Midwest Weekly Highlights - April 15-21, 2012

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Weather conditions varied greatly during the third week of April, starting out with severe weather in the western portions of the region, followed snow in the north the middle of the period, and more severe weather in the west at the end of the period.
 

Storms Bring Much Needed Precipitation

Precipitation was much above normal this week across the northern half of the Midwest, ranging from 200 to 500 percent of normal (Figure 1). In the southern half of the region precipitation varied much more, ranging from less than 50 percent of normal in western Missouri to 200 percent of normal in central Illinois. The largest departures were found across the northwestern half of Minnesota, where precipitation was more than five times normal for the week. Drought conditions have been persistent across the upper Midwest this spring (Figure 2), and fortunately the heaviest precipitation this week fell in the driest areas (Figure 3). Numerous daily precipitation records were set in Iowa, Illinois, Minnesota, Missouri, Wisconsin, Kentucky, and Indiana as major spring storm lifted northeastward through the region.
 

Cold North, Not as Warm Elsewhere

Daily average temperatures were 3°F to 6°F below normal this week across Minnesota and northwestern Wisconsin (Figure 4). Temperatures in a band across the central Midwest ranged from near normal to 3°F above normal. The largest departures occurred from Indiana eastward though Ohio where temperatures were 3°F to 7°F above normal. Daily temperature records were set mostly on April 16 and April 17, when numerous record high minimum temperatures were recorded across the region. However, a few record daily low temperatures and record low maximum temperatures were noted on April 17.
 

Exiting Storm Lashes Upper Midwest

The storm system that generated the outbreak severe weather in the Midwest on April 14 continued to flex its muscles as it moved northeast through the region April 15-17. Severe thunderstorms ahead of the cold front produced hail and damaging winds across portions of Minnesota, Missouri, and Illinois on April 15 (Figure 5). There were two confirmed tornadoes reported in southwestern Minnesota. On the morning of April 16 a very strong low pressure center was located near Eau Claire, WI (Figure 6). Snow was falling across northern Minnesota and Wisconsin, while showers and thunderstorms continued ahead of the cold front as it swept through Indiana and Ohio.

The most significant impact from this spring storm system turned out to be the high winds associated with the low's circulation. Wind advisories were issued for a large portion of the Midwest as winds gusted to 55 mph. The winds toppled trees and knocked over power lines, leaving 217,000 customers without power in Michigan on April 16. The high winds resulted in one fatality in Van Buren County, MI when a three-foot diameter tree fell on a van killing a woman. The winds along with heavy, wet snow snapped power lines in northern Minnesota. Almost a foot of snow fell in northern Minnesota (Figure 7, Figure 8), closing schools and prompting the Minnesota Department of Transportation to advise against travel in some areas due to the heavy snow.

 

More Snow and Tornadoes

A series of weak frontal system crossed through the Midwest the remainder of this week, producing scattered showers and thunderstorms. A clipper storm system moved from North Dakota to southern Minnesota on April 21 (Figure 9) igniting severe storms in southwestern Minnesota and more snow in northeastern Minnesota. Six tornadoes were reported in southwestern Minnesota and one in northern Iowa on April 21st (Figure 10), resulting in some building damage, most of it minor. As cold air poured in behind the clipper rain changed to heavy snow in northeastern Minnesota, resulting in almost six inches of accumulation in western (St. Louis County) (Figure 11).

 

Warm Weather Has Corn Planting Ahead of Schedule

The warm weather in March and early April has encouraged an early start to corn planting especially in the central Midwest. As of April 16 planting in Illinois was 35 percent ahead of the 5-year average, and 45 percent ahead of average in Kentucky. Unfavorable planting weather in Minnesota the last few weeks leaves it as the only state with corn planting behind average in the Midwest.

Corn Planting Progress as of April 16, 2012

State	Percent Complete	5-year Average
Illinois	41	6
Indiana	24	2
Iowa	5	3
Kentucky	59	14
Michigan	5	1
Minnesota	1	7
Missouri	39	15
Ohio	10	1
Wisconsin	2	-

 

-SDH-