Service Assessment

Oklahoma/Southern Kansas

Tornado Outbreak of May 3, 1999

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Weather Service

Silver Spring, Maryland
Cover: Supercell thunderstorms generated killer tornadoes in a swath from west-central

Oklahoma through southern Kansas. Visible satellite imagery from Geostationary Operational

Environmental Satellite-8, 6:45 p.m. Central Daylight Time (CDT), May 3, 1999. (Courtesy of

the National Oceanic and Atmospheric Administration (NOAA)/National Environmental Satellite,

Data and Information Service)
Service Assessment

Oklahoma/Southern Kansas 

Tornado Outbreak of May 3, 1999

August 1999

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
Preface

On May 3, 1999, one of the largest tornado outbreaks in history struck west-central

Oklahoma and southern Kansas, killing48 people, leaving thousands homeless and resulting in

over $1 billion in property damage. Due to the magnitude of this event, the National Weather

Service (NWS) conducted a Service Assessment to examine the effectiveness of NWS warnings

and other services in minimizing loss of life and injuries.

Service Assessments are critical to the ongoing efforts of the NWS to improve the quality

and timeliness of our warning services. Successful procedures are highlighted and shared with

other offices; shortcomings are identified and resolved. This review process ensures that NWS

forecast techniques, products and services will continue to evolve and improve.

l Assistant Administrator for

Weather Services

August 1999

ii
iii

Table of Contents

Page

Preface .................................................................. . ii

Acronyms and Abbreviations ................................................. . iv

Service Assessment Team ................................................... . vi

Event Overview ........................................................... . 1

Synoptic Overview ........................................................ . 5

Facts, Findings and Recommendations - Part 1

Oklahoma and Southern Kansas Outbreak Combined .......................... . 7

Oklahoma Outbreak Summary

NWSFO Norman, Oklahoma ............................................. . 9

Facts, Findings and Recommendations - Part 2

Oklahoma Outbreak ................................................... . 15

Southern Kansas Outbreak Summary

NWSO Wichita, Kansas ................................................ . 25

Facts, Findings and Recommendations - Part 3

Southern Kansas Outbreak .............................................. . 29

Practices to Emulate ....................................................... . 33

Appendix A Fujita Tornado Intensity Scale ................................... . A-1

Appendix B Event Statistics .............................................. . B-1

Appendix C Oklahoma/Southern Kansas Tornado Outbreak of May 3, 1999

NWSFO Norman Chronological Product Highlights ............... . C-1

Appendix D Oklahoma/Southern Kansas Tornado Outbreak of May 3, 1999

NWSO Wichita Chronological Product Log ...................... . D-1
iv

Acronyms and Abbreviations

AFB Air Force Base

AFOS Automation of Field Operations and Services

APO AWIPS Program Office

AWIPS Advanced Weather Interactive Processing System

CAP Civil Air Patrol

CAPE Convective Available Potential Energy

CDT Central Daylight Time

CRS Console Replacement System

CWA County Warning Area

EAS Emergency Alert System

EMWIN Emergency Managers Weather Information Network

EOC Emergency Operations Center

FOS Family of Services

HWO Hazardous Weather Outlook (Product Identifier)

KICT Wichita, Kansas, WSR-88D

KTLX Twin Lakes, Oklahoma, WSR-88D (metropolitan Oklahoma City radar)

LDAD Local Data Acquisition and Dissemination

LSR Local Storm Report (Product Identifier)

MIC Meteorologist in Charge

MSD Meteorological Services Division (National Weather Service)

NAWAS National Warning System

NCF Network Control Facility

NEXRAD Next Generation Radar

NIDS NEXRAD Information Dissemination Service

NOAA National Oceanic and Atmospheric Administration

NOW Short Term Forecast (Product Identifier)

NSSL National Severe Storms Laboratory

NWR NOAA Weather Radio

NWS National Weather Service

NWSFO NEXRAD Weather Service Forecast Office

NWSO NEXRAD Weather Service Office

NWWS NOAA Weather Wire Service

OCS Oklahoma Climatological Survey

OK-FIRST Oklahoma’s First-response Information Resource System using

Telecommunications

ORDA Open systems Radar Data Acquisition

ORPG Open systems Radar Product Generator

OSF Operational Support Facility (National Weather Service)

OSO Office of Systems Operations (National Weather Service)
v

PC Personal Computer

PNS Public Information Statement

PUP Principal User Processor

RUC II Rapid Update Cycle version II

SAME Specific Area Message Encoder

SEL Severe Thunderstorm or Tornado Watch (Product Identifier)

SKYWARN Term for Storm Spotter Network

SOO Science and Operations Officer

SPC Storm Prediction Center (National Weather Service)

SPS Special Weather Statement (Product Identifier)

SRH Southern Region Headquarters (National Weather Service)

SVR Severe Thunderstorm Warning (Product Identifier)

SVS Severe Weather Statement (Product Identifier)

SWO Severe Weather Outlook (Product Identifier)

TOR Tornado Warning (Product Identifier)

TPMS Transition Power Maintenance System

WarnGen Warning Generation (AWIPS software)

WCM Warning Coordination Meteorologist

WDSS Warning Decision Support System

WISEII Warning and Interactive Statement Editor, version II

WSOM Weather Service Operations Manual

WSR-88D Weather Surveillance Radar-1988 Doppler (NEXRAD)

ZFP Zone Forecast Product (Product Identifier)
vi

Service Assessment Team

The Service Assessment Team was activated on May 4, 1999. Team members traveled to

the Next Generation Radar (NEXRAD) Weather Service Forecast Office (NWSFO) Norman,

Oklahoma, on May 5 and left on May 10. A team meeting and an overview of the event was held

on May 5 with representatives from NWSFO Norman, Storm Prediction Center (SPC),

Operational Support Facility (OSF) and National Severe Storms Laboratory (NSSL) in

attendance. At that time it was learned that the emergency manager representative selected for

the team was unable to participate. Four team members were designated to begin the Service

Assessment in Oklahoma while the fifth was assigned to perform the Service Assessment in

southern Kansas. To assist the team member in Kansas, the team leader and NWSFO Norman

Meteorologist in Charge (MIC) coordinated with the OSF and selected an OSF individual to help

with the Kansas Service Assessment. Before leaving Oklahoma, the team completed the first

draft of the report. After completion of the field work, the team continued to gather information

and collaborate on the findings before preparation of the final version of this Service Assessment.

The team was comprised of the following individuals:

Ken Mielke Team Leader, MIC, NWSFO Great Falls, Montana

Craig Edwards MIC, NWSFO Minneapolis, Minnesota

Mike Foster Science and Operations Officer (SOO), NWSFO Fort Worth, Texas

Larry Vannozzi Warning Coordination Meteorologist (WCM), NWSFO Lubbock,

Texas

Curtis Carey Southern Region Headquarters (SRH), Public Affairs Officer, Fort

Worth, Texas

Other valuable contributors include:

Gayland Kitch Director, Emergency Management and Communications, Moore,

Oklahoma

Dan Carey Safety and Emergency Management Director, Cleveland County,

Oklahoma

Randall Duncan Emergency Management Director, Sedgwick County, Kansas

John Ferree OSF/Training Branch, Norman, Oklahoma (assisted the team with the

southern Kansas Service Assessment and the writing of this report)
vii

The tornado, which hit Moore/Oklahoma City, Oklahoma, is shown here

near Amber, Oklahoma, at 6:30 p.m. CDT, May 3, 1999. (Photograph

courtesy of the Oklahoma Climatological Survey)

Dennis Walts NWS Headquarters, AWIPS Program Office (APO), Boulder,

Colorado

William Lerner NWS Headquarters, Office of Meteorology, Silver Spring, Maryland

Linda Kremkau NWS Headquarters, Office of Meteorology, Silver Spring, Maryland

Robert Saffle NWS Headquarters, Office of Systems Development, Silver Spring,

Maryland

Jerry Stephens NWS Headquarters, Office of Systems Operations (OSO), Silver

Spring, Maryland

The Service Assessment Team also acknowledges the valuable information provided by the

staffs at NWSFO Norman, Oklahoma; NEXRAD Weather Service Office (NWSO) Wichita,

Kansas; and the SPC.
viii

Radar reflectivity image from the Twin Lakes, Oklahoma, WSR-88D radar at 

7:18 p.m. CDT, May 3, 1999, shows several severe thunderstorms in west-central

Oklahoma and southern Kansas. (Courtesy of NOAA/NSSL)
1

 All times listed in this Service Assessment are CDT.

1

Event Overview

A large part of the central United States was hit by a significant outbreak of tornadoes and

other severe weather on May 3 and 4, 1999. From the afternoon of May 3 through the evening of

May 4, there was an outbreak of tornadoes from southwest Texas through southeast South

Dakota. The most devastating part of this outbreak occurred during the late afternoon and

evening of May 3 over Oklahoma and southern Kansas (Figure 1).

Between 6:23 p.m. and 7:50 p.m. CDT1 on Monday evening, May 3, a long-track, violent

tornado traveled from near Chickasha, Oklahoma, to just east of Oklahoma City, Oklahoma. 

