Alert archive / Iowa / Severe Thunderstorm Warnings in 1991

Severe Thunderstorm Warning 33, NWS Des Moines, IA

April 27, 1991Mahaska County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Apr 27, 1991, 1:30 AM CDT for Mahaska County, Iowa. It was in force for 45 min. 3 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
Apr 27, 1991, 1:30 AM CDT (06:30 UTC)
Expired
Apr 27, 1991, 2:15 AM CDT
In force
45 min
Issued by
NWS Des Moines, IA
Area
Whole counties

County Mahaska County, IA

What was reported inside it

TimeReportWhereRemark
Apr 27, 1:30 AM CDTThunderstorm Wind 87Mahaska, IA
Apr 27, 1:40 AM CDTThunderstorm Wind 70Mahaska, IA
Apr 27, 2:00 AM CDTThunderstorm Wind 0Mahaska, 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. Storm Data before 1996 records only tornadoes, thunderstorm wind and hail.

The nearest sounding before it

Topeka, KS (KTOP), launched 00:00Z, 6.5 hours before the alert went out and 364 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, Topeka, KS at 00:00Z on 1991-04-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Topeka, KS at 00:00Z on 1991-04-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 409 square meters per square second.1939587897117Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
NaN m above ground
0-6 km bulk shear
79 kt
0-1 km storm-relative helicity
409 m²/s²
0-3 km storm-relative helicity
485 m²/s²
Significant tornado parameter
0.0
Supercell composite
17.2

Open this sounding in Storm Lab

The text

The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.

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, Apr 27, 12:14 AM CDT, 1 hour 16 minutes before
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>
Special weather statement, Apr 27, 12:20 AM CDT, 1 hour 10 minutes before
<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>
Local storm report, Apr 27, 12:45 AM CDT, 45 minutes before
LOCAL STORM REPORT
NATIONAL WEATHER SERVICE WATERLOO IA
1245 AM CDT SAT ARP 27 1991

                                EVENT AND LOCATION
HANCOCK COUNTY
        1040PM CDT   TORNADO REPORTED TO THE WEATHER OFFICE AT 1205
                     AM CDT.
                     EXTENSIVE TREE DAMAGE IN GARNER WITH 3 TO 5
                     TRAILER HOMES TIPPED OVER AND HEAVILY DAMAGED.
                     SOME HOME DAMAGE WITH NO SERIOUS INJURIES
                     REPORTED.  EVERYONE ACCOUNTED FOR.
Special weather statement, Apr 27, 12:49 AM CDT, 41 minutes before
IAZALL-270645-

SPECIAL WEATHER STATEMENT AND RADAR SUMMARY
NATIONAL WEATHER SERVICE DES MOINES IA
1248 AM CDT SAT APR 27 1991

...AT 1 PM...ONLY A SEVERE THUNDERSTORM WATCH WILL REMAIN IN EFFECT
   FOR A LARGE PORTION OF SOUTHERN AND EASTERN IOWA UNTIL 4 AM...

AT 1231 AM...SHOWERS AND THUNDERSTORMS CONTINUED OVER MUCH OF THE
WEST THREE QUARTERS OF IOWA...GENERALLY WEST OF A LINE FROM OTTUMWA TO
30 MILES EAST OF WATERLOO.

WITHIN THIS AREA...SCATTERED INTENSE STORMS WERE OVER SOUTH CENTRAL AND
CENTRAL IOWA.  THE STRONGEST STORMS WERE LOCATED FROM 30 MILES SOUTHWEST
OF DES MOINES...TO 45 MILES EAST OF DES MOINES NEAR NEW SHARON...AND
45 MILES NORTHEAST OF DES MOINES NEAR GRINNELL.
.
THESE INTENSE STORMS HAVE BEEN PRODUCING VERY HEAVY RAIN AND FREQUENT
DEADLY LIGHTNING...AND POSSIBLY HAIL AND BRIEF STRONG GUSTY WIND.

THE SHOWERS AND STORMS WERE MOVING NORTHEAST AT 45 MILES AN HOUR.

PEOPLE IN THE PATH OF THESE INTENSE THUNDERSTORMS SHOULD REMAIN ALERT
FOR RAPIDLY CHANGING CONDITIONS...AND BE PREPARED TO SEEK IMMEDIATE
SHELTER SHOULD THREATENING WEATHER APPROACH.

