Midwest Weekly Highlights - March 15-21, 2011

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A Taste of Spring Warmth

Temperatures third week of March were much above normal, in contrast to the cool weather the first half of the month. Average daily temperatures were well above normal across the entire region, with temperatures as much as 7°F to 9°F above normal from Missouri eastward through Ohio (Figure 1). There were numerous record high minimum and record high maximum temperatures set this week, most of them in the southern two-thirds of the region.

Most of the Midwest received less than normal precipitation this week, with two major exceptions (Figure 2). Precipitation was above normal across central Missouri, and most of this was associated with thunderstorms that developed ahead of a frontal wave on March 19-20 (Figure 3). This same system on March 20-21 was responsible for precipitation from 150 to more than 200 percent of normal from northeastern Iowa across most of Wisconsin and into southern lower Michigan (Figure 4). During the remainder of the week much of the central Midwest only experienced scattered showers that resulted in light amounts of rain.

At the beginning of the week areas depicted as dry on the U.S. Drought Monitor were shrinking (Figure 5). There were only two small areas depicted as being in Moderate drought. One was located in northeastern Indiana, and the other in the Arrowhead of Minnesota
 

Severe Weather

Thunderstorms developing ahead and along an advancing warm front on March 19-21 produced some severe hail (Figure 6). Most of the hail reported was no larger than one inch. Thunderstorm winds caused some minor damage in Ohio on March 21st.
 

Upper Midwest Anxiously Prepares for Flooding

At the end of this week there was still significant snow on the ground in the northwestern half of Minnesota, with as much as 12 to 20 inches still on the ground across the northern quarter of the state (Figure 7). The NOAA spring flood outlook issued on March 17th (Figure 8) indicated that the highest risk of flooding was along the Red River of the North and the upper Mississippi River from Minneapolis to St. Louis. In addition, many small rivers and streams are already or will be experiencing spring flooding. The Big Sioux River in western Iowa was flooding this week, and officials had to close a bridge connecting Iowa with South Dakota.

Communities along the Mississippi River were making preparations for the likelihood of spring flooding. Officials in Davenport, IA (Scott County) called for volunteers to fill sandbags and are holding flood preparedness meetings. City crews were inspecting levees and valves, making sure pumps were in operating condition, and beginning construction of flood structures. All vacation requests for city employees from March 28 to May 27 have been denied.

-SDH-