Along its path this tornado produced areas of F5 (see Appendix A, Fujita Tornado Intensity

Scale) damage to both rural sections of central Oklahoma as well as densely populated areas of

Oklahoma City and its suburbs. In the wake of this single tornado, 38 people were left dead and

several hundred injured. There were 4 additional fatalities outside the Oklahoma metropolitan

area as a result of other tornadoes that afternoon and evening. Soon thereafter, between

8:30 p.m. and 9 p.m., another violent tornado, rated F4 intensity, plowed through Haysville in

suburban Wichita, Kansas. This tornado was responsible for 6 deaths and 150 injuries. While

these two tornadoes received the greatest attention, they were just two of a rare and significant

outbreak of violent tornadoes. Over 70 tornadoes, many of them rated F3 or stronger, were

spawned by a dozen supercell thunderstorms across Oklahoma and southern Kansas. In

Oklahoma, 16 counties were declared disaster areas with $1 billion in damage; in Kansas, there

was $145 million in damage and one county was declared a disaster area. What was unusual

about this event was not just the number of tornadoes but the number of violent tornadoes. Event

statistics are given in Appendix B.

The outbreak began around 4 p.m., May 3, when a thunderstorm developed near Lawton,

Oklahoma. The storm became severe in a short time and became tornadic before 5 p.m. Moving

northeastward, this storm later produced the F5 tornado that devastated parts of Bridge Creek,

Oklahoma City, Moore, Del City and Midwest City. A second storm formed west of the Lawton

storm and soon became tornadic. By early evening, these storms and several others were cutting

a swath through central and north-central Oklahoma, with each storm producing one or more

violent tornadoes. Additional storms formed over extreme northern Oklahoma. These storms

soon crossed into southern Kansas and produced the tornadoes that struck Wichita. 

Oklahoma City and its suburbs have been struck by numerous tornadoes over the years,

most recently on June 13, 1998. Moore was hit by a tornado on October 4, 1998; the May 3,

1999, tornado crossed portions of Moore that were struck just 6 months earlier. The May 3

tornado was the first F5 tornado to strike Oklahoma City; F4 tornadoes have been reported in the

city seven times before. With 38 fatalities, the May 3, 1999, tornado was the most deadly in
2

Oklahoma City metropolitan area history; the previous most deadly tornado occurred on June 12,

1942, when 35 people were killed.

Wichita, Kansas, also has been struck by several tornadoes over the years. The most recent

violent tornado to strike the city was on April 26, 1991, when the large tornado which devastated

Andover, Kansas, killed 4 people in the southern part of the Wichita metropolitan area. The

May 3, 1999, tornado, with 6 fatalities, was the most deadly for Wichita and Sedgwick County.

The Norman NWSFO issued the first severe thunderstorm warning (SVR) of the event at 

4:15 p.m. and the first tornado warning at 4:47 p.m. for the storm near Lawton, Oklahoma. This

storm moved northeastward and struck Oklahoma City about an hour later. By 5:52 p.m., the

early stage of this eventual F5 tornado was 4 miles south of Verden, moving to the northwest side

of Chickasha at 6:19 p.m. and south of Amber at 6:26 p.m (see Figure 1). The Norman NWSFO

continued issuing effective warnings, short term forecasts (NOWs) and severe weather statements

(SVSs). Also by this time, Oklahoma City media outlets were running continuous live coverage

of the tornado with live helicopter and ground-level video. All warnings, forecasts and statements

were disseminated over the NOAA Weather Wire Service (NWWS), the NOAA Weather Radio

(NWR), the Family of Services (FOS), the Emergency Alert System (EAS), the National Warning

System (NAWAS), and the local amateur radio network. The wide coverage of the event by the

National Weather Service and media outlets, the long lead time of National Weather Service

warnings, and the high state of tornado preparedness of Oklahoma residents are credited with

saving many lives.

The Wichita NWSO provided an accurate warning on the development of a violent tornado

that first struck the town of Haysville and moved due north into heavily populated areas of

southern Wichita. The warning, based on a radar signature, received wide dissemination on

NWWS, local television and radio, NWR, EAS and NAWAS. The warning prompted the

activation of the siren system and initiated an all-channel cable override for Wichita. Residents

followed severe weather safety plans and took cover in the lowest levels of houses or apartments,

saving many lives.
3

Figure 1. Approximate damage paths and highest Fujita scale ratings for tornadoes which occurred

during the May 3, 1999, outbreak in west-central Oklahoma and southern Kansas. (Courtesy of

Steve Kruckenberg and Douglas Speheger, NWSFO Norman, Oklahoma)
4

Aerial view of the Moore/Oklahoma City, Oklahoma, May 3, 1999, tornado path. The

dark mud trail shows the path of the tornado in the middle foreground and center of

the picture. Interstate Highway 44 is visible in the lower right through the center of

the picture. (Photograph courtesy of John Jarboe, NWS Coordinator, Federal Aviation

Administration Academy, Oklahoma City, Oklahoma)

Ground view of the Moore/Oklahoma City, Oklahoma, May 3, 1999, tornado path. 

View is looking northeast towards Oklahoma City from the Bridge Creek Community

in Grady County, Oklahoma. Note swath of reddish brown earth extending to the

horizon where the tornado pulled grass and other vegetation from the ground. 

(Photograph courtesy of William Lerner, NWS Headquarters)
5

Synoptic Overview

Many elements of a classical Great Plains severe weather outbreak were in place during the

afternoon and evening of May 3, 1999. The synoptic-scale pattern was characterized by a largescale middle and upper tropospheric trough over the western United States and a downstream

ridge to the east (Figure 2). There was a strong upper-level jet stream on the west side of the

trough with wind speeds greater than 130 knots over the west coast of the United States. Moving

through the synoptic-scale trough were several smaller scale short waves, the most important of

which was located along the New Mexico/Texas border by late afternoon. At the surface, a low

pressure center was located along the Wyoming/Colorado border and a low pressure trough

extended southward along the lee of the Rockies. In response to the approaching jet stream and

short wave, several atmospheric adjustments took place over the Plains. The surface low and lee

trough deepened throughout the afternoon. This caused surface winds ahead of the dryline to

strengthen and a strong low-level, southerly jet stream developed from northwest Texas into

Oklahoma. As a result of the strengthening surface trough and low-level jet, deep low-level

moisture streamed northward into Oklahoma and Kansas. As surface heating proceeded through

the afternoon, mixing of the shallow moisture over southwest Texas moved the dryline to near the

western Oklahoma border. At the same time, the lapse rates in the mid-troposphere over Kansas

and Oklahoma were steepening, owing to the effects of the approaching upper-level jet and short

wave. These factors contributed to the development of the large atmospheric instability and

vertical wind shear profiles favorable for the development of supercell thunderstorms.

With an atmosphere conducive to the development of supercell thunderstorms, the last

element necessary was a triggering mechanism. By late afternoon, two bulges developed along

the dryline; one located southwest of Wichita Falls, Texas, and a second near Woodward,

Oklahoma. In addition, a pool of cooler, drier air over central Oklahoma resulted in a mesoscale

boundary, oriented from southwest Oklahoma to south-central Oklahoma, separating the cooler

air from the very warm, moist air which was streaming northward across western Oklahoma. The

presence of the dryline bulges and the mesoscale boundary led to prolonged enhanced moisture

convergence which resulted in explosive thunderstorm development over southwest Oklahoma by

late afternoon and northwest Oklahoma to south-central Kansas by early evening.
6

Figure 2. Significant features associated with the May 3, 1999, tornado outbreak. Depicted are the 

4 p.m. CDT positions of the upper-level and low-level jets, the dryline, surface winds, and a mesoscale

boundary in southwest Oklahoma. The shaded area is where the Convective Available Potential Energy

(CAPE) exceeded 3000 Joules Kg-1. (Courtesy of Mike Foster and Jason Jordan, NWSFO Ft. Worth,

Texas)
7

Facts, Findings and Recommendations - Part 1

Oklahoma and Southern Kansas Outbreak Combined

National Centers for Environmental Prediction Guidance, Products

and Services

FACT: The 11:15 a.m., May 3, 1999, SPC Day 1 Severe Weather Outlook

(SWO) was upgraded to a moderate risk for severe thunderstorms in the

Oklahoma/Kansas outbreak area based on 7 a.m. soundings, midday

profiler observations and Rapid Update Cycle II (RUC II) forecasts of

instability and shear.

FACT: The SPC began an Experimental Probabilistic Outlook in the spring of

1999. The forecast is made available on the SPC Forecast Products Web

Page. The Experimental Probabilistic Outlook issued at 3 p.m. for

Oklahoma and southern Kansas highlighted a significant chance for F2 or

greater tornadoes.

Finding 1: From mid-morning to mid-afternoon on May 3, 1-hour, 250-meter

interval vertical wind profiles from the profiler at Tucumcari, New

Mexico, showed a descending and strengthening jet approaching

Oklahoma. The jet was deeper, stronger and lower in the atmosphere

than forecasts from numerical models and favored development of

supercells. It was profiler data that led SPC forecasters to upgrade the

SWO from moderate to high risk for severe weather in the outbreak area

and caused F2 or stronger tornadoes to be highlighted in the

Experimental Probabilistic Outlook (see FACT above). In the opinion of

the Service Assessment Team, without profiler data, SPC forecasters

would not have upgraded from moderate to high risk. Also, the state of

readiness of NWS offices, emergency managers, and the media in the

severe weather outbreak area would not have been as high. The profiler

network is “experimental” and not funded by the NWS.

Recommendation 1: The NWS should make a decision on how to support the existing profiler

network so that the current data suite becomes a reliable, operational

data source.