DM/JAK
Special weather statement, Apr 27, 1:17 AM CDT, 13 minutes before
IAZALL-270710-

SPECIAL WEATHER STATEMENT AND IOWA WEATHER UPDATE
NATIONAL WEATHER SERVICE DES MOINES IA
118 AM CDT SAT APR 27 1991

...A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT FOR MUCH OF THE
   SOUTHEAST QUARTER OF IOWA UNTIL 4 AM...

AT 105 AM...SHOWERS AND THUNDERSTORMS CONTINUED OVER MUCH OF THE EAST
THREE QUARTERS OF IOWA.  MOST OF THE PRECIPITATION WAS EAST OF A LINE
FROM LAMONI...TO FORT DODGE...TO 30 MILES WEST OF MASON CITY.

WITHIN THIS AREA...SCATTERED INTENSE STORMS WERE LOCATED FROM SOUTH
CENTRAL INTO NORTHEAST IOWA.  THE STRONGEST STORMS WERE OCCURRING IN A
10 MILE WIDE BAND FROM 35 MILES SOUTHWEST OF OTTUMWA NEAR CENTERVILLE...
TO 35 MILES NORTHEAST OF DES MOINES NEAR NEWTON.  OTHER STRONG STORMS
WERE LOCATED FROM 15 MILES SOUTH OF WATERLOO TO 30 MILES WEST OF CEDAR
RAPIDS.

THESE INTENSE STORMS WERE PRODUCING BRIEF HEAVY RAIN AND FREQUENT DEADLY
LIGHTNING...AND POSSIBLY SOME HAIL AND STRONG GUSTY WINDS.

THE SHOWERS AND STORMS WERE MOVING NORTHEAST AT 45 MILES AN HOUR.

PEOPLE IN THE PATH OF THESE INTENSE THUNDERSTORMS SHOULD REMAIN ALERT
FOR RAPIDLY CHANGING CONDITIONS...AND BE PREPARED TO SEEK IMMEDIATE
SHELTER SHOULD THREATENING WEATHER APPROACH.

DM/JAK
Special weather statement, Apr 27, 1:21 AM CDT, 9 minutes before
IAZ002-003-006-007-270700-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE WATERLOO IA
1215 AM CDT SAT APR 27 1991

...A SEVERE THUNDERSTORM WATCH FOR PARTS OF NORTHEAST IOWA UNITL
4AM CDT...

AT 110 AM CDT AN AREA OF VERY STRONG THUNDERSTORMS EXTENDED FROM ABOUT
10 MILES EAST OF WATERLOO TO ABOUT 15 MILES SOUTHWEST OF WATERLOO. THESE
STRONG THUNDERSTORMS WERE PART OF A LARGER AREA OF SHOWERS AND
THUNDERSTORMS IN NORTHEAST AND NORTH CENTRAL IOWA THAT WERE GENERALLY
WEST OF A LINE FROM THE MINNESOTA BORDER NORTHWEST OF DECORAH TO NEAR
INDEPENDENCE.

THESE THUNDERSTORMS WERE PRODUCING VERY HEAVY RAIN...STRONG GUSTY WINDS
AND DANGEROUS LIGHTNING AS THEY MOVE NORTHEAST AT 40 MILES AN HOUR.

The office that day

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

IssuedProductOfficeCountiesLasted
Apr 26, 7:43 PM CDTSevere Thunderstorm WarningDMXCrawford32 min
Apr 26, 7:49 PM CDTTornado WarningDMXCrawford26 min
Apr 26, 8:19 PM CDTTornado WarningDMXSac56 min
Apr 26, 8:36 PM CDTSevere Thunderstorm WarningDMXBuena Vista29 min
Apr 26, 8:55 PM CDTSevere Thunderstorm WarningDMXRinggold30 min
Apr 26, 9:19 PM CDTSevere Thunderstorm WarningDMXDecatur35 min
Apr 26, 9:19 PM CDTSevere Thunderstorm WarningDMXClarke41 min
Apr 26, 9:46 PM CDTSevere Thunderstorm WarningDMXPolk, Warren44 min
Apr 26, 10:59 PM CDTSevere Thunderstorm WarningDMXLucas, Wayne31 min
Apr 26, 11:18 PM CDTTornado WarningDMXWayne27 min
Apr 26, 11:23 PM CDTTornado WarningDMXLucas37 min
Apr 27, 12:02 AM CDTSevere Thunderstorm WarningDMXMahaska, Marion, Monroe28 min
Apr 27, 2:04 AM CDTTornado WarningDMXIowa41 min
Apr 27, 2:04 AM CDTTornado WarningDMXKeokuk15 min

Nearby

Severe Thunderstorm Warnings in Iowa, 1991Every severe thunderstorm warning in 1991

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.