Alert archive / Iowa / Tornado Watches in 1998

Tornado Watch 472

May 31, 199826 counties in Iowa; Crawford County, Grant County, Wisconsin

The Storm Prediction Center issued this tornado watch at May 31, 1998, 12:00 AM CDT for 26 counties in Iowa; Crawford County, Grant County, Wisconsin. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
May 31, 1998, 12:00 AM CDT (05:00 UTC)
Expired
May 31, 1998, 5:00 AM CDT
In force
5 hr
Issued by
the Storm Prediction Center
All 28 counties

Allamakee County, IA, Benton County, IA, Black Hawk County, IA, Bremer County, IA, Buchanan County, IA, Butler County, IA, Cedar County, IA, Cerro Gordo County, IA, Chickasaw County, IA, Clayton County, IA, Clinton County, IA, Delaware County, IA, Dubuque County, IA, Fayette County, IA, Floyd County, IA, Franklin County, IA, Grundy County, IA, Iowa County, IA, Jackson County, IA, Johnson County, IA, Jones County, IA, Linn County, IA, Poweshiek County, IA, Scott County, IA, Tama County, IA, Winneshiek County, IA, Crawford County, WI, Grant County, WI

Warnings issued inside it

8 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
May 31, 12:26 AM CDTSevere Thunderstorm WarningARXChickasaw, Winneshiek64 min
May 31, 12:26 AM CDTSevere Thunderstorm WarningARXAllamakee64 min
May 31, 1:01 AM CDTSevere Thunderstorm WarningARXCrawford, Richland74 min
May 31, 1:10 AM CDTSevere Thunderstorm WarningARXClayton, Fayette65 min
May 31, 1:10 AM CDTSevere Thunderstorm WarningARXGrant65 min
May 31, 1:29 AM CDTSevere Thunderstorm WarningDVNBuchanan51 min
May 31, 1:36 AM CDTTornado WarningARXClayton, Fayette34 min
May 31, 1:45 AM CDTTornado WarningDVNDelaware50 min

The nearest sounding before it

Davenport, (KDVN), launched 00:00Z, 5.0 hours before the alert went out and 144 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, Davenport, at 00:00Z on 1998-05-31Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1779 joules per kilogram.LCLLFCEL10008507005003002001001 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, Davenport, at 00:00Z on 1998-05-31The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 221 square meters per square second.19395878Sfc1 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
1779 J/kg
Mixed-layer CIN
-287 J/kg
Mixed-layer LCL
1354 m above ground
0-6 km bulk shear
61 kt
0-1 km storm-relative helicity
221 m²/s²
0-3 km storm-relative helicity
565 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.9

Open this sounding in Storm Lab

The text

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

953 
WWUS9 KMKC 310435
SEL2  
MKC WW 310435
IAZ000-311000-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 472
STORM PREDICTION CENTER NORMAN OK
1135 PM CDT SAT MAY 30 1998

THE STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF

   NORTHEASTERN IOWA                               

EFFECTIVE THIS SUNDAY MORNING FROM MIDNIGHT CDT UNTIL 500 AM CDT.

TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS
TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS ALONG AND 70 STATUTE MILES EAST AND WEST
OF A LINE FROM 55 MILES EAST NORTHEAST OF MASON CITY IOWA TO 30
MILES SOUTHEAST OF CEDAR RAPIDS IOWA.

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. 
PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING
WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE
WARNINGS.

OTHER WATCH INFORMATION...  CONTINUE...WW 469...WW 470...WW 471...

DISCUSSION...LINE OF THUNDERSTORMS INCREASING AS THEY ADVANCE INTO
WATCH AREA WHERE CAPES EXCEED 3500 J/KG. 50 KT MID LEVEL FLOW
RESULTING IN WIND SHEAR SUFFICIENT FOR A FEW TORNADIC SUPERCELLS. 

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES.  EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 70 KNOTS.  A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. 
MEAN STORM MOTION VECTOR 28040.

...ROGASH

431,0905 413,0895 413,0923 431,0933

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 30, 8:30 PM CDTTornado WatchSPCAudubon, Boone, Buena Vista, Calhoun, Carroll, Cherokee and 33 more7 hr
May 30, 10:00 PM CDTTornado WatchSPCBarron, Burnett, Chippewa, Dunn, Pepin, Pierce and 6 more6 hr
May 30, 11:30 PM CDTSevere Thunderstorm WatchSPCAdams, Buffalo, Chippewa, Clark, Eau Claire, Jackson and 20 more6 hr
May 31, 1:00 AM CDTTornado WatchSPCAdams, Brown, Calumet, Columbia, Dane, Dodge and 27 more5 hr

Nearby

Tornado Watches in Iowa, 1998Tornado Watches in Wisconsin, 1998Every tornado watch in 1998

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.