Alert archive / Iowa / Severe Thunderstorm Warnings in 2013

Severe Thunderstorm Warning 204, NWS Des Moines, IA

August 6, 2013Jasper County, Marion County, Warren County, Iowa

NWS Des Moines, IA issued this severe thunderstorm warning at Aug 6, 2013, 6:46 PM CDT for Jasper County, Marion County, Warren County, Iowa. It was in force for 44 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: Aug 6, 2013, 6:46 PM CDT (23:46 UTC)
Expired: Aug 6, 2013, 7:30 PM CDT
In force: 44 min
Issued by: NWS Des Moines, IA
Area: Storm-based polygon
Hail: 1.0 in
Wind: 60.0 mph

Counties Jasper County, IA, Marion County, IA, Warren County, IA

The radar

The Des Moines radar (KDMX), 51 km from the middle of the area, began a volume at 23:47 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 nearest sounding before it

Omaha, NE (KOAX), launched 12:00Z, 11.8 hours before the alert went out and 262 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: 2968 J/kg
Mixed-layer CIN: -2 J/kg
Mixed-layer LCL: 509 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 1 m²/s²
0-3 km storm-relative helicity: 91 m²/s²
Significant tornado parameter: 1.9
Supercell composite: 7.8

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 Aug 6, 3:23 PM CDT, 3 hours 23 minutes earlier.

Area forecast discussion, Aug 6, 3:23 PM CDT, 3 hours 23 minutes before

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Hazardous weather outlook, Aug 6, 11:17 AM CDT, 7 hours 29 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1117 AM CDT TUE AUG 6 2013

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-071000-
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-
1117 AM CDT TUE AUG 6 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL IOWA.

.DAY ONE...THIS AFTERNOON AND TONIGHT

THUNDERSTORM CHANCES WILL INCREASE ACROSS THE AREA FROM WEST TO
EAST BY MID TO LATE AFTERNOON INTO TONIGHT. THERE IS A SLIGHT RISK
OF SEVERE STORMS...WITH LARGE HAIL AND DAMAGING WINDS THE MAIN
THREATS. AN ISOLATED TORNADO WILL BE POSSIBLE NORTH OF HIGHWAY 30.
LOCALLY HEAVY RAINFALL WILL BE POSSIBLE WITH THE STRONGEST
STORMS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

ADDITIONAL THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON AND NIGHT
SOUTH OF INTERSTATE 80. THE THREAT FOR SEVERE WEATHER IS LOW AT
THIS TIME.

THUNDERSTORMS ARE AGAIN POSSIBLE LATE SATURDAY NIGHT THROUGH SUNDAY
NIGHT. IT IS TOO EARLY TO DETERMINE THE RISK FOR SEVERE WEATHER AT
THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON INTO TONIGHT.

MJB

In the hours before

Special weather statement, Aug 6, 6:34 PM CDT, 12 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
634 PM CDT TUE AUG 6 2013

IAZ073-074-070030-
MARION-WARREN-
634 PM CDT TUE AUG 6 2013

...HAIL POSSIBLE OVER SOUTH CENTRAL IOWA...

AT 628 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 7 MILES EAST OF INDIANOLA...MOVING SLOWLY EAST
AT 15 MPH.

NICKEL SIZE HAIL...WINDS GREATER THAN 40 MPH AND BRIEF MODERATE
DOWNPOURS ARE POSSIBLE WITH THIS STORM.

LOCATIONS IMPACTED INCLUDE...
  SANDYVILLE...         HARTFORD...           SWAN...
  PLEASANTVILLE...

GUSTY WINDS MAY CAUSE SMALL OBJECTS SUCH AS TRASH BINS TO BLOW
AROUND. SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS
PASSED.

SMALL

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 6, 5:28 AM CDT	Dense Fog Advisory	DMX	Appanoose, Black Hawk, Bremer, Butler, Cerro Gordo, Davis and 16 more	6 hr

Nearby

Severe Thunderstorm Warnings in Iowa, 2013 Every severe thunderstorm warning in 2013

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.