A strong cold front moved into Iowa during the afternoon and evening of the 15th into the morning hours of the 16th.  The atmosphere was somewhat capped initially, however thunderstorms were able to develop after midnight.  The available CAPE was in the 2000 to 3000 J/kg range.  Downdraft CAPE was in the 800 to 1200 J/kg, with 700 J/kg available in the -10 to -30 C layer of the atmosphere.  The freezing level was quite high, in excess of 15,000 feet.  Deep moisture convergence took place during the evening of the 15th with precipitable water values around 1.6 inches.  The atmosphere was weakly sheared with about 30 kts of effective shear present.  The storms had strong cores present on radar, however the high freezing level and lack of tilt in the storms limited hail size.  Hail up to ping pong ball size fell in Dallas County.  Gusty winds of 45 to 55 MPH were reported across Guthrie, Dallas, and Polk Counties.  A wind gust of 62 MPH was measured northwest of Des Moines in Polk County.  Many of the storms produced winds in excess of 40 MPH.  In addition to the wind, numerous reports of hail from pea to nickel size were received.

Hail in GUTHRIE, IOWA
From 16-AUG-12 02:34:00 to 16-AUG-12 02:34:00 (CST-6)
Location: BAGLEY
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 5.00K
Reported by: Fire Department/Rescue

Relayed by the Guthrie County Emergency Manager.

Thunderstorm Wind in POLK, IOWA
From 16-AUG-12 02:45:00 to 16-AUG-12 02:45:00 (CST-6)
Location: LOVINGTON
Magnitude: 54.00 MG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Gusts of 59 and 62 MPH were measured by a home weather station in the Urbandale Cross Creek neighborhood.

Thunderstorm Wind in GUTHRIE, IOWA
From 16-AUG-12 02:05:00 to 16-AUG-12 02:05:00 (CST-6)
Location: MONTEITH
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: NWS Employee

Numerous tree branches greater than 6 inches in diameter down.

Thunderstorm Wind in POLK, IOWA
From 16-AUG-12 02:50:00 to 16-AUG-12 02:50:00 (CST-6)
Location: DODGE FLD ARPT
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Public

One foot diameter tree down in the 8300 block of Barnham Dr. in Johnston.  Lawn furniture and small pools blown around the city.  Report received from the Johnston Public Works Department.

Hail in DALLAS, IOWA
From 16-AUG-12 02:31:00 to 16-AUG-12 02:31:00 (CST-6)
Location: ADEL
Magnitude: 1.25 
Property damage: 5.00K
Crop damage: 10.00K
Reported by: Emergency Manager

Dallas County Emergency Management reported quarter to half dollar size hail falling in the Adel area along with 40 to 50 MPH winds.

Hail in DALLAS, IOWA
From 16-AUG-12 02:34:00 to 16-AUG-12 02:34:00 (CST-6)
Location: ORTONVILLE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 5.00K
Reported by: NWS Employee

Hail in MAHASKA, IOWA
From 16-AUG-12 05:35:00 to 16-AUG-12 05:35:00 (CST-6)
Location: ROSE HILL
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 5.00K
Reported by: CoCoRaHS

Hail in GUTHRIE, IOWA
From 16-AUG-12 02:11:00 to 16-AUG-12 02:11:00 (CST-6)
Location: HERNDON
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 10.00K
Reported by: Emergency Manager

Hail in GUTHRIE, IOWA
From 16-AUG-12 02:32:00 to 16-AUG-12 02:32:00 (CST-6)
Location: HERNDON
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 5.00K
Reported by: Emergency Manager

Reported at the intersection of Highway 4 and 141.