Storm Events Database

Event Details

Event Thunderstorm Wind
Magnitude 52 kts.
State IOWA
County/Area GRUNDY
WFO DMX
Report Source Trained Spotter
NCDC Data Source CSV
Begin Date 2012-07-25 20:38:00.0 CST-6
Begin Location 1SE CONRAD
Begin Lat/Lon 42.22/-92.87
End Date 2012-07-25 20:38:00.0 CST-6
Deaths Direct/Indirect 0/0 (fatality details below, when available...)
Injuries Direct/Indirect 0/0
Property Damage 2.00K
Crop Damage 0.00K
Episode Narrative A very hot airmass was in place over Iowa, though it was capped through the daytime hours. High temperatures reached the mid to upper 90s in the north and 100 to 108 across the south. A cold front moved into northwest Iowa during the afternoon. Dewpoint temperatures pooled along the front to the 65 to 70 degree range. The atmosphere became unstable with the lifted index falling to around -5 C and CAPE increasing to between 2000 and 4000 J/kg. CAPE in the -10 to -30 C layer of the atmosphere was between 400 and 700 J/kg, but the freezing level was around 15,000 feet and shear 20 kts or less. Precipitable water values were high at around 2 inches. The primary mode of severe weather was high winds. A line of thunderstorms formed along the cold front during the early evening hours, rapid intensification once they broke through the cap. The storms became cold pool dominated by mid evening with the outflow boundary leading the storms by about 30 miles. Most of the storms produced winds of 50 to 60 MPH, with a few gusts of 65 to 75 MPH. The highest winds were in Carroll and Poweshiek Counties. Downdraft CAPE was between 1200 and 1800 J/kg. There was little tornado threat with the LCL between 2500 and 3500 meters. There were a few reports of hail, but most of the hail was under an inch in diameter and not a primary event. One report of golf ball size hail was received from the Ruthven area in Palo Alto County. Winds caused numerous power outages and also damaged many trees. As a storm moved through Boone County, the Central Iowa Expo building was flattened. It was under construction with three sides of the building completed. High winds at the Ames Airport flipped a plane over from the same storm that moved through Boone County.
Event Narrative A large tree snapped in half by high winds.


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All events for this episode:

Location County/Zone St. Date Time T.Z. Type Mag Dth Inj PrD CrD
Totals: 0 0 490.00K 305.00K
ESTHERVILLE EMMET CO. IA 07/25/2012 17:17 CST-6 Heavy Rain 0 0 0.00K 0.00K
RUTHVEN PALO ALTO CO. IA 07/25/2012 17:23 CST-6 Hail 1.75 in. 0 0 10.00K 10.00K
DEPEW PALO ALTO CO. IA 07/25/2012 17:36 CST-6 Hail 0.88 in. 0 0 0.00K 5.00K
