Alert archive / Iowa / Severe Thunderstorm Warnings in 1987

Severe Thunderstorm Warning 93, NWS Des Moines, IA

July 11, 1987Buena Vista County, Pocahontas County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Jul 11, 1987, 8:54 PM CDT for Buena Vista County, Pocahontas County, Iowa. It was in force for 36 min.

The area

The counties it named.

The facts

Issued
Jul 11, 1987, 8:54 PM CDT (01:54 UTC)
Expired
Jul 11, 1987, 9:30 PM CDT
In force
36 min
Issued by
NWS Des Moines, IA
Area
Whole counties

Counties Buena Vista County, IA, Pocahontas 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

Omaha, NE (KOAX), launched 00:00Z, 1.9 hours before the alert went out and 198 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, Omaha, NE at 00:00Z on 1987-07-12Temperature 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, Omaha, NE at 00:00Z on 1987-07-12The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 98 square meters per square second.1939Sfc1 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
3602 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
98 m²/s²
0-3 km storm-relative helicity
145 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

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, 5:46 PM CDT, 3 hours 8 minutes before
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Special weather statement, Jul 11, 6:43 PM CDT, 2 hours 11 minutes before
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Special weather statement, Jul 11, 6:48 PM CDT, 2 hours 6 minutes before
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Special weather statement, Jul 11, 7:20 PM CDT, 1 hour 34 minutes before
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Special weather statement, Jul 11, 7:47 PM CDT, 1 hour 7 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
Special weather statement, Jul 11, 8:46 PM CDT, 8 minutes before
SEVERE WEATHER STATEMENT AND RADAR SUMMARY
NATIONAL WEATHER SERVICE DES MOINES IA
845 PM CDT SAT JUL 11 1987

...SEVERE THUNDERSTORM WATCH FOR MUCH OF NORTHERN AND CENTRAL IOWA
   UNTIL 1 AM...
...FLASH FLOOD WATCH FOR WEST CENTRAL...SOUTHWEST...AND SOUTH CENTRAL
   IOWA TONIGHT...

NO SEVERE WEATHER HAS BEEN REPORTED IN IOWA BETWEEN 740 PM AND 840 PM...

AT 840 PM...
SHOWERS AND INTENSE THUNDERSTORMS CONTINUED OVER ABOUT THE NORTHERN
HALF OF THE STATE...ROUGHLY NORTH OF A DENISON...WATERLOO...DECORAH
LINE.

THERE WERE 3 CLUSTERS OF INTENSE STORMS.  THE FIRST STRETCHED FROM
NEAR DECORAH TO NEAR WATERLOO...THE SECOND FROM JUST EAST OF ALGONA
TO NEAR FORT DODGE...AND THE THIRD FROM NEAR STORM LAKE TO ONAWA...
WHICH IS ABOUT 25 MILES SOUTH OF SIOUX CITY.
<
THE STORMS IN THESE CLUSTER WILL PRODUCE BRIEF HEAVY RAINS...SMALL
PEA TO MARBLE SIZED HAIL...AND WINDS OF UP TO 40 MILES AN HOUR.

ALL OF THE SHOWERS AND STORM
S IN THE STATE WERE MOVING EAST AT
35 MILES AN HOUR.

TRUETT/MILLER

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 11, 7:56 PM CDTSevere Thunderstorm WarningDMXChickasaw64 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.