFO Preparedness Activities

All WFOs in the affected areas conducted extensive preparedness activities. Some
examples include the following.

. The Wilmington, North Carolina, WFO held a Hurricane/Storm Surge Seminar
for all emergency managers and media in their warning area at the beginning of
the hurricane season. The WCM also made coordination visits to all emergency
managers in his warning area prior to hurricane season.

. During Hurricane Awareness Week, WFO Wakefield, Virginia, spent
considerable effort on inland hurricane effects, especially on flooding. They
issued Public Information Statements and participated in various interviews and
presentations, including the 1999 Virginia Emergency Management Conference.

. WFO Morehead City, North Carolina, held an Open House prior to hurricane
season for emergency management and media in their forecast area. The agenda
focused on coordination issues, NWS products, and hurricane presentations
dealing with the 1999 hurricane season forecast, storm surge components, and
inland flooding from hurricanes. The WFO also gave numerous hurricane
preparedness presentations throughout their area.

27


Weather Forecast Offices

The WFOs have the responsibility of issuing timely meteorologic and hydrologic
warnings, forecasts and statements. These offices are the contact for state, county and local
agencies, as well as the media and general public. During Hurricane Floyd, 13 WFOs were
impacted with high winds and tornadoes, coastal flooding. flash flooding and river flooding, or a
combination of all these events.

Six WFOs (Wakefield, VA; Raleigh, NC; Wilmington, NC; Morehead City, NC;
Mt. Holly, NJ; Brookhaven, NY) had record river flooding, record rainfall, or both. While
rainfall from Floyd was the primary contributor to the devastating flooding, rainfall from
Hurricane Dennis a week before set the stage for these events.

Nineteen official NWS river forecast points had record flooding due to the rainfall from
Dennis and Floyd. Another 36 forecast points had major flooding. Record river flooding
occurred in both the Southeast (NC, SC, VA) and the Northeast (NJ, PA). WFOs issued a total
of 300 Flood Warnings and Flood Statements for Hurricane Floyd flooding.

The coastal North Carolina WFOs were severely impacted by Hurricane Floyd. River
flooding due to Dennis was ongoing when Floyd brought high winds and tornadoes, and coastal
and flash flooding. The day before Floyd made landfall, WFOs Morehead City and Wilmington,
North Carolina, issued 28 tornado warnings in a 10-hour period. The resulting tornadoes were
occurring at the same time as hurricane force winds and flash flooding. The flash flooding was
more severe than residents had ever remembered.

The northeast WFOs did not have the long-lasting flooding of the South but were affected
by record flash and urban flooding. The hardest hit areas were along the Raritan River in Bound
Brook, New Jersey; other areas of New Jersey and southeastern Pennsylvania; small streams in
southwestern Connecticut; and in New Castle County, Delaware. Many locations in the
Northeast also experienced damage due to wind speeds in excess of 50 mph.

A particular problem in the Northeast region, where population density is high and terrain
is flat, is the extreme effect just a foot rise along some area tributaries can have on the areal
extent of flooding. This was particularly a problem in portions of New Jersey. The result was
property damage affecting thousands of homes and businesses.

Every WFO issued either a Special Weather Statement or Flood Potential Statement,
highlighting the high flood danger 30 to 48 hours before flooding began from Floyd. Flood or
Flash Flood Watches were issued by all affected WFOs from 12 to 36 hours before the onset of
flooding due to Floyd.

A total of 532 Flash Flood Warnings were issued by 13 WFOs for areas from northeast

South Carolina through New England. Verification of these warnings for the 13 WFOs
combined is outstanding (Table 1).

13


and 5-day track forecasts were much better than would be expected from extrapolating the
10-year average TPC 3-day forecast error.

Table 2. Average 4- and 5-day track forecast errors (nm) for Hurricane Floyd from HPC
and four global forecast models. The samples for HPC and each model are not
homogeneous. (NOGAPS errors provided by James Goerss, Naval Research Laboratory,
Monterey, California; others from David Reynolds, HPC)

4-day 5-day
Error (nm) #Cases Error (nm) #Cases
HPC 160 7 228 6
ECMWF 196 8 247 7
MRF 220 9 323 9
NOGAPS 217 10 382 8
UKMET 215 7 364 6

Because the medium-range track forecasts were very good, HPC recognized the potential
for heavy rainfall in eastern North Carolina 4 to 5 days in advance. For example, the HPC QPF
from September 12, about 4 days prior to landfall in North Carolina, placed 5-day areal average
rainfall totals of 6 to 8 inches from northeast South Carolina through eastern North Carolina into
southeast Virginia (Figure 6). Fairly consistent 5-day QPFs continued to be issued on
September 13 and 14.

In the short range, HPC continued to issue good temporal and spatial QPFs. One
parameter for verifying QPFs is the threat score which is based upon the amount of overlap
between the forecast and observed areas of precipitation greater than some specified threshold. If
there is no overlap between the forecast and observed areas, the threat score has a value of 0, and
if there is complete overlap (a perfect forecast), the value is 1.

Table 3 shows the average threat scores for the 2-inch threshold of the 24-hour manual
QPFs from HPC and the numerical guidance model QPFs for the period September 14-17. This
table shows that the HPC threat scores were comparable to those of the Nested Grid Model
(NGM) and Eta, and somewhat better than the aviation run (AVN) of the MRF. In addition, the
average threat scores of the HPC forecasts (0.59) during this period were much greater than the
mean of the scores from the previous 11 months, which was about 0.2. Although the threat
scores of the 0-24 hour QPFs for the 2-inch threshold for the Eta model were comparable or
better than the NGM and AVN, the Eta model did not perform as well in terms of higher rainfall

19


Accuracy of forecast crest with respect to lead time for selected record floods in Virginia
and North Carolina is shown in Figure 5. Flood warnings for these areas were issued by WFOs
Wakefield. Virginia, Morehead City and Raleigh, North Carolina, using river forecasts from
SERFC. Rivers in these areas rose and receded more slowly than those farther north in New
Jersey and Pennsylvania. Figure 5 shows the average forecast error decreased as the time
between forecast and crest decreased. Many of the initial flood warnings predicted river crests
too low due to underestimation of record rainfall. However, some initial flood warnings were
accurate. A record flood crest was forecast at Kinston on the Neuse River with a lead time of
178 hours—more than 7 days in advance. Flood forecasts at the Neuse River at Kinston, North
Carolina, and Tar River at Greenville, North Carolina, were within 2 feet of observed crest with
72-hour or greater lead time. Lead time to crest on these slower responding rivers on the coastal
plain averaged 108 hours.

ao

; $
anne oaer

ge Forecast Error (Feet)

\

Avera
o
ou

96 72 48 24
Average Lead Time (Hours) to Crest

Figure 5. Accuracy of forecast crest with respect to lead time for slow-
responding rivers. For more detailed information, see Appendix F.

During hurricane and tropical storm events, it is common practice for staff from non-
affected WFOs to be detailed to WFOs where the greatest impact from the storm is anticipated.
While additional NWS staff was detailed to WFOs Charleston, South Carolina, and Wilmington,
North Carolina, the historic and widespread river flooding affected WFOs in the Southeast that
had not received additional staffing. The impact of Dennis and Floyd was particularly long
lasting for the North Carolina WFOs, where flooding along the Tar and Neuse Rivers in North
Carolina and the Waccamaw River in South Carolina continued into mid-October. Some of

these rivers were in flood for over a month due to the combination of Dennis, Floyd and
subsequent rainfall events.

