Midwest Overview - March 2007

---

Winter-Like Start, Summer-Like End

The cold, snowy weather of February extend its reach into the month of March, but could not hang on much beyond the first week. The month began with another major blizzard across the upper Midwest, and below normal temperatures persisted through the first week (Figure 1). However, the transition to warmer weather was rather quick, and the month of March ended up warmer than normal across the entire region (Figure 2). There were two notable periods of much above normal warmth during the month when new records were set. The first was March 11 to March 14, when a handful of temperature records were set from Michigan south through Illinois, The more significant period of warmth was March 25-27, when either record high or record high minimum temperatures were set throughout the Midwest.

The precipitation distribution for the month of March was well above normal over the western portions of the region, and also in a band from northern Missouri across the northern half of Illinois, central Indiana, and the northern half of Ohio (Figure 3). The areas of much above normal precipitation were indicative of the mean position of frontal systems in the Midwest this month, many of which stalled through the central potions of the region and provided the focus for shower and thunderstorm development.

Snowfall was above normal across the northwestern third of the region, generally north of a line from the southwestern corner of Iowa to the tip of the thumb of Michigan (Figure 4). Most of the snow that fell in March occurred during the first three days of the month when a paralyzing winter storm dumped up to a foot and a half of snow and produced drifts up to 8 feet.

 

Spring Flooding

Melting snow, ice jams, and heavy spring rains all combined to cause flooding on many Midwestern rivers during the month from Minnesota south into Illinois (Figure 5). Toward the end of the month minor flooding was occurring on the Mississippi River and minor to moderate flooding on the Illinois River.

SDH