Alert archive / Iowa / Severe Thunderstorm Warnings in 1998

Severe Thunderstorm Warning 7, NWS Des Moines, IA

March 30, 1998Mahaska County, Poweshiek County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Mar 30, 1998, 3:50 PM CST for Mahaska County, Poweshiek County, Iowa. It was in force for 30 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
Mar 30, 1998, 3:50 PM CST (21:50 UTC)
Expired
Mar 30, 1998, 4:20 PM CST
In force
30 min
Issued by
NWS Des Moines, IA
Area
Whole counties

Counties Mahaska County, IA, Poweshiek County, IA

The radar

The Des Moines radar (KDMX), 98 km from the middle of the area, began a volume at 21:53 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

TimeReportWhereRemark
Mar 30, 4:00 PM CSTThunderstorm Wind 61New Sharon, 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.

IssuedProductOfficeLasted
Mar 30, 3:45 PM CSTSevere Thunderstorm WatchSPC5 hr

The nearest sounding before it

Davenport, (KDVN), launched 12:00Z, 9.8 hours before the alert went out and 174 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, Davenport, at 12:00Z on 1998-03-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1173 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Davenport, at 12:00Z on 1998-03-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 268 square meters per square second.19395878Sfc1 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
1173 J/kg
Mixed-layer CIN
-43 J/kg
Mixed-layer LCL
828 m above ground
0-6 km bulk shear
53 kt
0-1 km storm-relative helicity
268 m²/s²
0-3 km storm-relative helicity
302 m²/s²
Significant tornado parameter
1.8
Supercell composite
8.5

Open this sounding in Storm Lab

The text

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

238 
WUUS1 KDSM 302151 RRA
SVRDSM
IAC123-157-302220-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE DES MOINES IA
350 PM CST MON MAR 30 1998

* SEVERE THUNDERSTORM WARNING FOR
  NORTHERN MAHASKA COUNTY - SOUTHEASTERN IOWA
  POWESHIEK COUNTY - CENTRAL IOWA

* UNTIL 420 PM CST
 
* SOME AREAS AFFECTED
    NEW SHARON
    MONTEZUMA
    GRINNELL
    BROOKLYN

* AT 348 PM CST STORM SPOTTERS REPORTED A SEVERE THUNDERSTORM JUST
  NORTH OF PELLA OR 40 MILES SOUTHEAST OF DES MOINES MOVING NORTHEAST
  AT 50 MPH.

* THE STORM WILL BE NEAR MONTEZUMA BY 420 PM.

THIS STORM HAS A HISTORY OF PRODUCING LARGE HAIL. WIND GUSTS TO 60 MPH
ARE ALSO LIKELY WITH THIS STORM. 

PYTLAK

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, Mar 30, 11:16 AM CST, 4 hours 34 minutes before
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-302100-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1116 AM CST MON MAR 30 1998

HAZARD--THUNDERSTORMS THIS AFTERNOON COULD PRODUCE HEAVY RAINS AND
GUSTY WINDS IN EXCESS OF 58 MPH.

TIMING AND AREA OF CONCERN -SOUTHEAST OF A LINE FROM MASON CITY TO
CARROLL...WITH THE THREAT OF STRONG WINDS SOUTHEAST OF A LINE FROM
WATERLOO TO DES MOINES TO CRESTON. TIMING IS AFTER 200 PM.

METEOROLOGICAL COMMENTS -A STATIONARY FRONT EXTENDS FROM NORTHWEST OF
WATERLOO THROUGH DES MOINES AND TO THE SOUTHEAST OF
CRESTON...PROVIDING A STRONG CONTRAST IN WEATHER ACROSS IOWA. THE
FRONT WILL MOVE LITTLE TODAY AS A LOW PRESSURE CENTER IS FORECAST TO
MOVE NORTH ALONG THE FRONT TONIGHT. AS A RESULT...THE ATMOSPHERE WILL
BECOME QUITE WARM AND UNSTABLE THIS AFTERNOON OVER SOUTHEAST IOWA
WHILE REMAINING COOL AND DAMP IN THE NORTHWEST. DIVERGENT AIR FLOW
ALOFT WILL ALLOW THUNDERSTORMS TO REDEVELOP IN VICINITY OF THE FRONT
THIS AFTERNOON WITH STORMS TRACKING RAPIDLY TO THE NORTHEAST.

SOUTHEAST OF THE WATERLOO TO CRESTON LINE...INSTABILITY AND WIND
SHEAR WILL BE FAVORABLE FOR A FEW STORMS TO BECOME SEVERE...PRODUCING
HAIL UP TO 1 INCH AND WINDS OVER 58 MPH. NORTHWEST OF THIS AREA TO
MASON CITY AND CARROLL...THE THREAT IS ORIENTED MORE TOWARD EMBEDDED
THUNDERSTORMS WITH BRIEF HEAVY RAINS.  THIS WILL OCCUR AS VERY MOIST
AIR OVERRUNS THE FRONTAL BOUNDARY. AVERAGE RAINFALL IS EXPECTED TO BE
IN THE ONE HALF TO THREE QUARTER INCH RANGE THROUGH THIS
EVENING...WITH ISOLATED HEAVIER AMOUNTS. SINCE ONE HALF TO 1.5 INCHES
OF RAIN HAS ALREADY FALLEN OVER PORTIONS OF CENTRAL IOWA...RIVERS AND
STREAMS ARE RISING AND CHANCES FOR MINOR FLOODING WILL CONTINUE.