FACT: Tornado Watch #195 for western and central Oklahoma, including

Oklahoma City, was issued at 4:30 p.m., valid 4:45 p.m. to 10 p.m. The

first severe thunderstorm warning was issued by NWSFO Norman at
8

Total destruction of a residential area in Moore, Oklahoma, as an F5 tornado ripped

through this city during the evening of May 3, 1999. (Photograph courtesy of Curtis

Carey, NOAA/NWS Public Affairs)

4:15 p.m. Based on Weather Surveillance Radar-1988 Doppler (WSR88D) radar signatures, the first tornado warning followed at 4:47 p.m.

FACT: Tornado Watch #200 for Kansas, including Wichita, was issued at 

7:21 p.m., valid from 7:30 p.m. until 12 midnight. NWSO Wichita issued

its first tornado warning at 7:38 p.m. (Sumner County), a severe

thunderstorm warning for Sedgwick County at 7:49 p.m., and a tornado

warning for Sedgwick County at 8:16 p.m.
9

Oklahoma Outbreak Summary

NWSFO Norman, Oklahoma

Summary of Warning and Forecast Services

The potential for severe weather in Oklahoma was reflected in National Weather Service

forecast products as much as 36 hours prior to the outbreak. The May 2 SPC Day 2 SWO (valid

May 3) and the May 3 Day 1 SWO predicted a slight risk for severe weather. At 6:30 a.m. on

May 3, NWSFO Norman issued a Thunderstorm Outlook, noting a slight risk of severe storms in

western and central Oklahoma that afternoon and night. It mentioned the increasing low-level

moisture, dryline and approaching upper-level low pressure trough would combine to cause a

threat of hail, damaging winds and isolated tornadoes. It also cautioned emergency managers and

spotter groups to be prepared for possible activation in the afternoon.

Forecasts later that day advertised an increasing possibility of severe storms. The 11 a.m.

SPC Day 1 Outlook upgraded much of the eventual outbreak area to a moderate risk, as did the

12:30 p.m. Thunderstorm Outlook issued by NWSFO Norman. The increasing risk was further

reflected when the 3:49 p.m. SPC Day 1 Outlook upgraded the risk once again— this time to a

high risk.

The Norman NWSFO issued the first severe thunderstorm warning (SVR) of this event at

4:15 p.m. Soon after, the SPC issued Tornado Watch #195 for western and central Oklahoma,

valid from 4:45 p.m. until 10 p.m. The first tornado warning was issued at 4:47 p.m. About 

10 hours later, after the main part of this event concluded, NWSFO Norman had issued 

70 tornado warnings and 46 severe thunderstorm warnings for 32 of the 56 counties within its

county warning area (CWA) (see product chronology highlights in Appendix C).

The Norman Office of the National Weather Service was very successful in giving the public

significant advance warning of the individual tornadoes. They achieved a remarkable 

32-minute lead-time average for the first tornado warning issued in each of the Oklahoma City

metropolitan area counties that was affected by the F5 tornado. Warnings for this Oklahoma City

F5 tornado, which hit Grady, McClain, Cleveland and Oklahoma Counties, were issued with lead

times of 65, 18, 31 and 13 minutes, respectively.

These excellent lead times were a function of several factors. These included very good

severe weather knowledge and radar interpretation skills, modernized National Weather Service

equipment (especially the WSR-88D and the Advanced Weather Interactive Processing System

[AWIPS]), a well-trained and widespread spotter network and the long-lived nature of several of

the tornadoes. Another factor, cited by the NWSFO staff, was the use of “sectorized” warning

operations. The use of multiple AWIPS workstations, all with the same data and capabilities,

permitted forecasters to divide warning responsibility by geographic area. This geographic

division of responsibility improved efficiency and warning strategy during this widespread
10

outbreak. The NSSL-developed Warning Decision Support System (WDSS) software also

proved to be a useful tool during this event.

In addition to its excellent National Weather Service warnings, NWSFO Norman kept the

public informed with numerous SVSs, NOWs and Local Storm Reports (LSRs). During the most

active period of this event (4 p.m. until midnight), they issued 48 concise SVSs, 9 NOWs and

14 LSRs. 

At 5:41 p.m., a NOW was issued alerting the Oklahoma City metropolitan area of severe

thunderstorms and possible tornadoes. In part, this NOW read,

SEVERE THUNDERSTORMS...SOME PRODUCING TORNADOES...WILL

MOVE NORTHEAST ACROSS PORTIONS OF SOUTHWEST AND CENTRAL

OKLAHOMA THROUGH 6:30 PM. 

This NOW went on to state,

THE STORMS WILL BE MOVING TOWARD THE OKLAHOMA CITY

METROPOLITAN AREA. IN ADDITION TO VERY LARGE HAIL AND

DAMAGING WINDS...THESE STORMS MAY ALSO CONTINUE TO PRODUCE

TORNADOES. IF YOU ARE IN THE PATH OF THE THUNDERSTORMS...

EXERCISE YOUR TORNADO SAFETY PROCEDURES!

To heighten awareness of the severity of the situation, the office alarmed several SVSs on

NWR and issued an effective SVS at 6:57 p.m. that included the words “TORNADO

EMERGENCY” in the headline. Following is a portion of that SVS:

...TORNADO EMERGENCY IN SOUTH OKLAHOMA CITY METRO

AREA...

AT 657 P.M .CDT...A LARGE TORNADO WAS MOVING ALONG

INTERSTATE 44 WEST OF NEWCASTLE. ON ITS PRESENT PATH...THIS

LARGE DAMAGING TORNADO WILL ENTER SOUTHWEST SECTIONS

OF THE OKLAHOMA CITY METRO AREA BETWEEN 715 P.M. AND 

730 P.M. PERSONS IN MOORE AND SOUTH OKLAHOMA CITY SHOULD

TAKE IMMEDIATE TORNADO PRECAUTIONS!

THIS IS AN EXTREMELY DANGEROUS AND LIFE THREATENING

SITUATION.

All NWS warnings, forecasts and statements were disseminated via the NWWS, NWR,

FOS, EAS, NAWAS, the local amateur radio network, and the Emergency Managers Weather

Information Network (EMWIN). NWS information was also disseminated by local television and

radio stations, as well as through the Internet and OK-FIRST (Oklahoma’s First-response

Information Resource System using Telecommunications).
11

Two situations developed that could have impacted NWS warning services, but did not,

thanks to a competent staff and pre-existing agreements. First, a number of warnings were not

automatically sent through the Console Replacement System (CRS) to the NWR. Of the 

72 warnings that were issued within NWR listening areas, 14 (19 percent) had to be done

manually with only slight delays. The causes of most of the malfunctions were traced back to

software issues with CRS/Airwave/Bubble (Airwave and Bubble are product formatting software

which serve as an interface between AWIPS and CRS). Fixes for some of these problems were

tested just days after the outbreak.

Second, telephone service, including cellular, was intermittent (at best) from around 

6:30 p.m. until midnight— the duration of most of the outbreak. As the main tornadic storm

approached NWSFO Norman, staff members used NAWAS to contact surrounding NWS offices

to coordinate possible back-up support. Despite the lack of consistent phone service, numerous

severe weather reports continued to flow into the NWSFO thanks to spotters, amateur radio

operators and NAWAS.

Public Response

The fact that casualties were low (compared to the many thousands that were affected by

the main Oklahoma City tornado) is, in large part, attributable to the effective response of the

public to early National Weather Service severe weather warnings. To help enhance public

response, the Norman NWSFO has conducted an aggressive preparedness campaign for years in

Oklahoma. Within the 3 months prior to the outbreak, 32 spotter training classes were held. In

the 5-month period leading up to the outbreak, the office hosted 9 tours, conducted 4 safety

presentations, participated in 3 televised safety shows and presented 2 safety displays (information

booths) within its CWA. The office also has been active in the state’s annual severe weather

awareness week.

Oklahoma City radio and television stations also played a crucial role that led to effective

public response. They rapidly communicated National Weather Service warnings and gave hours

of live coverage of spotter reports, aerial video and ground-level video of the tornadoes. Using

the cable television override capability, the Moore City Emergency Manager broadcast NWS

warnings (audio only) to the community. Many radio stations provided simulcasts of the live

telecasts from the three primary television stations, as the main tornado approached the Oklahoma

City metropolitan area. One television station urged people to get out of the path of this

destructive tornado. This statement was cited as one of the reasons many people fled the path of

the tornado, only to return to damaged or demolished property. It should be noted that fleeing a

tornado is not recommended but was effective in this particular event due to lengthy National

Weather Service warning lead times, as well as the tornado’s intensity and longevity.
12

Post-Storm Feedback

Positive feedback after the outbreak was overwhelming. Local and national news coverage

often mentioned the advance warning provided by the National Weather Service and live video

coverage by Oklahoma City television stations. Interviews with a number of local radio stations

indicated the NWR information was very helpful in their efforts to alert the public. After the

event, NWSFO Norman issued a series of informative Public Information Statements (PNSs) on

May 4 and 5. These statements provided considerable detail regarding tornado paths, preliminary

intensities and comparisons to previous Oklahoma City tornadic events. In addition, NWSFO

Norman, as well as the SPC and NSSL, posted photographs, preliminary tornado tracks, storm

time lines and informative summaries on their Web pages which served as a source of information

for the media and other users.