15


The WFO Raleigh, North Carolina, hurricane focal point conducted extensive
preparedness activities before the hurricane season to focus on the effects of
hurricanes, emphasizing inland flooding. Lectures and preparedness talks were
given to television stations. newspapers, emergency management agencies and the
Civil Air Patrol. Several hurricane articles were published in newspapers and
journals. Emergency officials had high praise for these outreach efforts,
indicating they saved many lives.

WFO Mt. Holly, New Jersey, conducted two live, 1-hour interviews over NOAA
Weather Radio (NWR) addressing hurricanes and inland flooding. Call-in
questions were also accepted. Feedback from the NWR programs was very
positive and requests for copies of the programs were received.

WFO Mt. Holly hosted an annual hurricane/storm surge seminar for their
emergency managers. The 2-day event included discussion on hurricane-related
products issued by TPC and the WFO, and hands-on training on the use of
HURREVAC and SLOSH output. In addition, WFOs Mt. Holly and Wakefield
participated in a 5-day hurricane exercise for the Delmarva region. The training
helped emergency managers better understand NWS products and services.

WFO Sterling, Virginia, sent daily e-mails to all emergency managers in their
warning area beginning September 10. The e-mails focused on Floyd and
possible impacts. Earliest e-mails based outlooks on guidance from a Threats
Assessment Product issued by CPC.

WFO Brookhaven, New York, participated in a 3-day FEMA-sponsored
Hurricane Exercise for New York emergency management. The WFO was also
involved in the Hurricane Awareness Tour on Long Island with awareness
training given to emergency managers and schools.

SERFC Coordination and Outreach Activities

The SERFC was very proactive in relaying information to the internal and external user
community before and during the warning period. Some examples include the following.

Daily conference calls, initiated by the SERFC, brought together WFOs, USACE,
USGS, FEMA Hurricane Liaison Team, and Divisions of Emergency
Management in Virginia, North Carolina and South Carolina.

In an attempt to focus additional attention on the major inland flood threat, the

SERFC contacted CNN, The Weather Channel, NWS Eastern and Southern
Region Headquarters, and the FEMA Hurricane Liaison Team.

28


Flooding along the Tar River, Princeville, North Carolina. (Photograph courtesy of U.S. Army
Corps of Engineers.)


Flood Warnings were issued by 13 WFOs for areas from northeast South Carolina through New
England. Verification of these warnings indicated a much higher level of accuracy than normal.

On September 16-17, WFO Wakefield, Virginia, lost all phone service. WFOs Morehead
City, North Carolina, and Sterling, Virginia, are commended for their extra efforts to provide
quality warning and forecast services for the Wakefield area during this period of service backup.

The WFOs performed admirably during Hurricane Floyd. For example, the WFO
Wakefield staff spent hours navigating around closed or flooded roads trying to report to work.
A staff member of WFO Morehead City traveled about 60 miles to the Greenville forecast point
to manually take river observations. This employee traveled back and forth several days to take
readings, having to avoid numerous flooded highways.

All WFOs made numerous advance “heads up” calls to emergency officials from 2 to
5 days before rainfall from Floyd began. As the events of Floyd unfolded, WFOs continued to
conduct once- or twice-a-day conference calls with state and county officials.

Emergency Management and Media Response

Emergency management officials in all WFO service areas commended the WFOs on
their outstanding coordination efforts before and during Floyd. Officials stressed how they
appreciated the “person-to-person service” provided. They were pleased to know if they had
questions about NWS products or wanted specific detail, their questions were answered quickly
and courteously. Emergency officials were unanimous in their praise of WFO/RFC use of
conference calls to provide advance notice and continual updates of information.

Emergency officials found that flood forecasts that provided river forecast crest
comparisons were very helpful. Providing examples of how severe the flooding would be
compared to another historic flood crest gave them better insight for planning emergency
operations.

All WFOs received compliments from emergency management officials for their actions
during this event. An example of how well NWS services were received came from the
Emergency Management Coordinator for the City of Newport News, Virginia.

“As I stated during the last meeting, the Wakefield office without a doubt saved
lives in the City of Newport News during the Hurricane Floyd response. With the
timely forecast for heavy rains, we were able to position jon boats at each of the
fire stations. These boats were used to rescue 1100 people from flooded
apartments and homes. This is the kind of teamwork and help we have come to
rely on and appreciate during the work of emergencies affecting the City. Please
express our appreciation for a job well done to your fellow weather staff. You
should be very proud knowing you did help save the lives of our citizens.”


Systems and Communications

FACT:

Finding 7:

Recommendation 7:

FACT:

Affected WFOs switched to the Tropical Z/R relationship for the
Weather Surveillance Radar-1988 Doppler (WSR-88D) radar
precipitation estimates before Floyd. Several WFOs commented on the
excellent WSR-88D rainfall estimates during the event.

Precipitation estimates from the WFO Sterling, Virginia, WSR-88D
significantly underestimated observed rainfall during Floyd. This
problem with underestimating rainfall has previously been documented.

Fix the Sterling WSR-88D precipitation underestimation problem.
The Internet was used extensively during Hurricane Floyd. A special

effort was made to increase the accessibility of the TPC Web site, which
handled up to three million “hits” per day during Floyd.

Internal and External Coordination

Finding 8:

Recommendation 8:

FACT:

FACT:

WFO Wakefield, Virginia, collected hourly river stage observations for
Emporia, Virginia. When WFO Sterling, Virginia, assumed backup
responsibility for Wakefield, observations were collected every 6 hours.
Sterling was adhering to the Eastern Region policy that the servicing
RFC, in this case SERFC, should provide data collection during backup.
SERFC, however, was adhering to the Southern Region policy of data
collection being provided by the WFO with backup responsibility.

Make backup policy for collecting river stage observations consistent
nationwide.

All WFOs in the affected areas participated in or initiated numerous
conference calls with emergency managers, USGS, USACE, and other
decision-making agencies of government before, during and after the
event. WFO Taunton, Massachusetts, also conducted conference calls
with the media. These calls were well received and helped keep media
reports consistent with NWS products.

The Service Assessment Team interviews with state, county and local
emergency officials revealed a common remark: Emergency officials
were pleased with the accessability, cooperation and coordination by the
WFOs. Officials spoke highly of the “personal touch” provided to their
areas by the local WFO.

25


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Drought
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Figure 7. NWS Threats Assessment composite.

22


The team would like to thank those people with the following entities who took time to
talk to team members. Valuable information was gathered during these interviews.

NWS Offices

WFO Brookhaven. NY WFO State College, PA

WFO Mt. Holly, NJ WFO Sterling, VA

WFO Wakefield, VA WFO Raleigh, NC

WFO Morehead City, NC = WFO Wilmington, NC

Northeast River Forecast Center (NERFC), Taunton, MA

Middle Atlantic River Forecast Center (MARFC), State College, PA
Southeast River Forecast Center (SERFC), Peachtree City, GA
NWS Eastern Region Headquarters, Bohemia, NY

NWS Headquarters, Silver Spring, MD

Tropical Prediction Center (TPC), Miami, FL
Hydrometeorological Prediction Center (HPC), Camp Springs, MD
Climate Prediction Center (CPC), Camp Springs, MD

Marine Prediction Center (MPC), Camp Springs, MD

NESDIS Satellite Analysis Branch, Camp Springs, MD

State Emergency Managers

New York State Emergency Management Agency
North Carolina State Emergency Management Agency
Virginia Department of Emergency Services

County Emergency Managers

Somerset County, NJ Bucks County, PA

Nash County, NC Edgecombe County, NC
Craven County, NC New Hanover County, NC
Hertford County, NC Wayne County, NC

Georgetown County, SC Horry County, SC

City Emergency Managers
New York, NY Paramus, NJ

Paterson, NJ Franklin, VA
Newport News, VA

Other City Officials
West Paterson, NJ Totowa, NJ, Fire Department
Lincoln Park, NJ, Police

vii


Service Assessment Team

This Service Assessment Team was activated on September 30, 1999. All team members
traveled to Eastern Region Headquarters in Bohemia, New York, for an overview briefing on
October 5. The team then divided into groups. spending the rest of the week visiting NWS
offices and customers in the northeast United States and the National Centers for Environmental
Prediction (NCEP). The team reassembled the week of October 18, visiting with NWS offices
and customers in the Southeast. After completion of the field work, the team continued to gather
and review information before preparing the final version of this Service Assessment.

