A weak trough of low pressure swept southeast across Iowa during the day on the 14th.  The airmass became unstable with lifted indices falling to the -5 to -7 C. range.  About 1000 J/kg of uncapped cape was available by mid day with about 35 kts of effective shear.  Moisture pooled along the trough as a 35 kt wind in the low levels pooled 11 C. dewpoints at the 850 mb level.  The airmass was relatively cool with a freezing level of only 10,000 feet.  As such, hail was the primary mode of severe weather with this event.  Even with 300 J/kg of CAPE in the -10 to -30 C. layer of the atmosphere, the limited overall CAPE kept hail size to an inch or less.  The storms in Marshall, Hardin, and Tama Counties were prolific hail producers and stripped leaves from the trees.  In the Garwin area, quarter size hail completely covered the ground.  A few storms produced high winds of 60 MPH or higher.  Available downdraft CAPE was between 1000 and 1200 J/kg.  Severe thunderstorms fired along the trough from central into northeast Iowa.  They moved rather quickly, around 40 MPH, and exited the area by late afternoon.

Hail in TAMA, IOWA
From 14-JUN-08 14:00:00 to 14-JUN-08 14:00:00 (CST-6)
Location: TOLEDO
Magnitude: 1.00 
Property damage: 10.00K
Crop damage: 5.00K
Reported by: Law Enforcement

Winds were also estimated at 60 to 70 MPH.

Hail in BLACK HAWK, IOWA
From 14-JUN-08 13:50:00 to 14-JUN-08 13:50:00 (CST-6)
Location: WATERLOO RANCH ARPT
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail was at Lafayette and Zuma Streets.

Hail in BLACK HAWK, IOWA
From 14-JUN-08 14:05:00 to 14-JUN-08 14:05:00 (CST-6)
Location: DUNKERTON DAVIS ARPT
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 50.00K
Reported by: Trained Spotter

The hail caused extensive crop damage.

Thunderstorm Wind in MARSHALL, IOWA
From 14-JUN-08 13:31:00 to 14-JUN-08 13:31:00 (CST-6)
Location: MARSHALLTOWN
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in HARDIN, IOWA
From 14-JUN-08 12:45:00 to 14-JUN-08 12:45:00 (CST-6)
Location: HUBBARD
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in HARDIN, IOWA
From 14-JUN-08 12:45:00 to 14-JUN-08 12:45:00 (CST-6)
Location: HUBBARD
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winds of 60 MPH were also reported.  Hail was taking the leaves off of trees.

Thunderstorm Wind in MARSHALL, IOWA
From 14-JUN-08 13:30:00 to 14-JUN-08 13:30:00 (CST-6)
Location: MARSHALLTOWN ARPT
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Hail in HARDIN, IOWA
From 14-JUN-08 12:48:00 to 14-JUN-08 12:48:00 (CST-6)
Location: ELDORA MUNI ARPT
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in TAMA, IOWA
From 14-JUN-08 14:00:00 to 14-JUN-08 14:00:00 (CST-6)
Location: TOLEDO
Magnitude: 57.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in HARDIN, IOWA
From 14-JUN-08 12:45:00 to 14-JUN-08 12:45:00 (CST-6)
Location: NEW PROVIDENCE
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Dime to nickel size hail.

Hail in HARDIN, IOWA
From 14-JUN-08 13:03:00 to 14-JUN-08 13:03:00 (CST-6)
Location: UNION
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Hail in GRUNDY, IOWA
From 14-JUN-08 13:16:00 to 14-JUN-08 13:16:00 (CST-6)
Location: CONRAD
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 5.00K
Reported by: Law Enforcement

Hail in BLACK HAWK, IOWA
From 14-JUN-08 13:37:00 to 14-JUN-08 13:37:00 (CST-6)
Location: HUDSON
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Hail in MARSHALL, IOWA
From 14-JUN-08 13:38:00 to 14-JUN-08 13:38:00 (CST-6)
Location: GREEN MTN
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Hail was stripping leaves off of trees.  Very heavy rainfall was reported as well.

Hail in BLACK HAWK, IOWA
From 14-JUN-08 13:47:00 to 14-JUN-08 13:47:00 (CST-6)
Location: WATERLOO
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Hail in TAMA, IOWA
From 14-JUN-08 13:51:00 to 14-JUN-08 13:51:00 (CST-6)
Location: GARWIN
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 5.00K
Reported by: COOP Observer

Hail in GRUNDY, IOWA
From 14-JUN-08 13:23:00 to 14-JUN-08 13:23:00 (CST-6)
Location: BEAMAN
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Hail in TAMA, IOWA
From 14-JUN-08 13:40:00 to 14-JUN-08 13:40:00 (CST-6)
Location: GARWIN
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Hail up to the size of quarters covered the ground.

Hail in TAMA, IOWA
From 14-JUN-08 14:16:00 to 14-JUN-08 14:16:00 (CST-6)
Location: VINING
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Hail in MARSHALL, IOWA
From 14-JUN-08 13:25:00 to 14-JUN-08 13:25:00 (CST-6)
Location: MARSHALLTOWN ARPT
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Hail in BLACK HAWK, IOWA
From 14-JUN-08 13:45:00 to 14-JUN-08 13:45:00 (CST-6)
Location: WATERLOO
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 5.00K
Reported by: Trained Spotter

Hail in BLACK HAWK, IOWA
From 14-JUN-08 14:34:00 to 14-JUN-08 14:34:00 (CST-6)
Location: WASHBURN
Magnitude: 0.88 
Property damage: 3.00K
Crop damage: 5.00K
Reported by: Trained Spotter