Emergency managers were pleased with the severe weather information supplied by various

National Weather Service dissemination systems. Of special note was the Oklahoma

Climatological Survey’s (OCS) OK-FIRST, which emergency managers cited as a valuable tool

during the outbreak. A large Oklahoma City business called the Norman NWSFO after the

outbreak to express thanks for assistance in updating the company’s safety plan prior to this

event. Unlike the company’s previous plan, the new plan instructed employees to seek shelter at

that location rather than to drive away. Since the tornado passed close to this business, this

change in the plan may have saved lives and prevented injuries. 

The Norman NWSFO developed excellent working relationships with local emergency

managers. The strong partnerships eased the communication process during the severe weather

outbreak and also enabled NWS officials to gain access to the damaged areas to conduct surveys. 

Many of the severely damaged areas remained barricaded by the National Guard and/or local law

enforcement until at least May 9, 1999.

Summary

This was a unique event. Despite the large number of tornadoes in the NWSFO Norman

CWA and the tremendous devastation in residential areas, casualties were minimal for several

reasons.

< One very large tornado caused most of the damage and casualties.

< National Weather Service tornado warnings were issued with long lead times.

< There were live, on-the-scene broadcasts of the tornado on the local Oklahoma City

television stations well before it reached the densely populated metropolitan area.

< The main tornado struck in late afternoon and early evening after schools were out and

most commuter traffic had reached its destination.
13

An F5 tornado wrapped a large 4-wheel drive pickup around a utility pole, stripping

off most of the truck’s sheet metal. (Photograph courtesy of Curtis Carey,

NOAA/NWS Public Affairs)

< Residents were well-versed in tornado safety precautions due to extensive training and

outreach by the National Weather Service, local news media and emergency

management agencies.

Had this tornado struck during the late nighttime hours, even with the long National Weather

Service tornado warning lead times, the number of casualties could have been much higher.

In summary, the public was very well served by the National Weather Service in Norman

prior to and during this significant event. Effective warnings and follow-up statements minimized

loss of life and property.
14

F5 damage to a home in Moore, Cleveland County, Oklahoma, May 3, 1999. Note most debris has been

blown away. (Photograph copyright 1999. The Oklahoma Publishing Co.)

Wooden projectiles driven into the ground by the tornado on the west side of

Oklahoma City, Oklahoma, May 3, 1999. Note different directions of impact. 

(Photograph courtesy of William Lerner, NWS Headquarters)
15

Facts, Findings and Recommendations - Part 2

Oklahoma Outbreak

Local Office Warning and Forecast Service

FACT: At 12:30 p.m., May 3, a Thunderstorm Outlook was issued by NWSFO

Norman upgrading the western half of Oklahoma to a moderate risk of

severe thunderstorms. It noted the likelihood for some supercell

thunderstorms and isolated tornadoes. Emergency managers and spotter

groups were encouraged to be ready for possible activation later that

afternoon.

FACT: During the main part of this severe weather episode (4 p.m., May 3, until

2 a.m., May 4), NWSFO Norman issued 116 warnings (70 tornado

warnings; 46 severe thunderstorm warnings). In the Oklahoma City

metropolitan area, the average lead time for the first tornado, in each

county warned, was 32 minutes. NWSFO Norman’s average lead time

for all tornado warnings issued during this event was 18 minutes.

FACT: At 6:57 p.m., NWSFO Norman issued a uniquely worded SVS

(headlined “TORNADO EMERGENCY IN SOUTH OKLAHOMA

CITY METRO AREA”) which heightened awareness of this serious

situation. It urged people in Moore and south Oklahoma City to take

immediate tornado precautions (25 minutes before the tornado entered

those areas). This SVS was formatted with the Specific Area Message

Encoder (SAME) information and was tone-alerted on NWR. The

phrase was picked up by media outlets and credited with adding the

emphasis that prompted numerous residents to action.

FACT: Two members of the OSF assisted with the operations of the Norman

NWSFO Principal User Processor (PUP) during the event and provided

helpful feedback/analysis to the operational forecasters.
16

Systems

Weather Surveillance Radar-1988 Doppler (WSR-88D)

FACT: Most radar-based tornado warning decisions at NWSFO Norman were

made using the base reflectivity, storm relative velocity and Vertically

Integrated Liquid products from the WSR-88D.

FACT: One communications equipment malfunction (resulting in the loss of one

volume scan) occurred with the Twin Lakes WSR-88D (KTLX) radar

during the tornado event. The OSF Hotline staff (in the same building)

came to the NWSFO to reset the WSR-88D. The forecast office staff did

not have to become involved in problem resolution. That level of service

is not available at other NWS field offices.

FACT: This Service Assessment focuses on the Oklahoma City and Wichita area

tornadoes. However, it is noteworthy that, within this severe

thunderstorm and tornado outbreak area on May 3, NWSO Wichita and

NWSFO Tulsa were able to provide effective warning services during

this event through the use of nearby WSR-88Ds. This is a testimony to

the effectiveness of the redundant WSR-88D coverage (mainly east of the

Rockies) and the back-up procedures employed by these two offices.

Finding 2: The NWSFO Tulsa WSR-88D gearbox malfunctioned and dropped into

the azimuth electrical harness on May 2 at 10 a.m. Depot maintenance

was dispatched from OSF within 4 hours and brought the system up 

24 hours later.

Recommendation 2: Once the gearbox problem is determined, the OSF should implement

appropriate maintenance procedures and/or fixes at all WSR-88D sites.

Warning Decision Support System (WDSS)

FACT: The NSSL-developed WDSS provided useful information to the warning

staff at NWSFO Norman during the outbreak. WDSS offers access to

the full wide-band suite of reflectivity and velocity data, improved

algorithm guidance, and dynamic tables which rank storms according to

algorithm-derived severe weather threats.
17

Finding 3: WDSS severe storm cell tables and trend displays focused the

forecasters’ attention on those storms that could require warning. 

WDSS displays of full resolution velocity products were confidence

builders for tornado warning decisions. WDSS also incorporates

advanced versions of the NSSL mesocyclone detection and tornado

detection algorithms. The NEXRAD Open systems Radar Product

Generator (ORPG) is required to implement advanced algorithms and to

provide high resolution products to AWIPS for these WDSS capabilities. 

The NEXRAD Open systems Radar Data Acquisition (ORDA) will

provide improved base data (e.g., high resolution reflectivity, better

anomalous propagation suppression).

Recommendation 3: The National Weather Service should give high priority to the ORPG and

ORDA projects and to the incorporation of high resolution WSR-88D

data in the AWIPS Build 5.X series.

NOAA Weather Radio (NWR) / Console Replacement System (CRS)

Performance

FACT: The CRS automated voice was used by NWSFO Norman during the

event. CRS proved to be beneficial overall, as many statements and

warnings reached the public faster than would have been possible via

manual recordings. 

FACT: Despite the speed advantage provided by CRS, there were some adverse

occurrences. In NWSFO Norman’s NWR coverage areas, 14 warnings

(19 percent of the warnings broadcast) required manual transmission

through the CRS Emergency Override. Quick action by the NWS

enabled these warnings to be broadcast with delays of less than 

60 seconds.

FACT: Fourteen warnings were not automatically broadcast due to software

problems. CRS’s Airwave formatter did not accept warnings with three

bullets of information (compared to the “typical” four-bullet format

referenced in Operations Manual Letter 1-98). CRS did not accept

warnings that contained the “&” symbol (signifying a severe weather

report) if that symbol was positioned before the latitude/longitude

coordinates in WarnGen-created warnings; this symbol caused Airwave

to lock up. Two warnings were not automatically broadcast due to the

“Active/Inactive” bug (products flagged as neither active nor inactive,

thus are not broadcast). Also, a software problem occurred with

Bubble’s communication with CRS (the “escape-a” bug).
18

The first two problems listed above were fixed by field personnel within

days of the outbreak. The third was fixed with a patch from

CommPower (a work-a-round was available on the NWS CRS Home

Page 2 days after the outbreak). The fourth problem remains unsolved as

of this writing.

FACT: To heighten awareness, 24 of the 48 SVS products issued during this

event were broadcast using the warning alert tone. Because most SVS

products are not tone-alerted, these urgent SVSs required manual

intervention. CRS’s Airwave formatter, along with AWIPS’s WarnGen

software, do not have the capability to produce both non-tone-alerted

and tone-alerted SVS products.

Finding 4: Various CRS formatters in field offices provide a useful service but do

not satisfy the needs of all offices. In addition, there are operational

problems associated with most of these formatters. There is a need for

standardized CRS formatter software to provide an efficient, reliable

interface between AWIPS and CRS. Earlier this year, NWS regional

representatives provided OSO a set of field requirements for a universal

CRS formatter. 

Recommendation 4a: OSO should establish a schedule for the development and implementation

of universal, AWIPS-based, and nationally supported formatters for

CRS.

Recommendation 4b: In the interim, OSO should establish a national forum to collect and

publicize improvements and fixes that have been made to the CRS

formatters currently in use.

AWIPS Performance

FACT: AWIPS was critical to the success of this event. It would have been

impossible to duplicate the number of successful warnings and lead times

and to keep track of the large number of severe storms with a mixture of

PUPs, PCs and Automation of Field Operations and Services (AFOS)

systems.

