'Dangerous' severe weather event forecast for Midwest
Storms rolled through Ontario and Michigan on July 20, making their way into the Northeast.
Severe thunderstorm activity has been spotty in recent days as stifling heat has baked the East Coast and southern Plains, but AccuWeather meteorologists say a notable change in that pattern is expected by Saturday.
"The atmospheric setup on Saturday could result in a dangerous severe weather event," said AccuWeather Meteorologist La Troy Thornton.
Storms are forecast to develop by the early afternoon from central Minnesota to northern Wisconsin. The thunderstorms will quickly strengthen, with Minneapolis one of the first major cities in line for severe weather. As the storms progress to the south and east, they will intensify further, and all hazards will be possible.
"Thunderstorms with the potential to produce damaging wind gusts, locally large hail and isolated tornadoes could occur on Saturday," stated Thornton.
The highest tornado threat will occur as storms initially form. This will be due to the fact that storms are likely to be discrete cells as they first develop. If the storms are far enough apart, they will not interfere with each other and could begin to spin.
Another aspect of potential tornado formation is wind shear, which is the change in speed and direction of breezes at different levels of the atmosphere above the ground. When winds shift direction and increase in speed from near the ground to a mile or two up in the atmosphere, individual thunderstorms can begin to rotate and have a higher probability of producing damaging wind gusts and tornadoes.
Damaging wind gusts, hail and tornadoes will not be the only risks with the storms.
An unusually high amount of moisture could cause some of the storms to cause flash flooding, according to Thornton.
This will be especially true if multiple storms move over the same area, but even a single storm can drop heavy rain in a short period of time, which can also result in flooding.
The storms will continue eastward late in the afternoon and into the evening. As of Thursday, meteorologists say there is some question as to just how far south the storms will get. Even with some uncertainty, it looks likely that cities such as Minneapolis and Madison and Green Bay, Wisconsin, are just a couple of locations with a higher possibility of volatile storms. However, it would not take much of a shift in the pattern to send severe storms with high winds and flash flooding into the Chicago and/or Detroit metro areas.
The storms are then expected to cross Lake Michigan and move into the Lower Peninsula of Michigan overnight as the thunderstorms move eastward.
"With this threat likely continuing into the night, residents must have a way to be awoken and alerted if a severe thunderstorm or tornado warning is issued," said Thornton, who added that residents should also have a severe weather plan in place.
The main atmospheric energy will be moving into Canada on Sunday so the severe threat will be lower for the second half of the weekend, AccuWeather meteorologists say.
However, a cold front attached to a storm in Canada could cause some drenching thunderstorms on Sunday from western New York down through northwestern Pennsylvania and over central portions of Ohio, Indiana and Illinois. That cold front will eventually reach the East Coast and break the heat wave along part of the I-95 corridor by Monday or Tuesday of next week.
Want next-level safety, ad-free? Unlock advanced, hyperlocal severe weather alerts when you subscribe to Premium+ on the AccuWeather app. AccuWeather Alerts™ are prompted by our expert meteorologists who monitor and analyze dangerous weather risks 24/7 to keep you and your family safer.
Report a Typo
