Alert archive / Iowa / Severe Thunderstorm Warnings in 1998
Severe Thunderstorm Warning 296, NWS Des Moines, IA
NWS Des Moines, IA issued this severe thunderstorm warning at Sep 1, 1998, 5:16 PM CDT for Pocahontas County, Iowa. It was in force for 34 min. 2 reports 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
- Sep 1, 1998, 5:16 PM CDT (22:16 UTC)
- Expired
- Sep 1, 1998, 5:50 PM CDT
- In force
- 34 min
- Issued by
- NWS Des Moines, IA
- Area
- Whole counties
County Pocahontas County, IA
The radar
The Des Moines radar (KDMX), 137 km from the middle of the area, began a volume at 22:19 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 |
|---|---|---|---|
| Sep 1, 5:22 PM CDT | Hail 0.75 | Palmer, IA | |
| Sep 1, 5:25 PM CDT | Hail 2 | Palmer, 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
Omaha, NE (KOAX), launched 12:00Z, 10.3 hours before the alert went out and 210 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1545 m above ground
- 0-6 km bulk shear
- 15 kt
- 0-1 km storm-relative helicity
- -31 m²/s²
- 0-3 km storm-relative helicity
- 22 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
989 WUUS1 KDSM 012217 RRA SVRDSM IAC151-012250- BULLETIN - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE DES MOINES IA 516 PM CDT TUE SEP 1 1998 THE NATIONAL WEATHER SERVICE IN DES MOINES HAS ISSUED A * SEVERE THUNDERSTORM WARNING FOR... CENTRAL AND SOUTHERN POCAHONTAS COUNTY IN NORTHWESTERN IOWA * UNTIL 550 PM CDT * AT 515 PM CDT... DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM 26 MILES WEST NORTHWEST OF FORT DODGE OR 3 MILES NORTHWEST OF PALMER MOVING SOUTH SOUTHEAST AT 30 MPH. * THIS STORM CAN BE EXPECTED NEAR... PALMER BY 519 PM CDT THIS STORM HAS A HISTORY OF LARGE HAIL. GO INSIDE A STURDY BUILDING AND STAY AWAY FROM WINDOWS FAB
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, Sep 1, 3:10 PM CDT, 2 hours 6 minutes before
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086- 092>097-020400- CENTRAL IOWA THUNDERSTORM OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 310 PM CDT TUE SEP 1 1998 HAZARD--WIDELY SCATTERED THUNDERSTORMS...A FEW OF WHICH WILL PRODUCE UP TO DIME SIZE HAIL AND WIND GUSTS TO 45 MPH. AREA OF CONCERN--ALL OF CENTRAL IOWA. TIMING DETAILS--THROUGH 900 PM. METEOROLOGICAL COMMENTS--A LINE OF ISOLATED THUNDERSTORMS HAS DEVELOPED FROM SOUTHEAST WISCONSIN INTO FAR NORTHWEST IOWA AHEAD OF THE STRONG COLD FRONT DROPPING INTO THE STATE. MOISTURE CONVERGENCE ALONG THE FRONT REMAINS WEAK BUT DEWPOINTS HAVE CLIMBED INTO THE MID TO UPPER 60S...RESULTING IN RATHER STRONG INSTABILITY. MID LEVEL STEERING WINDS HAVE ALSO INCREASED TO 40 TO 45 MPH WHILE AT THE