Alert archive / Iowa / Severe Thunderstorm Warnings in 2002

Severe Thunderstorm Warning 24, NWS La Crosse, WI

April 18, 2002Floyd County, Iowa

NWS La Crosse, WI issued this severe thunderstorm warning at Apr 18, 2002, 4:31 PM CDT for Floyd County, Iowa. It was in force for 44 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Apr 18, 2002, 4:31 PM CDT (21:31 UTC)
Expired
Apr 18, 2002, 5:15 PM CDT
In force
44 min
Issued by
NWS La Crosse, WI
Area
Counties, with a storm outline in the text

County Floyd County, IA

The radar

The Des Moines radar (KDMX), 157 km from the middle of the area, began a volume at 21:35 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
Apr 18, 4:40 PM CDTHail 1.75Marble Rock, IA
Apr 18, 4:55 PM CDTHail 0.88Charles City, IA

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Apr 18, 4:15 PM CDTTornado WatchSPC5 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 9.5 hours before the alert went out and 218 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Minneapolis, MN at 12:00Z on 2002-04-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 12:00Z on 2002-04-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 745 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1064 m above ground
0-6 km bulk shear
63 kt
0-1 km storm-relative helicity
745 m²/s²
0-3 km storm-relative helicity
912 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
WUUS53 KARX 182131
SVRLSE
IAC067-182215-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE LA CROSSE WI
431 PM CDT THU APR 18 2002

THE NATIONAL WEATHER SERVICE IN LA CROSSE HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  FLOYD COUNTY IN NORTH CENTRAL IOWA

* UNTIL 515 PM CDT

* AT 431 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM 3 MILES SOUTH OF MARBLE ROCK...OR ABOUT 14
  MILES SOUTHWEST OF CHARLES CITY...MOVING NORTHEAST AT 40 MPH.

* THE SEVERE THUNDERSTORM IS EXPECTED TO BE...
  NEAR CHARLES CITY...AND FLOYD AT 445 PM CDT...

A TORNADO WATCH REMAINS IN EFFECT UNTIL 800 PM CDT THURSDAY EVENING
FOR WESTERN WISCONSIN. A TORNADO WATCH ALSO REMAINS IN EFFECT UNTIL
900 PM CDT THURSDAY EVENING FOR NORTHEASTERN IOWA AND SOUTHEAST
MINNESOTA AND WEST CENTRAL WISCONSIN.

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND GUSTS IN EXCESS OF 55
MPH...DESTRUCTIVE HAIL...DEADLY LIGHTNING AND VERY HEAVY RAIN. FOR
YOUR PROTECTION...MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF
YOUR HOME OR BUSINESS.

LAT...LON 4297 9299 4282 9287 4291 9254 4321 9268

KRC

The office that day

Everything else NWS La Crosse, WI issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 18, 1:30 AM CDTSevere Thunderstorm WarningARXFayette30 min
Apr 18, 1:47 AM CDTSevere Thunderstorm WarningARXWinneshiek58 min
Apr 18, 2:22 AM CDTSevere Thunderstorm WarningARXFayette38 min
Apr 18, 2:48 AM CDTSevere Thunderstorm WarningARXChickasaw42 min
Apr 18, 2:50 AM CDTSevere Thunderstorm WarningARXAllamakee55 min
Apr 18, 2:58 AM CDTSevere Thunderstorm WarningARXFayette47 min
Apr 18, 3:29 AM CDTSevere Thunderstorm WarningARXHoward46 min
Apr 18, 3:49 AM CDTSevere Thunderstorm WarningARXWinneshiek56 min
Apr 18, 4:01 AM CDTSevere Thunderstorm WarningARXAllamakee44 min
Apr 18, 4:57 PM CDTSevere Thunderstorm WarningARXChickasaw63 min
Apr 18, 5:25 PM CDTTornado WarningARXChickasaw50 min
Apr 18, 5:49 PM CDTSevere Thunderstorm WarningARXFayette, Winneshiek56 min
Apr 18, 5:53 PM CDTTornado WarningARXHoward, Winneshiek67 min
Apr 18, 6:31 PM CDTSevere Thunderstorm WarningARXAllamakee59 min
Apr 18, 6:34 PM CDTSevere Thunderstorm WarningARXChickasaw41 min
Apr 18, 6:49 PM CDTSevere Thunderstorm WarningARXWinneshiek56 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2002Every severe thunderstorm warning in 2002

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.