The team was comprised of the following individuals:

Steven Thomas

Harold Opitz
Julia Dian-Reed

James Noel

James Butch

John Leslie

Mark DeMaria

Jasmin Riad

Team Leader, Meteorologist in Charge, Weather Forecast Office (WFO)
St. Louis, Missouri

Hydrologist in Charge, Northwest River Forecast Center, Portland, Oregon
Service Hydrologist, WFO Wilmington, Ohio

Hydrometeorological Analysis and Support (HAS) Forecaster, Ohio River
Forecast Center, Wilmington, Ohio

Warning Coordination Meteorologist (WCM), WFO Jackson, Mississippi

National Oceanic and Atmospheric Administration (NOAA)/NWS Public
Affairs Officer, Silver Spring, Maryland

Regional and Mesoscale Meteorology Team Leader, National
Environmental Satellite, Data and Information Service (NESDIS)/
Cooperative Institute for Research in the Atmosphere, Fort Collins,
Colorado

Social/Community Psychologist, Disaster Research Center, University of
Delaware

vi


Warning and Forecast Performance

River Forecast Centers

The NWS includes 13 RFCs. The function of these centers is to produce timely
hydrologic daily and flood forecasts. During Hurricane Floyd, three centers were impacted:
SERFC, MARFC, and NERFC.

SERFC, MARFC, and NERFC performed admirably and are commended for their efforts
throughout the event. The RFCs recognized the potential for severe flooding early on. Upon
notification of the potential for a major hurricane event, the RFCs took appropriate and well-
timed preparedness actions before and during the storm. Several of the NWS field offices
interviewed during the flood assessment noted the excellent services provided by the RFCs.
Normal operation at these centers is 16 hours a day. However, all three impacted centers went to
24-hour hydrologic and HAS operations prior to the arrival of Floyd.

On Tuesday. September 14, SERFC and MARFC issued contingency forecasts prior to
the arrival of Hurricane Floyd based on 9 inches of forecast rainfall. This information was
coordinated internally via telephone and fax to impacted WFOs and communicated with many
emergency managers. These forecasts indicated the risk of major to record flooding if that
amount of rainfall were to occur. SERFC indicated in North Carolina and southeast Virginia the
flood potential from Floyd could be “similar to or greater than Hurricane Fran in 1996.”

RFCs issued timely river forecasts through the River Forecast (RVF) product. The
accuracy of these forecasts increased as flood crests approached. A total of 252 river forecasts
were issued during the flood by the three affected RFCs. These forecasts were issued daily and
were updated every 6 hours or when needed. The initial flood warnings were low and were
raised with the ingest of observed rainfall and higher Quantitative Precipitation Forecasts (QPF).
Official forecasts provided lead times of several hours to a few days prior to the onset of
flooding. depending on the response times of rivers. Lead times of up to several days were
achieved on river crest forecasts. In addition, hydrologists at all RFCs coordinated closely with
WFOs and local officials.

QPF for 24-hour durations was generated throughout the event by WFOs and RFC HAS
staff and used in river forecasts. QPF beyond 24 hours is not normally included in forecasts due
to uncertainties in the storm tracks and locations of heavy rainfall. NERFC requested 48-hour
QPF from WFOs prior to the arrival of Floyd. The QPF from WFOs and RFCs was comparable
to HPC guidance. The NERFC and associated WFOs improved the QPF on September 15 by
changing the forecast of the heaviest rainfall to areas farther inland.


Service Assessment Summary

Overview

Hurricane Floyd impacted the East Coast of the United States from September 14 to 17,
1999. Torrential rains fell from the Carolinas to New England, resulting in major river and urban
flooding. There were 56 deaths in the United States directly attributed to Floyd, and flood
damage estimates range from $4.5 billion to more than $6 billion. Due to the magnitude of
flooding, a Service Assessment Team was assembled to examine the flood-related aspects of
warning services provided by the NWS. The hurricane path resulted in the evacuation of nearly
3 million people from coastal areas of Florida, Georgia, and the Carolinas. An assessment of the
evacuation effort is provided in a Federal Emergency Management Agency (FEMA) and
U.S. Army Corps of Engineers (USACE) publication titled “Hurricane Evacuation Study
Program: Status Report on Lessons Learned.” It is available from FEMA Region IV.

Numerous NWS offices were involved in the forecasting and delivery of advanced
warnings for the threats from Floyd. These include WFOs along and near the coast and three
River Forecast Centers (RFCs). National Centers that played a major role include the Tropical
Prediction Center (TPC) and Hydrometeorological Prediction Center (HPC) of the National
Centers for Environmental Prediction (NCEP). Overall, NWS offices performed in an
outstanding manner in providing high-quality warning and forecast services to the impacted
areas.

The Southeast River Forecast Center (SERFC) in Peachtree City, Georgia; the Middle
Atlantic River Forecast Center (MARFC) in State College, Pennsylvania; and the Northeast
River Forecast Center (NERFC) in Taunton, Massachusetts, recognized the potential for severe
flooding several days in advance. Several of the NWS field offices noted the excellent services
provided by the RFCs. The three RFCs issued a total of 252 river forecast guidance products to
WFOs during the flood.

The SERFC was very proactive in relaying information to the user community. Daily
conference calls were initiated to the USACE, USGS, FEMA Hurricane Liaison Team, and
Divisions of Emergency Management in Virginia, North Carolina and South Carolina. In an
attempt to focus additional attention on the major inland flood threat, the SERFC contacted
Cable News Network (CNN) and The Weather Channel. An SERFC hydrologist was detailed to
Conway, South Carolina, where he worked with city officials to help determine the flood crest
and consequences of the severe flooding.

WFOs issued a total of 300 Flood Warnings and Flood Statements during Floyd. Every
WFO impacted by Floyd issued either a Special Weather Statement or Flood Potential Statement,
highlighting the high flood danger 30 to 48 hours before flooding began. A total of 532 Flash


While some of the manually read river gage reports from Cooperative Observers were not
available due to phone outages. the observers continued to take observations and relayed them to
the NWS once communications were restored. All WFOs found the cooperative observations
reliable and timely while communications were available. Overall, the cooperative network was
a tremendous asset to WFOs and RFCs.

WFOs began preparation for the hurricane season by conducting media and emergency
management workshops and outreach specifically on the dangers of hurricanes and flooding. All
offices conducted Hurricane Awareness Weeks prior to hurricane season with an emphasis on
inland flooding. Preparedness activities conducted by all WFOs in the affected areas helped
customers make the necessary preparations for flooding. Of particular note, the hurricane focal
point at WFO Raleigh conducted an extensive hurricane outreach program that emphasized the
dangers of inland flooding due to hurricanes. Statistics and graphics were presented to illustrate
the fact that inland flooding resulted in more hurricane deaths in North Carolina than any other
type of hurricane-related dangers. The program was presented through much of central North
Carolina to print and electronic media, as well as state, county and local emergency officials. It
was often a surprise to these groups that inland flooding due to hurricanes was so deadly, and
many came away with a new respect for this hurricane danger. Emergency officials had high
praise for this outreach effort by WFO Raleigh, indicating it saved many lives.

