Severe thunderstorm risk to stretch from Midwest to Northeast

A swath from the Midwest to Northeast will have a risk of severe weather to start the week before becoming confined more to the East by midweek.

Key Takeaways:

• Thunderstorms this week will rumble from the Midwest to Northeast into Tuesday before becoming more confined to the East by Wednesday.

• In the wake of the storms, much cooler and less humid air will move into the Midwest, Great Lakes and Northeast.

• The cold front responsible for the storms and cooler air will stall in the Southeast late this week.

The likelihood of thunderstorms, some packing severe weather, will expand from the Midwest to the Northeast into Tuesday, before departing from west to to east from Wednesday to Thursday. The storms will be locally damaging and disruptive, AccuWeather meteorologists warn.

Midwest risk continues through Monday night

A cold front that is a focus for the showers and thunderstorms will move southeastward through the Midwest during the first part of this week.

After a couple of rounds of severe weather over the weekend, thunderstorms became more spotty in nature by Monday morning from northern Minnesota to southern Minnesota and parts of South Dakota, but they will reorganize and trend severe as they progress eastward into Monday night. New storms will erupt ahead of the advancing line and may not weaken after sunset.

"The storms in Milwaukee and Chicago will be closer to the evening commute, and much of Michigan and Indiana, including Detroit and Indianapolis, will have their highest risk of severe thunderstorms during the overnight hours," explained AccuWeather Meteorologist Tyler Roys.

Like the storms Sunday, the thunderstorms at the start of the week will be capable of all severe hazards. This includes destructive winds, hail, flash flooding and isolated tornadoes.

Derecho risk Monday night to Tuesday morning in Midwest

As AccuWeather meteorologists mentioned last week for the particular weather pattern, there is the potential for a long-lived severe thunderstorm complex packing high wind gusts. When these complexes cover a distance of 400 miles with consistent high winds or wind damage incidents, a derecho may be declared by the National Weather Service.

“Storms that erupt Monday night in parts of Iowa, Missouri and Illinois and roll into Indiana Monday night could evolve into a derecho,” AccuWeather Chief Meteorologist Jon Porter warned.

The developing system may pass near Chicago and Milwaukee Monday night and there is the risk of the thunderstorm complex pushing all the way to the Ohio River as a derecho into Tuesday morning.

In the past, derecho events have resulted in considerable crop and property damage and triggered long-lasting regional power outages.

Thunderstorms in the Northeast

Farther to the east, only a few spotty thunderstorms developed over the weekend. AccuWeather meteorologists are concerned for a more widespread risk of severe weather into midweek.

"Across the Northeast, thunderstorms will have plenty of heat and humidity to work with along with energy that may be left over from the storms that affected the Ohio Valley on Sunday," explained Roys.

The chance for hail and tornadoes is negligible in the Northeast, with Roys highlighting damaging winds and downpours as the main hazards. Furthermore, the cities along the coast may largely be spared from the severe weather.

"The cities on the I-95 corridor could have thunderstorms, but the suburbs to their north and west will be more likely to have potentially severe thunderstorms on Monday," noted Roys.

Tuesday

Cooler and drier air will arrive in the wake of the cold front Tuesday, finally ending the threat of thunderstorms in Minnesota and Wisconsin. However, the hot and humid air and the east-advancing cold front will continue the severe thunderstorm risk farther to the south and east.

"The strongest storms will be from central Illinois to northwestern Ohio, where storms will be capable of producing flooding downpours, damaging wind gusts and hail," outlined Roys.

Another pocket with more extensive coverage of severe weather will exist over parts of upstate New York on Tuesday.

Outside of these zones, there will still be some risk of severe weather.

Regarding the heat, the exact timing of thunderstorms will impact high temperatures. Roys mentioned that places like St. Louis, Pittsburgh and Scranton, Pennsylvania, and Albany, New York, may run a bit lower than forecast if any thunderstorms occur in those locations before the late afternoon.

Wednesday

The Midwest will catch a break by Wednesday as the cold front moves to the East Coast.

"The cold front moving into a very hot and very muggy air mass in the northern Tennessee Valley and into the Northeast and mid-Atlantic will lead to explosive thunderstorm development," explained Roys.

AccuWeather experts are honing in on a zone from southern Maine to northern Virginia for the highest potential for severe weather at midweek. A large zone outside of that, stretching as far west as central and southern Missouri and as far south as South Carolina, will have some risk for severe weather Wednesday.

"This time, the big cities from Washington, D.C., to Boston are likely to have storms during the afternoon commute or in the early-evening hours, snarling travel for those driving home," said Roys.

In the wake of the front, widespread lower humidity and temperatures below the historical average will grace the Midwest, Great Lakes and interior Northeast Wednesday into Thursday. Just how far the front advances will affect the degree of air mass change along the East Coast. Even there, cooler and less humid air should arrive by Thursday night and Friday.

Late Week

"It may take an extra day [Thursday] for showers and thunderstorms to depart coastal areas of New England and the mid-Atlantic, as the front's forward speed may slow down," AccuWeather Senior Meteorologist Alex Sosnowski said, "This may delay the humidity drop until Thursday evening for these same areas."

As is typical in the summer, the cold front will eventually slow down and stall as it moves into the Southeast. This will set up a zone of potential downpours. This could cause instances of flooding, but much of the region is also in a drought. Therefore, the rain will largely be beneficial in the grand scheme of things.

The risk of severe thunderstorms will be lower late this week, but locally gusty storms are possible. AccuWeather meteorologists will continue to monitor this potential through the week, but the main hazard is likely to be heavy rain.