Heavy Snow in Iowa, January 4, 2004

The seasons first push of Arctic air took place during the weekend of the 3rd and 4th. A strong high pressure was located over northwest Canada and nosed southeast into the central U.S. At the same time, a vigorous upper air system lifted northeast out of the southwest U.S. during the day on the 4th. Low pressure formed over Colorado into the Texas panhandle during the afternoon and evening of the 3rd. This low pushed east-northeast across southern Missouri on the 4th and to northern Kentucky by the evening of the 4th. A strong thermal contrast was in place across the stationary front that the low moved along. Temperatures were in the 30s to low 40s just north of the front, with 70s to the south of it along with dew points in the low to mid 60s in the warm air. This provided a rich source of moisture for the system. Overrunning took place over a large part of the central U.S. Snow broke out over Iowa during the predawn hours of the 4th and continued through the day. The snow was of the light and fluffy variety with 850 mb temperatures in the -5 to -10 degree C. in most of the snow area. The snow caused quite a few accidents across the state, however it did not present a serious travel problem. Fortunately, winds were not strong during the event. They were generally in the 10 to 20 MPH range, resulting in considerable drifting of the snow along with some blowing snow. A sharp cut-off of the heavy snow accumulations took place nearly along Interstate 80. South of the Interstate, most areas received from 6 to 10 inches of snow. Amounts tapered off rapidly to the north and by the time you were 15 to 20 miles north of the heavy snow area little more than an inch was common. The heaviest snowfall occurred in south central into the east central parts of the state. Ten inches of snow was recorded in Decatur County at Leon as well as in Wapello County at Ottumwa. A 50 mile wide band of 8 to 10 inch snows was found between these two locations.