All of the WFOs impacted by Floyd were proactive in their efforts to get the word out
early. Perhaps most appreciated by emergency officials were WFO efforts in using conference
calls to provide advance notice and continual updates of Floyd’s track and resulting river flood
crests. All WFOs made advance “heads up” calls to numerous emergency officials from 2 to
5 days before rainfall from Floyd began. With the realization that Floyd would cause massive
inland flooding, emergency officials were again briefed days in advance. As the events of Floyd
unfolded, WFOs continued to conduct once- or twice-a-day conference calls with state and
county emergency officials. These conference calls typically occurred just following the internal
TPC/HPC/RFC/WFO conference calls, thus providing emergency officials with the latest updates
on Floyd.

Tropical Prediction Center

When averaged over the entire lifetime of the hurricane, the TPC track forecasts for Floyd
were excellent. The average official forecast errors at 12, 24, 36, 48 and 72 hours were 32, 61,
84, 84 and 120 miles. These are much smaller than the most recent 10-year average errors of 55,
103, 147, 189 and 279 miles. On average, the official forecasts were better than all of the model
guidance except the United Kingdom Meteorological Office’s (UKMET) global model which
had track errors comparable to the official forecast errors.

Although the overall average official track forecast errors for Floyd were small, the

official forecasts during the period when hurricane warnings were in effect for the United States
(5 p.m. on September 13 to 11 a.m. on September 16) were average. The average 24-hour track

17


Service Assessment

Hurricane Floyd Floods
of September 1999

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration
National Weather Service

Silver Spring, Maryland


Brandywine at Chadds 9 16/1112 13.0 17.15 9/17/99 4.15 13 hr, 48 min

Ford, PA 0100 EDT

(WFO Mt. Holly) 16/1648 15.5 -1.65 8 hr, 12 min
16/2055 18.5 +1.35 4 hr, 5 min

* Gage outage occurred during flood.

++ Only warnings/statements with updated crest values and/or times are included.

Average lead time to observed crest from initial flood warning: 11 hours, 11 minutes.

Average error for initial forecasts: 8.9 feet .
Average error for all updated forecasts: 3.4 feet.

E-2



16,

S» Beanodate 920 UTE
Tropa Crone “matte
Fe tints Bane Ps)

Figure 1. Track of Hurricane Floyd, September 7-17, 1999.



The NWS received favorable marks by media whose job it was to broadcast and translate
crucial NWS products. Leading up to Floyd's landfall in North Carolina, the national media
highlighted the intensity of Hurricane Floyd’s winds and size, often describing it as just as
powerful as Hurricane Andrew, but three times larger. This may have delayed focusing attention
from the threat of high winds and storm surge along the coast to the threat of severe inland
flooding. Many people evacuated because of the hurricane, but thousands more had to be
rescued from their homes and cars as flood waters rose.

Before Hurricane Floyd made landfall, NWS Eastern Region Public Affairs issued a press
release on September 15, 1999. The release stressed the dangers from flooding hundreds of
miles inland and was printed in numerous newspapers.

Local media made effective use of products issued by WFOs as Hurricane Floyd neared
the coast. The Governor of North Carolina was on statewide television the morning of
September 16, after Hurricane Floyd had passed, warning everyone that devastating flooding
still lay ahead.

Public Response

Of the 56 deaths from Hurricane Floyd, 48 were due to drowning in inland flooding. Of
those, more than half occurred when vehicles were either driven into high water or were swept
away by rapidly rising waters. Aggressive preparedness efforts by NWS offices prior to Floyd
continued to stress the dangers of inland flooding from hurricanes and the life-threatening
consequences of driving into flood waters. Although the loss of life was high due to the record
flooding, especially in North Carolina, emergency officials indicated NWS preparedness
initiatives prevented an even greater loss of life.

Tropical Summary

Floyd’s origin can be traced to a tropical wave that emerged from western Africa on
September 2, 1999. Tropical Depression Eight formed September 7 about 1000 miles east of the
Lesser Antilles (Figure 1). The system was upgraded to Tropical Storm Floyd on September 8.
Floyd became a hurricane at 8 a.m. Eastern Daylight Time (EDT)! on September 10 (see
Appendix A). Early on September 12, Floyd turned west and began a major strengthening
episode. The peak intensity of Floyd, 156 miles per hour (mph) maximum wind and
27.20 inches surface pressure, occurred on September 13. This was at the top end of Category 4
intensity on the Saffir-Simpson Hurricane Scale (Appendix B).

' All times listed in this Service Assessment are EDT.

3


Appendix D

U.S. Tropical Cyclone Deaths Directly Attributed to
Hurricane Floyd (1999)

(Data Provided by Dr. Edward N. Rappaport, TPC)

Date Cause County/Parish Age Gender
9/16/99 | Drown in vehicle* Delaware, PA 67 M
9/16/99 | Drown in vehicle* Montgomery, PA 49 M
9/16/99 | Drown in vehicle* Montgomery, PA 1 F
9/16/99 | Drown in vehicle* Montgomery, PA 47 M
9/16/99 Tree fell on home Chester, PA 53 F
9/16/99 | Tree fell on car Philadelphia, PA 48 M
9/16/99 Drown* Salem, NJ 40 M
9/16/99 Drown * Somerset, NJ 85 F
9/16/99 Drown * Somerset, NJ 58 M
9/16/99 | Drown near vehicle* Bergen, NJ 27 M
9/16/99 Drown* Bergen, NJ 53 M
9/16/99 Drown* Passaic, NJ 82 M
9/16/99 Drown swept into sewage pipe New Castle, DE 11 F
9/16/99 Drown swept into sewage pipe New Castle, DE 12 F
9/17/99 | Tree fell on camper Orange, VT 69 M
9/16/99 Drown swept into stream* Dutchess, NY 9 F
9/17/99 | Drown* Rockland, NY 53 M
9/16/99 | Drown kayaker on Quinnipiac River* New Haven, CT 34 M
9/16/99 | Tree blew on to car at 2030 UTC Fairfax, VA 61 F
9/16/99 Tree fell on trailer Halifax, VA 22 F
9/16/99 Drown from vehicle* Southampton, VA 9 F
9/16/99 Drown near vehicle* Bertie, NC 43 M
9/17/99 | Drown drove into flood waters* Craven, NC 76 M



Finding 4:

Recommendation 4a:

Recommendation 4b:

Finding 5:

Recommendation 5:

FACT:

Several WFOs requested MARFC and SERFC issue river forecasts
containing river stage every 6 hours instead of forecasts containing river
stage every 24 hours. The SERFC and NERFC now issue forecasts with
river stage every 6 hours.

MARFC should issue river forecasts containing river stage every
6 hours.

With input from partners, customers, and associated WFOs, the
remaining ten RFCs determine if river forecasts should contain river
stage information every 6 hours.

SERFC provided flood potential graphics on their Internet Web site.
Graphics depicted the threat of “widespread and major flooding” days in
advance of heavy rains. These products were well received by
customers, especially FEMA.

Based on customer feedback, RFCs determine whether similar flood
potential graphics should be provided.

SERFC, MARFC and NERFC issued a combined total of 252 River
Forecasts (RVFs) for Hurricane Floyd flooding.