ALGONA KOSSUTH CO. IA 07/25/2012 18:05 CST-6 Thunderstorm Wind 54 kts. MG 0 0 0.00K 0.00K
ALGONA MUNI ARPT KOSSUTH CO. IA 07/25/2012 18:10 CST-6 Thunderstorm Wind 54 kts. MG 0 0 0.00K 0.00K
WEST BEND PALO ALTO CO. IA 07/25/2012 18:11 CST-6 Hail 0.88 in. 0 0 0.00K 5.00K
ALGONA KOSSUTH CO. IA 07/25/2012 18:20 CST-6 Thunderstorm Wind 52 kts. EG 0 0 1.00K 0.00K
ALGONA KOSSUTH CO. IA 07/25/2012 18:20 CST-6 Hail 1.00 in. 0 0 2.00K 5.00K
BROCK RANCH ARPT HUMBOLDT CO. IA 07/25/2012 18:35 CST-6 Thunderstorm Wind 52 kts. EG 0 0 2.00K 0.00K
CARROLL NEU ARPT CARROLL CO. IA 07/25/2012 18:35 CST-6 Thunderstorm Wind 53 kts. MG 0 0 0.00K 0.00K
CARROLL CARROLL CO. IA 07/25/2012 18:37 CST-6 Thunderstorm Wind 61 kts. EG 0 0 50.00K 0.00K
GLIDDEN CARROLL CO. IA 07/25/2012 18:37 CST-6 Thunderstorm Wind 44 kts. EG 0 0 2.00K 0.00K
BREDA CARROLL CO. IA 07/25/2012 18:40 CST-6 Thunderstorm Wind 52 kts. EG 0 0 2.00K 0.00K
(FOD)FT DODGE MUNI A WEBSTER CO. IA 07/25/2012 18:45 CST-6 Thunderstorm Wind 52 kts. EG 0 0 10.00K 0.00K
CARROLL CARROLL CO. IA 07/25/2012 18:48 CST-6 Thunderstorm Wind 55 kts. MG 0 0 2.00K 0.00K
LOHRVILLE CALHOUN CO. IA 07/25/2012 18:49 CST-6 Thunderstorm Wind 61 kts. EG 0 0 25.00K 15.00K
ROCKWELL CITY CALHOUN CO. IA 07/25/2012 18:53 CST-6 Thunderstorm Wind 50 kts. EG 0 0 5.00K 0.00K
BREDA CARROLL CO. IA 07/25/2012 18:55 CST-6 Hail 1.00 in. 0 0 5.00K 5.00K
BRITT HANCOCK CO. IA 07/25/2012 18:55 CST-6 Hail 1.00 in. 0 0 10.00K 50.00K
CARROLL CARROLL CO. IA 07/25/2012 18:55 CST-6 Thunderstorm Wind 65 kts. EG 0 0 25.00K 50.00K
EAGLE GROVE WRIGHT CO. IA 07/25/2012 18:55 CST-6 Thunderstorm Wind 52 kts. EG 0 0 2.00K 0.00K
LANESBORO CARROLL CO. IA 07/25/2012 18:55 CST-6 Thunderstorm Wind 65 kts. EG 0 0 10.00K 50.00K
ARCADIA CARROLL CO. IA 07/25/2012 19:00 CST-6 Thunderstorm Wind 61 kts. EG 0 0 75.00K 50.00K
JEFFERSON GREENE CO. IA 07/25/2012 19:00 CST-6 Thunderstorm Wind 52 kts. EG 0 0 5.00K 5.00K
BELMOND WRIGHT CO. IA 07/25/2012 19:03 CST-6 Hail 1.00 in. 0 0 1.00K 10.00K
BELMOND WRIGHT CO. IA 07/25/2012 19:08 CST-6 Hail 1.00 in. 0 0 3.00K 0.00K
FARNHAMVILLE WEBSTER CO. IA 07/25/2012 19:10 CST-6 Thunderstorm Wind 52 kts. EG 0 0 2.00K 0.00K
GOWRIE WEBSTER CO. IA 07/25/2012 19:10 CST-6 Thunderstorm Wind 61 kts. EG 0 0 25.00K 5.00K
LIDDERDALE CARROLL CO. IA 07/25/2012 19:10 CST-6 Thunderstorm Wind 52 kts. EG 0 0 5.00K 0.00K
GOWRIE WEBSTER CO. IA 07/25/2012 19:12 CST-6 Thunderstorm Wind 50 kts. EG 0 0 2.00K 0.00K
BELMOND WRIGHT CO. IA 07/25/2012 19:15 CST-6 Hail 1.00 in. 0 0 2.00K 5.00K
BOXHOLM BOONE CO. IA 07/25/2012 19:15 CST-6 Thunderstorm Wind 56 kts. EG 0 0 15.00K 0.00K
