Alert archive / Iowa / Flash Flood Warnings in 1986
Flash Flood Warning 9, NWS Des Moines, IA
NWS Des Moines, IA issued this flash flood warning at Sep 20, 1986, 11:06 AM CDT for 4 counties in Iowa. It was in force for 114 min.
The area
The counties it named.
The facts
- Issued
- Sep 20, 1986, 11:06 AM CDT (16:06 UTC)
- Expired
- Sep 20, 1986, 1:00 PM CDT
- In force
- 114 min
- Issued by
- NWS Des Moines, IA
- Area
- Whole counties
Counties Iowa County, IA, Keokuk County, IA, Mahaska County, IA, Poweshiek 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
Peoria Regional, IL (KPIA), launched 12:00Z, 4.1 hours before the alert went out and 249 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.
- Mixed-layer CAPE
- 365 J/kg
- Mixed-layer CIN
- -114 J/kg
- Mixed-layer LCL
- 719 m above ground
- 0-6 km bulk shear
- 42 kt
- 0-1 km storm-relative helicity
- 3 m²/s²
- 0-3 km storm-relative helicity
- 81 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted, in the capitals the NWS used until 2016.
000 TTAA00 KDSM 201607 FFWDSM IAC157-095-107-123-125-201900- BULLETIN - IMMEDIATE BROADCAST REQUESTED/EBS ACTIVATION REQUESTED FLASH FLOOD WARNING NATIONAL WEATHER SERVICE DES MOINES IA 1106 AM CDT SAT SEP 20 1986 THE NATIONAL WEATHER SERVICE HAS ISSUED A FLASH FLOOD WARNING EFFECTIVE UNTIL 100 PM CDT FOR PEOPLE IN THE FOLLOWING COUNTIES OF SOUTH CENTRAL IOWA...POWESHIEK...SOUTHERN IOWA...KEOKUK...MAHASKA AND MARION A FLASH FLOOD WARNING MEANS FLOODING IS IMINENT OR IS OCCURRING. TAKE NECESSARY PRECAUTIONS IMMEDIATELY. AT 11 AM CDT A LINE OF THUNDERSTORMS WAS MOVING INTO AND THROUGH THE FIVE-COUNTY AREA DROPPING HEAVY RAINS. 1 TO 3 INCHES OF RAIN CAN OCCUR IN NEXT 30 MINTUES TO 1 HOUR PRODUCING FLASH FLOODING. REPORTS RECEIVED FROM JASPER COUNTY CONFIRM RAINFALL AMOUNTS. PEOPLE LIVING IN FLOOD PRONE AREAS SHOULD MOVE TO HIGHER GROUND AT ONCE. ACT QUICKLY..AS FLOOD WATERS OFTEN RISE VERY QUICKLY. IF YOU ARE DRIVING..DO NOT TRY TO DRIVE THROUGHC FLOOD WATERS OF UNKNOWN DEPTH. IF YOUR VEHICLE STALLS..ABANDON IT IMMEDIATELY AND SEEK HIGHER GROUND. DO NOT ATTEMPT TO CROSS A FLOWING STREAM ON FOOT WHERE THE WATER IS ABOVE YOUR KNEES. FORSTER
What forecasters said that day
The local office's own words before this flash flood 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, Sep 20, 5:43 AM CDT, 5 hours 23 minutes before
