Risk for violent thunderstorms to return to northern US by week’s end

By Kyle Elliott, AccuWeather meteorologist

A vigorous storm system will target parts of the northern Plains and Upper Midwest with strong-to-severe thunderstorms at the end of the week.

“Warm, moist air will flow northward into the northern Plains on Friday and clash with a cold front surging eastward from the Rockies,” AccuWeather Meteorologist Ryan Adamson said.

High temperatures on Friday will resemble those more typically reached in August across the northern United States, while high temperatures on the back side of the cold front will resemble those more typical of October in the Rockies.

These factors will combine to create a threat of widespread, feisty thunderstorms from Friday afternoon into Friday night.

Given the intensity of the cold front and abnormally moist air ahead of it, the threat for severe weather already appears quite high across the region, despite the threat still being three or four days away.

Thunderstorms will likely fire up across the central and eastern Dakotas on Friday afternoon before moving into parts of Minnesota and northwestern Iowa Friday night.

“Heavy rain will be the main threat with the storms, but strong to potentially damaging winds will also be a concern,” according to Adamson.

He added that, if the storms congeal into a powerful squall line, the threat for wind damage will be even greater.

During the first few hours following storm initiation, isolated incidents of large hail and even a brief tornado or two cannot be ruled out. The most likely areas for these threats to unfold will be across the eastern half of the Dakotas.

Cities that lie within the late-week threat zone include Fargo, North Dakota; Aberdeen and Sioux Falls, South Dakota; and Saint Paul, International Falls and potentially Minneapolis, Minnesota.

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Residents should prepare now by having a plan of action ready in case severe weather strikes. Having a mobile device or weather radio handy is a good way to receive severe weather alerts long before violent weather actually arrives.

People are urged to keep an eye on the sky and move indoors when the first rumble of thunder is heard, as it is at this time that lightning is close enough to strike.

In the case that a severe thunderstorm or tornado warning is issued, move indoors and away from doors and windows to minimize the risk of bodily injury. Ideally, take shelter in an interior room or basement to give yourself the maximum amount of protection from objects that could be turned into dangerous projectiles by strong winds.

The violent storms will also threaten to cause widespread tree, roof and property damage and isolated power outages.

In areas where thunderstorms repeat, there may be an enhanced threat for street and small stream flooding. Motorists are reminded to turn around and seek an alternate route if water is covering a roadway.

“The storms will likely continue into Saturday morning before the storm system lifts northward into western Ontario, with dry and much cooler conditions expected in its wake during the second half of the weekend,” Adamson said.

The calm and comfortable weather in the wake of the storms should provide an ideal setting for any cleanup and recovery efforts that ensue.

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