Alert archive / Iowa / Severe Thunderstorm Warnings in 1997

Severe Thunderstorm Warning 40, NWS Des Moines, IA

June 20, 1997Adair County, Cass County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Jun 20, 1997, 1:20 AM CDT for Adair County, Cass County, Iowa. It was in force for 50 min. 1 report came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued: Jun 20, 1997, 1:20 AM CDT (06:20 UTC)
Expired: Jun 20, 1997, 2:10 AM CDT
In force: 50 min
Issued by: NWS Des Moines, IA
Area: Whole counties

Counties Adair County, IA, Cass County, IA

The radar

The Des Moines radar (KDMX), 93 km from the middle of the area, began a volume at 06:21 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.

What was reported inside it

Time	Report	Where	Remark
Jun 20, 1:20 AM CDT	Hail 1	Cumberland, IA

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The watch it was issued in

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

Issued	Product	Office	Lasted
Jun 20, 1:00 AM CDT	Severe Thunderstorm Watch	SPC	5 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 6.3 hours before the alert went out and 139 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: 1320 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 2762 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 37 m²/s²
0-3 km storm-relative helicity: 58 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.4

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KDSM 200619 RRA
SVRDSM
IAC001-029-200710-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
120 AM CDT FRI JUN 20 1997

* SEVERE THUNDERSTORM WARNING FOR
  SOUTHERN ADAIR COUNTY - SOUTHWESTERN IOWA
  SOUTHEASTERN CASS COUNTY - SOUTHWESTERN IOWA

* UNTIL 210 AM CDT
 
* SOME AREAS AFFECTED
    MASSENA
    CUMBERLAND
    BRIDGEWATER
    FONTANELLE

* AT 120 AM CDT RADAR INDICATED A SEVERE THUNDERSTORM 50 MILES EAST OF
  COUNCIL BLUFFS MOVING SOUTHEAST AT 40 MPH.

* THE STORM WILL BE NEAR MASSENA BY 135 AM.

THIS IS A DANGEROUS STORM.  DO NOT GO OUTDOORS.

STARK

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, Jun 19, 9:28 PM CDT, 3 hours 52 minutes before

IAZ004>007-015>017-023>028-033>039-044>050-057>062-201200-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
928 PM CDT THU JUN 19 1997

...SEVERE THUNDERSTORM WATCH ISSUED FOR THE NORTHWEST QUARTER OF IOWA
UNTIL 200 AM...

HAZARD--SCATTERED SEVERE THUNDERSTORMS CAPABLE OF PRODUCING WIND GUSTS
UP TO 80 MPH...HAIL TO 1 INCH IN DIAMETER AND LOCALIZED RAINFALL UP TO 3
INCHES.

AREA OF CONCERN--NORTHWEST OF A WATERLOO-CHARITON LINE...WITH THE
HIGHEST THREAT NORTH OF INTERSTATE 80 AND WEST OF INTERSTATE 35.

TIMING DETAILS--THUNDERSTORMS RACING EAST ACROSS NEBRASKA AT 45 MPH WILL
ARRIVE IN NORTHWEST IOWA BY 1100 PM AND SPREAD OVER THE REST OF THE AREA
OVERNIGHT.

METEOROLOGICAL COMMENTS--SUPERCELL THUNDERSTORMS OVER NORTHERN NEBRASKA
HAVE BEGUN TO TAKE ON BOW ECHO CHARACTERISTICS AS THEY MOVE TOWARD THE
STATE. LIFTED INDICES REMAIN AS LOW AS MINUS 8 AS MID LEVEL WINDS OVER
SOUTH DAKOTA CONTINUE TO INCREASE AND CAUSE THE STORMS TO ACCELERATE.
STRENGTHENING WIND FIELDS...STRONG INSTABILITY...AND THE PRESENCE OF A
WARM FRONT JUST NORTH OF THE IOWA-MINNESOTA BORDER INDICATE THE MAIN
THREAT WILL BE FROM DAMAGING WINDS. SOME HAIL IS ALSO POSSIBLE...BUT THE
SIZES WILL BE SOMEWHAT LIMITED DUE TO THE FAIRLY WARM TEMPERATURES
ALOFT. AS THE NIGHT PROGRESSES...THE THUNDERSTORMS WILL CONSOLIDATE INTO
A THUNDERSTORM COMPLEX CAPABLE OF PRODUCING RAINFALL UP TO 3 INCHES IN
SPOTS.

PRECAUTIONS--SPOTTER ACTIVATION SHOULD BE UNDERWAY NORTHWEST OF DES
MOINES. ANY SEVERE THUNDERSTORM WARNINGS THAT MAY BE ISSUED OVERNIGHT
NEED TO BE TAKEN SERIOUSLY BECAUSE OF THE THREAT OF DAMAGING STRAIGHT
LINE WINDS. DOWNBURST WINDS HAVE BEEN KNOWN TO PRODUCE TORNADO-LIKE
DAMAGE. AROUND THREE INCHES OF RAIN IS NEEDED TO CAUSE FLASH FLOODING
IN MANY AREAS...SO THE HEAVY RAIN OVERNIGHT COULD CAUSE SOME RUNOFF
PROBLEMS.