Finding 5: All warnings at NWSFO Norman were generated with WarnGen

(AWIPS Build 4.1.1); the staff invested substantial effort during the

months prior to the event, customizing preformats for warnings and

SVSs, which included the generation of detailed city boundary

backgrounds.
19

Recommendation 5: NWS regions should ensure that all forecast offices customize warning

preformats and generate city boundary backgrounds for their CWAs.

Finding 6: AWIPS pixel replication zoom distortion led forecasters to supplement

WSR-88D velocity data with alternate display systems (e.g., WDSS). 

AWIPS Build 4.2 provides non-distorted magnification but requires more

time to display the product. Substantial improvement in performance will

not be possible with the existing AWIPS hardware.

Recommendation 6a: For the near term Build 5 time frame, the AWIPS Program Office (APO)

should make modifications that result in more rapid display of nondistorted magnified products within the existing AWIPS framework.

Recommendation 6b: For the long term, the APO should evaluate what improvements in

display time could be achieved for non-distorted magnification of WSR88D products as AWIPS hardware and software evolve.

Finding 7: The Norman NWSFO accessed, via the Internet, data sets not available

through AWIPS and helped forecasters focus on the convective initiation

over southwest Oklahoma. These included:

< Advanced Regional Prediction System model output from the Center

for the Analysis and Prediction of Storms at the University of

Oklahoma,

< RUC II model output, and

< the Oklahoma mesoscale network.

Methods for ingesting data sets into AWIPS, via Local Data Acquisition

and Dissemination (LDAD), have been implemented at a few forecast

offices but are not widely known or documented.

Recommendation 7: The APO should provide to the Regions for distribution to field offices

documentation and procedures for using LDAD to ingest data sets not

available through AWIPS.

FACT: The Norman NWSFO SOO alerted the Network Control Facility (NCF)

at 5 p.m. and requested enhanced monitoring. The NCF opened a

remote terminal session into Norman and was ready for problem

resolution. When one of the radar data streams stopped coming into the

AWIPS, the SOO notified NCF personnel who promptly performed a

modem reset. This was the only modem reset required during this event.

FACT: The AWIPS program that sends data to AFOS failed once and delayed

one warning by 30 seconds. Because this process fails often at NWSFO
20

Norman, the SOO anticipated this and had a remote terminal window

open and ready to run “startAFOS.”

Finding 8: AWIPS performed very well during this event. However, two

interruptions of AWIPS processes (e.g., AWIPS to AFOS

communication and WSR-88D to AWIPS communication) led to delays

in product receipt and transmission. An additional delay was caused by

having to contact the NCF. Also, a potential AWIPS point of failure,

with respect to contacting the NCF, is possible when phone lines are

unavailable, as was often the case at NWSFO Norman during this event.

Recommendation 8: The APO should develop a method to allow local restart of basic AWIPS

processes, saving valuable time during severe weather events.

Internal and External Coordination

FACT: The Norman NWSFO’s strong partnership with the amateur radio

community in central and western Oklahoma proved very valuable on

May 3. Amateur radio information played a crucial role in the warning

process and in subsequent follow-up information (SVSs and LSRs). 

Seventy-five severe event reports were received via the amateur radio

network. The office’s amateur radios were of even greater importance

that night since its phone service was often interrupted for several hours

(6:30 p.m. until at least midnight).

FACT: Amateur radio repeaters helped keep the Norman NWSFO in contact

with spotters and Emergency Operations Centers (EOCs) throughout the

far reaching counties in its CWA. This was critical for these outlying

communities because local TV coverage was focused on the Oklahoma

City metropolitan area F5 tornado.

FACT: Post-storm visibility with the media was very positive. Local and

national news coverage focused on the advance warning provided by the

National Weather Service and the extensive live video coverage by the

Oklahoma City TV stations. NWS Headquarters, SRH, NWSFO

Norman, SPC, OSF and NSSL all participated in interviews following the

event. There were over 200 media contacts following this event. 

Pro-active efforts by NOAA Public Affairs included:

< Press conference by NWSFO Norman, the SPC, OSF and NSSL on

May 4, 1999. 

< Press conference in Washington, DC, by NOAA Administrator 

D. James Baker and NWS Deputy Director John Jones.
21

< Several press releases and media advisories.

< A multitude of pro-active interviews with local reporters. Coverage

included stories in several major newspapers and news magazines

plus interviews and related coverage by the major television

networks.

FACT: Soon after the live broadcast of the Presidential visit to the city on

May 8, 1999, a TV newscaster from the Oklahoma City NBC affiliate,

KFOR, thanked the National Weather Service for the advance warning. 

FACT: The Moore Emergency Manager included a severe weather awareness

insert in the city’s water bills to residents during severe weather

awareness week (held 2 months prior to the tornado). The insert gave

specific instructions on what the residents should do in the event of a

tornado. The Norman NWSFO gave technical assistance to the

emergency manager on this project.

FACT: A large Oklahoma City area telecommunications company called

NWSFO Norman after the tornado to express thanks for their assistance

in updating the company’s severe weather safety plan, completed prior to

the tornado. The new plan instructed employees not to travel home

during a tornado for safety reasons. This was a significant change from

the previous plan, which allowed employees to go home. The new plan

may have saved lives since the F5 tornado passed within 1 mile of the

company.

Dissemination

FACT: Interviews with several Oklahoma City radio stations (KNOR, KOMA,

KQCV, KTOK, KATT, KYIS, KCYI, KNTL and WWLS) indicated that

NWR information was used often in their operations during the outbreak. 

One general manager said that he was “grateful” for the NWR service,

while another station’s official said that his station “lives and dies by”

NWR.

FACT: CRS voice quality was not a major issue in this event, at least with the

limited number of customers interviewed. During the event, some

stations played the actual NWR automated voice on the air, although one

radio station’s general manager acknowledged that they did not air the

actual broadcast due to CRS’s “poor voice quality.” In the weeks

following the event, NWSFO Norman received some voice quality

complaints from the public.
22

FACT: The Deputy Director of the Oklahoma Civil Emergency Management

agency stated EMWIN provided prompt information to the emergency

managers during this event. He further stated EMWIN is one of the most

valuable emergency management tools to come along in many years.

FACT: Local emergency management officials cited the OK-FIRST system as a

very helpful weather information tool. The OK-FIRST system includes

Internet access to real-time WSR-88D radar data plus all NWS text

products. This system was developed by the Oklahoma Climatological

Survey. The Norman NWSFO staff and OSF Training Branch assisted

the OCS in its extensive training of OK-FIRST users.

Finding 9: In addition to the NWS text products, such as warnings and follow-up

statements, real-time radar data was available to some emergency

managers via OK-FIRST. These radar data provided valuable

information on storm structure, location and track of the storms. A basic

set of WSR-88D products will soon be available (in Build 4.3) on the

AWIPS Satellite Broadcast Network. However, these products cannot

be made available outside the NWS until the NEXRAD Information

Dissemination Service (NIDS) contract expires.

Recommendation 9: The APO should devise a method that can be implemented, once the

NIDS vendor contract expires, whereby partners and customers can

access a basic set of radar products in real-time.

Response

FACT: The ample National Weather Service warning lead times and live local

TV coverage allowed many individuals to escape the path of this tornado

(from their homes) via automobile.

FACT: A Grady County resident living in an area with primarily mobile homes

credited advance National Weather Service warnings with saving many

lives in his neighborhood. The early warning gave his family time to

gather neighbors into his storm cellar. Thirty-five people crammed into

the cellar. The winds from the F5 tornado pulled the cellar door open,

but all survived. Their mobile homes were destroyed.

FACT: Citing advance National Weather Service warnings, a Grady County

Deputy Sheriff was able to pre-position himself close to the projected

path of the tornado to immediately deploy into the stricken area after it

passed. As a result, he was on the scene of some of the worst

destruction in his county and delivered emergency care to casualties.
23

FACT: An award ceremony at West Moore High School could have ended in

disaster without the quick thinking of the school’s assistant principal. 

The assistant school principal ushered the participants and guests into the

interior hallways and bathrooms. The roof of the gym was ripped off by

the tornado. There were no fatalities at the school.

FACT: Using National Weather Service warnings and radar information, as well

as their own radars, TV stations in Oklahoma City are credited with

helping save many lives. TV coverage of the Oklahoma City metro area

F5 tornado is regarded as an extraordinary event. Two news helicopters

flew adjacent to the tornado reporting the location and path to the public. 

One station simultaneously showed a text box on the screen with

projected street names the tornado would hit and approximate time the

tornado would reach a particular site.

Finding 10: Two deaths were attributed to individuals seeking shelter under highway

overpasses during this event. There were also reports of people who

were severely injured after seeking shelter under overpasses.

Recommendation 10: NOAA Public Affairs, with assistance from the Office of Meteorology,

should update tornado safety brochures with statements which warn

against seeking shelter under overpasses during a tornadic event.

