Alert archive / Iowa / Flash Flood Warnings in 1997

Flash Flood Warning 7, NWS Des Moines, IA

July 24, 1997Polk County, Iowa

NWS Des Moines, IA issued this flash flood warning at Jul 24, 1997, 5:26 AM CDT for Polk County, Iowa. It was in force for 6 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: Jul 24, 1997, 5:26 AM CDT (10:26 UTC)
Expired: Jul 24, 1997, 11:25 AM CDT
In force: 6 hr
Issued by: NWS Des Moines, IA
Area: Whole counties

County Polk County, IA

The radar

The Des Moines radar (KDMX), 13 km from the middle of the area, began a volume at 10:29 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

Omaha, NE (KOAX), launched 00:00Z, 10.4 hours before the alert went out and 236 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: 4495 J/kg
Mixed-layer CIN: -48 J/kg
Mixed-layer LCL: 1166 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 143 m²/s²
0-3 km storm-relative helicity: 208 m²/s²
Significant tornado parameter: 2.4
Supercell composite: 16.9

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
TTAA00 KDSM 241026
FFWDSM
IAC153-241625-

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
526 AM CDT THU JUL 24 1997

* FLASH FLOOD WARNING FOR
  POLK COUNTY - CENTRAL IOWA

* UNTIL 1125 AM CDT
 
* SOME STREAMS AFFECTED
    WALNUT CREEK

* CAUSE AND EFFECT
  A NEARLY STATIONARY LINE OF THUNDERSTORMS HAS DROPPED 3 TO 4 PLUS
  INCHES OF RAIN OVER THE WEST HALF OF THE DES MOINES METRO AREA.
  ADDITIONAL RAIN BY 600 AM WILL CAUSE FURTHER RISES THIS MORNING.

* FORECAST CONDITIONS
  THE CREEK WILL CONTINUE TO RISE WITH A PRELIMINARY CREST EXPECTED
  NEAR 15 FEET AROUND MID MORNING THIS MORNING.

LEAVE FLOOD PRONE OR LOW LYING AREAS IMMEDIATELY.
 
MOST FLOOD DEATHS (OCCUR IN AUTOMOBILES. DO NOT DRIVE INTO FLOODED
ROADWAYS.

&

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

Local storm report, Jul 24, 12:13 AM CDT, 5 hours 13 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1213 AM CDT THU JUL 24 1997

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0756 AM    1 E DENISON               IA   .75 INCH HAIL
07/23/97   CRAWFORD

0803 AM    DENISON                   IA   1.75 INCH HAIL
07/23/97   CRAWFORD

Local storm report, Jul 24, 12:14 AM CDT, 5 hours 12 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
1213 AM CDT THU JUL 24 1997

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....COUNTY LOCATION....

07"56 AM    1 E DENISON               IA   .75 INCH HAIL
07/23/97   CRAWFORD

0803 AM    DENISON                   IA   1.75 INCH HAIL
07/23/97   CRAWFORD

Special weather statement, Jul 24, 12:57 AM CDT, 4 hours 29 minutes before

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-241200-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1257 AM CDT THU JUL 24 1997

HAZARD--SCATTERED THUNDERSTORMS WITH INTENSE RAINFALL RATES AND
FREQUENT LIGHTNING.  THERE IS A SMALL THREAT FOR LARGE HAIL AND DAMAGING
WINDS.

AREA OF CONCERN--MAINLY WEST OF A MASON CITY--KNOXVILLE--BLOOMFIELD
LINE.

TIMING DETAILS--

THROUGH 400 AM...MAINLY IN A CORRIDOR FROM DES MOINES THROUGH CHARITON
AND CORYDON.

AFTER 400 AM...ADDITONAL DEVELOPMENT WILL OCCUR FURTHER NORTHWEST INTO
THE FORT DODGE AND ESTHERVILLE AREAS CLOSER TO 600 AM.

