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Storm Events Database
Event Details
| Event | Hail |
| Magnitude | 1.75 in. |
| State | IOWA |
| County/Area | PALO ALTO |
| WFO | DMX |
| Begin Date | 07/17/2010 22:25:00 CST-6 |
| Begin Range | 4 |
| Begin Azimuth | W |
| Begin Location | GRAETTINGER |
| Begin Lat/Lon | 43.24/-94.85 |
| End Date | 07/17/2010 22:25:00 CST-6 |
| Deaths Direct/Indirect | 0/0 (fatality details below, when available...) |
| Injuries Direct/Indirect | 0/0 |
| Property Damage | 5.00K |
| Crop Damage | 15.00K |
| Episode Narrative | A very unstable airmass was in place over Iowa as a cold front approached from the west. High temperatures the previous day were in the upper 80s and 90s for the most part, with 101 at Fairfield. Dewpoint readings were in the 70s east to near 80 over the west. CAPE was in the 4000 to 5000 J/kg range with lifted indices of -8 to -11 C. Downdraft CAPE was quite high, 1200-1400 J/kg. CAPE in the -10 to -30 C layer of the atmosphere was between 300 and 500 J/kg. The atmosphere was quite strongly sheared with 45 to 60 kts of shear. Precipitable water was low, only 1 to 1.5 inches. With the relatively dry air, the LCL was between 1500 and 2500 meters. The airmass was also quite warm with the freezing level around 15,600 feet. Thunderstorms formed in two clusters. One extended from Minnesota southwest into eastern South Dakota. The other area was over central Nebraska. The convective area from South Dakota dropped southeast into Iowa during the late evening hours. It produced high winds and hail as it did. Hail was not the major mode of severe weather. Most of the larger hail occurred during the early stages of the storm. Golf ball size hail fell west of Graettinger in Palo Alto County for the largest hail report. The cluster of storms organized into a small derecho as it approached Fort Dodge. The derecho raced southeast through the Des Moines area and into southeast Iowa. It produced some hail as it did, but by in large high winds were the primary threat. Winds of 60 to 75 MPH were common, causing considerable tree damage. High winds of 65 to 75 MPH roared through Ames. A shelter at the Iowa State Veterinary Medicine School was blown over. Several horses were injured by the collapse. University officials has to euthanize one horse due to severe injuries. A measured wind gust of 84 MPH was recorded on the northwest side of the Des Moines Metro area. Power was knocked out to nearly 40,000 customers in central Iowa by the storms. Damage reports from along the path of the derecho were widespread. Grain bins were destroyed as well as numerous out buildings. Tree and power line damage was extensive all the way from the Minnesota border through south central Iowa. Heavy rain was also an issue with the storms. Rainfall of 1 to 2 inches per hour fell with the storms from Fort Dodge into the Des Moines area. Flash flooding was reported