With the overall picture becoming a little clearer this morning, confidence is rising the a mid-scale severe weather outbreak could take shape across the Upper Midwest today. As you can see above, the Storm Prediction Center has posted a slight risk for a large area including portions of Iowa, Nebraska, the Dakotas, Minnesota and Wisconsin.
As we’ve been talking about for a couple days, a warm front will push from south to north through Iowa today, setting up a very warm and unstable air mass over this area. But the focus for supercell development will lie further north and west. Storms are expected to fire in eastern portions of the Dakotas and into parts of central Minnesota. This is where the greatest threat exists for tornadoes to form. You can see that risk area in the graphic to the right.
There is also a secondary area that will need to be monitored in portions of southern Illinois, Indiana and Ohio as well as northern Kentucky. But for now we’ll focus on the primary threat area further northwest.
Once storms begin firing, coverage area of these storms are expected to increase rapidly after sunset, as a low level jet kicks in and storms fire further to the south. Eventually these storms will impact many areas of Iowa. The primary threats tonight in Iowa are strong, damaging winds and large hail. A tornado or two also cannot be ruled out (hence the 2% risk area).
But the primary threat will come from large hail. That’s represented in the graphic to the left where a mid-range threat area is posted for much of western and northern Iowa. This are could also see hail bigger than golf balls, reaching up to 2” in diameter or higher.
Another concern tonight is the heavy rain potential. Many areas in Iowa could see rainfall totals in excess of 2-3” in the coming days. Fortunately this is good news for drought-plagued areas of northwest Iowa. But flash flooding and river flooding will need to be monitored with such an active weather pattern taking shape for at least the next week.
WeatherLiveTV’s Ben McMillan will be out in the elements today, tracking these storms. We plan to bring you his live video feed from today’s chase and up to the second warning and damage information as it comes in from across the Upper Midwest.