Severe thunderstorms to target Missouri to Pennsylvania

After severe thunderstorms walloped southern Minnesota with large hail Thursday, the threat for severe thunderstorms will shift eastward and cover a more widespread area through Friday night, AccuWeather meteorologists say.

More than 30 large hail reports were documented across southern Minnesota Thursday. Some of the hailstones that fell were photographed and measured at around 2 to 3 inches in diameter, which is roughly the size of a tennis ball or baseball. Buildings and vehicles were reportedly damaged by hail near the city of Cannon Falls, located about 45 miles southeast of Minneapolis.

More large hail is in the forecast as the thunderstorms spread across the Ohio Valley and middle portion of the Mississippi Valley into Friday evening.

This radar image taken at Friday midday, June 18, 2021, shows thunderstorms (rainbow colors) from southern Iowa and northern Missouri to Ohio. (AccuWeather)

"A storm system is expected to bring showers and thunderstorms to the Midwest into Friday night, some of which can be severe, and produce large hail and damaging wind gusts," said AccuWeather Meteorologist Jessica Storm.

A line of thunderstorms is expected to redevelop during the late afternoon across central Indiana and central Ohio. These storms are then forecast to expand in coverage to include far southern Iowa, northern Missouri and central Illinois by Friday evening. In areas where multiple storms occur, flash flooding may also become a concern.

"Motorists are urged to avoid driving through flooded roadways and utilize the phrase 'turn around, don't drown' when traveling into Friday night," said Storm.

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The risk of tornadoes will be low with this event, but the threat cannot be completely discounted. This will be especially true in northern Ohio, where the morning storms dissipate and new storms develop during the late afternoon.

NOAA's Storm Prediction Center reported a potential wedge tornado near the border of Indiana and Ohio just before 4 p.m. EST, estimated to be about 200 yards wide.

Interstates 55, 70 and 80 could all be impacted by the storms. St. Louis, Indianapolis, Cleveland and Cincinnati are all at risk for severe weather into Friday evening. The threat even extends as far to the east as Pittsburgh.

There is an enhanced risk for severe weather from central Illinois through much of Indiana and Ohio into Friday evening. This covers cities such as Indianapolis, and Cincinnati and Columbus, Ohio. According to the National Weather Service's Storm Prediction Center, about 12.6 million people live in the area covered by the enhanced risk, which is the third-highest threat level for severe weather.

More than 11.5 million are facing a slight risk of severe weather. The slight risk covers cities such as Cleveland and Pittsburgh.

The map above shows the Storm Prediction Center severe weather outlook for Friday, June 18, 2021.

By later Friday night, storms will dive southward into southern Illinois and Indiana and northern Kentucky.

"Storms will shift slightly to the south and east overnight as winds change direction and move in from the west," Storm said.

The threat for severe weather will be lower Saturday, but the risk will still be present. A wide area from New England through the Ohio Valley can experience thunderstorms Saturday. Most of the storms will contain heavy rain, but the strongest storms may contain additional hazards.

The active pattern is expected to continue as storms are forecast to redevelop Saturday from northeastern Indiana to central Pennsylvania. These storms can unleash hail and damaging winds, according to Storm.

Ahead of a cold front, more thunderstorms will be possible Sunday. Iowa, northern and central Missouri and much of Illinois, Indiana and Ohio could have severe weather Sunday.

With some of the same areas at risk for thunderstorms through Sunday, flooding will become a concern. Residents in areas not affected by hail or damaging winds will want to have a plan in place ahead of time in case floodwaters begin to rise.

Gusty storms could potentially reach the East Coast by late or Monday or Tuesday, while areas farther west are finally expected to have dry weather.

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