Storm Events Database

Event Details

Event Thunderstorm Wind
Magnitude 52 kts.
State IOWA
County/Area GRUNDY
WFO DMX
Begin Date 08/20/2007 22:53:00 CST-6
Begin Range 1
Begin Azimuth SW
Begin Location GRUNDY CENTER
Begin Lat/Lon 42.36/-92.78
End Date 08/20/2007 22:53:00 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 Little change took place in the overall weather pattern with a nearly stationary frontal boundary remaining over the state. The morning convection moved off allowing for afternoon solar isolation to take place, destabilizing the atmosphere once again. Temperatures over the southwest half of the state warmed into the mid to upper 80s with dew points in the low to mid 70s. West of Iowa it warmed into the mid 90s with mid 70 dew points. The airmass became very unstable with CAPE in the the 5000 to 8000 J/kg range from western Iowa west. Lifted indices fell into the -10 to -14 C. range by late afternoon. A considerable amount of shear remained in place with 40 to 55 kts present at the time of thunderstorm development. The LCL was reasonably high however at 1000 to 1500 meters. Thunderstorms developed in to a linear complex that showed a few bow echo elements along the leading edge. The main weather features with this system were high winds and hail. The available downdraft CAPE was between 1200 and 1500 J/kg and was favorable for high winds. There was 600 to 900 J/kg of available CAPE in the -10 to -30 C. layer of the atmosphere. In spite of the high values, hail size was limited by the high freezing levels, between 14,500 feet to over 15,500 feet. As the storms moved into the western part of the CWA, winds were the strongest. Reports of winds between 60 and 70 MPH were common along the leading edge of the line. The winds diminished as the storms moved east. Hail reports were spotty with this event. The hail was relatively small with most of it in the three quarter to one inch diameter range. The storms produced heavy rainfall once again with 1.6 to 1.8 inches of precipitable water available. The heavy rain fell in areas that were affected by the past several days of rain. Calhoun and Webster had some flash flooding, but it was relatively minor and limited to road closures caused by water flowing over the roads.
Event Narrative


All events for this episode:

Location County/Zone St. Date Time T.Z. Type Mag Dth Inj PrD CrD
Totals: 0 0 208.00K 95.00K
AUDUBON AUDUBON CO. IA 08/20/2007 19:50 CST-6 Thunderstorm Wind 61 kts. EG 0 0 30.00K 0.00K
AUDUBON AUDUBON CO. IA 08/20/2007 19:52 CST-6 Hail 1.00 in. 0 0 5.00K 50.00K
ATLANTIC CASS CO. IA 08/20/2007 19:55 CST-6 Thunderstorm Wind 57 kts. MG 0 0 10.00K 5.00K
IVEYVILLE ADAMS CO. IA 08/20/2007 20:05 CST-6 Thunderstorm Wind 52 kts. EG 0 0 1.00K 0.00K
CORNING ADAMS CO. IA 08/20/2007 20:19 CST-6 Thunderstorm Wind 50 kts. MG 0 0 2.00K 0.00K
PRESCOTT ADAMS CO. IA 08/20/2007 20:23 CST-6 Thunderstorm Wind 52 kts. EG 0 0 2.00K 0.00K
GRAVITY TAYLOR CO. IA 08/20/2007 20:28 CST-6 Thunderstorm Wind 56 kts. EG 0 0 10.00K 5.00K
NODAWAY ADAMS CO. IA 08/20/2007 20:30 CST-6 Thunderstorm Wind 52 kts. EG 0 0 3.00K 0.00K
GRAVITY TAYLOR CO. IA 08/20/2007 20:30 CST-6 Thunderstorm Wind 56 kts. EG 0 0 10.00K 10.00K
CLEARFIELD TAYLOR CO. IA 08/20/2007 20:31 CST-6 Thunderstorm Wind 65 kts. EG 0 0 75.00K 10.00K
IVEYVILLE ADAMS CO. IA 08/20/2007 20:31 CST-6 Thunderstorm Wind 52 kts. EG 0 0 3.00K 0.00K
CRESTON UNION CO. IA 08/20/2007 20:47 CST-6 Thunderstorm Wind 53 kts. EG 0 0 3.00K 0.00K
MANSON CALHOUN CO. IA 08/20/2007 21:02 CST-6 Hail 1.00 in. 0 0 10.00K 0.00K
MT AYR RINGGOLD CO. IA 08/20/2007 21:15 CST-6 Thunderstorm Wind 57 kts. EG 0 0 25.00K 10.00K
DODGE FLD ARPT POLK CO. IA 08/20/2007 21:19 CST-6 Hail 1.00 in. 0 0 2.00K 0.00K
ANKENY POLK CO. IA 08/20/2007 21:35 CST-6 Hail 0.75 in. 0 0 0.00K 0.00K
EAGLE GROVE WRIGHT CO. IA 08/20/2007 21:42 CST-6 Hail 1.00 in. 0 0 5.00K 0.00K
TARA WEBSTER CO. IA 08/20/2007 21:42 CST-6 Flash Flood 0 0 5.00K 0.00K
RICHARDS CALHOUN CO. IA 08/20/2007 21:48 CST-6 Flash Flood 0 0 5.00K 0.00K
GRUNDY CENTER GRUNDY CO. IA 08/20/2007 22:53 CST-6 Thunderstorm Wind 52 kts. EG 0 0 2.00K 0.00K
MARK DAVIS CO. IA 08/20/2007 23:00 CST-6 Hail 0.75 in. 0 0 0.00K 5.00K
Totals: 0 0 208.00K 95.00K