A strong warm front was located to the south of Iowa as a very strong push of warm and moist air was driven north into the area by a 60 kt low level jet.  The airmass was very unstable with CAPE greater than 5000 J/kg with lifted indices near -10 just to the south of the front.  The airmass was relatively capped with 700 mb temperatures around +15 C.  Precipitable water values increased to near 2 inches.  Convection developed rapidly over southwest Iowa during the late evening  The activity became severe quickly, producing hail of quarter to ping pong ball in size.  Intense rainfall also occurred with the storms with rainfall of one to three inches per hour reported.  As the storm system evolved, the storms began to turn into wind producing storms over southern Iowa.  Winds of around 60 MPH blew across the southern two tiers of counties, causing damage to trees, power lines, and some minor damage to outbuildings in the area.  One of the stronger storms blew the awning off of a camper and ripped siding from part of a house northeast of Russell in Lucas County.  As the night progressed, thunderstorms continued to develop and wind became more of an issue.  High winds also caused damage in Cass County at Atlantic.  Numerous locations reported winds of 50 MPH with the storms as well.  One tornado touched down in Mahaska County near New Sharon.  It was a small tornado with damage embedded in a narrow path of straight line wind damage.  Most of the damage was to trees and occurred on the south side of New Sharon and 2 miles to the west and east.   The tornado destroyed one quarter of a rental building and carried it up to one quarter of a miles across a cemetery and part of the high school track.  At least 40 gravestones were toppled by the wind and carried debris.

Heavy Rain in POLK, IOWA
From 19-JUN-11 23:00:00 to 20-JUN-11 06:00:00 (CST-6)
Location: WINDSOR HGTS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Rainfall since midnight with 2 inches falling from 0300 to 0600 CST.

Thunderstorm Wind in DECATUR, IOWA
From 19-JUN-11 23:15:00 to 19-JUN-11 23:15:00 (CST-6)
Location: LEON
Magnitude: 61.00 EG
Property damage: 200.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Significant tree damage in the town of Leon.  An estimated 100 to 200 trees felled in town with large trees littering the town.  Trees fell on the roofs of many houses, but no major structural damage.

Thunderstorm Wind in CASS, IOWA
From 20-JUN-11 02:27:00 to 20-JUN-11 02:27:00 (CST-6)
Location: ATLANTIC
Magnitude: 57.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Six inch branches down and a 40-50 foot tree fell on top of a house.

Thunderstorm Wind in MAHASKA, IOWA
From 20-JUN-11 04:05:00 to 20-JUN-11 04:10:00 (CST-6)
Location: NEW SHARON
Magnitude: 57.00 EG
Property damage: 100.00K
Crop damage: 10.00K
Reported by: Emergency Manager

Damage to power lines, trees and houses.

Thunderstorm Wind in DECATUR, IOWA
From 19-JUN-11 23:12:00 to 19-JUN-11 23:12:00 (CST-6)
Location: LEON
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Heavy rain and pea size hail also reported west of Leon.  Wind speed estimated.

Hail in CLARKE, IOWA
From 20-JUN-11 01:31:00 to 20-JUN-11 01:31:00 (CST-6)
Location: MURRAY
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Thunderstorm Wind in MONROE, IOWA
From 20-JUN-11 00:15:00 to 20-JUN-11 00:15:00 (CST-6)
Location: ALBIA
Magnitude: 57.00 EG
Property damage: 75.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous small branches and limbs down along with a few portions of larger trees with some of the trees blocking portions of the road.  Another tree fell onto a vehicle at the Chinese restaurant on east Benton.

Hail in ADAIR, IOWA
From 20-JUN-11 01:50:00 to 20-JUN-11 01:50:00 (CST-6)
Location: ROSSERDALE
Magnitude: 1.50 
Property damage: 10.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Hail dented a truck.

Thunderstorm Wind in LUCAS, IOWA
From 19-JUN-11 23:45:00 to 19-JUN-11 23:45:00 (CST-6)
Location: CHARITON
Magnitude: 54.00 MG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in POLK, IOWA
From 20-JUN-11 00:05:00 to 20-JUN-11 00:05:00 (CST-6)
Location: ANKENY
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

In the northwest part of Ankeny.

Hail in DALLAS, IOWA
From 20-JUN-11 02:11:00 to 20-JUN-11 02:11:00 (CST-6)
Location: DEXTER
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 5.00K
Reported by: Post Office

Hail in POLK, IOWA
From 19-JUN-11 23:48:00 to 19-JUN-11 23:48:00 (CST-6)
Location: RIDER
Magnitude: 1.50 
Property damage: 50.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Tornado in MAHASKA, IOWA
From 20-JUN-11 03:59:00 to 20-JUN-11 04:01:00 (CST-6)
Location: NEW SHARON
Tornado F-scale: EF1
Property damage: 150.00K
Crop damage: 3.00K
Reported by: NWS Storm Survey

Winds estimated at 110 MPH.  Numerous trees downed with some trees on top of houses. Power lines down and storage shed shifted from its foundation and cars pushed into a ditch.

Hail in UNION, IOWA
From 19-JUN-11 21:33:00 to 19-JUN-11 21:33:00 (CST-6)
Location: ARISPE
Magnitude: 1.50 
Property damage: 5.00K
Crop damage: 10.00K
Reported by: Emergency Manager

Hail in ADAIR, IOWA
From 20-JUN-11 02:10:00 to 20-JUN-11 02:10:00 (CST-6)
Location: HOWE
Magnitude: 1.75 
Property damage: 20.00K
Crop damage: 10.00K
Reported by: Public

Thunderstorm Wind in MONROE, IOWA
From 20-JUN-11 00:17:00 to 20-JUN-11 00:17:00 (CST-6)
Location: ALBIA
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Estimated winds of 60 MPH.

Thunderstorm Wind in LUCAS, IOWA
From 19-JUN-11 23:53:00 to 19-JUN-11 23:53:00 (CST-6)
Location: RUSSELL
Magnitude: 61.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

An awning of a camper was torn off, some siding from a house was also removed.  Power reported out.

Hail in POLK, IOWA
From 19-JUN-11 23:56:00 to 20-JUN-11 00:03:00 (CST-6)
Location: HERROLD
Magnitude: 1.25 
Property damage: 5.00K
Crop damage: 2.00K
Reported by: NWS Employee

At the National Weather Service office.

Hail in ADAIR, IOWA
From 19-JUN-11 23:29:00 to 19-JUN-11 23:42:00 (CST-6)
Location: HOWE
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 15.00K
Reported by: Trained Spotter

Hail covering the ground.  Some tree limbs down and some leaves removed from trees.  Lasted 10 to 15 minutes.

Hail in UNION, IOWA
From 19-JUN-11 21:35:00 to 19-JUN-11 21:35:00 (CST-6)
Location: ARISPE
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Thunderstorm Wind in RINGGOLD, IOWA
From 19-JUN-11 22:52:00 to 19-JUN-11 22:52:00 (CST-6)
Location: KELLERTON
Magnitude: 57.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Four mature trees down along with numerous 6 inch diameter limbs.  Two power lines were downed.  An abandon mobile home was blown off its foundation.