Service Assessment
Spencer, South Dakota, Tornado
May 30, 1998
Photos: The Spencer tornado viewed from about 4 miles
east of town on Highway 38 (courtesy of Keith Brown), and the Spencer water
tower, an example of the catastrophic damage inflicted on the town (courtesy
of Dr. Josh Wurman).
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
Contents
- Preface
- Service
Assessment Team
- Acronyms
- Event Summary
- Facts,
Findings and Recommendations
- Appendix A:
Fujita Tornado Intensity Scale
- Appendix
B: Spencer, South Dakota, Tornado, May 30, 1998, Chronological Log
Preface
The violent tornado which struck Spencer,
South Dakota, on the evening of May 30, 1998, killed six residents and destroyed
almost the entire town. The National Weather Service (NWS) conducted a Service
Assessment to examine the effectiveness of the warning process that evening,
focusing on the performance of the Next Generation Weather Radar (NEXRAD)
Weather Service Forecast Office (NWSFO) at Sioux Falls, the usefulness of
NWS warnings and forecasts from the perspective of our partners in the media
and emergency agencies, and the public response.
Service Assessments are critical to the
ongoing efforts of the NWS to improve the quality and timeliness of our
warning and forecast services, especially as offices like NWSFO Sioux Falls
complete the transition to a fully modernized Weather Forecast Office (WFO).
By reviewing the performance of one operational team at one forecast office
during one such devastating event, we look for ways to ensure that the application
of new technology and new concepts will yield the most timely and accurate
warnings and forecasts.
John J. Kelly, Jr., Assistant Administrator
for Weather Services, August 1998
Service
Assessment Team
The NWS assembled a Service Assessment Team to review the effectiveness
of the warning process during the evening of May 30, 1998, when a violent
tornado struck the town of Spencer, South Dakota. The team met in Sioux
Falls on June 2 and spent the following 3 days in South Dakota collecting
information and conducting interviews with the NWS staff at the Sioux Falls
NWSFO, emergency managers, law enforcement officials, media representatives,
and a number of residents of Spencer. Additional information was obtained
from the NWS Storm Prediction Center (SPC) in Norman, Oklahoma, from other
NWS meteorologists who participated in post-storm damage surveys, and from
engineers at the National Institute of Science and Technology.
The team was comprised of the following individuals:
- Dennis H. McCarthyTeam Leader, Meteorologist
in Charge (MIC), NWSFO Norman, Oklahoma
- Ricky L. ShanklinWarning Coordination Meteorologist
(WCM), NEXRAD Weather Service Office (NWSO) Paducah, Kentucky
- Patrick J. SlatteryPublic Affairs Specialist, NWS
Central Region Headquarters, Kansas City, Missouri
- James G. LaDueMeteorologist (Instructor), WSR-88D
Operational Support Facility, Operations Training Branch, Norman, Oklahoma
- Randall C. DuncanEmergency Management Coordinator,
Cowley County, Kansas, President, International Association of Emergency
Managers
- Other valuable contributors include:
- D. Gregory HarmonMIC, NWSFO Sioux Falls, South Dakota
- Todd A. HeitkampWCM, NWSFO Sioux Falls, South Dakota
- David L. AndraScience and Operations Officer (SOO),
NWSFO Norman, Oklahoma
- Brian E. SmithWCM, NWSFO Omaha, Nebraska
- William F. BuntingWCM, NWSO Pleasant Hill (Kansas
City), Missouri
- Michael FosterSOO, NWSFO Fort Worth, Texas
- David A. ImyChief, Operations Branch, NWS SPC, Norman,
Oklahoma
- David DowellGraduate Research Assistant, University
of Oklahoma
- Long PhanNational Institute of Science and Technology
- Dat Duthinh
- William H. LernerWeather Service Headquarters (WSH),
Office of Meteorology, Silver Spring, Maryland
- Linda S. KremkauTechnical Editor, WSH, Office of Meteorology,
Silver Spring, Maryland
- Argus LeaderDaily Sioux Falls Newspaper
Acronyms
- AFOS: Automation of Field Operations and Services
- AWIPS:Advanced Weather Interactive Processing System
- CAPE: Convective Available Potential Energy
- CDT:Central Daylight Time
- CRS:Console Replacement System
- CWA:County Warning Area
- DOW:Doppler on Wheels
- EAS:Emergency Alert System
- EMWIN:Emergency Management Weather Information Network
- GOES:Geostationary Operational Environmental Satellite
- HMT:Hydrometeorological Technician
- MCD:Mesoscale Convective Discussion
- MIC:Meteorologist in Charge
- m/s: meters per second
- NAWAS:National Warning System
- NEXRAD: Next Generation Weather Radar
- NOAA:National Oceanic and Atmospheric Administration
- NOW:Short Term Forecast (product identifier)
- NWR:NOAA Weather Radio
- NWS:National Weather Service
- NWSO:NEXRAD Weather Service Office
- NWSFO:NEXRAD Weather Service Forecast Office
- NWWS: NOAA Weather Wire Service
- PC:Personal Computer
- PDS:Particularly Dangerous Situation
- PSD:Peripheral Sharing Device
- PUP:Principal User Processor
- RFD:Rear Flank Downdraft
- ROTATE:Radar Observation of Tornadoes and Thunderstorms
Experiment
- SEL:Severe Thunderstorm or Tornado Watch (product
identifier)
- SFP:State Forecast Product (product identifier)
- SOO: Science and Operations Officer
- SPC:Storm Prediction Center
- SPS:Special Weather Statement (product identifier)
- SVR:Severe Thunderstorm Warning (product identifier)
- SVS:Severe Weather Statement (product identifier)
- SWO:Severe Weather Outlook (product identifier)
- TOR:Tornado Warning (product identifier)
- TVS:Tornado Vortex Signature
- VCP:Volume Coverage Pattern
- WCM:Warning Coordination Meteorologist
- WFO:Weather Forecast Office
- WISE:Warning and Interactive Statement Editor
- WSH: Weather Service Headquarters
- WSR-88D:Weather Surveillance Radar-1988 Doppler
- ZFP:Zone Forecast Product (product identifier)
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