A strong storm system lifted east-northeast across the central U.S. during the overnight hours of 2-3 April.  Low pressure developed over eastern Colorado and advanced across Kansas into Iowa.  A warm front extended east from the low and lifted northward into southern Iowa during the overnight hours.  Very strong theta-e advection took place during the evening north of the warm front as the low level jet increased to between 50 and 60 kts. Though surface based CAPE was limited, elevated CAPE from around 750 mb was near 2500 J/kg with a lifted index from that level of -8 C.  With the relatively dry air in the lower levels, the tornado threat was limited with the LCL in the 1500 plus meter range.  There was considerable shear available with effective shear values in the 50 to 60 kt range.  With much of the CAPE elevated in nature, there was a fair amount of CAPE in the -10 to -30 C. layer of the atmosphere with a little over 200 J/kg available.  Thunderstorms erupted first during the mid evening hours to the north of the warm front as moisture moved into the area.  They developed very rapidly.  At the same time, an intense bow echo developed over western Nebraska and raced east.  During the late evening hours, the storms north of the warm front became very numerous and diminished in intensity.  As the bow echo approached from Nebraska, the enhanced low level jet ahead of it fired up another round of severe thunderstorms along and north of the warm front.  The thunderstorms that formed north of the warm front were prolific hail producers.  There were numerous reports of hail covering the ground with these storms in both the mid evening and early morning rounds of storms.  Much of the hail was one half inch or less in diameter however.  Nearly all of the storms produced at least some hail and many did pulse to severe levels occasionally.  Hail reports were quite numerous with hail size in the three quarter to 1 inch diameter range.  One storm produced golf ball size hail in Black Hawk County near Hudson.  As the bow echo moved into western Iowa from Nebraska, wind became the more significant threat.  The system weakened as it moved into Iowa, but did produce a widespread area of winds of 40 to 50 MPH.  Spotty damage occurred with the bow echo with a wind gust of 61 MPH in Adair County at Adair.  The storms produced spotty hail as well with the largest reported in Mahaska County east of Oskaloosa, where golf ball size hail fell.

Hail in WEBSTER, IOWA
From 02-APR-07 20:06:00 to 02-APR-07 20:06:00 (CST-6)
Location: (FOD)FT DODGE MUNI A
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in WEBSTER, IOWA
From 02-APR-07 20:13:00 to 02-APR-07 20:13:00 (CST-6)
Location: (FOD)FT DODGE MUNI A
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in WEBSTER, IOWA
From 02-APR-07 20:14:00 to 02-APR-07 20:14:00 (CST-6)
Location: VINCENT
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in CALHOUN, IOWA
From 02-APR-07 20:45:00 to 02-APR-07 20:45:00 (CST-6)
Location: LAKE CITY
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in FRANKLIN, IOWA
From 02-APR-07 21:00:00 to 02-APR-07 21:00:00 (CST-6)
Location: HAMPTON MUNI ARPT
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in HAMILTON, IOWA
From 02-APR-07 21:02:00 to 02-APR-07 21:02:00 (CST-6)
Location: ELLSWORTH
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: NWS Employee

Hail in AUDUBON, IOWA
From 03-APR-07 00:45:00 to 03-APR-07 00:45:00 (CST-6)
Location: AUDUBON
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in CASS, IOWA
From 03-APR-07 00:50:00 to 03-APR-07 00:50:00 (CST-6)
Location: FLETCHER CHAPEL
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in AUDUBON, IOWA
From 03-APR-07 00:53:00 to 03-APR-07 00:53:00 (CST-6)
Location: AUDUBON
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in HARDIN, IOWA
From 03-APR-07 01:06:00 to 03-APR-07 01:06:00 (CST-6)
Location: STEAMBOAT ROCK
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in GRUNDY, IOWA
From 03-APR-07 01:25:00 to 03-APR-07 01:25:00 (CST-6)
Location: WELLSBURG
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in DALLAS, IOWA
From 03-APR-07 01:40:00 to 03-APR-07 01:40:00 (CST-6)
Location: DALLAS CENTER
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in POLK, IOWA
From 03-APR-07 01:56:00 to 03-APR-07 01:56:00 (CST-6)
Location: SAYLORVILLE
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in WAPELLO, IOWA
From 03-APR-07 03:31:00 to 03-APR-07 03:31:00 (CST-6)
Location: OTTUMWA
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in ADAIR, IOWA
From 03-APR-07 01:11:00 to 03-APR-07 01:11:00 (CST-6)
Location: ADAIR
Magnitude: 53.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Hail in HAMILTON, IOWA
From 02-APR-07 21:04:00 to 02-APR-07 21:04:00 (CST-6)
Location: WILLIAMS
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in HARDIN, IOWA
From 02-APR-07 21:25:00 to 02-APR-07 21:25:00 (CST-6)
Location: IOWA FALLS
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in BLACK HAWK, IOWA
From 02-APR-07 21:36:00 to 02-APR-07 21:36:00 (CST-6)
Location: EVANSDALE
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in BLACK HAWK, IOWA
From 02-APR-07 21:40:00 to 02-APR-07 21:40:00 (CST-6)
Location: ORANGE
Magnitude: 1.75 
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Hail in HARDIN, IOWA
From 02-APR-07 21:45:00 to 02-APR-07 21:45:00 (CST-6)
Location: IOWA FALLS
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in BUTLER, IOWA
From 02-APR-07 22:00:00 to 02-APR-07 22:00:00 (CST-6)
Location: DUMONT
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: COOP Observer

Hail in BLACK HAWK, IOWA
From 02-APR-07 22:15:00 to 02-APR-07 22:15:00 (CST-6)
Location: CEDAR FALLS ARPT
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in WEBSTER, IOWA
From 02-APR-07 20:53:00 to 02-APR-07 21:03:00 (CST-6)
Location: DUNCOMBE
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

Hail in MAHASKA, IOWA
From 03-APR-07 03:32:00 to 03-APR-07 03:32:00 (CST-6)
Location: KEOMAH
Magnitude: 1.75 
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter