The warmer weather in the mid and eastern part of the United States is also bringing with it a threat for severe thunderstorms by the end of the work week. A powerful low pressure system will push a large mass of strong winds starting Wednesday night over the mid section of the country heading eastward on Thursday. This weather pattern will draw warm, moist air northward out of the Gulf of Mexico to make conditions favorable for a round of severe weather for the Southeast and the Ohio Valley region.
The biggest threat of thunderstorms will start before midnight Wednesday over portions of Kansas and Missouri. Then on Thursday, the Ohio Valley will be under threat for severe weather as will parts of the Mississippi Valley. The largest threat of this system will be strong, damaging winds but it is possible that a few tornadoes form. The National Weather Service stated late Tuesday that there is a risk for tornadoes Thursday in the Southeast and Ohio Valley regions but that a widespread tornado outbreak is unlikely. Instead, there may be a few smaller twisters and especially south of the Ohio River.
The NWS also said that storms may exceed severe storm criteria from near Chicago, IL to Indianapolis and Columbus with the possibility of up to 2-inch sized hail and locally heavy rainfall that could cause flash flooding. And, because the ground is still frozen, there’s a elevated risk of river and stream flooding across the Ohio Valley by the end of the week.
There’s a chance of supercell thunderstorms taking shape from Bowling Green and Louisville, KY and southward to Nashville by Thursday night. This area may see straight-line thunderstorms with 60 to 70 mile per hour winds gusts which can take down trees and powerlines. Large hail is also possible as is tornado activity with smaller twisters more likely to form that larger tornadoes.
While rainfall won’t be heavy enough for widespread river flooding in the Ohio Valley region, the combination of melting snowpack and 1 ½ inches of rain or more could create mild to moderate flooding problems in places like Indianapolis, South Bend and Toledo. Meanwhile, in the Upper Midwest, a snowstorm will dump heavy snowfall with blizzard conditions possible by Thursday evening for Des Moine, Minneapolis/St. Paul, Duluth and the greater portion of western Wisconsin.