PYTLAK

Special weather statement, Jun 19, 9:29 PM CDT, 3 hours 51 minutes before

IAZ004>007-015>017-023>028-033>039-044>050-057>062-201200-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
928 PM CDT THU JUN 19 1997

...SEVERE THUNDERSTORM WATCH ISSUED FOR THE NORTHWEST QUARTER OF IOWA
UNTIL 200 AM...

HAZARD--SCATTERED SEVERE THUNDERSTORMS CAPABLE OF PRODUCING WIND GUSTS
UP TO 80 MPH...HAIL TO 1 INCH IN DIAMETER AND LOCALIZED RAINFALL UP TO 3
INCHES.

AREA OF CONCERN--NORTHWEST OF A WATERLOO-CHARITON LINE...WITH THE
HIGHEST THREAT NORTH OF INTERSTATE 80 AND WEST OF INTERSTATE 35.

TIMING DETAILS--THUNDERSTORMS RACING EAST ACROSS NEBRASKA AT 45 MPH WILL
ARRIVE IN NORTHWEST IOWA BY 1100 PM AND SPREAD OVER THE REST OF THE AREA
OVERNIGHT.

METEOROLOGICAL COMMENTS--SUPERCELL THUNDERSTORMS OVER NORTHERN NEBRASKA
HAVE BEGUN TO TAKE ON BOW ECHO CHARACTERISTICS AS THEY MOVE TOWARD THE
STATE. LIFTED INDICES REMAIN AS LOW AS MINUS 8 AS MID LEVEL WINDS OVER
SOUTH DAKOTA CONTINUE TO INCREASE AND CAUSE THE STORMS TO ACCELERATE.
STRENGTHENING WIND FIELDS...STRONG INSTABILITY...AND THE PRESENCE OF A
WARM FRONT JUST NORTH OF THE IOWA-MINNESOTA BORDER INDICATE THE MAIN
THREAT WILL BE FROM DAMAGING WINDS. SOME HAIL IS ALSO POSSIBLE...BUT THE
SIZES WILL BE SOMEWHAT LIMITED DUE TO THE FAIRLY WARM TEMPERATURES
ALOFT. AS THE NIGHT PROGRESSES...THE THUNDERSTORMS WILL CONSOLIDATE INTO
A THUNDERSTORM COMPLEX CAPABLE OF PRODUCING RAINFALL UP TO 3 INCHES IN
SPOTS.

PRECAUTIONS--SPOTTER ACTIVATION SHOULD BE UNDERWAY NORTHWEST OF DES
MOINES. ANY SEVERE THUNDERSTORM WARNINGS THAT MAY BE ISSUED OVERNIGHT
NEED TO BE TAKEN SERIOUSLY BECAUSE OF THE THREAT OF DAMAGING STRAIGHT
LINE WINDS. DOWNBURST WINDS HAVE BEEN KNOWN TO PRODUCE TORNADO-LIKE
DAMANGE. AROUND THREE INCHES OF RAIN IS NEEDED TO CAUSE FLASH FLOODING
IN MANY AREAS...SO THE HEAVY RAIN OVERNIGHT COULD CAUSE SOME RUNOFF
PROBLEMS.

PYTLAK

Special weather statement, Jun 20, 12:15 AM CDT, 1 hour 5 minutes before

IAZ004>007-015>017-023>028-033>039-044>050-057>062-201200-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1215 AM CDT FRI JUN 20 1997

...SEVERE THUNDERSTORM WATCH ISSUED FOR THE NORTHWEST QUARTER OF IOWA
UNTIL 200 AM...

HAZARD--SCATTERED SEVERE THUNDERSTORMS CAPABLE OF PRODUCING WIND GUSTS
UP TO 80 MPH...HAIL TO 1 INCH IN DIAMETER AND LOCALIZED RAINFALL
AMOUNTS OF UP TO 3 INCHES.

AREA OF CONCERN--NORTHWEST OF A WATERLOO-CHARITON LINE...WITH THE
HIGHEST THREAT NORTH OF INTERSTATE 80 AND WEST OF INTERSTATE 35.

TIMING DETAILS--SCATTERED THUNDERSTORMS WILL CONTINUE TO MOVE
SOUTHEAST INTO CENTRAL IOWA AND EXPAND IN AREAL COVERAGE THROUGH 500
AM.

METEOROLOGICAL COMMENTS--SUPERCELL THUNDERSTORMS THAT MOVED INTO FAR
NORTHWEST IOWA FROM NORTHEAST NEBRASKA DECREASED IN INTENSITY AS THEY
MOVED INTO A SOMEWHAT MORE STABLE ENVIRONMENT EARLY THIS MORNING.
HOWEVER...STORMS SHOULD INTENSIFY AS THEY MOVE FURTHER EAST INTO
IOWA...SOUTH OF A WARM FRONTAL BOUNDARY THAT REMAINED DRAPED ACROSS
NORTHERN IOWA.  DEW POINTS IN THIS AREA WERE IN THE UPPER 60S TO LOWER
70S AND NUMEROUS OUTFLOW BOUNDARIES WERE IN PLACE TO ACT AS A LIFTING
MECHANISM FOR ANY DEVELOPING/INTENSIFYING STORMS.  LIFTED INDICES IN
CENTRAL IOWA REMAINED AROUND -8.  A SOUTHERLY LOW LEVEL JET AT 30 KTS
WILL PROVIDE INFLOW TO THE STORMS.