in Marion County. Heavy rainfall of 2 to 4 inches in under 2 hours flooded city streets in Knoxville, some 4 feet deep, with cars stalled in city streets. Water was also over the road southeast of Melcher-Dallas in Marion County. Flash flooding was reported in Webster City. Flooding blew manhole covers off and stalled several cars in the city. As the storm moved through the Raymond area of Black Hawk County, lightning struck a house. It blew a basketball size hole in the roof and caused electrical damage to the house and some structural damage to ceilings. |
| Event Narrative |
All events for this episode:
| Location | County/Zone | St. | Date | Time | T.Z. | Type | Mag | Dth | Inj | PrD | CrD |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Totals: | 0 | 0 | 3.108M | 840.00K | |||||||
| ESTHERVILLE | EMMET CO. | IA | 07/17/2010 | 22:10 | CST-6 | Hail | 1.00 in. | 0 | 0 | 1.00K | 10.00K |
| GRAETTINGER | PALO ALTO CO. | IA | 07/17/2010 | 22:25 | CST-6 | Hail | 1.25 in. | 0 | 0 | 5.00K | 200.00K |
| GRAETTINGER | PALO ALTO CO. | IA | 07/17/2010 | 22:25 | CST-6 | Hail | 1.75 in. | 0 | 0 | 5.00K | 15.00K |
| EMMETSBURG | PALO ALTO CO. | IA | 07/17/2010 | 22:40 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 10.00K | 10.00K |
| WHITTEMORE | KOSSUTH CO. | IA | 07/17/2010 | 23:10 | CST-6 | Thunderstorm Wind | 52 kts. EG | 0 | 0 | 5.00K | 0.00K |
| HAVELOCK | POCAHONTAS CO. | IA | 07/17/2010 | 23:20 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 25.00K | 50.00K |
| PLOVER | POCAHONTAS CO. | IA | 07/17/2010 | 23:38 | CST-6 | Hail | 1.00 in. | 0 | 0 | 1.00K | 10.00K |
| DAKOTA CITY | HUMBOLDT CO. | IA | 07/17/2010 | 23:40 | CST-6 | Thunderstorm Wind | 65 kts. EG | 0 | 0 | 200.00K | 100.00K |
| DAKOTA CITY | HUMBOLDT CO. | IA | 07/18/2010 | 00:00 | CST-6 | Thunderstorm Wind | 65 kts. EG | 0 | 0 | 100.00K | 0.00K |
| FT DODGE | WEBSTER CO. | IA | 07/18/2010 | 00:00 | CST-6 | Heavy Rain | 0 | 0 | 0.00K | 0.00K | |
| DAKOTA CITY | HUMBOLDT CO. | IA | 07/18/2010 | 00:05 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 25.00K | 0.00K |
| BADGER | WEBSTER CO. | IA | 07/18/2010 | 00:21 | CST-6 | Thunderstorm Wind | 56 kts. EG | 0 | 0 | 50.00K | 10.00K |
| EAGLE GROVE | WRIGHT CO. | IA | 07/18/2010 | 00:28 | CST-6 | Thunderstorm Wind | 50 kts. MG | 0 | 0 | 10.00K | 0.00K |
| WEBSTER CITY | HAMILTON CO. | IA | 07/18/2010 | 00:45 | CST-6 | Thunderstorm Wind | 65 kts. EG | 0 | 0 | 250.00K | 100.00K |
| PALM GROVE | WEBSTER CO. | IA | 07/18/2010 | 00:45 | CST-6 | Thunderstorm Wind | 65 kts. EG | 0 | 0 | 50.00K | 10.00K |
| WEBSTER CITY ARPT | HAMILTON CO. | IA | 07/18/2010 | 01:00 | CST-6 | Thunderstorm Wind | 52 kts. EG | 0 | 0 | 2.00K | 0.00K |
| POLK CITY | POLK CO. | IA | 07/18/2010 | 01:00 | CST-6 | Heavy Rain | 0 | 0 | 0.00K | 0.00K | |
| SLATER | STORY CO. | IA | 07/18/2010 | 01:00 | CST-6 | Heavy Rain | 0 | 0 | 0.00K | 0.00K | |
| GOWRIE | WEBSTER CO. | IA | 07/18/2010 | 01:00 | CST-6 | Thunderstorm Wind | 53 kts. EG | 0 | 0 | 5.00K | 0.00K |
| BOXHOLM | BOONE CO. | IA | 07/18/2010 | 01:05 | CST-6 | Thunderstorm Wind | 52 kts. EG | 0 | 0 | 10.00K | 0.00K |
| BOONE | BOONE CO. | IA | 07/18/2010 | 01:12 | CST-6 | Thunderstorm Wind | 65 kts. EG | 0 | 0 | 200.00K | 50.00K |
| WEBSTER CITY | HAMILTON CO. | IA | 07/18/2010 | 01:15 | CST-6 | Flash Flood | 0 | 0 | 100.00K | 0.00K | |
| BOONE | BOONE CO. | IA | 07/18/2010 | 01:23 | CST-6 | Thunderstorm Wind | 56 kts. MG | 0 | 0 | 25.00K | 0.00K |
| BOONE | BOONE CO. | IA | 07/18/2010 | 01:23 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 75.00K | 0.00K |
| BOONE MUNI ARPT | BOONE CO. | IA | 07/18/2010 | 01:25 | CST-6 | Thunderstorm Wind | 52 kts. EG | 0 | 0 | 5.00K | 0.00K |
| MADRID | BOONE CO. | IA | 07/18/2010 | 01:27 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 100.00K | 50.00K |
| ERICSON | BOONE CO. | IA | 07/18/2010 | 01:28 | CST-6 | Thunderstorm Wind | 63 kts. MG | 0 | 0 | 50.00K | 0.00K |
| AMES | STORY CO. | IA | 07/18/2010 | 01:30 | CST-6 | Thunderstorm Wind | 65 kts. EG | 0 | 0 | 500.00K | 100.00K |
| AMES | STORY CO. | IA | 07/18/2010 | 01:30 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 25.00K | 0.00K |
| AMES | STORY CO. | IA | 07/18/2010 | 01:38 | CST-6 | Thunderstorm Wind | 62 kts. MG | 0 | 0 | 50.00K | 0.00K |
| NEVADA MUNI ARPT | STORY CO. | IA | 07/18/2010 | 01:40 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 50.00K | 100.00K |
| MADRID | BOONE CO. | IA | 07/18/2010 | 01:40 | CST-6 | Thunderstorm Wind | 51 kts. MG | 0 | 0 | 5.00K | 0.00K |
| AMES | STORY CO. | IA | 07/18/2010 | 01:40 | CST-6 | Thunderstorm Wind | 52 kts. MG | 0 | 0 | 25.00K | 0.00K |
| AMES | STORY CO. | IA | 07/18/2010 | 01:43 | CST-6 | Thunderstorm Wind | 58 kts. MG | 0 | 0 | 25.00K | 0.00K |
| ANKENY | POLK CO. | IA | 07/18/2010 | 01:46 | CST-6 | Thunderstorm Wind | 56 kts. EG | 0 | 0 | 100.00K | 0.00K |
| DODGE FLD ARPT | POLK CO. | IA | 07/18/2010 | 01:50 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 10.00K | 0.00K |
| WINDSOR HGTS | POLK CO. | IA | 07/18/2010 | 01:55 | CST-6 | Thunderstorm Wind | 65 kts. EG | 0 | 0 | 75.00K | 0.00K |
| HERROLD | POLK CO. | IA | 07/18/2010 | 01:57 | CST-6 | Thunderstorm Wind | 57 kts. MG | 0 | 0 | 3.00K | 0.00K |
| GILBERT | STORY CO. | IA | 07/18/2010 | 02:00 | CST-6 | Thunderstorm Wind | 57 kts. EG | 0 | 0 | 10.00K | 0.00K |
| LOVINGTON | POLK CO. | IA | 07/18/2010 | 02:00 | CST-6 | Thunderstorm Wind | 65 kts. EG | 0 | 0 | 150.00K | 0.00K |
| LOVINGTON | POLK CO. | IA | 07/18/2010 | 02:00 | CST-6 | Thunderstorm Wind | 73 kts. MG | 0 | 0 | 200.00K | 0.00K |
| GRIMES | POLK CO. | IA | 07/18/2010 | 02:01 | CST-6 | Thunderstorm Wind | 69 kts. EG | 0 | 0 | 50.00K | 0.00K |
| SHULER MINE | DALLAS CO. | IA | 07/18/2010 | 02:04 | CST-6 | Thunderstorm Wind | 56 kts. EG | 0 | 0 | 15.00K | 0.00K |
