The cold front that entered the state on the 15th made slow progress east during the day on the 16th.  The atmosphere became unstable by early to mid afternoon with CAPE values rising to 2000 to 4000 J/kg and the lifted index falling to the -4 to -9 C range.  Downdraft CAPE was not as high as the previous day, in the 500 to 800 J/kg range.  Precipitable water was relatively high, in the 1.5 to 1.7 inch range.  The freezing level remained around 14,000 feet, helping to limit hail production somewhat.  Available CAPE in the -10 to -30 C layer of the atmosphere was between 400 and 600 J/kg.  The LCL remained a relatively high 1250 meters.  Moderate shear was available with 35 to 45 kts present.  Thunderstorms formed along and ahead of the cold front.  The strongest storms formed across southern Iowa, where the greatest instability and deeper moisture were present.  The cluster of stronger storms then pushed east across the southern two to three tiers of Iowa counties.  Heavy rainfall of one to three inches occurred in Ringgold County, along with nickel to quarter size hail.  One inch diameter hail occurred in Davis County, with quarter size hail also reported in Taylor County.  The storms moved and developed eastward.  As they did, wind became more of an issue.  Wind damage occurred southwest of Lamoni in Decatur County.  As the storms moved through the southeast part of the CWA, 62 MPH winds were recorded at the Ottumwa Airport.  As the cluster of storms moved east they became more cold pool dominated.  Winds of 65 to 75 MPH were recorded before the storms left the Des Moines CWA.

Thunderstorm Wind in WAPELLO, IOWA
From 16-JUN-12 15:28:00 to 16-JUN-12 15:28:00 (CST-6)
Location: OTTUMWA
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Unknown

Three inch and larger branches down.

Hail in RINGGOLD, IOWA
From 16-JUN-12 13:35:00 to 16-JUN-12 13:35:00 (CST-6)
Location: MT AYR
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 5.00K
Reported by: Trained Spotter

A trained spotter reported mostly pea to nickel size hail with a few quarter size mixed in.

Hail in DAVIS, IOWA
From 16-JUN-12 15:00:00 to 16-JUN-12 15:00:00 (CST-6)
Location: WEST GROVE
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Thunderstorm Wind in WAPELLO, IOWA
From 16-JUN-12 15:20:00 to 16-JUN-12 15:20:00 (CST-6)
Location: RUTLEDGE
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous branches six inches or larger were blown down.

Thunderstorm Wind in WAPELLO, IOWA
From 16-JUN-12 15:34:00 to 16-JUN-12 15:34:00 (CST-6)
Location: (OTM)OTTUMWA INDSTRL
Magnitude: 54.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: ASOS

Heavy Rain in RINGGOLD, IOWA
From 16-JUN-12 12:26:00 to 16-JUN-12 14:26:00 (CST-6)
Location: MT AYR MUNI ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported 2.3 inches of rain in the past two hours.  No flooding observed.

Heavy Rain in RINGGOLD, IOWA
From 16-JUN-12 14:39:00 to 16-JUN-12 14:39:00 (CST-6)
Location: MT AYR
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported 3.3 inches of rain so far today.

Thunderstorm Wind in WAPELLO, IOWA
From 16-JUN-12 15:30:00 to 16-JUN-12 15:30:00 (CST-6)
Location: RUTLEDGE
Magnitude: 50.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Medium size tree down along with numerous branches.  Minor street flooding.

Heavy Rain in RINGGOLD, IOWA
From 16-JUN-12 14:30:00 to 16-JUN-12 14:30:00 (CST-6)
Location: MT AYR
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported 2.8 inches of rain so far today.

Thunderstorm Wind in WAPELLO, IOWA
From 16-JUN-12 15:45:00 to 16-JUN-12 15:45:00 (CST-6)
Location: FARSON
Magnitude: 57.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous four to six inch diameter tree branches were downed by winds estimated in the 65 MPH range.

Hail in TAYLOR, IOWA
From 16-JUN-12 13:04:00 to 16-JUN-12 13:04:00 (CST-6)
Location: BEDFORD ARPT
Magnitude: 1.00 
Property damage: 1.00K
Crop damage: 5.00K
Reported by: Public

Thunderstorm Wind in DECATUR, IOWA
From 16-JUN-12 14:11:00 to 16-JUN-12 14:11:00 (CST-6)
Location: LAMONI
Magnitude: 50.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

Several three to four inch branches were down across the yard.

Hail in RINGGOLD, IOWA
From 16-JUN-12 13:35:00 to 16-JUN-12 13:35:00 (CST-6)
Location: MT AYR
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Trained spotter on the west side of Mount Ayr reported nickel size hail and wind gusts of 35 MPH.

Thunderstorm Wind in WAPELLO, IOWA
From 16-JUN-12 15:44:00 to 16-JUN-12 15:44:00 (CST-6)
Location: OTTUMWA
Magnitude: 65.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Larger than one foot diameter trees down.  A light pole was also blown down. One large tree was snapped off on the trunk near the school.

Thunderstorm Wind in WAPELLO, IOWA
From 16-JUN-12 15:32:00 to 16-JUN-12 15:32:00 (CST-6)
Location: OTTUMWA
Magnitude: 54.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Measured by an IDOT RWIS site near Ottumwa on Highway 63.