Local Offices Warnings, Forecasts and Services

Finding 6:

Recommendation 6:

FACT:

FACT:

WFOs issue a Flood Warning (FLW) when a river is forecast to reach or
exceed flood stage. A Flood Statement (FLS) is issued to update a river
forecast when a river is in flood. Flood Statements do not raise public
awareness as do Flood Warnings but may be the only place where an
update to major or record flooding is mentioned.

Change policy to require WFOs to issue a Flood Warning rather than a
Flood Statement.

WFOs issued a total of 300 Flood Warnings and Flood Statements for
Hurricane Floyd flooding.

A total of 532 Flash Flood Warnings were issued by WFOs for areas
from northeast South Carolina through New England.

24


Appendix F

Verification of Selected Record Floods at

NWS Forecast Points for Hurricane Floyd
Southeast RFC Area

(Data Provided by NWS/USGS)

Station Lo. Flood | River Flood Forecast | Observed Departure Lead Time
(Note: All Stations in Stage Warning/ Crest Crest (ft)/time | (forecast (issuance to
table had gage outages (feet) | Statement (feet) of Crest crest - observed
sometime during Time++ observed Crest)
flooding) crest) in feet
Nottoway River nr 16 16/0652 21.0 27.1 9/19/99 ~6.1 73 hr, 8 min
Sebrell, VA (WFO ~ 0800 EDT
Wakefield)
16/1358 24.9 -2.2 66 hr, 2 min
Issued by WFO Sterling 16/2250 25.5 -1.6 57 hr, 10 min
Issued by WFO Sterling 17/1245, 26-27 -I.1to -0.1 | 43 hr, 15 min
18/2240 27 -0.1 9 hr, 20 min
Neuse River at Kinston, 14 15/1310 21.5 27.71 _ 9/23/99 -6.21 201 hr, 35
NC (WFO Morehead City) 2245 EDT min
16/1243 23-24 -4.71 to -3.71 | 178 hr, 2 min
20/1300 24-25 -3.71 to -2.71 | 81 hr, 45 min
20/2244 26 -1.71 72 hr, | min
21/1249 27 -0.71 57 hr, 56 min
21/2318 27.5, -0.21 46 hr, 33 min
22/1246 28 +0.29 33 hr, 29 min
Tar River at Greenville, 13 15/1310 18.0 29.73 9/21/99 -11.73 140 hr, 50
NC (WFO Morehead City) ~1000 EDT min
16/1000 24-25 -4.73 120 hr
17/1425 26.5 -3,23 91 br, 35 min
18/1135 28.5 -1.23 70 br, 25 min
18/1925 29 -0.73 62 hr, 35 min
19/1245 29.5-30 -0.23 to +0.27 | 45 hr, 15 min
20/1300 30 +0.27 27 br

F-1



Facts, Findings and Recommendations

Observations

Finding 1:

Recommendation 1:

The USGS is the agency responsible for maintaining the national stream
gage network. The Geostationary Operational Environmental Satellite
(GOES) transmission schedule of stream gage data during Hurricane
Floyd was every 4 hours. This hindered RFC forecasters’ ability to
provide more timely and accurate river forecasts.

Regions should instruct field offices to contact the USGS with their
requests for hourly GOES data collection and distribution.

NCEP Products and Services

Finding 2:

Recommendation 2:

Coastal WFOs received real-time Sea, Lake, and Overland Surge from
Hurricanes (SLOSH) forecasts from TPC during Hurricane Floyd.
These products are not routinely provided during hurricanes. WFOs
indicated these forecasts allowed them to provide more specific storm
surge forecasts to their customers, and requested real-time SLOSH
output during hurricanes.

Provide real-time SLOSH output to WFOs when a hurricane is within
12 hours of landfall.

RFC Models and Guidance

Finding 3:

Recommendation 3:

RFCs provide Flash Flood Guidance (FFG) to WFOs on the amount of
rainfall needed to cause flash flooding. WFO Wakefield is served by
MARFC and SERFC. MARFC, serving the northern portion of the
warning area, provided lower values than the SERFC. It was difficult
for Wakefield forecasters to determine which guidance to use.

Ensure Flash Flood Guidance is consistent across RFC boundaries.

23


Federal Officials

Federal Emergency Management Agency (FEMA) Region II, New York, NY

U.S. Geological Survey (USGS), West Trenton, NJ
USGS, Raleigh. NC

FEMA Region IV Contact
William G. Massey

Hurricane Program Manager
FEMA, Region IV

3003 Chamblee-Tucker Road
Atlanta, GA 30341
Telephone: (770) 220-5430
Fax: (770) 220-5230

bill.massey @fema.gov

Media

Free Press, Morehead City, NC
WNBC-TV, New York, NY
WWBT-TV, Richmond, VA
WECT-TV, Wilmington, NC
WAAV-TV, Wilmington, NC
WNCT-TV, Greenville, NC
WCTI-TV, New Bern, NC

Other valuable contributors include:

Glenn Austin

Roger Pierce

Larry Wenzel

William Lerner

Linda Kremkau

Acting Chief, Hydrologic Operations Division, Office of Hydrology, NWS
Headquarters, Silver Spring, Maryland

Hydrologic Services Program Manager, Office of Hydrology, NWS
Headquarters, Silver Spring, Maryland

Hydrometeorological Technician, Office of Hydrology, NWS
Headquarters, Silver Spring, Maryland

Meteorologist, Office of Meteorology, NWS Headquarters, Silver Spring,
Maryland

Technical Editor, Office of Meteorology, NWS Headquarters, Silver
Spring, Maryland

viii


Table 1. Flash Flood Warning Verification During Hurricane Floyd

(combined statistics for 13 WFOs).

During 1998

Floyd NWS-wide
Probability of Detection 0.97 0.85
False Alarm Rate 0.13 0.42
Critical Success Index 0.85 0.52
Lead Time (minutes) 99 52

Accuracy of forecast crest with respect to lead time for selected record floods in New
Jersey and Pennsylvania is shown in Figure 4 below. Flood warnings for these locations were
issued by WFOs Brookhaven, New York, and Mt. Holly, New Jersey, using river forecasts from
MARFC. Figure 4 shows the average forecast error decreased as the time between forecast and
crest decreased. Average forecast error is the difference between forecast and observed river
crest. Lead time from the initial flood warning to observed flood crest was more than I] hours.
Lead time is the time, in hours, the forecast was issued prior to the observed crest. Flood
forecasts issued the morning of September 16 were too low due to underestimation of rainfall
and were raised during the day with the inclusion of observed rainfall and higher QPF. See
Appendix E for more details on record floods in New Jersey and Pennsylvania.

_10

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12 6 1
Average Lead Time (Hours) to Crest

Figure 4. Accuracy of forecast crest with respect to lead time for fast-
responding rivers. For more detailed information, see Appendix E.

14


Completed Actions

These findings, identified by the Service Assessment Team, have actions that are
completed.

Issue 1: Telemetered river gages were invaluable to RFCs and WFOs. However, at least
15 critical river gages became inoperable during the flood. Gage houses were
submerged and telecommunications were lost. This loss of data had a negative
impact on the quality of river forecasts.

Action 1: The Office of Hydrology, using input from RFCs and WFOs. provided the USGS
with NWS stream gaging requirements. The Office of Hydrology will monitor
progress on meeting these requirements at quarterly NOAA/USGS meetings.

Issue 2: WFOs were unable to interrogate several automated river-gaging stations via
computer. Gaging stations that had to be manually dialed were Sutrons (primarily
in the northeast) and Campbell dataloggers (in Virginia).

Action 2: The Office of Hydrology developed software to enhance the capabilities of
AWIPS Local Data Acquisition and Dissemination to collect data from remote
sensors. The ability to interrogate Campbell dataloggers is scheduled for AWIPS
Release 5.0. The ability to interrogate Sutron dataloggers is scheduled for Release
5.1.

