Midwest Weekly Highlights - March 11-17, 2009
Dry and Gradually Warmer
The week started out much colder than normal, but most of the region enjoyed some brief periods of warm spring weather. The cold start resulted in temperature departures for the week ranging from -8°F in northwestern Minnesota to +2°F in southeastern Ohio, with much of the region ranging from -3°F in the west to +1°F in the east (Figure 1).
Most of the Midwest saw little precipitation this week (Figure 2). Precipitation was above normal from northern Indiana through northwestern Ohio and in northwestern Minnesota, but most of that was from the storm that departed the region on March 11. Precipitation was normal to above normal in southeastern Kentucky as the result of storm systems moving through the Gulf states. The U.S. Drought Monitor on March 17 remained essentially unchanged across the Midwest, with drought conditions still existing in parts of Minnesota, Wisconsin, and Michigan (Figure 3).
With the warmer weather during the week there was a significant retreat in the snow cover across the Midwest. At the end of the week snow depth of 4 inches or more existed only in the northern half of Minnesota, extreme northern Wisconsin, the Michigan U. P., and northern Lower Michigan (Figure 4).
March Takes a Breather
High pressure settled in over the Midwest for much of this week. This initially brought much colder than normal weather to region, but the weather gradually warmed as the high moved to the east and skies remained sunny. Maximum temperatures on March 12 were in the teens across Minnesota, Wisconsin, and northern Michigan, and only in the 30s as far south as Kentucky (Figure 5). Many locations across the upper and central Midwest set new record low maximum temperatures from March 12-14. By The end of the week, high temperatures were in the 50s and 60s in the northern Midwest and the balmy 70s from Missouri eastward through Ohio and as far north as southern Wisconsin (Figure 6). High temperature records were set at many locations across the Midwest on March 16-17.
While this large high pressure system kept most of the Midwest dry, a series of low pressure systems traveling eastward through the southern Gulf states did spread some precipitation northward into Kentucky. The heaviest precipitation fell in southeastern Kentucky with totals from 0.50 to 1.50 inches common, and amounts exceeded two inches in a number of locations.
Flooding Continues on Some Rivers
The lack of precipitation this week allowed many of the rivers and streams that flooded after heavy rain early in the month to steadily fall. In Ohio, Michigan, northern Indiana, and southern Wisconsin minor flooding was reported on a few rivers, but in general rivers levels were near or below flood stage. The Rock River and Fox River in southern Wisconsin and northern Illinois were experiencing minor flooding (Figure 7). Major flooding was still occurring in northern Indiana on the Kankakee River, and moderate flooding was occurring on the the Tippecanoe River at the end of the week (Figure 8). A levee break on March 15 on the Kankakee River in Porter County, IN prompted officials to issue a flash flood warning for the affected area near Dunns, IN. Moderate to major flooding was occurring on the Illinois River from La Salle to Valley City (Figure 9). A stage of 31.52 feet reached at Henry on March 13 was the third highest crest on record. The river rose to 27.94 feet at Peoria on March 14, the fourth highest on record. The river slowly fell during the last half of the week and a continued fall was expected. However, the river will likely remain above flood stage on the lower half of the river for at least another week to ten days.