Midwest Weekly Highlights - September 24-30, 2012
Rains Miss North
The northern half of the Midwest was mostly rain free in the last week of September (Figure 1). Light rains fell in northern Michigan but most of Minnesota, Iowa, Wisconsin, and the northern third of Illinois saw no precipitation at all. The southern Midwest was a different story with thunderstorms bringing heavy downpours and severe weather. The heaviest rains fell in southern Illinois with many reports of 3" to 5", several inches above normal (Figure 2). Dozens of daily precipitation records were set with over two dozen in both Illinois and Missouri. The dry conditions in northwest Minnesota led to a degradation to extreme drought (Figure 3).
Severe weather was limited to the southern extents of the Midwest with large hail reports extending from Missouri to Ohio (Figure 4). The largest hail fell in Clinton County in Illinois where multiple reports of hail from 2" to 3" in diameter were reported on the 25th. Also on the 25th, strong thunderstorm winds damaged trees and buildings in Missouri and Illinois. There were also tornado reports in Clinton County and Washington County with damage to buildings and trees along with two overturned semi-trailers on Interstate 64.
The last week of September started out cold with some early frosts in the northwest, but temperatures warmed by the end of the month. On average, temperatures ranged from a few degrees above normal in southwest Missouri and northwest Minnesota to slightly below normal across most of Illinois, Wisconsin, Michigan, Indiana, and Ohio. Daily temperature records were dominated by record lows in Iowa early in the week (Figure 5).