PRECAUTIONS--SPOTTERS SHOULD REMAIN ALERT TO RAPIDLY DEVELOPING OR
INTENSIFYING STORMS ESPECIALLY NORTHWEST OF DES MOINES.  THESE STORMS
HAVE A HISTORY OF PRODUCING DAMAGING STRAIGHT LINE WINDS.  AROUND
THREE INCHES OF RAIN IS NEEDED TO CAUSE FLASH FLOODING IN MANY
AREAS...SO THE HEAVY RAIN OVERNIGHT COULD CAUSE SOME RUNOFF PROBLEMS.

STARK

Special weather statement, Jun 20, 12:18 AM CDT, 1 hour 2 minutes before

IAZ004>007-015>017-023>028-033>039-044>050-057>062-201200-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1215 AM CDT FRI JUN 20 1997

...SEVERE THUNDERSTORM WATCH ISSUED FOR THE NORTHWEST QUARTER OF IOWA
UNTIL 200 AM...

HAZARD--SCATTERED SEVERE THUNDERSTORMS CAPABLE OF PRODUCING WIND GUSTS
UP TO 80 MPH...HAIL TO 1 INCH IN DIAMETER AND LOCALIZED RAINFALL
AMOUNTS OF UP TO 3 INCHES.

AREA OF CONCERN--NORTHWEST OF A WATERLOO-CHARITON LINE...WITH THE
HIGHEST THREAT NORTH OF INTERSTATE 80 AND WEST OF INTERSTATE 35.

TIMING DETAILS--SCATTERED THUNDERSTORMS WILL CONTINUE TO MOVE
SOUTHEAST INTO CENTRAL IOWA AND EXPAND IN AREAL COVERAGE THROUGH 500
AM.

METEOROLOGICAL COMMENTS--SUPERCELL THUNDERSTORMS THAT MOVED INTO FAR
NORTHWEST IOWA FROM NORTHEAST NEBRASKA DECREASED IN INTENSITY AS THEY
MOVED INTO A SOMEWHAT MORE STABLE ENVIRONMENT EARLY THIS MORNING.
HOWEVER...STORMS SHOULD INTENSIFY AS THEY MOVE FURTHER EAST INTO
IOWA...SOUTH OF A WARM FRONTAL BOUNDARY THAT REMAINED DRAPED ACROSS
NORTHERN IOWA.  DEW POINTS IN THIS AREA WERE IN THE UPPER 60S TO LOWER
70S AND NUMEROUS OUTFLOW BOUNDARIES WERE IN PLACE TO ACT AS A LIFTING
MECHANISM FOR ANY DEVELOPING/INTENSIFYING STORMS.  LIFTED INDICES IN
CENTRAL IOWA REMAINED AROUND -8.  A SOUTHERLY LOW LEVEL JET AT 30 KTS
WILL PROVIDE INFLOW TO THE STORMS.

PRECAUTIONS--SPOTTERS SHOULD REMAIN ALERT TO RAPIDLY DEVELOPING OR
INTENSIFYING STORMS ESPECIALLY NORTHWEST OF DES MOINES.  THESE STORMS
HAVE A HISTORY OF PRODUCING DAMAGING STRAIGHT LINE WINDS.  AROUND
THREE INCHES OF RAIN IS NEEDED TO CAUSE FLASH FLOODING IN MANY
AREAS...SO THE HEAVY RAIN OVERNIGHT COULD CAUSE SOME RUNOFF PROBLEMS.

STARK

The office that day

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

Issued	Product	Office	Counties	Lasted
Jun 20, 12:48 AM CDT	Severe Thunderstorm Warning	DMX	Cass	32 min
Jun 20, 5:02 AM CDT	Severe Thunderstorm Warning	DMX	Webster	33 min
Jun 20, 5:17 AM CDT	Severe Thunderstorm Warning	DMX	Hamilton, Wright	33 min
Jun 20, 5:48 AM CDT	Severe Thunderstorm Warning	DMX	Franklin, Hardin	32 min
Jun 20, 6:09 AM CDT	Severe Thunderstorm Warning	DMX	Butler, Grundy	36 min
Jun 20, 6:45 AM CDT	Severe Thunderstorm Warning	DMX	Black Hawk	45 min
Jun 20, 7:25 AM CDT	Severe Thunderstorm Warning	DMX	Butler	35 min
Jun 20, 4:39 PM CDT	Severe Thunderstorm Warning	DMX	Warren	31 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1997 Every severe thunderstorm 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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.