Issue 3: AWIPS does not have the capability to graphically display hurricane information
contained in TPC products.

Action 3: The capability to plot current and forecast hurricane positions from TPC products
will be included in AWIPS Release 4.3.1. The capability to plot wind radii.
hurricane strike probabilities, and hurricane track forecasts from guidance models
is scheduled for Release 5.0.

31


Appendix A

Hurricane Floyd
September 7-17, 1999

National Hurricane Center Best Track

Date/Time Position Pressure Wind Stage
(UTC) (mb) Speed
Lat. (°N) | Lon. (°W) (kt)

7/1800 14.6 45.6 1008 25 tropical depression

8/0000 15.0 46.9 1007 30 “
0600 15.3 48.2 1005 35 tropical storm
1200 15.8 49.6 1003 40 ‘
1800 16.3 51.1 1000 45 ‘

9/0000 16.7 52.6 1000 45 “
0600 17.1 53.9 1003 45 “
1200 17.3 55.1 1003 50 “
1800 17.9 56.3 996 60

10/0000 18.3 57.2 995 60 “
0600 18.6 58.2 990 60 “
1200 19.3 58.8 989 70 hurricane
1800 20.2 59.6 975 70 “

11/0000 20.8 60.4 971 80 “
0600 21.4 61.1 963 95 “
1200 21.9 62.0 962 95 “
1800 22.5 63.0 966 90 “

12/0000 22.7 64.1 967 85 “
0600 22.8 65.2 960 95 “
1200 23.0 66.2 955 105 “
1800 23.2 67.4 940 115 “

13/0000 23.4 68.7 931 125 “
0600 23.6 70.0 922 135 “
1200 23.9 71.4 921 135 “
1800 24.1 72.9 923 125 “

14/0000 24.5 74.0 924 115 “
0600 24.9 75.3 927 105 “
1200 25.4 76.3 930 105 “

A-l



amounts. The 24-hour QPF threat score for September 14-17 for the 4-inch threshold of the Eta
model was only 0.12, compared with 0.42, 0.41 and 0.27 for HPC, the NGM and the AVN,
respectively.

Table 3. Combined Quantitative Precipitation Forecast threat scores of the 2-inch rainfall
threshold for HPC and three numerical forecast models for the period September 14-17,
1999. Threat scores can range from 0 (useless) to 1 (perfect).

Forecast Period | HPC NGM ETA AVN
0-24 hr 0.59 0.60 0.60 0.52
0-6 hr 0.31 0.31 0.02 0.25
6-12 hr 0.36 0.24 0.00 0.23
12-18 hr 0.33 0.22 0.00 0.26

HPC is also responsible for issuing 6-hour rainfall totals for forecasts periods of 0-6,
6-12, 12-18, 18-24, and 24-30 hours. Threat scores for the HPC 6-hour rainfall forecasts and the
numerical guidance models are also shown in Table 3. Although the scores are not as large as for
the 24 hour totals (which is typically the case), HPC added value to the model forecasts and had
threat scores much larger than their longer term averages.

HPC also issues an Excessive Rainfall Outlook. In this product, flash flood areas were
identified prior to the onset of flash flooding due to Floyd.

Climate Prediction Center

The CPC is responsible for issuing guidance beyond Day 5. In addition, beginning in the
summer of 1999, the CPC issued an experimental U.S. Threats Assessment product available via
the CPC Web site. This product describes possible threats from a number of weather conditions
in the 3-10 day range. The CPC correctly identified the threat of heavy rain, high winds and risk
of flooding about a week prior to Floyd making landfall, as shown in Figure 7.

20


Preface

Hurricane Floyd impacted the U.S. East Coast from September 14 to 17. 1999. Torrential
rains caused major river and flash flooding from the Carolinas to New England. In some areas,
particularly North Carolina, the magnitude of the flooding was unprecedented and lasted through
much of October. There were 56 deaths in the United States directly attributed to Floyd—the
deadliest hurricane in more than a quarter of a century. Flood damage estimates range from
$4.5 billion to over $6 billion.

Due to the magnitude of the flooding, a Service Assessment Team was assembled to
examine the flood-related aspects of warning services provided by the National Weather Service
(NWS) offices to citizens and public officials of the areas affected. Service assessments are
critical to the ongoing efforts of the NWS to improve the quality and timeliness of our warning
services. Findings and recommendations resulting from this review ensure NWS forecast
techniques, products and services will continue to improve.

Assistant Administrator
for Weather Services

June 2000


Verification of Selected Record Floods at
NWS Forecast Points for Hurricane Floyd
Middle Atlantic RFC Area

Appendix E

(Data Provided by NWS/USGS)

Station Flood | River Flood Forecast | Observed Departure Lead Time
Stage Warning/ Crest Crest (ft)/time | (forecast (issuance to
(feet) | Statement (feet) of Crest crest - observed
Time (EDT)++ observed Crest)
crest) in feet

Saddle River at Lodi, 5 16/1259 10.0 13.94 9/17/99 -3.94 11 hr, }min

NJ* ~0000 EDT

(WFO Brookhaven) 16/1622 10.0 -3.94 Thr, 38 min
16/1943 10.5 -3.44 4 hr, 17 min

N. Raritan River nr 10 16/0942 9.0 18.78 9/16/99 -9.78 13 hr, 18 min

Raritan, NJ 2300 EDT

(WFO Mt. Holly) 16/1510 10.5 -8.28 7 hr, 50 min
16/1916 15.5 -3.37 3 hr, 44 min
16/2159 19.0 +0.22 lL hr, 1 min

Raritan River at 12 16/0942 14.5 27.50 9/17/99 -13.0 12 hr, 18 min

Manville, NJ* 0000 EDT

(WFO Mt. Holly) 16/1510 19.5 8.0 8 hr, 50 min
16/1916 27.0 -0.5 4 hr, 44 min

Millstone River at 9 16/0942 11.0 20.97 _ 9/17/99 -9.97 18 hr, 3 min

Blackwells Mills, NJ 0345 EDT

(WFO Mt. Holly) 16/1510 12.5 -8.47 12 hr, 35 min
16/1916 18.5 -2.47 8 hr, 29 min
16/2159 20.5 -0.47 Shr, 46 min
17/0212 21.5 +0.53 1 hr, 33 min

Raritan at Bound Brook, 26 16/0942 29.8 42.13 9/16/99 -12.33 12 hr, 48 min

NJ* 2230 EDT

(WFO Mt. Holly) 16/1510 33.5 -8.63 7 hr, 20 min
16/1916 40.0 -2.13 3 hr, 14 min
16/2159 41.0 -1.13 31 min