SAME TIME MID LEVEL TEMPERATURES COOLED. THE COMBINATION OF ALL THESE FACTORS WILL ALLOW ANY STORMS THAT DEVELOP TO PRODUCE SMALL HAIL AND GUSTY WINDS. ONCE THE SUN SETS THIS EVENING...THE WEAK CONVERGENCE AND LOSS OF DAYTIME HEATING WILL CAUSE THE STORMS TO GRADUALLY DISSIPATE. PRECAUTIONS--SPOTTER ACTIVATION MAY BE NEEDED FOR AN HOUR OR TWO THIS EVENING AS THIS LINE COMES THROUGH. COVERAGE WILL BE VERY SPOTTY...HOWEVER. EVEN IF A THUNDERSTORM DOES NOT PASS DIRECTLY OVERHEAD...LIGHTNING CAN STRIKE MANY MILES AWAY FROM IT. AS SOON AS YOU HEAR THUNDER...MOVE INDOORS. PYTLAK
Special weather statement, Sep 1, 3:10 PM CDT, 2 hours 6 minutes before
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086- 092>097-020400- CENTRAL IOWA THUNDERSTORM OUTLOOK NATIONAL WEATHER SERVICE DES MOINES IA 310 PM CDT TUE SEP 1 1998 HAZARD--WIDELY SCATTERED THUNDERSTORMS...A FEW OF WHICH WILL PRODUCE UP TO DIME SIZE HAIL AND WIND GUSTS TO 45 MPH. AREA OF CONCERN--ALL OF CENTRAL IOWA. TIMING DETAILS--THROUGH 900 PM. METEOROLOGICAL COMMENTS--A LINE OF ISOLATED THUNDERSTORMS HAS DEVELOPED FROM SOUTHEAST WISCONSIN INTO FAR NORTHWEST IOWA AHEAD OF THE STRONG COLD FRONT DROPPING INTO THE STATE. MOISTURE CONVERGENCE ALONG THE FRONT REMAINS WEAK BUT DEWPOINTS HAVE CLIMBED INTO THE MID TO UPPER 60S...RESULTING IN RATHER STRONG INSTABILITY. MID LEVEL STEERING WINDS HAVE ALSO INCREASED TO 40 TO 45 MPH WHILE AT THE SAME TIME MID LEVEL TEMPERATURES COOLED. THE COMBINATION OF ALL THESE FACTORS WILL ALLOW ANY STORMS THAT DEVELOP TO PRODUCE SMALL HAIL AND GUSTY WINDS. ONCE THE SUN SETS THIS EVENING...THE WEAK CONVERGENCE AND LOSS OF DAYTIME HEATING WILL CAUSE THE STORMS TO GRADUALLY DISSIPATE. PRECAUTIONS--SPOTTER ACTIVATION MAY BE NEEDED FOR AN HOUR OR TWO THIS EVENING AS THIS LINE COMES THROUGH. COVERAGE WILL BE VERY SPOTTY...HOWEVER. EVEN IF A THUNDERSTORM DOES NOT PASS DIRECTLY OVERHEAD...LIGHTNING CAN STRIKE MANY MILES AWAY FROM IT. AS SOON AS YOU HEAR THUNDER...MOVE INDOORS. PYTLAK
Special weather statement, Sep 1, 3:31 PM CDT, 1 hour 45 minutes before
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086- 092>097-020400- CENTRAL IOWA THUNDERSTORM OUTLOOK...CORRECTION NATIONAL WEATHER SERVICE DES MOINES IA 331 PM CDT TUE SEP 1 1998 HAZARD--WIDELY SCATTERED THUNDERSTORMS...A FEW OF WHICH WILL PRODUCE UP TO DIME SIZE HAIL AND WIND GUSTS TO 45 MPH. AREA OF CONCERN--ALL OF CENTRAL IOWA. TIMING DETAILS--THROUGH 900 PM. METEOROLOGICAL COMMENTS--A LINE OF ISOLATED THUNDERSTORMS HAS DEVELOPED FROM SOUTHWEST WISCONSIN INTO FAR NORTHWEST IOWA AHEAD OF THE STRONG COLD FRONT DROPPING INTO THE STATE. MOISTURE CONVERGENCE ALONG THE FRONT REMAINS WEAK BUT