A strong upper level low moved northeast out of the southern Rockies into the central U.S. during the night of the 3rd into the day of the 4th.  There wasn't a strong reflection at the surface with this storm.  Strong isentropic lift, coupled with a layer of unstable air aloft, created significant lift across southern Iowa during the late night hours of the 3rd through mid day on the 4th.  The atmosphere was quite warm, so much of the precipitation started out initially as rain or a rain and snow mix.  As the stronger dynamics moved into the area, precipitation rates increased and the rain changed to snow.  Some thunder occurred with the snow, further enhancing snowfall rates.  During the peak of the storm, snowfall rates of 1 to 2 inches per hour occurred with visibility reduced to around 1/4 mile.  Winds during the storm were northeast at 15 to 20 MPH, with some higher gusts.  Blowing snow was not a major problem as the storm was very springlike in nature with surface temperatures remaining near to just above freezing through the event.  The heavy wet snow blanketed west central into parts of southwest and central Iowa.  The heaviest snowfall in the Des Moines CWA was in Cass County near Cumberland with 11.5 inches.  Other heavy amounts included 9.1 inches at the NWS office in Polk County at Johnston, 8 inches in Union County at Creston and in Dallas County near Waukee, 7.8 inches in Dallas County at Adel, and 7 inches in Audubon County near Gray.  The snow caused some travel problems, however with the warm conditions during the snow, and unseasonable warmth prior to the storm, most roads remained wet to slushy except during the period of heaviest snow.  By the evening hours, reports indicated that roads were mainly wet with only scattered slick spots.

Heavy Snow in AUDUBON, IOWA
From 04-FEB-12 03:00:00 to 04-FEB-12 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Snow in CASS, IOWA
From 04-FEB-12 03:00:00 to 04-FEB-12 19:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Snow in GUTHRIE, IOWA
From 04-FEB-12 03:00:00 to 04-FEB-12 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Snow in DALLAS, IOWA
From 04-FEB-12 03:00:00 to 04-FEB-12 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Snow in ADAIR, IOWA
From 04-FEB-12 03:00:00 to 04-FEB-12 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Snow in MADISON, IOWA
From 04-FEB-12 03:00:00 to 04-FEB-12 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Snow in ADAMS, IOWA
From 04-FEB-12 03:00:00 to 04-FEB-12 19:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Snow in UNION, IOWA
From 04-FEB-12 03:00:00 to 04-FEB-12 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Heavy Snow in POLK, IOWA
From 04-FEB-12 03:00:00 to 04-FEB-12 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Heavy Snow in CARROLL, IOWA
From 04-FEB-12 03:00:00 to 04-FEB-12 17:00:00 (CST-6)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter