Alert archive / Iowa / Flash Flood Warnings in 1998
Flash Flood Warning 33, NWS Des Moines, IA
NWS Des Moines, IA issued this flash flood warning at Aug 20, 1998, 9:07 PM CDT for Hamilton County, Iowa. It was in force for 4 hr. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Aug 20, 1998, 9:07 PM CDT (02:07 UTC)
- Expired
- Aug 21, 1998, 1:00 AM CDT
- In force
- 4 hr
- Issued by
- NWS Des Moines, IA
- Area
- Whole counties
County Hamilton County, IA
The radar
The Des Moines radar (KDMX), 73 km from the middle of the area, began a volume at 02:11 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Minneapolis, MN (KMPX), launched 00:00Z, 2.1 hours before the alert went out and 274 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1771 m above ground
- 0-6 km bulk shear
- 25 kt
- 0-1 km storm-relative helicity
- -14 m²/s²
- 0-3 km storm-relative helicity
- 20 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
000 TTAA00 KDSM 210207 FFWDSM IAC079-210600- BULLETIN - EAS ACTIVATION REQUESTED FLASH FLOOD WARNING NATIONAL WEATHER SERVICE DES MOINES IA 907 PM CDT THU AUG 20 1998 THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A * FLASH FLOOD WARNING FOR... HAMILTON COUNTY IN CENTRAL IOWA * UNTIL 100 AM CDT * THROUGH 900 PM... NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED HEAVY RAINFALL OF 4 TO 6 INCHES OVER PORTIONS OF HAMILTON COUNTY NEAR AND TO THE EAST OF WEBSTER CITY. * THIS WILL CAUSE A RAPID RISE ON THE BOONE RIVER AND ITS TRIBUTARIES BY MIDNIGHT. THE RIVER STAGE AT WEBSTER CITY MAY REACH 10 TO 12 FEET BEFORE FALLING QUICKLY AGAIN AFTER MIDNIGHT. THIS WILL CAUSE MAINLY AGRICULTURAL FLOODING...BUT ANY PEOPLE CURRENTLY NEAR THE BOONE RIVER SHOULD MOVE TO HIGHER GROUND. SOME STREAMS AFFECTED INCLUDE... BOONE RIVER AND TRIBUTARIES. MOVE TO HIGHER GROUND IF FLOOD WATERS THREATEN AND DO NOT DRIVE INTO WATER. JUNGBLUTH
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, Aug 20, 3:47 PM CDT, 5 hours 20 minutes before
IAZ044>046-057-058-070-071-081-082-092-093-210000- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 347 PM CDT THU AUG 20 1998 ADVISORY INFORMATION--A HEAT ADVISORY REMAINS IN EFFECT UNTIL EARLY EVENING FOR SOUTHWEST IOWA. RECENT REPORTS--HEAT INDICES WERE IN THE 105 TO 115 DEGREE RANGE THROUGHOUT SOUTHWEST IOWA. EVEN IN CENTRAL IOWA...HEAT INDICES HAVE CLIMBED TO AROUND 105 DEGREES THIS AFTERNOON. TEMPERATURES WERE TOPPING OUT IN THE MID 90S BUT DEWPOINTS WERE NEAR 80 DEGREES. SLOW COOLING IS NOT EXPECTED TO OCCUR UNTIL AFTER 700 PM. PRECAUTIONS--DELAY ANY OUTDOOR ACTIVITIES UNTIL LATER THIS EVENING. IF YOU MUST BE OUTSIDE AIR CONDITIONING...TAKE APPROPRIATE PRECAUTIONS. PYTLAK
Special weather statement, Aug 20, 7:10 PM CDT, 1 hour 57 minutes before
IAZ044>046-057-058-070-071-081-082-092-093-210100- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 710 PM CDT THU AUG 20 1998 ADVISORY INFORMATION--THE HEAT ADVISORY WHICH WAS IN EFFECT FOR PORTIONS OF SOUTHWEST IOWA HAS EXPIRED. RECENT REPORTS--AS OF 700 PM HEAT INDICES WERE FALLING BACK BELOW THE 100 DEGREE MARK DUE TO THE SETTING SUN AND COOLER OUTFLOW FROM THUNDERSTORMS. DEWPOINTS WERE STILL IN THE 70S HOWEVER...AND IT WILL BE A MUGGY EVENING UNTIL SCATTERED THUNDERSTORMS DEVELOP. LOCATIONS ALONG HIGHWAY 30 WERE THE FIRST TO SEE RELIEF FROM THE HEAT. JUNGBLUTH
Special weather statement, Aug 20, 7:10 PM CDT, 1 hour 57 minutes before
IAZ044>046-057-058-070-071-081-082-092-093-210100- SPECIAL WEATHER STATEMENT NATIONAL WEATHER SERVICE DES MOINES IA 710 PM CDT THU AUG 20 1998 ADVISORY INFORMATION--THE HEAT ADVISORY WHICH WAS IN EFFECT FOR PORTIONS OF SOUTHWEST IOWA HAS EXPIRED. RECENT REPORTS--AS OF 700 PM HEAT INDICES WERE FALLING BACK BELOW THE 100 DEGREE MARK DUE TO THE SETTING SUN AND COOLER OUTFLOW FROM THUNDERSTORMS. DEWPOINTS WERE STILL IN THE 70S HOWEVER...AND IT WILL BE A MUGGY EVENING UNTIL SCATTERED THUNDERSTORMS DEVELOP. LOCATIONS ALONG HIGHWAY 30 WERE THE FIRST TO SEE RELIEF FROM THE HEAT. JUNGBLUTH
Nearby
Flash Flood Warnings in Iowa, 1998Every flash flood warning 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; radar from the NEXRAD Level II archive.