A major storm is quickly intensifying Saturday morning in the central U.S. and will bring a significant severe weather outbreak to parts of the Midwest Saturday afternoon and evening – including the threat for dangerous, significant, long-track tornadoes.
Radar Saturday morning is showing the organizing storm with a rain shield that stretches from the Great Plains through the Great Lakes and the Mid-Atlantic. Some of the thunderstorms Saturday morning, especially in northern Illinois, are capable of producing 1 to 2 inches of rainfall. There is a flash flood watch issued for parts of Indiana and Ohio, where 1-2 inches of rain is likely in the next 36 hours.
Storms on Friday evening produced greater than baseball-sized hail in parts of Oklahoma and Missouri.
On the colder side of the system, winter weather advisories, and blizzard warnings have been issued for the upper Midwest and the Plains, where locally up to 6 inches of snow is possible this week.
There is a moderate risk area for severe weather in northern Illinois and the extreme eastern edge of Iowa. In Peoria, Illinois, there is a moderate risk for long-track, strong tornadoes.
There is potential that an upgrade to a high-risk alert will be coming later Saturday from the National Weather Service Storm Prediction Center.
In the enhanced risk and slight risk areas, tornadoes, damaging winds and large hail will be possible. Regardless of the risk area, some strong tornadoes are possible Saturday. Some of the cities in the enhanced and slight risk areas include Nashville, Little Rock, Arkansas, St. Louis, Chicago and Indianapolis.
Storms will approach the Midwest and Mississippi River valley by mid to late Saturday afternoon. The increased concern will occur later in the evening as we head towards dusk and first couple hours of night, when the low-level jet will strengthen along the cold front. This low-level jet will greatly enhance the shear with the thunderstorms, and allow the storms to rotate. Therefore, there is a possibility of significant severe weather during the night hours Saturday night.
The storm will be sliding eastward on Sunday and some of the severe weather will try to move into parts of Ohio Valley and Western Appalachians. However, the intensity of the storms is expected to decrease with only general thunderstorms expected for now, with a couple of stronger storms possible.
Additionally, some snow will be possible in parts of the upper Midwest, including Duluth, Minnesota and Minneapolis.
By Monday, the storm will have cleared much of the country, with little weather impact remaining.