Target: Upper Midwest
June 20, 2012 by Thomas A. Horne, Editor At Large
Last week we began seeing Mesoscale Convective Complexes (MCCs) affecting the upper midwest–mainly Wisconsin. Well, guess what. The same basic weather dyanmics are still in place! There’s a warm- or stationary frontal boundary lying across Wisconsin and Minnesota, with its parent low now over eastern North Dakota. Winds aloft at 6,000 feet are 60 knots out of the south-southwest from Oklahoma to Minnesota. And that means warm, moist air is riding up and over the frontal boundary, setting Minnesota and Wisconsin up for trouble. Again. This will be almost a week of the same-old, same-old for the upper midwest. Today the Storm Prediction Center identifies Wisconsin as having a slight chance of severe thunderstorms. Will another MCC be in the offing? Maybe. After all, there’s a huge area of rainfall in the area already. That said, a check of ceilings and visibilities during the last MCC event showed mostly MVFR weather. On the other hand, yesterday featured a monster bow echo, which signals strong winds and turbulence ahead of onrushing cold outflows from storm centers. Below is this morning’s setup, but this afternoon is when the curtain may raise on the main event. Meanwhile, the eastern US roasts under high pressure. Time for density altitude calculation practice!
Precipitation shield over MN
Winds aloft 6,000 ft msl
