An intense low pressure lifted out of the south central U.S. into western Iowa during the afternoon hours of the 31st.  The upper low virtually captured the surface system by late afternoon.  Thunderstorms formed along two boundaries.  The first was a warm frontal boundary that lifted into central Iowa by early afternoon.  The second was a strong dryline that advanced into southwest and central Iowa by the late afternoon hours.  With the steep lapse rates, there was little in the way of CIN and once the clouds began to break.  Surface Based CAPE was in the 1000-2000 J/kg range with CAPE in the -10 to -30 C. layer around 200 J/kg.  The freezing level was quite low, ranging from 8,700 to 10,000 feet across the CWA.  Lifted indices fell to the -6 to -9 C. range by the mid afternoon hours.  In spite of the LCL being quite low, in the 500 to 1000 meter range, there were several reports of funnels, but no confirmed touchdowns.  Thunderstorms formed in two lines.  The first was along the warm front across central Iowa. The second along the dryline.  There were numerous reports of pea to marble size hail and surprisingly few reports of larger hail.  The hail that did fall was in the three quarter to one inch diameter range.  One inch diameter hail covered the ground in Davis County at Bloomfield.  Some damage was done to vinyl siding in the city of Bloomfield as well.  A few of the storms produced high winds with tree damage and some building damage.  A roof was blown off a shed in Polk County in Pleasant Hill.  Outbuildings were destroyed by another storm in Story and Marshall Counties, and a garage was blown over in Marshall County in the Marshalltown area.  High winds from the dryline storms caused damage in Waukee with damage to house siding and a metal fence in the area.

Hail in WARREN, IOWA
From 31-MAR-07 13:25:00 to 31-MAR-07 13:25:00 (CST-6)
Location: MILO
Magnitude: 1.00 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm Wind in HARDIN, IOWA
From 31-MAR-07 14:46:00 to 31-MAR-07 14:46:00 (CST-6)
Location: NEW PROVIDENCE
Magnitude: 52.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in POLK, IOWA
From 31-MAR-07 14:00:00 to 31-MAR-07 14:00:00 (CST-6)
Location: YOUNGSTOWN
Magnitude: 61.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Funnel Cloud in CALHOUN, IOWA
From 31-MAR-07 16:10:00 to 31-MAR-07 16:10:00 (CST-6)
Location: JOLLEY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in MARSHALL, IOWA
From 31-MAR-07 14:45:00 to 31-MAR-07 14:45:00 (CST-6)
Location: MARSHALLTOWN
Magnitude: 55.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in JASPER, IOWA
From 31-MAR-07 13:55:00 to 31-MAR-07 13:55:00 (CST-6)
Location: MONROE
Magnitude: 52.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Thunderstorm Wind in BREMER, IOWA
From 31-MAR-07 16:08:00 to 31-MAR-07 16:08:00 (CST-6)
Location: HORTON
Magnitude: 52.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Public

Hail in WAPELLO, IOWA
From 31-MAR-07 13:38:00 to 31-MAR-07 13:38:00 (CST-6)
Location: OTTUMWA
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in DALLAS, IOWA
From 31-MAR-07 15:55:00 to 31-MAR-07 15:55:00 (CST-6)
Location: WAUKEE
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Hail in GREENE, IOWA
From 31-MAR-07 14:47:00 to 31-MAR-07 14:47:00 (CST-6)
Location: ADAZA
Magnitude: 1.00 
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Hail in FRANKLIN, IOWA
From 31-MAR-07 15:21:00 to 31-MAR-07 15:21:00 (CST-6)
Location: GENEVA
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Hail in DAVIS, IOWA
From 31-MAR-07 13:22:00 to 31-MAR-07 13:22:00 (CST-6)
Location: BLOOMFIELD
Magnitude: 1.00 
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Thunderstorm Wind in MARSHALL, IOWA
From 31-MAR-07 14:33:00 to 31-MAR-07 14:33:00 (CST-6)
Location: STATE CENTER
Magnitude: 56.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorm Wind in STORY, IOWA
From 31-MAR-07 14:30:00 to 31-MAR-07 14:30:00 (CST-6)
Location: ZEARING
Magnitude: 61.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in JASPER, IOWA
From 31-MAR-07 14:17:00 to 31-MAR-07 14:17:00 (CST-6)
Location: BAXTER
Magnitude: 0.88 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorm Wind in MARSHALL, IOWA
From 31-MAR-07 14:30:00 to 31-MAR-07 14:30:00 (CST-6)
Location: STATE CENTER
Magnitude: 56.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Thunderstorm Wind in HARDIN, IOWA
From 31-MAR-07 14:55:00 to 31-MAR-07 14:55:00 (CST-6)
Location: PT PLEASANT
Magnitude: 71.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Funnel Cloud in BUTLER, IOWA
From 31-MAR-07 15:48:00 to 31-MAR-07 15:48:00 (CST-6)
Location: CLARKSVILLE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Hail in GREENE, IOWA
From 31-MAR-07 14:45:00 to 31-MAR-07 14:45:00 (CST-6)
Location: ADAZA
Magnitude: 1.00 
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Funnel Cloud in CALHOUN, IOWA
From 31-MAR-07 15:10:00 to 31-MAR-07 15:10:00 (CST-6)
Location: KNIERIM
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement