Part 1 of 2: The seasons first major winter storm moved into Iowa during the late afternoon and evening of the 19th and continued into the day on the 20th.  A strong low pressure developed over southeast Colorado and pushed east across southern Kansas.  The low turned northeast through Missouri and into southern Lake Michigan by the 20th.  At the same time, a strong upper level trough of low pressure became negatively tilted as it lifted northeast across the central U.S.  A strong push of moisture took place ahead of the storm.  A mixture of rain and snow developed north and northwest of the low pressure track.  As the dry slot lifted northeast toward Iowa, the airmass became increasingly unstable.  A large area, for December, of thunderstorms developed over northeast Kansas into northwest Missouri, then pushed rapidly across Iowa during the evening of the 19th.  A mixture of rain and snow occurred across southern Iowa during the early evening.  The rain/snow line shifted southeast with much of the thunderstorm activity occurring as thundersnow.  The thunderstorms brought with them a mixture of snow and some freezing rain.  Though the freezing rain was not of a significant amount, it did help to cake the snow that was falling at a one to two inch per hour rate onto trees and power lines.  The snow spread north quickly through the evening and early morning hours.  The heaviest snow fell in a band about 50 miles wide that extended from near the Omaha-Council Bluffs area, through Des Moines and Waterloo, and all the way to Marquette.  Snowfall of 8-12 inches was common in this band.  Some of the heavier snowfall amounts included 14.5 inches in Ankeny, 13.8 inches in Johnston, 13.4 inches in Grimes, 13 inches in Conrad and Marshalltown, 12.4 inches at the Des Moines Airport and 11.5 inches south of Madrid.  Roads became treacherous quickly with the heavy snow falling on road surface temperatures that were just above freezing.  Numerous traffic accidents and injuries were reported, along with some fatalities.  The largest accident occurred on Interstate 30 near the Williams exit.  Thirty cars were involved with two fatalities reported.  Icing on trees and power lines became a major issue, especially as winds increased later in the night.  Snow and ice laden trees and power lines produced considerable damage through much of the area.  Branches and full trees fell on power lines, knocking out power for 150,000 to 200,000 customers, 139,000 in the MidAmerican Service area alone.  Conditions became bad enough that most activities in the state were cancelled for both the 20th and 21st.  In addition to the snow, strong winds caused considerable blowing and drifting of snow.  Snowdrifts of 5 to 10 feet were common.  Winds were sustained above 25 MPH across the area, with much of the state reaching frequent gusts of 50 MPH or more.  Blizzard conditions were reported over most of the Des Moines CWA.  This will be addressed via a separate entry.

Winter Storm in GREENE, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in GUTHRIE, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in UNION, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in CLARKE, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in MADISON, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in DALLAS, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in BOONE, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in WARREN, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in MARION, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in POLK, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in JASPER, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in POWESHIEK, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in STORY, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in MARSHALL, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in TAMA, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in MAHASKA, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in SAC, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in CALHOUN, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in WEBSTER, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in HAMILTON, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in POCAHONTAS, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in HUMBOLDT, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in WRIGHT, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in GRUNDY, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in HARDIN, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in BLACK HAWK, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in FRANKLIN, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in BUTLER, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in BREMER, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in KOSSUTH, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 12:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in PALO ALTO, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 12:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in WORTH, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in WINNEBAGO, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in HANCOCK, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in CERRO GORDO, IOWA
From 19-DEC-12 22:00:00 to 20-DEC-12 14:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in ADAMS, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in CASS, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in ADAIR, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in AUDUBON, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in CRAWFORD, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Winter Storm in CARROLL, IOWA
From 19-DEC-12 19:00:00 to 20-DEC-12 07:00:00 (CST-6)
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Trained Spotter