Date

Cause County/Parish Age Gender
9/22/99 | Drown* Craven, NC 55 M
9/16/99 | Drown in vehicle* Duplin, NC 42 M
9/16/99 | Drown in vehicle* Duplin, NC 63 M
9/17/99 | Drown* Duplin, NC 70 M
9/16/99 | Drown* Edgecombe, NC 75 M
9/16/99 | Drown in capsized boat* Edgecombe, NC 24 F
9/16/99 | Drown in capsized boat* Edgecombe, NC 45 F
9/16/99 | Drown in capsized boat* Edgecombe, NC 51 M
9/16/99 Drown in capsized boat* Edgecombe, NC s F
9/16/99 | Drown in capsized boat* Edgecombe, NC 5 F
9/16/99 | Drown in capsized boat* Edgecombe, NC 3 F
9/16/99 Drown* Edgecombe, NC 51 M
9/16/99 Drown in vehicle* Halifax, NC 65 M
9/16/99 Drown in vehicle* Johnston, NC 30 M
9/16/99 | Drown in vehicle* Johnston, NC 31 M
9/16/99 Drown in vehicle* Johnston, NC 5 F
9/16/99 | Drown* Jones, NC 65 M
9/16/99 | Drown near vehicle* Lenoir, NC 55 M
9/16/99 Drown in vehicle* Nash, NC 87 F
9/16/99 | Drown in vehicle* Nash, NC 79 M
9/16/99 Drown in vehicle* Nash, NC 46 M
9/16/99 | Drown in vehicle* Nash, NC 40 M
9/17/99 Drown in vehicle* Nash, NC 47 F
9/16/99 Drown in yehicle* Pender, NC 47 M
9/16/99 | Drown in yehicle* Pender, NC 70 M
9/16/99 | Drown in vehicle* Pitt, NC 26 M
9/16/99 | Drown in vehicle* Pitt, NC 18 M
9/16/99 | Drown in vehicle* Pitt, NC 27 M
9/16/99 Drown near vehicle* Pitt, NC 43 M

D-2



Total Precipitation (inches) from Hurricane Dennis
August 29 - September 5, 1999

2’ to 4”
4’ to 8”

HR 8 to 12”

ow

CLIMATE PREDICTION
CENTER

SC

1 Based on reports from the River Forecast Centers

and regional Weather Service Offices

Figure 3. Total Precipitation (inches) from Hurricane Dennis, August 29-September 5, 1999.


Of the 56 deaths, 48 were due to drowning in inland, freshwater flooding. Vehicle-
related deaths accounted for 55 percent of casualties. and of these. about 80 percent were male.
Floyd was the deadliest hurricane in the United States since Agnes of 1972.

Damage estimates as a result of Floyd range from $4.5 billion to over $6 billion. Portions
of ten states were declared major disaster areas, from Florida north to Connecticut. Whole towns
were under water: roads flooded, including portions of Interstate highways: bridges washed out:
dams failed: livestock drowned; water treatment plants failed and water supplies were cut off.

North Carolina alone had damage over $3 billion, with over 7000 homes destroyed.
56.000 homes damaged, 1500 people rescued from flooded areas, and more than 500,000
customers without electricity.


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Service Assessment

Hurricane Floyd Floods
of September 1999

June 2000

U.S. DEPARTMENT OF COMMERCE
William M. Daley, Secretary

National Oceanic and Atmospheric Administration
D. James Baker, Administrator

National Weather Service
John J. Kelly, Jr., Assistant Administrator


The SERFC provided flood potential information through the use of GIS graphics.
Up to 50 graphics were disseminated, via a SERFC Hurricane Floyd Web site,
pin-pointing the threat of “widespread and major flooding” days in advance of
heavy rains. These products were well received by customers, especially FEMA.

The SEREFC issued a product called the ESD to convey flood impact and forecast
information to customers. An ESD, disseminated 3 to 7 days in advance of rivers
cresting and even before the rain started to fall, called for major flooding over the
areas that were impacted the most.

An SERFC hydrologist was detailed to Conway, South Carolina, where he worked
with city officials to help determine the flood crest and consequences of the severe
flooding.

29


forecast error for this latter period was roughly the same as the most recent 10-year average. The
track forecasts during the latter period had a westward bias and were somewhat slow. For
example, the 36-hour track forecasts during the period when hurricane warnings were in effect
for the United States were an average of 120 miles too far west and 81 miles too far south. All of
the track guidance models showed a similar westward and slow bias.

The official intensity forecasts averaged over Floyd’s lifetime were good. The average
official errors at 12, 24, 36, 48 and 72 hours were 12, 17, 20, 20 and 14 mph, respectively. These
errors were considerably smaller than the errors of forecasts based upon climatology and
persistence (the usual benchmark for evaluation of forecast skill) of 15, 22, 28, 32 and 44 mph.
However, there were some large under-forecasts of intensity, by as much as 30 to 40 mph, from
September 10-12 when Floyd was strengthening rapidly. After Floyd reached its maximum
intensity, the official forecasts did not predict enough weakening. From September 13 onward,
the wind speed was over-forecast in the advisories at practically every forecast interval.

When Floyd moved towards south Florida and then up the U.S. East Coast. tropical storm
warnings were issued from as far south as the Florida Keys to as far north as Merrimack River,
Massachusetts. Hurricane warnings were posted along sections of the coastline from Florida
City, Florida, to Plymouth, Massachusetts, at various times during the storm. In reality, only a
small fraction of the coast with hurricane warnings experienced sustained hurricane force winds.

Hurricane warnings were issued for the coast of North Carolina at 11 p.m. on
September 14. This is about 27 hours prior to the arrival of the eyewall in the Cape Fear area.
For the coasts of South Carolina and North Carolina, hurricane warnings were issued at least
24 hours before the onset of tropical storm force winds.

Hydrometeorological Prediction Center

The HPC is responsible for issuing short-range (Day 1 and Day 2) and medium-range
(Day 3-5) QPFs. HPC also produces extended range (Day 3-5) surface pressure charts which
include tropical cyclone positions. The tropical cyclone positions on the extended range forecast
charts are coordinated with TPC once a day.

The primary tools for the extended range track forecasts are the output from the NCEP
Medium-Range Forecast Model (MRF), the European Center for Medium-Range Weather
Forecasting (ECMWF) global model, the UKMET’s Unified Model, and the Navy Operational
Global Atmospheric Prediction System (NOGAPS). Table 2 shows the average errors of the 4-
and 5-day track forecasts for HPC and the four global forecast models. Although long-term error
statistics of the 4- and 5-day forecasts were not available, the 10-year average track errors from
TPC increase with time from 24 to 72 hours. Extrapolating the 10-year average TPC track errors
would imply average errors of 367 and 454 miles at 4 and 5 days, respectively. Table 2 shows
HPC and model errors were smaller than what might be expected from extrapolated TPC errors.
Just as the overall TPC track errors were much lower than average through Day 3, the HPC 4-

18


Cover: Hurricane Floyd Floods of September 1999. Aerial view of Grifton, North Carolina,

with flooding from the Neuse River. (Photograph courtesy of the U.S. Army Corps of
Engineers.)


Tar River at Rocky 15 15/1430 23 32.40 9/16/99 -9.40 28 hr, 30 min
Mount, NC (WFO ~1900 EDT
Raleigh)
16/0940 34-35 +1.6 to +2.6 9 hr, 20 min
Tar River at Tarboro, 19 15/1409 26 41,5 9/19/99 -15.5 96 hr, 51 min
NC (WFO Raleigh) ~1500 EDT
16/0940 33-34 -8.5 10 -7.5 77 hr, 20 min
16/2204 34 -7.5 64 hr, 56 min
17/2000 38 -3.5 43 hr

++ Only warnings/statements with updated crest values and/or times are included.
Average lead time to observed crest from initial flood warning: 108 hours, 11 minutes.
Average error for initial forecasts: 9.8 feet.

Average error for all updated forecasts: 2.4 feet.

F-2



FACT:

Response

FACT:

Media

FACT:

FACT:

Prior to the hurricane season, all offices conducted Hurricane Awareness
Weeks with emphasis on inland flooding. Awareness Week activities
included seminars, conferences, office visitations and mailings.
Preparedness activities conducted by all WFOs in the affected areas
helped customers make the necessary preparations for the record floods.

Of the 56 deaths directly attributed to Hurricane Floyd, 48 (86 percent)
were due to freshwater, inland flooding. Vehicle-related deaths
accounted for 55 percent of casualties, and of these, about 80 percent
were male.

