An unstable airmass was in place over Iowa during the day on the 31st, though not as unstable as was the case during the first part of the month.  Lifted indices were as low as -8 to -10 C. during the late afternoon hours over northeast Iowa with CAPE values in the 2000 to 3000 J/kg range.  Dew points were in the mid 60s to near 70 through the afternoon into the evening hours with a narrow ribbon of moisture feeding into northeast and north central Iowa through the afternoon and evening hours.  Thunderstorms fired during the afternoon, mainly northeast of the Des Moines CWA.  One storm developed in Black Hawk County and dropped golf ball size hail in the town of Dunkerton.  The weather was fairly quiet during the early evening as a cold front approached from the northwest.  Thunderstorms developed ahead of the front as the area of convection to the northeast of Iowa developed westward into north central Iowa.  The storms produced hail in several counties.  With freezing levels relatively low, at around 12,000 feet, some of the hail became quite large.  In Cerro Gordo County, hail from golf ball up to baseball size was reported in the Rockwell area.  The hail caused considerable damage.  In addition, several head of sheep were killed by the large hail on a farm near Rockwell.  In Butler, quarter to baseball size hail pelted the area.  The hail covered the ground in places resulting in near total destruction of crops south of the Dumont area.

Hail in CERRO GORDO, IOWA
From 31-JUL-03 21:20:00 to 31-JUL-03 21:20:00 (CST)
Location: CLEAR LAKE
Magnitude: 1.00 
Property damage: 5K
Crop damage: 10K
Reported by: UNKNOWN

Hail in BUTLER, IOWA
From 31-JUL-03 22:46:00 to 31-JUL-03 22:46:00 (CST)
Location: DUMONT
Magnitude: 1.00 
Property damage: 5K
Crop damage: 10K
Reported by: LAW ENFORCEMENT

Hail in CERRO GORDO, IOWA
From 31-JUL-03 22:00:00 to 31-JUL-03 22:00:00 (CST)
Location: ROCKWELL
Magnitude: 2.75 
Property damage: 25K
Crop damage: 25K
Reported by: UNKNOWN

Hail in POCAHONTAS, IOWA
From 31-JUL-03 21:39:00 to 31-JUL-03 21:39:00 (CST)
Location: PLOVER
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: UNKNOWN

Hail in CERRO GORDO, IOWA
From 31-JUL-03 21:32:00 to 31-JUL-03 21:32:00 (CST)
Location: MASON CITY
Magnitude: 1.75 
Property damage: 25K
Crop damage: 10K
Reported by: LAW ENFORCEMENT

Hail in CERRO GORDO, IOWA
From 31-JUL-03 21:58:00 to 31-JUL-03 21:58:00 (CST)
Location: ROCKWELL
Magnitude: 2.50 
Property damage: 50K
Crop damage: 10K
Reported by: UNKNOWN

Hail in CERRO GORDO, IOWA
From 31-JUL-03 22:00:00 to 31-JUL-03 22:00:00 (CST)
Location: ROCKWELL
Magnitude: 1.75 
Property damage: 20K
Crop damage: 5K
Reported by: UNKNOWN

Hail in FRANKLIN, IOWA
From 31-JUL-03 23:02:00 to 31-JUL-03 23:02:00 (CST)
Location: HAMPTON
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in FRANKLIN, IOWA
From 31-JUL-03 23:25:00 to 31-JUL-03 23:25:00 (CST)
Location: HAMPTON
Magnitude: 0.88 
Property damage: 1K
Crop damage: 5K
Reported by: GENERAL PUBLIC

Hail in CERRO GORDO, IOWA
From 31-JUL-03 21:55:00 to 31-JUL-03 21:55:00 (CST)
Location: ROCKWELL
Magnitude: 1.75 
Property damage: 20K
Crop damage: 10K
Reported by: UNKNOWN

Hail in HANCOCK, IOWA
From 31-JUL-03 22:10:00 to 31-JUL-03 22:10:00 (CST)
Location: GARNER
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: NWS EMPLOYEE(OFF DUTY)

Hail in BUTLER, IOWA
From 31-JUL-03 22:57:00 to 31-JUL-03 22:57:00 (CST)
Location: DUMONT
Magnitude: 2.75 
Property damage: 25K
Crop damage: 200K
Reported by: NEWSPAPER

Hail in PALO ALTO, IOWA
From 31-JUL-03 21:30:00 to 31-JUL-03 21:30:00 (CST)
Location: MALLARD
Magnitude: 0.75 
Crop damage: 5K
Reported by: UNKNOWN

Hail in POCAHONTAS, IOWA
From 31-JUL-03 22:00:00 to 31-JUL-03 22:00:00 (CST)
Location: ROLFE
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: UNKNOWN

Hail in BUTLER, IOWA
From 31-JUL-03 22:55:00 to 31-JUL-03 22:55:00 (CST)
Location: DUMONT
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in BLACK HAWK, IOWA
From 31-JUL-03 16:07:00 to 31-JUL-03 16:07:00 (CST)
Location: DUNKERTON
Magnitude: 1.75 
Property damage: 25K
Crop damage: 10K
Reported by: LAW ENFORCEMENT

Hail in BUTLER, IOWA
From 31-JUL-03 22:51:00 to 31-JUL-03 22:51:00 (CST)
Location: DUMONT
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Hail in POCAHONTAS, IOWA
From 31-JUL-03 21:46:00 to 31-JUL-03 21:46:00 (CST)
Location: PLOVER
Magnitude: 0.88 
Property damage: 3K
Crop damage: 2K
Reported by: UNKNOWN