Alert archive / Iowa / Tornado Warnings in 1997

Tornado Warning 11, NWS Des Moines, IA

August 16, 1997Warren County, Iowa

NWS Des Moines, IA issued this tornado warning at Aug 16, 1997, 8:26 PM CDT for Warren County, Iowa. It was in force for 14 min. 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 16, 1997, 8:26 PM CDT (01:26 UTC)
Expired
Aug 16, 1997, 8:40 PM CDT
In force
14 min
Issued by
NWS Des Moines, IA
Area
Whole counties

County Warren County, IA

The radar

The Des Moines radar (KDMX), 46 km from the middle of the area, began a volume at 01:30 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 watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 16, 7:15 PM CDTSevere Thunderstorm WatchSPC6 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 1.4 hours before the alert went out and 235 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 1997-08-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1159 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Omaha, NE at 00:00Z on 1997-08-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 96 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
1159 J/kg
Mixed-layer CIN
-284 J/kg
Mixed-layer LCL
1161 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
96 m²/s²
0-3 km storm-relative helicity
245 m²/s²
Significant tornado parameter
0.0
Supercell composite
18.2

Open this sounding in Storm Lab

The text

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

890 
WFUS1 KDSM 170125
TORDSM

IAC181-170140-

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
826 PM CDT SAT AUG 16 1997

* TORNADO WARNING FOR
  WARREN COUNTY - SOUTH CENTRAL IOWA

* UNTIL 840 PM CDT
 
* SOME AREAS AFFECTED
    INDIANOLA
    NORWALK
    ACKWORTH

* AT 825 PM CDT THE PUBLIC REPORTED A TORNADO 10 MILES SOUTH OF DES
  MOINES MOVING NORTHEAST AT 10 TO 15 MPH.

* THE STORM WILL BE ONE STORM JUST OF INDIANOLA BY 835 PM CDT.
  THE OTHER STORM WILL REMAIN AROUND THE NORWALK VICINITY.

IF YOU ARE NEAR THIS DANGEROUS STORM...TAKE COVER IMMEDIATELY IN THE
LOWEST FLOOR AND INNER MOST ROOM OF A BUILDING.

FORSTER/KUBINA

What forecasters said that day

The local office's own words before this tornado 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 16, 3:32 PM CDT, 4 hours 54 minutes before
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-171200-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
332 PM CDT SAT AUG 16 1997

HAZARD--SCATTERED EVENING SEVERE THUNDERSTORMS WITH DAMAGING WIND THE
PRIMARY CONCERN.

AREA OF CONCERN AND TIMING--SOUTH OF AN ATLANTIC-DUBUQUE LINE AFTER 6 OR
7 PM.

METEOROLOGICAL COMMENTS--MOST OF SOUTHERN IOWA REMAINS QUITE UNSTABLE
WITH LIFTED INDICES AROUND -10 DEGREES AND SATELLITE MEASURED CAPES OF
3000-4000 J/KG. A DEWPOINT FRONT LYING ALONG A DUBUQUE-DES MOINES-
ATLANTIC LINE MAY ACT AS A FOCUS FOR THUNDERSTORMS DEVELOPMENT THIS
EVENING. THE BEST LOW LEVELING FORCING REMAINS IN NORTHEAST KANSAS
HOWEVER WHERE STRONGER LOW LEVEL WINDS ARE IMPINGING THE DEWPOINT FRONT.
A WEAK UPPER LEVEL DISTURBANCE IS NEARING THIS AREA FROM WESTERN KANSAS
NOW...WHICH MAY INDUCE THUNDERSTORMS TO DEVELOP. PRECIPITABLE WATER
VALUES ARE NEAR 2 INCHES SOUTH OF THE FRONT...SO RAINFALL WILL BE
INTENSE IN LOCALIZED AREAS. THE THREAT OF STRONG DAMAGING WINDS HAS
LESSENED A BIT FROM EARLIER TODAY BUT WINDS TO 70 MPH COULD OCCUR.
BETWEEN SUNSET AND MIDNIGHT THE WEATHER THREAT WILL BE REPEAT HEAVY
RAINS OVER THE SAME AREA. RAINFALL AMOUNTS COULD EASILY EXCEED 3-4
INCHES IN SMALL AREAS BETWEEN 10 PM AND 3 AM.

PRECAUTIONS--PEOPLE WITH OUTDOOR PLANS SHOULD STAY ABREAST OF THE
WEATHER THIS EVENING...AND BE PREPARED TO CHANGE PLANS. SPOTTER
ACTIVATION COULD BE NEEDED SOUTH OF AN ATLANTIC-DUBUQUE LINE.

MYERS
Special weather statement, Aug 16, 3:33 PM CDT, 4 hours 53 minutes before
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-171200-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
332 PM CDT SAT AUG 16 1997

HAZARD--SCATTERED EVENING SEVERE THUNDERSTORMS WITH DAMAGING WIND THE
PRIMARY CONCERN.

AREA OF CONCERN AND TIMING--SOUTH OF AN ATLANTIC-DUBUQUE LINE AFTER 6 OR
7 PM.

METEOROLOGICAL COMMENTS--MOST OF SOUTHERN IOWA REMAINS QUITE UNSTABLE
WITH LIFTED INDICES AROUND -10 DEGREES AND SATELLITE MEASURED CAPES OF
3000-4000 J/KG. A DEWPOINT FRONT LYING ALONG A DUBUQUE-DES MOINES-
ATLANTIC LINE MAY ACT AS A FOCUS FOR THUNDERSTORMS DEVELOPMENT THIS
EVENING. THE BEST LOW LEVELING FORCING REMAINS IN NORTHEAST KANSAS
HOWEVER WHERE STRONGER LOW LEVEL WINDS ARE IMPINGING THE DEWPOINT FRONT.
A WEAK UPPER LEVEL DISTURBANCE IS NEARING THIS AREA FROM WESTERN KANSAS
NOW...WHICH MAY INDUCE THUNDERSTORMS TO DEVELOP. PRECIPITABLE WATER
VALUES ARE NEAR 2 INCHES SOUTH OF THE FRONT...SO RAINFALL WILL BE
INTENSE IN LOCALIZED AREAS. THE THREAT OF STRONG DAMAGING WINDS HAS
LESSENED A BIT FROM EARLIER TODAY BUT WINDS TO 70 MPH COULD OCCUR.
BETWEEN SUNSET AND MIDNIGHT THE WEATHER THREAT WILL BE REPEAT HEAVY
RAINS OVER THE SAME AREA. RAINFALL AMOUNTS COULD EASILY EXCEED 3-4
INCHES IN SMALL AREAS BETWEEN 10 PM AND 3 AM.

PRECAUTIONS--PEOPLE WITH OUTDOOR PLANS SHOULD STAY ABREAST OF THE
WEATHER THIS EVENING...AND BE PREPARED TO CHANGE PLANS. SPOTTER
ACTIVATION COULD >BE NEEDED SOUTH OF AN ATLANTIC-DUBUQUE LINE.

MYERS

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 16, 7:51 PM CDTTornado WarningDMXWarren34 min
Aug 16, 8:34 PM CDTSevere Thunderstorm WarningDMXMonroe36 min
Aug 16, 8:51 PM CDTSevere Thunderstorm WarningDMXMarion34 min
Aug 16, 8:58 PM CDTSevere Thunderstorm WarningDMXPolk32 min

Nearby

Tornado Warnings in Iowa, 1997Every tornado warning in 1997Tornadoes 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.