PRECAUTIONS SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON SOUTHEAST
OF THE WATERLOO TO CRESTON LINE. AS STREAMS CONTINUE TO RISE...USE
CAUTION IN FLOOD PRONE AREAS AND KEEP ABREAST OF THE LATEST
FORECASTS.

JUNGBLUTH
Special weather statement, Mar 30, 11:16 AM CST, 4 hours 34 minutes before
IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-302100-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1116 AM CST MON MAR 30 1998

HAZARD--THUNDERSTORMS THIS AFTERNOON COULD PRODUCE HEAVY RAINS AND
GUSTY WINDS IN EXCESS OF 58 MPH.

TIMING AND AREA OF CONCERN -SOUTHEAST OF A LINE FROM MASON CITY TO
CARROLL...WITH THE THREAT OF STRONG WINDS SOUTHEAST OF A LINE FROM
WATERLOO TO DES MOINES TO CRESTON. TIMING IS AFTER 200 PM.

METEOROLOGICAL COMMENTS -A STATIONARY FRONT EXTENDS FROM NORTHWEST OF
WATERLOO THROUGH DES MOINES AND TO THE SOUTHEAST OF
CRESTON...PROVIDING A STRONG CONTRAST IN WEATHER ACROSS IOWA. THE
FRONT WILL MOVE LITTLE TODAY AS A LOW PRESSURE CENTER IS FORECAST TO
MOVE NORTH ALONG THE FRONT TONIGHT. AS A RESULT...THE ATMOSPHERE WILL
BECOME QUITE WARM AND UNSTABLE THIS AFTERNOON OVER SOUTHEAST IOWA
WHILE REMAINING COOL AND DAMP IN THE NORTHWEST. DIVERGENT AIR FLOW
ALOFT WILL ALLOW THUNDERSTORMS TO REDEVELOP IN VICINITY OF THE FRONT
THIS AFTERNOON WITH STORMS TRACKING RAPIDLY TO THE NORTHEAST.

SOUTHEAST OF THE WATERLOO TO CRESTON LINE...INSTABILITY AND WIND
SHEAR WILL BE FAVORABLE FOR A FEW STORMS TO BECOME SEVERE...PRODUCING
HAIL UP TO 1 INCH AND WINDS OVER 58 MPH. NORTHWEST OF THIS AREA TO
MASON CITY AND CARROLL...THE THREAT IS ORIENTED MORE TOWARD EMBEDDED
THUNDERSTORMS WITH BRIEF HEAVY RAINS.  THIS WILL OCCUR AS VERY MOIST
AIR OVERRUNS THE FRONTAL BOUNDARY. AVERAGE RAINFALL IS EXPECTED TO BE
IN THE ONE HALF TO THREE QUARTER INCH RANGE THROUGH THIS
EVENING...WITH ISOLATED HEAVIER AMOUNTS. SINCE ONE HALF TO 1.5 INCHES
OF RAIN HAS ALREADY FALLEN OVER PORTIONS OF CENTRAL IOWA...RIVERS AND
STREAMS ARE RISING AND CHANCES FOR MINOR FLOODING WILL CONTINUE.

PRECAUTIONS SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON SOUTHEAST
OF THE WATERLOO TO CRESTON LINE. AS STREAMS CONTINUE TO RISE...USE
CAUTION IN FLOOD PRONE AREAS AND KEEP ABREAST OF THE LATEST
FORECASTS.

JUNGBLUTH

The office that day

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

IssuedProductOfficeCountiesLasted
Mar 30, 1:52 PM CSTSevere Thunderstorm WarningDMXTama33 min
Mar 30, 2:27 PM CSTSevere Thunderstorm WarningDMXDallas, Madison33 min
Mar 30, 2:44 PM CSTSevere Thunderstorm WarningDMXPolk31 min
Mar 30, 3:10 PM CSTSevere Thunderstorm WarningDMXPolk, Story35 min
Mar 30, 3:18 PM CSTSevere Thunderstorm WarningDMXWarren27 min
Mar 30, 3:27 PM CSTSevere Thunderstorm WarningDMXJasper, Marion33 min
Mar 30, 4:06 PM CSTSevere Thunderstorm WarningDMXLucas, Wayne34 min
Mar 30, 4:17 PM CSTSevere Thunderstorm WarningDMXPoweshiek18 min
Mar 30, 4:21 PM CSTSevere Thunderstorm WarningDMXPoweshiek19 min
Mar 30, 4:49 PM CSTSevere Thunderstorm WarningDMXMonroe, Wapello31 min
Mar 30, 5:06 PM CSTSevere Thunderstorm WarningDMXMahaska34 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.