DEWPOINTS HAVE CLIMBED INTO THE MID TO UPPER 60S...RESULTING IN RATHER STRONG INSTABILITY. MID LEVEL STEERING WINDS HAVE ALSO INCREASED TO 40 TO 45 MPH WHILE AT THE SAME TIME MID LEVEL TEMPERATURES COOLED. THE COMBINATION OF ALL THESE FACTORS WILL ALLOW ANY STORMS THAT DEVELOP TO PRODUCE SMALL HAIL AND GUSTY WINDS. ONCE THE SUN SETS THIS EVENING...THE WEAK CONVERGENCE AND LOSS OF DAYTIME HEATING WILL CAUSE THE STORMS TO GRADUALLY DISSIPATE. PRECAUTIONS--SPOTTER ACTIVATION MAY BE NEEDED FOR AN HOUR OR TWO THIS EVENING AS THIS LINE COMES THROUGH. COVERAGE WILL BE VERY SPOTTY...HOWEVER. EVEN IF A THUNDERSTORM DOES NOT PASS DIRECTLY OVERHEAD...LIGHTNING CAN STRIKE MANY MILES AWAY FROM IT. AS SOON AS YOU HEAR THUNDER...MOVE INDOORS. PYTLAK CORRECTION FOR THUNDERSTORM LOCATION IN MET COMMENTS SECTION
Special weather statement, Sep 1, 3:31 PM CDT, 1 hour 45 minutes before
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086- 092>097-020400- CENTRAL IOWA THUNDERSTORM OUTLOOK...CORRECTION NATIONAL WEATHER SERVICE DES MOINES IA 331 PM CDT TUE SEP 1 1998 HAZARD--WIDELY SCATTERED THUNDERSTORMS...A FEW OF WHICH WILL PRODUCE UP TO DIME SIZE HAIL AND WIND GUSTS TO 45 MPH. AREA OF CONCERN--ALL OF CENTRAL IOWA. TIMING DETAILS--THROUGH 900 PM. METEOROLOGICAL COMMENTS--A LINE OF ISOLATED THUNDERSTORMS HAS DEVELOPED FROM SOUTHWEST WISCONSIN INTO FAR NORTHWEST IOWA AHEAD OF THE STRONG COLD FRONT DROPPING INTO THE STATE. MOISTURE CONVERGENCE ALONG THE FRONT REMAINS WEAK BUT DEWPOINTS HAVE CLIMBED INTO THE MID TO UPPER 60S...RESULTING IN RATHER STRONG INSTABILITY. MID LEVEL STEERING WINDS HAVE ALSO INCREASED TO 40 TO 45 MPH WHILE AT THE SAME TIME MID LEVEL TEMPERATURES COOLED. THE COMBINATION OF ALL THESE FACTORS WILL ALLOW ANY STORMS THAT DEVELOP TO PRODUCE SMALL HAIL AND GUSTY WINDS. ONCE THE SUN SETS THIS EVENING...THE WEAK CONVERGENCE AND LOSS OF DAYTIME HEATING WILL CAUSE THE STORMS TO GRADUALLY DISSIPATE. PRECAUTIONS--SPOTTER ACTIVATION MAY BE NEEDED FOR AN HOUR OR TWO THIS EVENING AS THIS LINE COMES THROUGH. COVERAGE WILL BE VERY SPOTTY...HOWEVER. EVEN IF A THUNDERSTORM DOES NOT PASS DIRECTLY OVERHEAD...LIGHTNING CAN STRIKE MANY MILES AWAY FROM IT. AS SOON AS YOU HEAR THUNDER...MOVE INDOORS. PYTLAK CORRECTION FOR THUNDERSTORM LOCATION IN MET COMMENTS SECTION
The office that day
Everything else NWS Des Moines, IA issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 1, 4:03 PM CDT | Severe Thunderstorm Warning | DMX | Palo Alto | 32 min |
| Sep 1, 4:29 PM CDT | Severe Thunderstorm Warning | DMX | Pocahontas | 31 min |
Nearby
Severe Thunderstorm Warnings in Iowa, 1998Every 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.