Training

FACT: The Norman NWSFO staff completed a severe weather drill just prior to

the May 3, 1999, outbreak. One part of the drill was a scenario which

simulated a violent tornado approaching Oklahoma City. Each forecaster

was required to write appropriate warnings and NOWs for such an event.
24

Devastating tornado damage in the small community of Haysville, south of Wichita,

Kansas. (Photograph courtesy of John Ogren, NWSO Wichita, Kansas)

Management Procedures

FACT: The Norman NWSFO has encouraged and nurtured a productive

partnership with the local agencies, the University of Oklahoma and the

public to assist in weather-related scenarios. Early in the morning on

May 4 following the tornado outbreak, there were enough qualified

volunteers (including volunteers from all local NOAA components) to

assemble nine storm survey teams. These quality surveys were posted on

the NWSFO Norman Home Page soon after the event. This was very

helpful to the Service Assessment Team. Although such a rapid and

thorough survey cannot be expected at other offices in the country, it

does point to the importance of being prepared for a quick response.
25

Southern Kansas Outbreak Summary

NWSO Wichita, Kansas

A destructive tornado moved through south-central Kansas on the evening of May 3, 1999

(see Figure 1). The hardest hit area extended from Haysville northward into the southern sections

of Wichita. NWSO Wichita provided accurate information on the tornado as it developed in

northern Sumner County and moved north into Sedgwick County. As the tornado tracked

towards the southern sections of the city of Wichita, it veered to the northeast, sparing a strike on

the center of the city.

Summary of Warning and Forecast Services

Early in the day, the operational staff was aware that there was potential for severe

thunderstorms on Monday evening, May 3. The SPC included the area in a slight risk for severe

thunderstorms in the 7 a.m. Day 1 SWO. Following the 11:15 a.m. Day 1 SWO, elevating the

potential to a moderate risk, NWSO Wichita issued a Hazardous Weather Outlook (HWO) at

12:18 p.m. for the potential of severe thunderstorms and the possibility of isolated tornadoes. At

3:49 p.m., the SPC upgraded the Day 1 SWO to indicate the high risk for severe thunderstorms in

central Oklahoma and central Kansas.

A NOW was issued at 4:12 p.m., announcing the expected development of thunderstorms

between 5 p.m. and 7 p.m. stating,

“SOME OF THE THUNDERSTORMS WILL BE SEVERE...PRODUCING LARGE

HAIL AND DAMAGING WINDS. ISOLATED TORNADOES ARE ALSO

POSSIBLE.”

Another NOW was issued at 6:38 p.m. indicating,

“THUNDERSTORMS WILL DEVELOP RAPIDLY THIS EVENING.... NOW IS

THE TIME TO REVIEW YOUR SEVERE WEATHER SAFETY PLANS.”

Thunderstorms developed rapidly over south-central Kansas between 6:45 p.m. and 7 p.m. 

The shift supervisor called to request SKYWARN activation around 7 p.m. At 7:17 p.m., NWSO

Wichita issued a severe thunderstorm warning for Harper County, based on the potential for large

hail, as indicated by the WSR-88D. The SPC issued Tornado Watch #200 at 7:21 p.m., valid

from 7:30 p.m. to midnight.

At 7:19 p.m., the Wichita WSR-88D malfunctioned. The shift supervisor initiated

immediate remedial actions by calling the OSF Hotline. Next, he attempted to correct the failure

by working with the OSF from the Radar Data Acquisition site. In the intervening time, the other
26

forecaster initiated a dial back-up to the Vance Air Force Base (AFB) radar to ingest imagery on

the PUP. At 7:38 p.m., the Vance AFB WSR-88D indicated strong rotation in Sumner County,

and a tornado warning was issued by NWSO Wichita valid until 8:15 p.m. for northern Sumner

County.

Since NWSO Wichita was dialed into the Vance AFB WSR-88D via the PUP, radar

imagery was not available on AWIPS. The full capability of WarnGen, the AWIPS-resident

warning generation tool, cannot be realized without current radar imagery. Therefore, the staff

used the back-up PC-resident software (Warning and Interactive Statement Editor, version II

[WISEII]) to issue severe weather warnings. It should be noted that AWIPS Build 4.2, which

will be installed at all NWS offices this summer, will have a continuous dial capability to nearby

radars allowing forecasters to use the full capability of WarnGen if the primary WSR-88D should

malfunction.

A severe thunderstorm warning was issued for Sedgwick County at 7:49 p.m. based on a

spotter report of dime-size hail at 7:45 p.m. near Haysville. The storm later produced golfballsize hail in the city of Wichita. Based on radar data from the Vance AFB WSR-88D, which

depicted a dramatic increase in the rotational velocities within the mesocyclone, NWSO Wichita

issued a tornado warning for northern Sumner County and southeast Sedgwick County at 

8:16 p.m., valid until 9:20 p.m. The warning was corrected 2 minutes later to indicate the

warning was for northern Sumner and eastern Sedgwick County. The tornado warning was

relayed from NWSO Wichita to the Sedgwick County EOC at 8:17 p.m. The 911 dispatcher

activated the siren system and initiated an all-channel cable override for Wichita.

A tornado entered Sedgwick County moving north at 30 mph from Sumner County. 

Damage was rated at F1 as it crossed into Sedgwick County about 8:30 p.m. Around 8:35 p.m.,

the tornado struck the town of Haysville with F2 to F3 intensity. An isolated section in north

Haysville suffered F4 damage.

An SVS issued at 8:33 p.m. read, 

“TRAINED SPOTTERS AND RADAR INDICATED A TORNADO ON THE

GROUND NEAR PECK ON THE SUMNER/SEDGWICK COUNTY LINE. THIS

TORNADO WILL PASS THE KANSAS TURNPIKE JUST SOUTH OF

HAYSVILLE AT ANY TIME.” 

Another SVS issued at 8:46 p.m. asserted,

“AT 8:43 P.M. ...DOPPLER RADAR INDICATED A TORNADO ENTERING

SOUTH WICHITA...FROM THE HAYSVILLE AREA. ...A TORNADO WAS

REPORTED IN HAYSVILLE WITH STRUCTURAL DAMAGE AROUND

8:35 P.M. PERSONS IN WICHITA SHOULD TAKE SHELTER IMMEDIATELY.”

As the tornado turned to the northeast, it moved across the southern sections of the city of

Wichita. The SVS issued at 8:52 p.m. noted,
27

“TRAINED WEATHER SPOTTERS REPORTED DAMAGE FROM A TORNADO

AT MACARTHUR AND SENECA ROAD. THIS DANGEROUS STORM WILL

CONTINUE TO MOVE NORTH AT 30 MPH THROUGH THE MIDDLE OF

WICHITA.”

From the damage path and reports from spotters, the tornado lifted about 8:53 p.m. in

eastern Sedgwick County. A chronology of the products issued by NWSO Wichita and the SPC

is given in Appendix D.

Public Response

Warnings and statements, disseminated by the National Weather Service via the NWWS,

FOS and NWR, were relayed by the local radio and television stations. Extensive coverage on

local television and radio allowed for widespread awareness of the approaching tornado. On-site

interviews were conducted in Haysville where the tornado did considerable damage. Those

interviewed said the warnings were very good, stating that the siren lead time was 10 to

15 minutes. Residents followed severe weather safety plans and took cover in the lowest levels of

the houses or apartments. Several had time to invite neighbors to their basements. No fatalities

occurred in automobiles. There were no reports of travelers seeking shelter under overpasses.

Additional interviews with those affected by the storm indicated that radio station KFDI

provided effective weather information of the approaching tornado. A telephone interview was

conducted with a reporter from KFDI AM/FM radio in Wichita who commented that the products

and services from the National Weather Service were timely. He believed that the report of the

tornado in Sumner County at 7:40 p.m. elevated the awareness of the station and the listeners.

Post-Storm Feedback

The Sedgwick County Emergency Management team cited several National Weather

Service products as being valuable in preparing the county emergency staff for this tornado event. 

These included the Day 1 and Day 2 SWOs from the SPC and the HWO issued at 

12:18 p.m. by NWSO Wichita. The NOW issued by NWSO Wichita at 4:12 p.m., predicting the

expected development of thunderstorms between 5 p.m. and 7 p.m. with the potential for isolated

tornadoes, heightened awareness. Also, the tornado warning for Sumner County at 7:38 p.m.

elevated public awareness of the tornado potential for the Wichita area, enhancing the

effectiveness of the response to the 8:16 p.m. tornado warning for southeast Sedgwick County.

Just before the issuance of the tornado watch around 7:15 p.m., the Sedgwick County

Communication Officer initiated spotter activation. The county EOC monitors the weather

warnings and forecasts through EMWIN. Two other video monitors are used to view cable

television delivery of radar imagery on Cable TV channels 51 and 52. The county EOC also has a

Data Transmission Network and NWR with the SAME feature.
28

The Sedgwick County EOC has the lead responsibility for siren activation in Wichita. The

county EOC is co-located with the 911 Dispatch. There is a direct line between NWSO Wichita

and the communication center. Sirens were activated upon receipt of the tornado warning at

8:17 p.m. The county EOC staff was very complimentary of the relationship with the NWSO and

the services provided during this event.

The WCM began the first field survey of damage in Sedgwick County Tuesday afternoon,

May 4. An aerial assessment was made by the WCM during a fly-over of the damage path in a

police helicopter. From the aerial survey, it was determined that portions of the damage track

were category F4. A lead forecaster from Wichita conducted a ground survey of damage in

Sumner County on Wednesday, May 5. A ground survey of the damage in Sedgwick County was

conducted by the WCM and a member of the Service Assessment Team on Friday, May 7. By

that time, the damaged area was contaminated by removal of debris and bulldozing efforts.

To reduce the influx of media inquiries, the WCM prepared a well-worded PNS Tuesday

morning, May 4, listing pertinent details of the previous evening’s event. This PNS was released

at 9:30 a.m. and was deemed valuable in minimizing follow-up interviews from the media. 