EARLHAM MADISON CO. IA 07/25/2012 19:27 CST-6 Thunderstorm Wind 52 kts. EG 0 0 2.00K 0.00K
THORNTON CERRO GORDO CO. IA 07/25/2012 19:30 CST-6 Thunderstorm Wind 57 kts. EG 0 0 15.00K 0.00K
BOXHOLM BOONE CO. IA 07/25/2012 19:31 CST-6 Thunderstorm Wind 50 kts. EG 0 0 3.00K 0.00K
OGDEN BOONE CO. IA 07/25/2012 19:31 CST-6 Thunderstorm Wind 52 kts. EG 0 0 60.00K 0.00K
HAVERHILL MARSHALL CO. IA 07/25/2012 19:37 CST-6 Thunderstorm Wind 56 kts. MG 0 0 5.00K 10.00K
POLK CITY POLK CO. IA 07/25/2012 19:39 CST-6 Thunderstorm Wind 52 kts. MG 0 0 0.00K 0.00K
ALEXANDER FRANKLIN CO. IA 07/25/2012 19:40 CST-6 Thunderstorm Wind 52 kts. EG 0 0 10.00K 0.00K
BOONE MUNI ARPT BOONE CO. IA 07/25/2012 19:40 CST-6 Thunderstorm Wind 50 kts. EG 0 0 2.00K 0.00K
CALLENDER WEBSTER CO. IA 07/25/2012 19:40 CST-6 Thunderstorm Wind 50 kts. EG 0 0 3.00K 0.00K
MAXWELL STORY CO. IA 07/25/2012 19:40 CST-6 Thunderstorm Wind 52 kts. EG 0 0 2.00K 0.00K
MARSHALLTOWN MARSHALL CO. IA 07/25/2012 19:43 CST-6 Thunderstorm Wind 55 kts. MG 0 0 0.00K 0.00K
PLEASANT HILL BOONE CO. IA 07/25/2012 19:46 CST-6 Thunderstorm Wind 50 kts. EG 0 0 1.00K 0.00K
AMES ARPT STORY CO. IA 07/25/2012 19:49 CST-6 Thunderstorm Wind 59 kts. EG 0 0 20.00K 0.00K
AMES STORY CO. IA 07/25/2012 19:50 CST-6 Thunderstorm Wind 52 kts. EG 0 0 5.00K 0.00K
AMES ARPT STORY CO. IA 07/25/2012 19:50 CST-6 Thunderstorm Wind 59 kts. MG 0 0 10.00K 5.00K
STORY CITY STORY CO. IA 07/25/2012 19:51 CST-6 Thunderstorm Wind 50 kts. EG 0 0 1.00K 0.00K
NEVADA STORY CO. IA 07/25/2012 19:53 CST-6 Thunderstorm Wind 57 kts. EG 0 0 10.00K 0.00K
ROLAND STORY CO. IA 07/25/2012 19:54 CST-6 Thunderstorm Wind 52 kts. EG 0 0 3.00K 0.00K
STORY CITY STORY CO. IA 07/25/2012 19:57 CST-6 Thunderstorm Wind 52 kts. EG 0 0 1.00K 0.00K
COLO STORY CO. IA 07/25/2012 20:03 CST-6 Thunderstorm Wind 58 kts. MG 0 0 5.00K 0.00K
ROLAND STORY CO. IA 07/25/2012 20:04 CST-6 Thunderstorm Wind 52 kts. EG 0 0 10.00K 0.00K
HUXLEY STORY CO. IA 07/25/2012 20:05 CST-6 Thunderstorm Wind 52 kts. EG 0 0 3.00K 0.00K
STORY CITY STORY CO. IA 07/25/2012 20:07 CST-6 Hail 1.00 in. 0 0 1.00K 10.00K
COLFAX JASPER CO. IA 07/25/2012 20:09 CST-6 Thunderstorm Wind 52 kts. EG 0 0 5.00K 0.00K
JEWELL HAMILTON CO. IA 07/25/2012 20:12 CST-6 Thunderstorm Wind 61 kts. MG 0 0 10.00K 0.00K
SWANWOOD POLK CO. IA 07/25/2012 20:14 CST-6 Hail 0.75 in. 0 0 0.00K 5.00K
RED ROCK MARION CO. IA 07/25/2012 20:30 CST-6 Thunderstorm Wind 64 kts. MG 0 0 0.00K 0.00K
CONRAD GRUNDY CO. IA 07/25/2012 20:38 CST-6 Thunderstorm Wind 52 kts. EG 0 0 2.00K 0.00K
BROOKLYN POWESHIEK CO. IA 07/25/2012 21:02 CST-6 Thunderstorm Wind 57 kts. MG 0 0 3.00K 5.00K
Totals: 0 0 490.00K 305.00K