METEOROLOGICAL COMMENTS--A SITUATION SIMILAR TO LAST NIGHT HAS
DEVELOPED WITH A WARM AND MOISTURE ADVECTION ZONE SET UP ACROSS
NORTHWEST THROUGH SOUTH CENTRAL IOWA.  A STRONG VEERING WIND PROFILE
EXISTS DESPITE WEAK LOW-LEVEL WINDS.  THIS PROFILE IS ENHANCING STORM
RELATIVE INFLOW INTO THE STORMS THAT DEVELOP WHILE MOVING NEARLY
DUE SOUTH AT 30 MPH.  CLUSTERS OF THUNDERSTORMS OVER EASTERN SOUTH
DAKOTA ARE FORECAST TO DEVELOP AS WELL...POSSIBLY FORMING INTO A
THUNDERSTORM COMPLEX.  STEERING WINDS WILL LIKELY PULL THIS SOUTHEAST
INTO MUCH OF CENTRAL IOWA TOWARDS SUNRISE AS THE LOW-LEVEL JET
INCREASES AND POINTS MORE INTO NORTHWEST IOWA.

PRECAUTIONS--STORM SPOTTERS MAY NEED ACTIVATION EARLY THIS MORNING.
STAY ABREAST OF SHORT TERM FORECASTS FOR ADDITIONAL INFORMATION.  THOSE
CAMPING OUTDOORS SHOULD ALSO PREPARE TO TAKE SHELTER IF A STORM
APPROACHES.  FREQUENT LIGHTNING IS A THREAT FROM TONIGHT/S
THUNDERSTORMS.

KULA

Special weather statement, Jul 24, 12:58 AM CDT, 4 hours 28 minutes before

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-241200-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1257 AM CDT THU JUL 24 1997

HAZARD--SCATTERED THUNDERSTORMS WITH INTENSE RAINFALL RATES AND
FREQUENT LIGHTNING.  THERE IS A SMALL THREAT FOR LARGE HAIL AND DAMAGING
WINDS.

AREA OF CONCERN--MAINLY WEST OF A MASON CITY--KNOXVILLE--BLOOMFIELD
LINE.

TIMING DETAILS--

THROUGH 400 AM...MAINLY IN A CORRIDOR FROM DES MOINES THROUGH CHARITON
AND CORYDON.

AFTER 400 AM...ADDITONAL DEVELOPMENT WILL OCCUR FURTHER NORTHWEST INTO
THE FORT DODGE AND ESTHERVILLE AREAS CLOSER TO 600 AM.

METEOROLOGICAL COMMENTS--A SITUATION SIMILAR TO LAST NIGHT HAS
DEVELOPED WITH A WARM AND MOISTURE ADVECTION ZONE SET UP ACROSS
NORTHWEST THROUGH SOUTH CENTRAL IOWA.  A STRONG VEERING WIND PROFILE
EXISTS DESPITE WEAK LOW-LEVEL WINDS.  THIS PROFILE IS ENHANCING STORM
RELATIVE INFLOW INTO THE STORMS THAT DEVELOP WHILE MOVING NEARLY
DUE SOUTH AT 30 MPH.  CLUSTERS OF THUNDERSTORMS OVER EASTERN SOUTH
DAKOTA ARE FORECAST TO DEVELOP AS WELL...POSSIBLY FORMING INTO A
THUNDERSTORM COMPLEX.  STEERING WINDS WILL LIKELY PULL THIS SOUTHEAST
INTO MUCH OF CENTRAL IOWA TOWARDS SUNRISE AS THE LOW-LEVEL JET
INCREASES AND POINTS MORE INTO NORTHWEST IOWA.

PRECAUTIONS--STORM SPOTTERS MAY NEED ACTIVATION EARLY THIS MORNING.
STAY ABREAST OF SHORT TERM FORECASTS FOR ADDITIONAL INFORMATION.  THOSE
CAMPING OUTDOORS SHOULD ALSO PREPARE TO TAKE SHELTER IF A STORM
APPROACHES.  FREQUENT LIGHTNING IS A THREAT FROM TONIGHT/S
THUNDERSTORMS.

KULA

Nearby

Flash Flood Warnings in Iowa, 1997 Every flash flood warning in 1997

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.