Alert archive / Iowa / Severe Thunderstorm Warnings in 1991

Severe Thunderstorm Warning 112, NWS Des Moines, IA

June 18, 19914 counties in Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Jun 18, 1991, 8:47 PM CDT for 4 counties in Iowa. It was in force for 58 min. 3 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Jun 18, 1991, 8:47 PM CDT (01:47 UTC)
Expired: Jun 18, 1991, 9:45 PM CDT
In force: 58 min
Issued by: NWS Des Moines, IA
Area: Whole counties

Counties Chickasaw County, IA, Fayette County, IA, Howard County, IA, Winneshiek County, IA

What was reported inside it

Time	Report	Where
Jun 18, 8:55 PM CDT	Hail 2.5	Chickasaw, IA
Jun 18, 9:10 PM CDT	Tornado F1	Chickasaw, IA
Jun 18, 9:10 PM CDT	Thunderstorm Wind 60	Howard, 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. Storm Data before 1996 records only tornadoes, thunderstorm wind and hail.

The nearest sounding before it

Minneapolis, MN (KSTC), launched 00:00Z, 1.8 hours before the alert went out and 225 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 199 J/kg
Mixed-layer CIN: -70 J/kg
Mixed-layer LCL: 1675 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 28 m²/s²
0-3 km storm-relative helicity: 46 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

In the hours before

Special weather statement, Jun 18, 8:36 PM CDT, 11 minutes before

IAZALL-190235-

SPECIAL WEATHER STATEMENT AND RADAR SUMMARY
NATIONAL WEATHER SERVICE DES MOINES IA
835 PM CDT TUE JUN 18 1991

AT 827 PM...AN ISOLATED VERY STRONG THUNDERSTORM WAS OCCURRING IN
NORTHEAST IOWA...45 MILES NORTH OF WATERLOO...OR JUST SOUTHWEST OF
CRESCO.  THIS STORM WAS PRODUCING VERY HEAVY RAIN...GUSTY WINDS AND
POSSIBLY SOME HAIL.

AN ISOLATED SHOWER WAS ALSO 40 MILES WEST OF WATERLOO...OR JUST SOUTH
OF IOWA FALLS.

THE SHOWERS AND STORMS WERE MOVING SOUTH AT AROUND 10 MILES AN HOUR.

JAK

The office that day

Everything else NWS Des Moines, IA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 18, 7:45 PM CDT	Severe Thunderstorm Warning	DMX	Howard	60 min
Jun 18, 9:00 PM CDT	Tornado Warning	DMX	Chickasaw	45 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1991 Every severe thunderstorm warning in 1991

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.