A follow-up press release was issued by the WCM at 4 p.m. as a PNS on Tuesday, May 4. 

In this release, the WCM announced the damage was assessed as category F4. The press release

contained pertinent information on the damage path and the timetable of warnings and statements

issued by NWSO Wichita. On May 6, NWSO Wichita posted a tornado track map on its Web

page.

Interviews were conducted with the staffs of all three major TV network affiliations

(KAKE-TV10 ABC, KWCH-TV12 CBS, KSNW-TV3 NBC) in Wichita. These television

stations indicated that NWSO Wichita performed an excellent service with effective warnings and

statements. All three TV stations broke into programming after the issuance of the 7:38 p.m.

tornado warning for Sumner County. Continuous on-air television coverage began in the 8:16 to

8:22 p.m. time frame and continued for 1 1⁄2 hours.

As was the case in the Oklahoma City area, effective warnings and follow-up statements by

NWSO Wichita served the public very well during this event. It is noteworthy that these services

were provided despite the malfunction of the Wichita WSR-88D, about 1 hour before the event. 

The NWSO Wichita staff is commended for their proficiency in using back-up procedures.
29

Facts, Findings and Recommendations - Part 3

Southern Kansas Outbreak

Local Office Warning and Forecast Service

FACT: NWSO Wichita issued two NOWs at 4:12 p.m. and 6:38 p.m., predicting

the potential for severe thunderstorms and the possibility of isolated

tornadoes.

FACT: The initial tornado warning for southeast Sedgwick County was issued at

8:16 p.m, with a lead time of 14 minutes. This warning was corrected 2

minutes later to include eastern Sedgwick County. SVSs issued at 8:33

p.m., 8:46 p.m. and 8:52 p.m. contained information on the tornado’s

location or damage, as reported by spotters in Sedgwick County.

Systems

FACT: The NWSO Wichita WSR-88D radar (KICT) failed at 7:19 p.m. The

Wichita electronic technician replaced a trigger amplifier and two shorted

backswing diodes in the modulator. The radar was brought back on-line

at about 10:15 p.m. The failure does not appear to be associated with

any specific action on the part of the radar operator (e.g., power source

change, or Volume Coverage Pattern change). However, these

components could weaken over time due to power transfers and surges. 

The OSF is in the process of installing Transition Power Maintenance

Systems (TPMSs) at all WSR-88D sites, which will ease power

transitions and surges. The NWSO Wichita WSR-88D TPMS

installation is scheduled for the year 2000.

FACT: Two of the local television stations have their own local radars, in

addition to the NIDS products, such as the composite radar imagery from

Weather Services Incorporated. The other station had continuous NIDS

access to the Vance AFB WSR-88D via a NIDS vendor. Most of the

time, this station’s meteorologist displays the Vance AFB radar data

when storms are close to the KICT radar. All television stations said

they were able to communicate the threat of the approaching tornado

despite the outage of the Wichita WSR-88D.

Internal and External Coordination
30

FACT: NWSO Wichita has developed a strong working relationship with the

SKYWARN program and has expanded it within the amateur radio

community. This partnership resulted in the prompt and accurate

communication of tornado and damage reports throughout the event.

Finding 11: When NWSO Wichita began receiving detailed locations of tornado

damage (i.e., street addresses), personnel were not readily equipped to

identify the location, since they did not have a local city map. The only

map of Wichita was in the Yellow Pages of the phone directory.

Recommendation 11: NWS Regions should ensure that offices have up-to-date, detailed maps

for the larger metropolitan areas in their CWA to track significant

weather movement and damage reports.

Dissemination

FACT: The sirens were activated by the 911 dispatcher through the Sedgwick

County EOC upon receipt of the NWS warning at 8:17 p.m. Lead time

on the siren alert to residents in the tornado’s path ranged from

approximately 12 minutes (Haysville) to 20 minutes (south Wichita).

FACT: The 911 dispatchers disseminated the warning via the All-Channel

Override of the Cable Television at 8:18 p.m. to warn television viewers

who were not tuned to the local Wichita TV stations.

FACT: Wichita is home to Weather Data Incorporated which had several clients

in both Oklahoma and Kansas affected by this event. Using WSR-88D

data obtained via NIDS and other data sets, including National Weather

Service warnings, the Weather Data Incorporated forecasters

disseminated several warnings to their clients. Mike Smith, President of

Weather Data Incorporated, cited this event as a good example where the

“public-private partnership worked well.”

Response

FACT: All those interviewed in the damaged areas commented that they had

heard the National Weather Service warnings before the tornado struck. 

Citizens were clear on the information of the approaching tornado and

followed recommended safety measures.
31

FACT: Employees of Norland Plastics in Haysville were warned via NWR. 

Eighty-five employees were directed by the supervisor to the

designated shelter area in the basement. None were injured, although

the building was heavily damaged.

FACT: Monthly community tornado drills proved beneficial. Thirteen clients

of a residential facility for disabled adults moved to the bath tubs and

covered themselves. None were injured, although their homes, built on

concrete slabs, were almost destroyed.

FACT: Since the Wichita area Civil Air Patrol (CAP) does not have access to

aircraft for aerial storm surveys, the WCM arranged for an aerial

helicopter survey with the Wichita police. Note: A National

Memorandum of Understanding between the CAP and the Office of the

Federal Coordinator for Meteorological Services and Supporting

Research for support of aerial storm surveys, already exists (August

1997) for those NWS offices with active CAP units in their area.

Finding 12: On May 4, the day after the event, a ground survey in Sedgwick and

Sumner Counties could not be done due to more severe weather. An

aerial survey was conducted in Sedgwick County on May 4, and a

ground survey was completed in Sumner County on May 5. Weather

Service Operations Manual (WSOM) Chapter J-02, section 4.3.3, reads

in part: “[It] is the responsibility of the local Meteorologist in Charge

or their designated representative to go to the site, survey the damage,

and obtain overflight capabilities....”

Recommendation 12a: Regions should reemphasize the requirement contained in WSOM

Chapter J-02, section 4.3.3, that NWS offices should conduct ground

surveys as soon as practical after a severe weather event where there

are fatalities, a large number of injuries or significant damage.

Recommendation 12b: NWS Regional Meteorological Services Divisions (MSDs) should

establish procedures to perform prompt post-storm surveys at forecast

offices needing assistance from nearby forecast offices or the regional

headquarters.
32

Training

FACT: Proficiency in back-up procedures was critical to the smooth transition

of the warning program once the radar failed. In late February and

March, the NWSO Wichita staff completed proficiency checks on

WarnGen, WISEII, transfer power, calling NCF and use of CRS.

Finding 13: The National Weather Service Wichita forecasters were skilled in using

the back-up dial-in feature of the PUP to access radar imagery from the

Vance AFB WSR-88D.

Recommendation 13: NWS Regional MSDs should ensure that office drills include

proficiency checks in using the back-up dial-in feature of the PUP.

Supporting Activities

FACT: Sedgwick County Emergency Management, in cooperation with the

local NWS office, conducted 21 separate spotter training/public safety

programs from March 1 to April 8 for over 1,000 participants. The

NWSO Wichita WCM conducted two of the sessions and had earlier

trained the Sedgwick County Deputy Director to provide the other

training seminars.

FACT: Within 24 hours of the event, two separate press releases were issued

as PNSs at 9:30 a.m. and 4 p.m, May 4, by the NWSO Wichita WCM. 

These press releases were valuable in reducing the need for media

interviews and communicated the information on the tornado’s intensity

and the timeliness of NWS products.
33

Practices to Emulate

The Service Assessment Team identified practices at NWSFO Norman and NWSO Wichita

that were particularly effective and which other field office managers may wish to emulate. Those

practices having widespread applicability were also identified as Recommendations earlier in this

Service Assessment.

Sectorization of Warning Operations: During the height of the tornado outbreak, NWSFO

Norman divided warning responsibility by geographical

area, using multiple AWIPS workstations. This

geographical division of responsibility improved efficiency

and warning strategy and is recommended during a

widespread outbreak of severe weather.

AWIPS Map Customization: NWSFO Norman created AWIPS map background

boundaries for the major metropolitan areas within its

CWA. As a result, forecasters were able to generate

warnings faster and provide more detail in their warning

products. (See Recommendation 5)

Tone-alerted SVSs: Typically, SVSs are not tone-alerted. However, during this

widespread tornado outbreak, NWSFO Norman forecasters

tone-alerted 24 of 48 SVSs which helped maintain a high

level of public awareness. 

Familiarization with Back-up Procedures: Demonstrated proficiency in using WSR-88D dial back-up

procedures was included in NWSO Wichita’s spring drill. 

This proved valuable, as their primary radar malfunctioned

just prior to this event. (See Recommendation 13)

 
2

 From J. Atmos. Sci., August, 1981, p. 1517-1519

A-1

Appendix A

Fujita Tornado Intensity Scale2

The Fujita Tornado Intensity Scale is a scale of wind damage intensity which wind speeds are

inferred from an analysis of wind damage.

Category Definition and Effect

F0 Gale tornado (40-72 mph): Light damage. Some damage to chimneys;

break branches off trees; push over shallow-rooted trees; damage sign boards.

