Alert archive / Iowa / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 97, NWS Des Moines, IA

May 20, 1998Mahaska County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at May 20, 1998, 11:45 AM CDT for Mahaska County, Iowa. It was in force for 20 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: May 20, 1998, 11:45 AM CDT (16:45 UTC)
Expired: May 20, 1998, 12:05 PM CDT
In force: 20 min
Issued by: NWS Des Moines, IA
Area: Whole counties

County Mahaska County, IA

The radar

The Des Moines radar (KDMX), 100 km from the middle of the area, began a volume at 16:48 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
May 20, 11:47 AM CDT	Hail 1	Rose Hill, 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 nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 4.8 hours before the alert went out and 181 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2431 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 50 m²/s²
0-3 km storm-relative helicity: 176 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

Open this sounding in Storm Lab

The text

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

802 
WUUS1 KDSM 201646 RRA
SVRDSM
IAC123-201705-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
1145 AM CDT WED MAY 20 1998

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTHEASTERN MAHASKA COUNTY IN SOUTH CENTRAL IOWA

* UNTIL 1205 PM CDT

* AT 1144 AM CDT... DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM 17
  MILES NORTH OF OTTUMWA OR 3 MILES NORTH NORTHEAST OF FREMONT
  MOVING EAST AT 40 MPH.

* THIS STORM IS EXPECTED TO REMAIN IN RURAL AREAS.

THIS STORM HAS A HISTORY OF LARGE HAIL. GO INSIDE A STURDY BUILDING
AND STAY AWAY FROM WINDOWS

SMITH

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, May 20, 6:37 AM CDT, 5 hours 8 minutes before

IAZ044>046-057-058-070-071-081-082-092-093-201205-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
637 AM CDT WED MAY 20 1998

SEVERE THUNDERSTORM WATCH 377 HAS BEEN CANCELLED FOR WEST CENTRAL
AND SOUTHWEST IOWA.  AREAS ALONG AND WEST OF A LINE FROM JEFFERSON
TO GUTHRIE CENTER TO CRESTON TO MOUNT AYR ARE NO LONGER INCLUDED IN
THE WATCH.  THE CITIES OF DENISON...CARROLL...AUDUBON...ATLANTIC...
GREENFIELD...CORNING AND BEDFORD HAVE BEEN CLEARED.

THE WATCH REMAINS IN EFFECT UNTIL 8 AM FOR AREAS TO THE EAST.

STARK

Special weather statement, May 20, 7:44 AM CDT, 4 hours 1 minute before

IAZ047>050-059>062-072>075-083>086-094>097-201315-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
744 AM CDT WED MAY 20 1998

SEVERE THUNDERSTORM WATCH 377 WILL BE ALLOWED TO EXPIRE AT 8 AM FOR
THE CENTRAL AND SOUTH CENTRAL PORTIONS OF IOWA.  NO WATCHES ARE IN
EFFECT FOR IOWA AT THIS TIME.

STARK

Special weather statement, May 20, 7:44 AM CDT, 4 hours 1 minute before

IAZ047>050-059>062-072>075-083>086-094>097-201315-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
744 AM CDT WED MAY 20 1998

SEVERE THUNDERSTORM WATCH 377 WILL BE ALLOWED TO EXPIRE AT 8 AM FOR
THE CENTRAL AND SOUTH CENTRAL PORTIONS OF IOWA.  NO WATCHES ARE IN
EFFECT FOR IOWA AT THIS TIME.

STARK

Local storm report, May 20, 8:24 AM CDT, 3 hours 21 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
824 AM CDT WED MAY 20 1998

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

0413 AM    DOW CITY                  IA   70 MPH TSTM GUST
05/20/98   CRAWFORD

0533 AM    DOW CITY                  IA   60 MPH TSTM GUST
05/20/98   CRAWFORD

0540 AM    CUMMING                   IA   63 MPH TSTM GUST
05/20/98   WARREN

0555 AM    DES MOINES ARPT           IA   60 MPH TSTM GUST
05/20/98   POLK                           PILOT REPORT ON GROUND

Local storm report, May 20, 8:24 AM CDT, 3 hours 21 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
824 AM CDT WED MAY 20 1998

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

0413 AM    DOW CITY                  IA   70 MPH TSTM GUST
05/20/98   CRAWFORD

0533 AM    DOW CITY                  IA   60 MPH TSTM GUST
05/20/98   CRAWFORD

0540 AM    CUMMING                   IA   63 MPH TSTM GUST
05/20/98   WARREN

0555 AM    DES MOINES ARPT           IA   60 MPH TSTM GUST
05/20/98   POLK                           PILOT REPORT ON GROUND

The office that day

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

Issued	Product	Office	Counties	Lasted
May 19, 7:23 PM CDT	Severe Thunderstorm Warning	DMX	Appanoose	47 min
May 19, 7:31 PM CDT	Severe Thunderstorm Warning	DMX	Warren	34 min
May 19, 7:59 PM CDT	Severe Thunderstorm Warning	DMX	Lucas	36 min
May 20, 3:46 AM CDT	Severe Thunderstorm Warning	DMX	Crawford	49 min
May 20, 3:53 AM CDT	Severe Thunderstorm Warning	DMX	Audubon, Cass	62 min
May 20, 4:31 AM CDT	Severe Thunderstorm Warning	DMX	Carroll	49 min
May 20, 5:20 AM CDT	Severe Thunderstorm Warning	DMX	Dallas, Madison, Polk, Warren	60 min
May 20, 5:47 AM CDT	Severe Thunderstorm Warning	DMX	Jasper, Marion	48 min
May 20, 10:19 AM CDT	Severe Thunderstorm Warning	DMX	Marion	36 min
May 20, 10:21 AM CDT	Severe Thunderstorm Warning	DMX	Marion	34 min
May 20, 10:50 AM CDT	Severe Thunderstorm Warning	DMX	Monroe	35 min
May 20, 11:05 AM CDT	Severe Thunderstorm Warning	DMX	Wapello	35 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1998 Every severe thunderstorm 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; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.