Midwest Overview - March 2010
A Mild, Dry Month
Winter made a quick transition to spring across the Midwest in March. Temperatures gradually warmed as the month progressed, with a rapid warm up at the end of the month that pushed temperatures into the 70s across the region. Temperature departures were near normal to 1°F below normal south of the Ohio River and across much of Missouri and southwestern Iowa. Over the rest of the region, the gradient in temperature departures northward was remarkable (Figure 1). Temperatures from Iowa eastward through Ohio were generally 1°F to 4°F above normal. From there, temperature departures ranged from 5°F in central Minnesota and Wisconsin to 10°F above normal from northern Minnesota to the western U. P. of Michigan.
March was also very dry across the northern Midwest, with precipitation less than 25 percent of normal across most of Wisconsin and Michigan, and less than 10 percent of normal across the Michigan Upper Peninsula (Figure 2). The U.S. Drought Monitor continues to depict Moderate to Severe Drought in northern Wisconsin and the western Michigan U. P. Precipitation was less than 50 percent of normal over central Kentucky, and Abnormal Dryness was depicted there. The central portion of Kentucky, including Louisville, Lexington, and Bowling Green, has experienced five consecutive months of below normal rainfall. For this area, precipitation is around 5 to 10 inches below normal for the November to March time period which ranks among the top ten driest such periods. In the remainder of the region, precipitation was at least 75 percent of normal. Far western Missouri received normal precipitation, and a band from northwest Missouri across north-central Illinois and into central Indiana and Ohio received from 100 to 125 percent of normal. The precipitation occurred mostly during the second week of March. Another round of significant precipitation occurred during the last ten days of the month. The episodic precipitation was often associated with slow moving low pressure systems, and resulted in heavy rain which caused flash flooding.
Flooding Begins to Subside
Runoff from the melting of a deep snow cover in the northern Midwest and additional rain resulted in flooding along many rivers and streams in Minnesota, Iowa, Illinois, and Missouri (Figure 3). Major rivers in flood this month included the Red River in Minnesota, the Des Moines River in Iowa, the Mississippi River from the headwaters to south of St. Louis, and the Illinois River. Lack of precipitation in the northern Midwest kept flooding from becoming worse, and by the end of the month river and stream levels, while still above flood stage in many areas, were falling (Figure 4).
Snow and Severe Weather Scarce
Southwestern and western Missouri was the only part of the Midwest to receive above normal snow fall during March (Figure 5), and all of this snow came in one storm March 19-20. The dry and warmer than normal weather in the northern Midwest brought an early end to the snow season there. March snowfall in the upper Midwest was more than 20 inches below normal (Figure 6). From Grand Rapids to Rochester, Minnesota, scores of observers reported a snowless March (Figure 7), the first time in history for many. In the Twin Cities it was the first snowless March since 1878. In Iowa, the statewide average snowfall was 2.0 inches for the month, or 2.8 inches less than normal. This ranks as the 23rd lowest March total among 123 years of record. However, the meager March snowfall was enough to push the statewide average seasonal snowfall total to 47.7 inches or seventh highest of record (greatest total since 1978-1979 winter).
Severe weather occurred on a scattered basis during the month. All of the severe weather reports were confined to the southern Midwest, from the Ozarks of Missouri eastward through the Ohio Valley (Figure 8).