SPECIAL WEATHER STATEMENT RADAR SUMMARY NATIONAL WEATHER SERVICE DES MOINES IA 542 AM CDT SAT SEP 20 1986 AT 531 AM CDT... VERY STRONG THUNDERSTORMS WERE LOCATED OVER NORTHWEST IOWA. THEY WERE ABOUT 50 MILES EAST OF SIOUX CITY...BETWEEN CHEROKEE AND ROCK- WELL CITY. THESE STORMS WILL PRODUCE VERY HEAVY RAIN...BRIEF GUSTY WINDS...AND POSSIBLY SOME SMALL HAIL AS THEY PASS OVERHEAD. THESE STORMS WERE PART OF A LARGER AREA OF THUNDERSTORMS THAT COVERED ABOUT THE NORTHWEST THIRD OF THE STATE. ELSEWHERE...SCATTERED THUNDERSHOWERS CONTINUED OVER THE SOUTHEAST COUNTIES OF THE STATE. THEY WERE IN A 50 MILE WIDE BAND BETWEEN THE RATHBUN RESERVOIR AND THE SOUTHEAST CORNER OF THE STATE. THE RAIN WAS ALL MOVING NORTHEAST AT 25 MILES AN HOUR. SCHUMACHER
Special weather statement, Sep 20, 6:45 AM CDT, 4 hours 21 minutes before
SPECIAL WEATHER STATEMENT RADAR SUMMARY NATIONAL WEATHER SERVICE DES MOINES IA 643 AM CDT SAT SEP 20 1986 AT 634 AM CDT... VERY STRONG THUNDERSTORMS WERE LOCATED OVER NORTHWEST AND NORTH CENTRAL IOWA. THEY WERE IN A 15 MILE WIDE AREA EXTENDING FROM STORM LAKE TO JUST NORTHEST OF FORT DODGE. ANOTHER VERY STRONG STORM WAS LOCATED OVER NORTHEAST NEBRASKA. IT WILL MOVE INTO NORTHWEST IOWA... NORTH OF SIOUX CITY BY 715 AM THIS MORNING. THESE STRONG STORMS WILL PRODUCE VERY HEAVY RAIN...GUSTY WINDS...AND SOME SMALL HAIL AS THEY PASS OVERHEAD. THE STORMS WERE PART OF A LARGER AREA OF SHOWERS AND STORMS THAT COVERED THE NORTHWEST QUARTER OF IOWA. ELSEWHERE...SCATTERED SHOWERS AND THUNDERSHOWERS CONTINUED OVER THE SOUTH TWO TIERS OF IOWAS SOUTH CENTRAL AND SOUTHEAST COUNTIES. THE RAIN WAS ALL MOVING NORTHEAST AT 30 MILES AN HOUR. SCHUMACHER
Special weather statement, Sep 20, 9:37 AM CDT, 1 hour 29 minutes before
SPECIAL WEATHER STATEMENT RADAR SUMMARY NATIONAL WEATHER SERVICE DES MOINES IA 940 AM CDT SAT SEP 20 1986 AT 925 AM...SEVERAL INTENSE THUNDERSTORMS WERE OCCURRING IN NORTHWEST... CENTRAL...AND SOUTHEAST IOWA. THESE STORMS WERE LOCATED ABOUT 35 MILES EAST OF SIOUX CITY...20 MILES NORTH OF DES MOINES...AND BETWEEN MARSHALLTOWN AND OTTUMWA. SEVERE WEATHER WAS NO LONGER INDICATED WITH ANY OF THESE STORMS... ALTHOUGH SMALL HAIL AND GUSTY WINDS WERE LIKELY. ELSEWHERE...NUMEROUS SHOWERS AND THUNDERSTORMS WERE OCCURRING THROUGHOUT MUCH OF NORTHERN AND EASTERN IOWA. ALL OF THE SHOWERS AND THUNDERSTORMS WERE MOVING EAST AT 25 MILES AN HOUR. THERE HAD BEEN SOME DECREASE IN INTENSITY. BINGHAM
The office that day
Everything else NWS Des Moines, IA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 20, 7:39 AM CDT | Severe Thunderstorm Warning | DMX | Hamilton | 36 min |
| Sep 20, 8:17 AM CDT | Severe Thunderstorm Warning | DMX | Hamilton | 28 min |
| Sep 20, 8:42 AM CDT | Severe Thunderstorm Warning | DMX | Hardin, Story | 28 min |
| Sep 20, 10:52 AM CDT | Severe Thunderstorm Warning | DMX | Iowa, Poweshiek | 28 min |
| Sep 20, 11:06 AM CDT | Flash Flood Warning | DMX | Marion | 114 min |
Nearby
Flash Flood Warnings in Iowa, 1986Every flash flood warning in 1986
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.