MINNEAPOLIS – Those in the Upper Midwest must keep their eyes on the skies and their ears to their favorite weather alerts Thursday as a round of severe thunderstorms threatens the region.
Ferocious wind gusts and large hail are expected on a day that, in between storms, will feel around 100 degrees, if not hotter in parts of the threatened region.
While some thunderstorms were already roaming the region Thursday morning, they will strengthen into the afternoon along a frontal boundary in north-central Minnesota into northwestern Wisconsin.
The initial storms will be more individual in nature and carry a large hail risk in addition to heavy rains and frequent lightning. But thunderstorms are expected to congeal into a line later in the afternoon and evening and form a more damaging wind threat that will sweep through the region into Thursday night.
NOAA‘s Storm Prediction Center has put a swath of southern Minnesota and northern Wisconsin in a Level 2 of their 5-point severe weather risk scale.
Generally, areas in the threat zone have the potential to see severe thunderstorms with gusts to 60 mph and quarter-sized hail, but SPC forecasters have indicated a more significant threat of more enhanced storms around the Minneapolis area into northwestern Wisconsin that could see wind gusts to 75 mph or more with golf-ball sized hail.
An isolated tornado is possible as well.
A lower Level 1 risk of severe thunderstorms extends south into Iowa and southern Wisconsin.
In addition to the storm threat, heat will be an issue Thursday. Heat Advisories are in effect along the southern boundary of the severe weather threat Thursday, with Excessive Heat Warnings posted for the greater Minneapolis-St. Paul Metro area.
Temperatures in the 90s will combine with high humidity to push heat index values well over 100, perhaps as high as 105 in some areas.
With a damaging wind threat looming in severe storms Thursday afternoon and evening, power outages are possible in the region, cutting off access to cooling fans and air conditioning.
Temperatures won’t be quite as hot in northern Minnesota and northern Wisconsin, with highs forecast to reach the mid-upper 80s.
The severe thunderstorm and damaging wind threat will carry through Thursday night into southern Wisconsin and even into northern Illinois, but storms may weaken enough to reduce the threat of impacts overnight.
As this complex of storms continues to trek to the east-southeast, the severe weather threat renews with daytime warming Friday farther south into the mid-Mississippi Valley and Upper Great Lakes, with Chicago and Milwaukee among the areas inside a Level 2 severe weather threat.
Storms will likely move into the lower Great Lakes late Friday night into Saturday morning, according to the FOX Forecast Center. Again, damaging wind gusts and large hail are the primary threats from these storms.