Before Hurricane Floyd made landfall, NWS Eastern Region Public
Affairs, in collaboration with NOAA Public Affairs, issued a press
release to the media on September 15, 1999, about the dangers of inland
flooding along the East Coast. The release was printed in numerous
newspapers.

The Associated Press ran a story on September 21, 1999, for worldwide

distribution complimentary of the Hurricane Floyd forecast, based on an
interview with Louis Uccellini, Director of NCEP.

26


Appendix C

Record Floods at NWS Forecast Points

for Hurricane Floyd (1999)

(Data Provided by NWS/USGS)

Date Location Flood Stage (Ft) Old New
=>

9/17/99 Nottoway River near Sebrell, VA 16 24.43 27.01
9/17/99 Tar River at Louisburg, NC 20 25.34 26.05
9/7/99 Tar River near Rocky Mount, NC 15 23.67 32.35
9/18/99 Fishing Creek near Enfield, NC 16 17.72 21.65
9/20/99 | Tar River at Tarboro, NC 19 31.77 41.51
9/21/99 Tar River at Greenville, NC 13 22.07 29.72
9/17/99 Neuse River near Clayton, NC 9 20.12 20.67
9/20/99 Neuse River near Goldsboro, NC 14 26.21 28.85
9/23/99 Neuse River at Kinston, NC 14 23.26 27.71
9/18/99 Cape Fear River at Chinquapin, NC 13 20.16 23.51
9/17/99 Saddle River at Lodi, NJ 5 12.36 13.94
9/17/99 North Raritan River near Raritan, NJ 10 15.51 18.78
9/17/99 | Raritan River at Manville, NJ 14 23.80 27.50
9/7/99 Millstone River at Blackwells Mills, NJ 9 18.68 20.97
9/17/99 | Raritan River at Bound Brook, NJ 28 37.47 42.13
9/17/99 Rahway River at Springfield, NJ 5.5 9.76 10.67
9/17/99 Christina at Coochs Bridge, DE 9 13.12 13.92
9/17/99 | E. Br. Brandywine blw Downingtown, PA 7 13.40 14.74
9/17/99 Brandywine Creek at Chadds Ford, PA 9 16.56 17.15





Floyd came withing 110 miles of Cape Canaveral as it paralleled the Florida coast on
September 15. Floyd then moved slightly east of north and increased in forward speed, coming
ashore near Cape Fear, North Carolina, at 2:30 a.m. on September 16. At the time of landfall,
Floyd was a Category 2 hurricane with maximum winds of 104 mph. Floyd continued to
accelerate north-northeast after landfall. Its center passed over extreme eastern North Carolina
and over Norfolk, Virginia. Floyd then weakened to a tropical storm and moved swiftly along
the coasts of the Delmarva Peninsula and New Jersey, reaching Long Island by 8 p.m.
September 16. The system was extratropical by the time it reached the coast of Maine at
8 a.m. September 17.

Sustained tropical storm force winds and gusts close to hurricane strength were recorded
at many locations from the Florida Keys to New York. Sustained winds of 96 mph with gusts to
122 mph were measured by a University of Oklahoma portable anemometer (10-meter height)
near Topsail Beach, North Carolina, around 3 a.m. on September 16. Storm surge values as high
as 10 feet were reported along the North Carolina coast.

Heavy Rains and Flooding

Much of Floyd’s impact was due to extreme rainfall (Figure 2). Although Floyd was
moving quickly, its large circulation interacted with a pre-existing frontal zone extending from
central North Carolina through the mid-Atlantic states. This caused the heaviest rainfall to fall
along and left of Floyd’s track. Rainfall totals of 4 to 12 inches were common from northeast
South Carolina through eastern North Carolina, eastern Virginia, eastern Maryland, Delaware,
eastern Pennsylvania, New Jersey, eastern New York into the Northeast. Within this region, two
areas of extreme rainfall occurred with totals as high as 15 to 20 inches recorded in portions of
eastern North Carolina and southeast Virginia. At Wilmington, North Carolina, the storm total
of 19.06 inches included a 24-hour record of 15.06 inches. In Yorktown, Virginia, the storm
total was 18.13 inches. The second region of extreme rainfall totaled 10 to 14 inches in parts of
Maryland, Delaware, New Jersey, southeast Pennsylvania and southeast New York. A new
record was set in Philadelphia for most rain on a calendar day—6.63 inches.

This heavy rainfall caused widespread flooding and flash flooding from northeast South
Carolina to southern New England. The flooding in North Carolina was the most damaging in
the State’s history. Some rivers in eastern North Carolina were already in flood due to 5 to
10 inches of rainfall from Hurricane Dennis (Figure 3) occurring about a week prior to Floyd.
The extreme rainfall produced by Floyd across the Carolinas and Virginia caused widespread
flooding on larger rivers and tributaries as well as flash flooding on smaller streams and creeks.

Nine record floods occurred on rivers in North Carolina and one in Virginia (see Appendix C).
Farther north across the remainder of the mid-Atlantic states and into parts of the Northeast,
rainfall and faster-responding streams and rivers produced serious flash and urban flooding. This
was especially the case in the major metropolitan areas of Philadelphia and New York City.


Record river flooding occurred in parts of New Jersey and southeast Pennsylvania with six record
floods in New Jersey and two in Pennsylvania.

In the SERFC area of responsibility, record flooding occurred in the Cape Fear, Chowan,
Neuse, Pee Dee, Tar, and Waccamaw River Basins. There were ten record floods at SERFC
forecast points. Hardest hit were the Tar and Neuse River Basins. New record floods were
recorded at Louisburg, Rocky Mount, Enfield, Tarboro, and Greenville, North Carolina, in the
Tar River Basin, with greater than a 500-year flood occurring at Tarboro, Rocky Mount. and
Enfield. In the Neuse River Basin, new record floods occurred at Clayton, Goldsboro, and
Kinston, North Carolina. Two additional forecast points observed record floods—Chinquapin,
North Carolina, in the Cape Fear River Basin, and Sebrell, Virginia, in the Chowan River Basin.

Farther north in the MARFC area of responsibility, major to record flooding occurred in
the Raritan, Passaic, Delaware, Schuylkill and Christina River Basins. There were nine record
floods at MARFC forecast points. Hardest hit was the Raritan River Basin in north-central New
Jersey. Record floods were recorded at Bound Brook, Manville, and near Raritan along the
Raritan River. In addition, new record floods occurred at Blackwells Mills, New Jersey, along
the Millstone River and at Lodi, New Jersey, along the Saddle River. In southeast Pennsylvania,
a record flood occurred in the Lower Delaware River Basin at Chadds Ford along Brandywine
Creek.

Major flooding in the NERFC area was confined to the Schoharie Creek River Basin in
Prattsville, New York. The river crested near 18 feet, short of the record flood of 19.4 feet.
Elsewhere, minor to moderate flooding occurred along some NERFC forecast points in New
York, Connecticut, New Hampshire, and Maine. Even though rainfall was in the 4- to 12-inch
range across the Northeast, the prolonged drought prior to Floyd helped lessen the flooding.
Reservoirs were very low and able to store water. This was not the case farther south as prior
rains in late August and early September had already begun lifting reservoir levels.

Casualty and Damage Summary

There were 57 deaths directly attributed to Floyd—S6 in the United States and one in
Grand Bahama Island (see Appendix D). The death toll by state is as follows.

North Carolina 35
Pennsylvania 6
New Jersey 6
Virginia 3
Delaware 2
New York 2
Connecticut 1
Vermont 1