A very unstable airmass was in place over Iowa during the afternoon of the 28th.  Surface temperatures were generally in the upper 80s to mid 90s, with dew point temperatures in the 70s to low 80s.  By late afternoon, CAPE values were between 4000 and 6000 J/kg with lifted indices below -10 C.  Temperatures aloft were quite warm with 700 mb temperatures around +11 C.  This tended to cap convection through the day.  A strong MCS tracked across southern Minnesota during the afternoon.  The outflow boundary from this system dropped into northwest Iowa during the early evening.  Thunderstorms formed along the boundary and produced hail of three quarters of an inch to one inch in diameter  during the initiation stage.  The severe weather tapered off afer a couple hours.  Meanwhile, an area of thunderstorms lifted north out of Missouri.  By early evening the intensified as they moved into the more unstable air over Iowa.  They became severe for a brief period of time and produced winds of up to 70 MPH, along with one and one quarter inch diameter hail in central Iowa from Warren County, into Marion and Jasper Counties.  The storms weakened after that time.  A cold front moved across the state during the night, kicking off additional thunderstorms.  These storms remained below severe limits.

Hail in PALO ALTO, IOWA
From 28-JUL-02 17:20:00 to 28-JUL-02 17:20:00 (CST)
Location: GRAETTINGER
Magnitude: 0.75 
Crop damage: 5K
Reported by: OTHER FEDERAL AGENCY

Hail in EMMET, IOWA
From 28-JUL-02 19:45:00 to 28-JUL-02 19:47:00 (CST)
Location: WALLINGFORD
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in JASPER, IOWA
From 28-JUL-02 19:54:00 to 28-JUL-02 19:54:00 (CST)
Location: COLFAX
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Hail in MARION, IOWA
From 28-JUL-02 19:25:00 to 28-JUL-02 19:25:00 (CST)
Location: SWAN
Magnitude: 1.25 
Property damage: 5K
Crop damage: 10K
Reported by: AMATEUR RADIO

Thunderstorm Wind in JASPER, IOWA
From 28-JUL-02 19:35:00 to 28-JUL-02 19:35:00 (CST)
Location: PRAIRIE CITY
Magnitude: 61 E
Property damage: 5K
Crop damage: 5K
Reported by: TRAINED SPOTTER

Hail in EMMET, IOWA
From 28-JUL-02 18:00:00 to 28-JUL-02 18:00:00 (CST)
Location: WALLINGFORD
Magnitude: 0.88 
Property damage: 2K
Crop damage: 5K
Reported by: UNKNOWN

Hail in EMMET, IOWA
From 28-JUL-02 18:15:00 to 28-JUL-02 18:15:00 (CST)
Location: WALLINGFORD
Magnitude: 0.75 
Crop damage: 5K
Reported by: OTHER FEDERAL AGENCY

Thunderstorm Wind in SAC, IOWA
From 28-JUL-02 20:09:00 to 28-JUL-02 20:09:00 (CST)
Location: SCHALLER
Magnitude: 52 E
Property damage: 5K
Reported by: TRAINED SPOTTER

Hail in PALO ALTO, IOWA
From 28-JUL-02 18:17:00 to 28-JUL-02 18:17:00 (CST)
Location: GRAETTINGER
Magnitude: 1.00 
Property damage: 5K
Crop damage: 10K
Reported by: BROADCAST MEDIA

Thunderstorm Wind in PALO ALTO, IOWA
From 28-JUL-02 21:00:00 to 28-JUL-02 21:00:00 (CST)
Location: CYLINDER
Magnitude: 52 E
Property damage: 5K
Reported by: TRAINED SPOTTER

Thunderstorm Wind in WARREN, IOWA
From 28-JUL-02 19:24:00 to 28-JUL-02 19:24:00 (CST)
Location: HARTFORD
Magnitude: 61 E
Property damage: 10K
Crop damage: 5K
Reported by: LAW ENFORCEMENT

Thunderstorm Wind in WARREN, IOWA
From 28-JUL-02 19:24:00 to 28-JUL-02 19:24:00 (CST)
Location: HARTFORD
Magnitude: 61 E
Property damage: 5K
Crop damage: 5K
Reported by: LAW ENFORCEMENT