| ANKENY | POLK CO. | IA | 07/18/2010 | 02:05 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 10.00K | 0.00K |
| ANKENY | POLK CO. | IA | 07/18/2010 | 02:05 | CST-6 | Thunderstorm Wind | 65 kts. EG | 0 | 0 | 50.00K | 0.00K |
| HADDEN HILL | DALLAS CO. | IA | 07/18/2010 | 02:08 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 10.00K | 0.00K |
| ADEL | DALLAS CO. | IA | 07/18/2010 | 02:08 | CST-6 | Thunderstorm Wind | 65 kts. EG | 0 | 0 | 50.00K | 0.00K |
| URBANDALE | POLK CO. | IA | 07/18/2010 | 02:09 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 25.00K | 0.00K |
| NEVADA | STORY CO. | IA | 07/18/2010 | 02:10 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 10.00K | 0.00K |
| (DSM)DES MOINES INTL | POLK CO. | IA | 07/18/2010 | 02:14 | CST-6 | Thunderstorm Wind | 52 kts. MG | 0 | 0 | 2.00K | 0.00K |
| CLARKSON | WARREN CO. | IA | 07/18/2010 | 02:15 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 25.00K | 15.00K |
| (DSM)DES MOINES INTL | POLK CO. | IA | 07/18/2010 | 02:20 | CST-6 | Thunderstorm Wind | 53 kts. MG | 0 | 0 | 2.00K | 0.00K |
| WINTERSET | MADISON CO. | IA | 07/18/2010 | 02:21 | CST-6 | Thunderstorm Wind | 69 kts. EG | 0 | 0 | 25.00K | 10.00K |
| BONDURANT | POLK CO. | IA | 07/18/2010 | 02:25 | CST-6 | Thunderstorm Wind | 52 kts. EG | 0 | 0 | 2.00K | 0.00K |
| HADDEN HILL | DALLAS CO. | IA | 07/18/2010 | 02:26 | CST-6 | Thunderstorm Wind | 57 kts. EG | 0 | 0 | 100.00K | 0.00K |
| INDIANOLA | WARREN CO. | IA | 07/18/2010 | 02:26 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 15.00K | 0.00K |
| WINTERSET | MADISON CO. | IA | 07/18/2010 | 02:28 | CST-6 | Thunderstorm Wind | 61 kts. MG | 0 | 0 | 5.00K | 0.00K |
| WINTERSET | MADISON CO. | IA | 07/18/2010 | 02:30 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 15.00K | 0.00K |
| PLEASANTVILLE | MARION CO. | IA | 07/18/2010 | 02:40 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 10.00K | 0.00K |
| RAYMOND | BLACK HAWK CO. | IA | 07/18/2010 | 02:50 | CST-6 | Lightning | 0 | 0 | 10.00K | 0.00K | |
| CHARITON | LUCAS CO. | IA | 07/18/2010 | 03:07 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 10.00K | 0.00K |
| KNOXVILLE | MARION CO. | IA | 07/18/2010 | 03:43 | CST-6 | Heavy Rain | 0 | 0 | 0.00K | 0.00K | |
| MORAVIA | APPANOOSE CO. | IA | 07/18/2010 | 03:48 | CST-6 | Thunderstorm Wind | 65 kts. EG | 0 | 0 | 50.00K | 0.00K |
| RATHBUN | APPANOOSE CO. | IA | 07/18/2010 | 03:54 | CST-6 | Thunderstorm Wind | 52 kts. EG | 0 | 0 | 5.00K | 0.00K |
| MYSTIC | APPANOOSE CO. | IA | 07/18/2010 | 03:55 | CST-6 | Thunderstorm Wind | 61 kts. EG | 0 | 0 | 10.00K | 0.00K |
| CLARKDALE | APPANOOSE CO. | IA | 07/18/2010 | 04:00 | CST-6 | Thunderstorm Wind | 63 kts. MG | 0 | 0 | 25.00K | 0.00K |
| KNOXVILLE | MARION CO. | IA | 07/18/2010 | 04:50 | CST-6 | Flash Flood | 0 | 0 | 25.00K | 0.00K | |
| COLUMBIA | MARION CO. | IA | 07/18/2010 | 04:50 | CST-6 | Flash Flood | 0 | 0 | 15.00K | 0.00K | |
| Totals: | 0 | 0 | 3.108M | 840.00K |
