Temperatures tumble this week

After a gorgeous weekend a big pattern change will make the last week of summer feel anything but that.  A strong cold front stretching from northern Wisconsin southwest through Rochester, MN to Sioux City, IA this morning will quickly race southeast this afternoon.  Cloud cover has been increasing ahead of the front and is expected to continue into the afternoon.  Showers, with a few embedded thunderstorms, have been developing just behind the front as a very strong jetstream helps to carve out a trough of low pressure in the northern Plains.  The rain will likely maintain itself through the afternoon and evening due to the strong jetstream despite the lack of sunshine we're currently experiencing.  Behind the front very cold air will filter into the Plains and Midwest beginning tonight with temperatures in Minnesota and northern Wisconsin expected to plummet into the upper 20s/low 30s.  That cold air will be in our neck of the woods Tuesday night as a surface high pressure system moves in overhead.  The center of the high is expected to be almost overhead once the sun sets Tuesday and this will likely set the stage for temperatures to nose dive into the upper 30s before an increase in cloud cover arrives by daybreak Wednesday.  Right now I'm forecasting a low temperature of 37° which is just three short degrees away from the record low of 34° set back in 1929.  It's also possible that patchy frost could develop Tuesday night with the greatest potential to the north where temperatures will likely be the coldest.  On average, the first frost usually occurs within the first week of October usually around the 10th (give or take a few days).  Is it certain that there will be frost, no.  But it's something to keep in mind for Tuesday. 

The afternoon on Tuesday will also be cold with the high temperature only expected to be right around 60°.  Highs will remain cool this week as a series of cold fronts move through; the first today, the second on Wednesday and the third Thursday night.  As each front passes it will continue to pull down a cool air mass just in time for the weekend.