F1 Moderate tornado (73-112 mph): Moderate damage. The lower limit is

the beginning of hurricane wind speed; peel surface off roofs; mobile homes

pushed off foundations or overturned; moving autos pushed off the roads.

F2 Significant tornado (113-157 mph): Considerable damage. Roofs torn off

frame houses; mobile homes demolished; boxcars pushed over; large trees

snapped or uprooted; light-object missiles generated.

F3 Severe tornado (158-206 mph): Severe damage. Roofs and some walls

torn off well-constructed houses; trains overturned; most trees in forest

uprooted; heavy cars lifted off ground and thrown.

F4 Devastating tornado (207-260 mph): Devastating damage. Wellconstructed houses leveled; structure with weak foundation blown off some

distance; cars thrown and large missiles generated.

F5 Incredible tornado (261-318 mph): Incredible damage. Strong frame

houses lifted off foundations and carried considerable distance to disintegrate;

automobile-sized missiles fly through the air in excess of 100 yards; trees

debarked; steel-reinforced structures badly damaged; incredible phenomena

will occur.
B-1

Appendix B

Event Statistics#

May 3-4, 1999

4 p.m.-3 a.m.

` NWSFO Norman 

 CWA

NWSO Wichita 

 CWA

# Tornadoes 57 * 3

# Tornado Warnings 70 7

Avg Lead Time for All Tornado

Warnings

18 min 11 min

# Severe Thunderstorm Warnings 46 4

Fatalities 42 6

Injuries 795 150

Homes Destroyed 3,315 1,114

Homes Damaged 4,722 2,272

Schools Destroyed 2 2

Businesses Destroyed 164 72

Businesses Damaged 90 38

Damage Cost $1 billion $145 million

# Most of the data in this table was provided by the May 14 Daily Oklahoman; Sedgwick

County, Kansas, Emergency Management; American Red Cross; and the Oklahoma

Department of Civil Emergency Management.

* 65 tornadoes in all of Oklahoma during this event period.
C-1

Appendix C

Oklahoma/Southern Kansas

Tornado Outbreak

of May 3, 1999

NWSFO Norman

Chronological Product Highlights

Valid Time

(CDT)

Product Issued

or Severe Report

Area/Counties Affected Remarks

1204 5/2/99 SWODY2 Most of Oklahoma Slight risk of severe storms

0055 5/3/99 SWODY1 Most of Oklahoma Slight risk of severe storms late this

afternoon and tonight

0430 ZFP NWSFO Norman CWA Severe storms possible later today and/or

tonight for most zones

0630 SPS NWSFO Norman CWA Slight risk of severe storms this

afternoon and tonight; isolated tornadoes

possible

1115 SWODY1 Most of Oklahoma Part of the Slight risk area upgraded to

Moderate risk

1230 SPS NWSFO Norman CWA Moderate risk of severe storms later this

afternoon through tonight

1549 SWODY1 Western/Central

Oklahoma

Part of the Moderate risk area upgraded

to High risk

1523 SWOMCD Western/Central

Oklahoma

Increasing threat of supercells near the

dryline late afternoon and evening

1600 ZFP NWSFO Norman CWA “Some thunderstorms may be severe”

mentioned in most zones for tonight

1615-1700 SVR Comanche Co. First warning of the event issued
C-2

1620 HAIL Lawton (in Comanche

Co.)

First severe occurrence (1-inch diameter

hail) of this event

1645 SEL5 Western/Central

Oklahoma

Tornado Watch #195 issued; “tornadoes,

hail to 3 inches, and wind gusts to 80

mph possible”

1647-1730 TOR Comanche, Grady, and

Caddo Counties

First tornado warning of the event issued

1651 TORNADO 7 miles east-northeast of

Medicine Park

(Comanche Co.)

Spotters report first tornado of this event

(near I-44)

1713 SOFTBALLSIZED HAIL5 miles north of Altus

(Jackson Co.)

Spotters report the first occurrence of

very large hail of this event

1741 NOW Oklahoma City Metro

Area

Potential for tornadoes to move into the

area that evening

1752 TORNADO Grady Co. First tornado in Grady County (4 miles

south of Verden)

1830 NOW NWSFO Norman CWA Ongoing tornadic storms detailed for

some counties; rest of area informed that

“threat for tornadoes will continue to be

high through the evening”

1840-1930 TOR Cleveland and McClain

Co.

First tornado warning that was issued for

these counties

1858 TORNADO McClain Co. First tornado in McClain County (along

Interstate 44 west of Newcastle)

1857 SVS Oklahoma City Metro

Area

Headlined, “...Tornado Emergency in

South Oklahoma City Metro Area...”

Predicts large damaging tornado will

enter southwest metro area between

7:15-7:30 p.m. “Persons in Moore and

south Oklahoma City should take

immediate tornado precautions!”

1859 SEL8 Central Oklahoma Tornado Watch #198 replaced #195;

“particularly dangerous situation with

destructive tornadoes possible”
C-3

1911 TORNADO Cleveland Co. First tornado in Cleveland County

(crossed South Canadian River near SW

149th Street)

1917-2000 TOR Oklahoma Co. First tornado warning that was issued for

this county 

1925 TORNADO City of Moore Tornado moved through Moore

1930 TORNADO Oklahoma Co. First tornado in Oklahoma County

(entered southern part of county east of

Interstate 35)

1931 SVS Oklahoma City Metro

Area

Headlined, “...Large Damaging Tornado

Moving Through Oklahoma City

Metro...” Also states, “Persons in

southeast Oklahoma City and Midwest

City are in danger!”

1934 TORNADO Oklahoma Co. Tornado near Tinker Air Force Base

NOTE: This table reflects only the highlights of the Oklahoma chronology. It lists some of the key statements,

watches, warnings and severe reports but does not attempt to recreate all of the products that were issued and all

the reports received during this extended tornado outbreak.
D-1

Appendix D

Oklahoma/Southern Kansas

Tornado Outbreak

of May 3, 1999

NWSO Wichita

Chronological Product Log

Valid Time

(CDT)

Product

Type

Area/Counties

Affected

Remarks

1204 5/2/99 SWODY2 Eastern Kansas Slight risk of severe storms

0055 5/3/99 SWODY1 Eastern 2/3 

Kansas

Slight risk of severe storms

1115 SWODY1 Southern Kansas Upgraded to moderate risk

1218-0000 SPS NWSO Wichita

CWA

Highlighted threat of hail, damaging

winds, and isolated tornadoes

1549 SWODY1 Southern Kansas Upgraded to high risk

1612-1900 NOW Sumner and

Sedgwick

Counties

Forecast rapid storm development

between 1700-1900

1836-2100 NOW Sumner, 

Sedgwick and

Harper Counties

Forecast rapid storm development

between 1900-2100

1917-2000 SVR Harper Co. 18SW Anthony radar indicated hail up

to 1 inch and winds over 55 mph

1921 SEL0 Central Kansas Tornado Watch #200 1930-midnight

1938-2015 TOR N Sumner Co. Radar indicated strong rotation 2E of

Mayfield

1944 SVS N Sumner Co. Tornado 1N of Mayfield

1949-2050 SVR Sedgwick Co. Hail near Haysville
D-2

2002 SVS N Sumner Co. Tornado 3NW of Wellington

2004 SVS Sedgwick Co. Hail in downtown Wichita

2016-2120 TOR SE Sedgwick and

N Sumner

Counties

Tornado 4NW Wellington, strong

rotation 2NE Wichita. Reissue for N

Sumner 1 min after previous TOR

expired

2016-2120 TOR E Sedgwick and

N Sumner

Counties

Corrected warning to include all of east

Sedgwick County

2023-2230 NOW NWSO Wichita

CWA

Forecast of continued development of

severe storms with large hail, damaging

winds, and isolated tornadoes possible

2029 SVS Sedgwick Co. Strong rotation near Kechi quarter

sized hail near Andale

2033 SVS E Sedgwick and

N Sumner

Counties

Tornado near Peck, possible tornado

7NW Wellington

2046 SVS E Sedgwick Co. Tornado entering S Wichita

1

st mention of Wichita being in path

2047-2150 SVR W Sedgwick Co. Warning re-issuance— radar indicated

severe storm near Anness

2052 SVS E Sedgwick Co. Tornado moving through middle of

Wichita

2059-2200 TOR W Butler Co. Radar indicated strong rotation near

Andover

2107 SVS W Sedgwick Co. Radar indicated severe storm near

Anness

2111 SVS W Butler Co. Radar indicated tornado near Rosehill

2116 SVS E Sedgwick and

N Sumner

Counties

Allow warning to expire at 2120

2121 SVS W Butler Co. Tornado 1SW Augusta

2129-2215 SVR Sumner Co. Nickel sized hail near Perth
D-3

2130-2300 NOW NWSO Wichita

CWA

Severe storms to continue developing

near and E of Anthony/Wichita/Marion

2132 SVS W Sedgwick Co. Warning canceled

2137-2225 TOR Butler Co. Radar indicated strong rotation 10NE

and 8SW El Dorado

2145 SVS Butler Co. Tornado NE of El Dorado

2151 SVS Sumner Co. Radar indicated severe near Dalton and

Oxford

2201 SVS Butler Co. Wall cloud N of El Dorado Lake

2209 SVS Sumner Co. Warning canceled

2211 SVS Butler Co. Warning canceled

2227 SPS NWSO Wichita

CWA

HWO indicating continued potential for

storms overnight