Alert archive / Iowa / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 267, NWS Des Moines, IA

July 15, 1998Dallas County, Guthrie County, Polk County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Jul 15, 1998, 3:01 AM CDT for Dallas County, Guthrie County, Polk County, Iowa. It was in force for 64 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: Jul 15, 1998, 3:01 AM CDT (08:01 UTC)
Expired: Jul 15, 1998, 4:05 AM CDT
In force: 64 min
Issued by: NWS Des Moines, IA
Area: Whole counties

Counties Dallas County, IA, Guthrie County, IA, Polk County, IA

The radar

The Des Moines radar (KDMX), 27 km from the middle of the area, began a volume at 08:01 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.

Issued	Product	Office	Lasted
Jul 15, 1:30 AM CDT	Severe Thunderstorm Watch	SPC	4 hr

The nearest sounding before it

Omaha, NE (KOAX), launched 00:00Z, 8.0 hours before the alert went out and 198 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: 2762 J/kg
Mixed-layer CIN: -97 J/kg
Mixed-layer LCL: 1213 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 22 m²/s²
0-3 km storm-relative helicity: 191 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

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

239 
WUUS1 KDSM 150800 RRA
SVRDSM
IAC077-153-169-150905-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
301 AM CDT WED JUL 15 1998

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  GUTHRIE COUNTY IN WEST CENTRAL IOWA
  POLK COUNTY IN CENTRAL IOWA
  STORY COUNTY IN CENTRAL IOWA

* UNTIL 405 AM CDT

* AT 259 AM CDT... DOPPLER RADAR INDICATED A LINE OF SEVERE
  THUNDERSTORMS 25 MILES NORTH OF DES MOINES OR 5 MILES NORTH OF
  HUXLEY MOVING SOUTH SOUTHEAST AT 30 MPH.

* THIS STORM CAN BE EXPECTED NEAR...
   HUXLEY             BY 300 AM CDT
   SHELDAHL           BY 300 AM CDT
   SAYLORVILLE RESERVOIR BY 318 AM CDT
   ANKENY             BY 322 AM CDT
   DES MOINES         BY 320 AM CDT
   DALLAS CENTER      BY 310 AM CDT
   AMES               NOW

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

FORSTER

1 follow-up statement

264 
WUUS1 KDSM 150806 RRB
SVRDSM
IAC049-077-153-169-150905-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING...CORRECTION TO ADD DALLAS COUNTY
NATIONAL WEATHER SERVICE DES MOINES IA
301 AM CDT WED JUL 15 1998

THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  GUTHRIE COUNTY IN WEST CENTRAL IOWA
  DALLAS COUNTY IN CENTRAL IOWA
  POLK COUNTY IN CENTRAL IOWA
  STORY COUNTY IN CENTRAL IOWA

* UNTIL 405 AM CDT

* AT 259 AM CDT... DOPPLER RADAR INDICATED A LINE OF SEVERE
  THUNDERSTORMS 25 MILES NORTH OF DES MOINES OR 5 MILES NORTH OF
  HUXLEY MOVING SOUTH SOUTHEAST AT 30 MPH.

* THIS STORM CAN BE EXPECTED NEAR...
   HUXLEY             BY 300 AM CDT
   SHELDAHL           BY 300 AM CDT
   SAYLORVILLE RESERVOIR BY 318 AM CDT
   ANKENY             BY 322 AM CDT
   DES MOINES         BY 320 AM CDT
   DALLAS CENTER      BY 310 AM CDT
   AMES               NOW

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

FORSTER

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, Jul 14, 10:06 PM CDT, 4 hours 55 minutes before

IAZ004>007-015>017-023>025-033-034-044-151100-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1006 PM CDT TUE JUL 14 1998

HAZARD--A LINE OF THUNDERSTORMS WITH STRONG WIND GUSTS TO 50 MPH
AND HEAVY RAIN.

AREA OF CONCERN--ALONG AND NORTHWEST OF A MASON CITY TO DENISON LINE.

TIMING DETAILS--MOVING TOWARDS A SPENCER--ESTHERVILLE--NORTHWOOD
BETWEEN 300 AND 500 AM...POSSIBLY SPREADING AS FAR SOUTHEAST AS
MASON CITY...CLARION AND DENISON CLOSER TO 600 AM.

METEOROLOGICAL COMMENTS--AT 1000 PM...A LINE OF STRONG TO SEVERE
THUNDERSTORMS WAS LOCATED FROM NEAR THE TWIN CITIES WEST INTO EAST
CENTRAL SOUTH DAKOTA NEAR WATERTOWN.  THIS LINE OF STORMS WAS
TRENDING A SOUTHWARD PROPAGATION INTO A MOISTURE AND INSTABILITY
AXIS LOCATED FROM NORTHEAST NEBRASKA INTO NORTH CENTRAL IOWA.  LOW-
LEVEL WINDS WERE INCREASING JUST ABOVE THE GROUND INCREASING
CONVERGENCE INTO THE STORMS.  THERE REMAINS A SLIGHT CHANCE THAT
THESE STORMS WILL HOLD TOGETHER INTO THE AREA OF CONCERN LATE
TONIGHT.  NEGATIVE FACTORS ARE A LACK OF UPPER LEVEL SUPPORT OVER
NORTHERN AND NORTHWEST IOWA WITH MORE STABLE AIR TRYING TO WORK
INTO THE STATE FROM ILLINOIS AND MISSOURI.

PRECAUTIONS--NO IMMEDIATE ACTION IS NEEDED...HOWEVER...IT IS ADVISED
THAT SPOTTER GROUPS KEEP CHECKING NATIONAL WEATHER SERVICE SHORT
TERM FORECASTS AND ANY UPDATES TONIGHT.

KULA

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 15, 1:46 AM CDT	Severe Thunderstorm Warning	DMX	Calhoun, Humboldt, Pocahontas, Webster	64 min
Jul 15, 1:46 AM CDT	Severe Thunderstorm Warning	DMX	Cerro Gordo, Hancock, Wright	64 min
Jul 15, 1:46 AM CDT	Severe Thunderstorm Warning	DMX	Worth	64 min
Jul 15, 2:05 AM CDT	Severe Thunderstorm Warning	DMX	Carroll, Greene	60 min
Jul 15, 2:05 AM CDT	Severe Thunderstorm Warning	DMX	Hamilton	60 min
Jul 15, 2:22 AM CDT	Severe Thunderstorm Warning	DMX	Hardin	63 min
Jul 15, 2:22 AM CDT	Severe Thunderstorm Warning	DMX	Boone	63 min
Jul 15, 2:30 AM CDT	Severe Thunderstorm Warning	DMX	Crawford	65 min
Jul 15, 3:01 AM CDT	Severe Thunderstorm Warning	DMX	Story	64 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.