Storm Events Database

Event Details

Event Hail
Magnitude 0.75 in.
State IOWA
County/Area GRUNDY
WFO DMX
Report Source Trained Spotter
NCDC Data Source CSV
Begin Date 2010-05-12 18:18:00.0 CST-6
Begin Location 3SW ZANETA
Begin Lat/Lon 42.37/-92.59
End Date 2010-05-12 18:18:00.0 CST-6
Deaths Direct/Indirect 0/0 (fatality details below, when available...)
Injuries Direct/Indirect 0/0
Property Damage 0.00K
Crop Damage 0.00K
Episode Narrative A strong upper level low pressure trough over the western U.S. moved into the central states during the day on the 12th. The situation was quite similar to the event 2 days prior, though the severe weather was farther north. The 850 mb front was stretched across Iowa, with a strong surface front south of the state. A significant cool layer was in place over Iowa with surface temperatures remaining in the 40s through the day. Significant instability was in place south of Iowa with most unstable CAPE values of 1000 to 2000 J/kg in place. A considerable amount of moisture was transported north into the central U.S. on a 60 kt low level jet. Precipitable water values were between 1.5 and 1.75 inches. The freezing level was in the 12,000 to 13,000 foot range. CAPE in the -10 to -30 C layer of the atmosphere was between 100 and 400 J/kg. There was significant shear present, with the effective shear around 60 kts. Thunderstorms formed during the predawn hours of the 12th and moved across Iowa during the morning of the 12th. Once these storms moved out, another area of thunderstorms formed along the 850 mb front. Most of the storms produced hail up to dime size. Some of the stronger thunderstorms produced quarter size hail with one producing 1 1/4 inch diameter hail in Marshall County. Several of the storms also produced large amounts of hail, with reports of the ground being covered by hail. Successive rounds of thunderstorms continued to push into central and northeast Iowa. Most hail was below the size of quarters from the late afternoon rounds. Heavy rain became a problem with spotty flash flooding reported. Flooding took place in Butler County due to rainfall of nearly 3 inches that fell just a day after a general 1 to 2 inch rainfall occurred. Flooding was largely limited to agricultural lands. In Polk County, heavy rainfall of around 2 inches fell after the area had received about an inch in the 36 hours prior. Flash flooding occurred on the east side of the Des Moines metropolitan area. A ramp on Highway 65 was flooded by high water and an intersection southeast of Altoona was washed out. As the storms moved through the Wavery area, lightning struck a house causing s small fire. It was extinguished quickly, resulting in little damage.
Event Narrative


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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 92.00K 0.00K
BRAYTON AUDUBON CO. IA 05/12/2010 12:33 CST-6 Hail 0.75 in. 0 0 0.00K 0.00K
BLAIRSBURG HAMILTON CO. IA 05/12/2010 13:07 CST-6 Hail 0.88 in. 0 0 1.00K 0.00K
BLAIRSBURG HAMILTON CO. IA 05/12/2010 13:07 CST-6 Hail 0.88 in. 0 0 3.00K 0.00K
STATE CENTER MARSHALL CO. IA 05/12/2010 13:15 CST-6 Hail 1.25 in. 0 0 10.00K 0.00K
BAGLEY GUTHRIE CO. IA 05/12/2010 13:31 CST-6 Hail 1.00 in. 0 0 5.00K 0.00K
DOWS WRIGHT CO. IA 05/12/2010 13:35 CST-6 Hail 0.75 in. 0 0 0.00K 0.00K
COULTER FRANKLIN CO. IA 05/12/2010 13:37 CST-6 Hail 1.00 in. 0 0 3.00K 0.00K
COOPER GREENE CO. IA 05/12/2010 13:48 CST-6 Hail 1.00 in. 0 0 3.00K 0.00K
TRAER TAMA CO. IA 05/12/2010 13:54 CST-6 Hail 1.00 in. 0 0 5.00K 0.00K
BEAVER BOONE CO. IA 05/12/2010 14:09 CST-6 Hail 1.00 in. 0 0 5.00K 0.00K
RIDGEPORT BOONE CO. IA 05/12/2010 14:38 CST-6 Hail 1.00 in. 0 0 3.00K 0.00K
ARBOR HILL ADAIR CO. IA 05/12/2010 15:23 CST-6 Hail 1.00 in. 0 0 3.00K 0.00K
ALLEMAN POLK CO. IA 05/12/2010 15:30 CST-6 Hail 1.00 in. 0 0 5.00K 0.00K
MARSHALLTOWN ARPT MARSHALL CO. IA 05/12/2010 17:52 CST-6 Hail 1.00 in. 0 0 3.00K 0.00K
MARSHALLTOWN ARPT MARSHALL CO. IA 05/12/2010 17:55 CST-6 Hail 0.88 in. 0 0 1.00K 0.00K
ZANETA GRUNDY CO. IA 05/12/2010 18:18 CST-6 Hail 0.75 in. 0 0 0.00K 0.00K
KNOXVILLE MARION CO. IA 05/12/2010 18:40 CST-6 Hail 0.75 in. 0 0 2.00K 0.00K
ALTOONA POLK CO. IA 05/12/2010 19:00 CST-6 Flash Flood 0 0 25.00K 0.00K
WASHBURN BLACK HAWK CO. IA 05/12/2010 19:22 CST-6 Hail 0.75 in. 0 0 0.00K 0.00K
HASTIE POLK CO. IA 05/12/2010 19:30 CST-6 Flash Flood 0 0 5.00K 0.00K
WAVERLY BREMER CO. IA 05/12/2010 20:05 CST-6 Lightning 0 0 5.00K 0.00K
CLARKSVILLE BUTLER CO. IA 05/12/2010 22:52 CST-6 Flash Flood 0 0 5.00K 0.00K
Totals: 0 0 92.00K 0.00K