Midwest Weekly Highlights - May 1-10, 2008
A Cool, Wet Start
The cool and unsettled weather pattern that ended April continued through the first ten days of May. Temperatures during this period were near to below normal across most of the Midwest (Figure 1). Temperatures from eastern Indiana through Ohio and eastern Kentucky were near normal to 2°F above normal. Over the central portions of the region, temperatures were generally 1°F to 2°F below normal. Much of Minnesota, northern Wisconsin, and the Michigan UP recorded temperatures from 3°F to 8°F below normal.
There were two distinct areas of heavier precipitation this period. The first extended from northwestern Iowa through southeastern Minnesota into the Michigan UP (Figure 2). The second was from southwestern Missouri east-northeastward through Ohio. Precipitation in both of these regions was 100 to 200 percent of normal. Notable dry areas were northwestern Minnesota, northwestern Illinois, and southeastern Kentucky.
On May 10 there was still snow on the ground in the Arrowhead of Minnesota, as well as in northwestern Minnesota (Figure 3).
Storms Clobber Missouri
Residents of western Missouri began the month of May with a round of severe thunderstorms late on May 1 and into the early morning hours of May 2. The severe storms were clustered around the Kansas City area and in southwestern Missouri. A number of tornadoes were reported, and there were numerous reports of damaging thunderstorm winds. A wind gust of 83 mph occurred in Independence, Mo (Jackson County), and extensive damage to several buildings was reported. The thunderstorm winds also damaged 200 homes north of Kansas City, with 10 houses totally off of their foundations. Five people suffered injuries as a result of the storms. Tornadoes also touched down in northwestern Iowa. For more information on the severe weather in Missouri, visit the NWS Kansas City web site
More severe weather occurred ahead of the cold front in Illinois and southeastern Missouri on May 2, but the storms were more scattered and resulted in mostly minor damage. A major tornado outbreak occurred in Arkansas, Tennessee, and northern Mississippi, but none were reported in the nine Midwestern states. The warm spring weather that helped fuel the thunderstorms was replaced by much cooler air as a cold front swept through the region on May 2 and May 3. Rochester, MN reported a trace of snow on May 3 as the cold air spread southward.
A Break, then More Storms
Two days of warming and fair weather were followed by more storms in the region on May 6. A cold front was draped across the southern Great Lakes (Figure 4), and by afternoon storms developed in the warm air south of this boundary in the northern half of Iowa and southern Minnesota. Two possible tornadoes were reported in Winona County, MN.
The front slowly pushed through the Midwest on May 7-8, and a low pressure wave developing on the front produced a shield of rain across the southern half of the Midwest. Rainfall amounts from 1.50 to 4.00 inches occurred from Southwestern Missouri through southern Illinois (Figure 5). Two brief tornado touchdowns were reported in Ohio on May 8, the only severe weather in the Midwest that day.
The first ten days of May ended with high pressure bringing sunny and cool weather to most of the region (Figure 6). However, a new storm system was already pushing into western Minnesota, Iowa, and Missouri setting the stage for a wild start to the second full week of May. Severe storms erupted in northeastern Oklahoma and southwestern Missouri during the late afternoon of May 10. At least four tornadoes occurred with the storms. One tornado, rated as producing EF-4 damage, crossed into southwestern Missouri from Oklahoma (Figure 7). This long-track tornado, on the ground for a distance of 74 miles, grew to be a mile wide at times, causing extensive damage and at 16 fatalities in Newton, Barry, and Jasper counties. One firefighter from Seneca, MO (Newton County) died from critical injuries received while trying to warn people about the storm. Additional information on this outbreak, including maps of the tornado tracks and a meteorological analysis of the event, can be found at the NWS Springfield, MO web site.