Parts of the Midwest and Great Lakes States will have the potential for a severe weather outbreak on Sunday. According to the Storm Prediction Center, there is a slight risk of severe thunderstorms for the following cities:
Milwaukee, Madison, Rockford, Cedar Rapids, Davenport, Peoria, Springfield, St. Louis, and Carbondale.
There is an enhanced risk for severe thunderstorms for the following cities: Chicago, Joliet, Champaign, Bloomington-Normal, Indianapolis, Evansville, Louisville, Cincinnati, Ft. Wayne, Detroit, Lansing, and Grand Rapids.
A strengthening area of low pressure will eject out of the Plains toward Northern Wisconsin during the morning hours. Ahead of a strong cold front, thunderstorms are expected to explode ahead of it. While some models fire the storms over the Mississippi River, tracking eastward, this model (RPM) has storm initiation occurring along the I-39 corridor with damaging wind quickly moving into the Chicago area by 3pm. Mature thunderstorms then affect the enhanced risk area of Northern Indiana, Southern Michigan, and Northwestern Ohio.
The main threats for the Rockford Metro will be all or nothing. A few things are very interesting to me. The folks at St. Louis University have developed a computer program called CIPS. It takes the computer model output and compares it with similar outcomes in the past. Ominously, the CIPS analog shows the closest comparison to be the November 22, 2010 outbreak that produced tornadoes here in Northern Illinois and Southern Wisconsin. (See Caledonia tornado information here) (See Caledonia tornado photos here).
Another thing that is concerning is if a “triple point” is present here in Northern Illinois. This maximizes the amount of turning wind with height. In this surface map by the NWS, a cold front (blue), a warm front (red), and an occluded front (pink) intersect in Northern Illinois. A triple point was close by for both the Caledonia and Poplar Grove tornadoes.
For the Rockford Metro, there will be a severe weather threat (mainly straight line wind) between 3am and 9am. A few isolated tornadoes will be possible, especially east of I-39 between 9am and 1pm. After 1pm, the front and chance of severe weather will sweep east by 50 miles each hour.
Posted under severe weather
This post was written by Eric Sorensen on November 16, 2013