Alert archive / Iowa / Severe Thunderstorm Warnings in 2009

Severe Thunderstorm Warning 44, NWS Des Moines, IA

May 8, 2009Wapello County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at May 8, 2009, 6:46 PM CDT for Wapello County, Iowa. It was in force for 29 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
May 8, 2009, 6:46 PM CDT (23:46 UTC)
Expired
May 8, 2009, 7:15 PM CDT
In force
29 min
Issued by
NWS Des Moines, IA
Area
Storm-based polygon

County Wapello County, IA

The radar

The Des Moines radar (KDMX), 134 km from the middle of the area, began a volume at 23:46 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.

IssuedProductOfficeLasted
May 8, 1:21 PM CDTSevere Thunderstorm WatchSPC6 hr

The nearest sounding before it

Lincoln, IL (KILX), launched 12:00Z, 11.8 hours before the alert went out and 336 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, Lincoln, IL at 12:00Z on 2009-05-08Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 185 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, Lincoln, IL at 12:00Z on 2009-05-08The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -29 square meters per square second.1939587897117136Sfc1 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
185 J/kg
Mixed-layer CIN
-46 J/kg
Mixed-layer LCL
627 m above ground
0-6 km bulk shear
56 kt
0-1 km storm-relative helicity
-29 m²/s²
0-3 km storm-relative helicity
65 m²/s²
Significant tornado parameter
0.0
Supercell composite
-0.6

Open this sounding in Storm Lab

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.

NWS Des Moines, IA wrote its last area forecast discussion before this severe thunderstorm warning went out at May 8, 6:40 PM CDT, 6 minutes earlier.

Area forecast discussion, May 8, 6:40 PM CDT, 6 minutes before
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Hazardous weather outlook, May 8, 12:00 PM CDT, 6 hours 46 minutes before
HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1200 PM CDT FRI MAY 8 2009

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-
081>086-092>097-091700-
EMMET-KOSSUTH-WINNEBAGO-WORTH-PALO ALTO-HANCOCK-CERRO GORDO-
POCAHONTAS-HUMBOLDT-WRIGHT-FRANKLIN-BUTLER-BREMER-SAC-CALHOUN-
WEBSTER-HAMILTON-HARDIN-GRUNDY-BLACK HAWK-CRAWFORD-CARROLL-GREENE-
BOONE-STORY-MARSHALL-TAMA-AUDUBON-GUTHRIE-DALLAS-POLK-JASPER-
POWESHIEK-CASS-ADAIR-MADISON-WARREN-MARION-MAHASKA-ADAMS-UNION-
CLARKE-LUCAS-MONROE-WAPELLO-TAYLOR-RINGGOLD-DECATUR-WAYNE-
APPANOOSE-DAVIS-
1200 PM CDT FRI MAY 8 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

SCATTERED THUNDERSTORMS ARE EXPECTED ACROSS CENTRAL IOWA THIS
AFTERNOON INTO THE EARLY EVENING. SEVERE STORMS ARE POSSIBLE WITH
LARGE HAIL AND DAMAGING WIND THE MAIN THREAT. HAIL SIZE BETWEEN A
QUARTER AND A HALF DOLLAR IS POSSIBLE WITH THE STRONGER STORMS
ALONG WITH 60 MPH WIND GUSTS. ISOLATED TORNADOES  A FEW
THUNDERSTORMS ARE POSSIBLE ACROSS THE AREA TODAY. A FEW TORNADOES
ARE ALSO POSSIBLE MAINLY THIS AFTERNOON.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

ADDITIONAL THUNDERSTORM CHANCES ARE FORECAST FOR TUESDAY THROUGH WEDNESDAY
NIGHT. THE MOST WIDESPREAD THUNDERSTORM POTENTIAL ARRIVES TUESDAY NIGHT.
THE POTENTIAL FOR SEVERE WEATHER DURING THIS PERIOD WILL BE RESOLVED
WITH FUTURE FORECASTS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EARLY EVENING.

FAB

In the hours before

Local storm report, May 8, 5:38 PM CDT, 1 hour 8 minutes before
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Special weather statement, May 8, 6:01 PM CDT, 45 minutes before
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Special weather statement, May 8, 6:14 PM CDT, 32 minutes before
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Special weather statement, May 8, 6:15 PM CDT, 31 minutes before
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Special weather statement, May 8, 6:44 PM CDT, 2 minutes before
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Local storm report, May 8, 6:46 PM CDT, 0 minutes before
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The office that day

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

IssuedProductOfficeCountiesLasted
May 8, 5:15 PM CDTSevere Thunderstorm WarningDMXMarshall, Tama45 min
May 8, 5:27 PM CDTSevere Thunderstorm WarningDMXMarshall, Poweshiek, Tama32 min
May 8, 6:26 PM CDTSevere Thunderstorm WarningDMXMonroe22 min

Nearby

Severe Thunderstorm Warnings in Iowa, 2009Every severe thunderstorm warning in 2009

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.