Alert archive / Iowa / Severe Thunderstorm Warnings in 1987

Severe Thunderstorm Warning 92, NWS Des Moines, IA

July 11, 1987Chickasaw County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Jul 11, 1987, 7:56 PM CDT for Chickasaw County, Iowa. It was in force for 64 min.

The area

The counties it named.

The facts

Issued
Jul 11, 1987, 7:56 PM CDT (00:56 UTC)
Expired
Jul 11, 1987, 9:00 PM CDT
In force
64 min
Issued by
NWS Des Moines, IA
Area
Whole counties

County Chickasaw County, IA

The radar

The WSR-88D network and its archive begin in 1991, so there is no radar volume for this alert.

The nearest sounding before it

Minneapolis, MN (KSTC), launched 00:00Z, 0.9 hours before the alert went out and 224 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 00:00Z on 1987-07-12Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2069 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, Minneapolis, MN at 00:00Z on 1987-07-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 4 square meters per square second.193958Sfc1 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
2069 J/kg
Mixed-layer CIN
-19 J/kg
Mixed-layer LCL
1014 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
4 m²/s²
0-3 km storm-relative helicity
71 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.1

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, Jul 11, 3:20 PM CDT, 4 hours 36 minutes before
SPECIAL WEATHER STATEMENT AND RADAR SUMMARY
NATIONAL WEATHER SERVICE DES MOINES IA
314 PM CDT SAT JUL 11 1987

...A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR MOST OF WESTERN
AND NORTHERN IOWA UNTIL 9PM THIS EVENING...

AT 310 PM...A 20 MILE WIDE BAND OF SHOWERS AND ISOLATED INTENSE
THUNDERSTORMS WAS LOCATED OVER THE FAR NORTHWEST COUNTIES OF IOWA.

THE STRONGEST STORMS WERE LOCATED ABOUT 25 MILES NORTHWEST OF SPENCER
IN EXTREME NORTHEAST OSCEOLA COUNTY...THE OTHER STORM WAS LOCATED
40 MILES NORTHWEST OF SPENCER IN THE EXTREME SOUTHEAST CORNER OF
LYON COUNTY.

ALTHOUGH THESE STORMS DO NOT APPEAR TO BE SEVERE AT THIS TIME...VERY
HEAVY RAIN...STRONG GUSTY WINDS ALONG WITH SMALL HAIL AND DANGEROUS
LIGHTNING CAN BE EXPECTED WITH THE PASSAGE OF THESE STORMS.

PEOPLE ON OR AROUND AREA LAKES IN EXTREME NORTHWEST IOWA SHOULD BE
PREPARED TO MOVE QUICKLY TO A PLACE OF SHELTER IF THESE STORMS
APPROACH.

MOVEMENT OF THE SHOWERS AND STORMS WAS EAST NORTHEAST AT 40 MILES
AN HOUR.

BARLOW/MILLER
Special weather statement, Jul 11, 5:46 PM CDT, 2 hours 10 minutes before
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Special weather statement, Jul 11, 6:43 PM CDT, 1 hour 13 minutes before
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Special weather statement, Jul 11, 6:48 PM CDT, 1 hour 8 minutes before
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Special weather statement, Jul 11, 7:20 PM CDT, 36 minutes before
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Special weather statement, Jul 11, 7:47 PM CDT, 9 minutes before
SPECIAL WEATHER STATEMENT AND RADAR SUMMARY
NATIONAL WEATHER SERVICE DES MOINES IA
740 PM CDT SAT JUL 11 1987

...A SEVERE THUNDERSTORM WATCH IS IN EFFECT FOR MOST OF WESTERN
AND NORTHERN IOWA UNTIL 9PM THIS EVENING...

...A FLASH FLOOD WATCH REMAINS IN EFFECT FOR WEST CENTRAL...SOUTHWEST
...AND SOUTH CENTRAL IOWA TONIGHT...

NO SEVERE WEATHER WAS REPORTED BETWEEN 630 PM AND 730 PM.

AT 730 PM CDT...VERY STRONG THUNDERSTORMS WERE LOCATED OVER NORTHWEST
AND NORTH CENTRAL IOWA.

THERE WERE TWO CLUSTERS OF VERY STRONG THUNDERSTORMS...ONE...
OVER NORTHWEST IOWA...15 MILES WIDE...FROM JUST SOUTH OF CHEROKEE...TO
15 MILES NORTHEAST OF STORM LAKE...OR FROM 30 MILES EAST NORTHEAST OF
SIOUX CITY...TO 75 MILES NORTHEAST OF SIOUX CITY.  THE OTHER CLUSTER
OF VERY STONG THUNDERSTORMS...10 MILES WIDE...WAS LOCATED FROM 25 MILES
EAST SOUTHEAST OF MASON CITY....TO 25 MILES NORTHEAST OF FORT DODGE.

THESE VERY STRONG STORMS WERE PRODUCING VERY LARGE AMOUNTS OF RAINFALL
...AND COULD PRODUCE SOME SMALL HAIL AS WELL AS STRONG GUSTY WIND...AND
WERE PRODUCING FREQUENT DANGEROUS LIGHTNING.

OVER THE REMAINDER OF EXTREME NORTHWEST AND NORTH CENTRAL IOWA...
SCATTERED SHOWERS AND THUNDERSTORMS CONTINUED.

THE SHOWERS AND STORMS WERE MOVING HEAST AT 30 MILES AN HOUR.
MARTIN/MILLER

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 11, 8:54 PM CDTSevere Thunderstorm WarningDMXBuena Vista, Pocahontas36 min
Jul 11, 11:30 PM CDTSevere Thunderstorm WarningDMXMarshall, Story40 min
Jul 11, 11:50 PM CDTSevere Thunderstorm WarningDMXBlack Hawk, Grundy55 min
Jul 11, 11:57 PM CDTTornado WarningDMXMarshall28 min
Jul 12, 3:05 AM CDTFlash Flood WarningDMXRinggold, Taylor, Union4 hr
Jul 12, 3:05 AM CDTFlash Flood WarningDMXAdair, Adams65 min
Jul 12, 3:06 AM CDTFlash Flood WarningDMXDallas, Polk4 hr
Jul 12, 4:10 AM CDTFlash Flood WarningDMXAdams3 hr

Nearby

Severe Thunderstorm Warnings in Iowa, 1987Every severe thunderstorm warning in 1987

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.