This blog post summarizes the latest forecast for a significant severe weather event unfolding across the central United States.
Forecasters warn of a Level 3 risk for severe thunderstorms from Minneapolis to Green Bay, Wisconsin, with large hail likely to exceed 2 inches late Monday into the evening.
The outlook also includes elevated threats across parts of the Upper Midwest, the Great Plains, and the Midwest.
This is driven by a breaking atmospheric cap and an incoming strong low-pressure system that will enable more intense storms to develop.
Overview of the forecast
As the day progresses, the cap that has kept storm activity in check is forecast to erode.
This will allow a broader swath of thunderstorms to form.
The day-to-day evolution centers on how far storms can surface and how they organize.
Forecasters are also watching where the atmosphere becomes most supportive for damaging winds, large hail, and, in some areas, tornadoes.
In addition to the Level 3 corridor, notable risk is identified for Chicago and Milwaukee with a Level 2 outlook, where large hail is the primary hazard.
A separate Level 2 risk lies along a dryline stretching from central Oklahoma into North Texas, where tornadoes or very large hail are possible.
Level 3 risk corridor: Minneapolis to Green Bay
Key drivers: A strong low-pressure system moves in from the northern Plains while a lingering cap breaks late, removing a major restraint on storm development.
The resulting atmosphere can support more vigorous updrafts and organized storms into the evening hours.
- Large hail greater than 2 inches is possible.
- Tornado potential increases if storms can form closer to the surface along a warm front that drapes through the Level 3 corridor.
- Damaging wind gusts and heavy downpours are also hazards, with the potential for localized flooding in areas that receive repeated downpours.
Level 2 risk: Chicago and Milwaukee metro areas
The urban centers of Illinois and Wisconsin fall under a Level 2 risk where large hail stands out as the primary hazard.
Any storm that can intensify near the surface along a warm front could still pose a brief tornado risk in these metro areas.
- Large hail is the primary concern, with possible numbers large enough to cause property damage and complications for outdoor activities.
- Damaging winds and downpours may accompany storms, contributing to localized travel disruptions.
Level 2 risk: dryline over central Oklahoma and parts of North Texas
A separate but significant risk region exists along the dryline in the southern Plains, where discrete supercells can produce tornadoes or very large hail.
The potential impacts include disruptions to communities around Abilene and the Oklahoma City metro area.
- Tornado potential increases if storms form in a favorable vertical wind shear environment near the dryline.
- Very large hail and damaging winds are possible with stronger cells.
Level 1 flash flood risk: Texas to Michigan
A broad Level 1 flash flood risk covers a corridor spanning from Texas to Michigan.
Repeated heavy rainfall in thunderstorms could lead to localized flooding, road closures, and water-related hazards, particularly in urban areas and places with poor drainage.
- Localized flash flooding is the primary concern, especially where storms train or drop back-to-back heavy downpours.
- Travel disruptions and water ponding on roadways may occur during peak storm periods.
Forecast timeline and impacts
Forecasts indicate the severe weather threat will broaden Tuesday, potentially impacting more than 70 million people from the Big Bend of Texas to Lake Michigan.
The strongest storms are expected to fire across eastern Iowa, southern Wisconsin, and northern Illinois, including the Chicago and Milwaukee metropolitan regions.
Thunderstorms are likely to shift toward the Mississippi River Valley, bringing a combination of damaging winds, large hail, tornadoes, and heavy rainfall of 1–2 inches in many areas.
Safety and preparedness tips
Residents and travelers should stay ahead of the evolving outlook by monitoring local forecasts and having a plan in place.
The following actions can reduce risk during severe weather events:
- Identify the fastest route to a sturdy shelter away from windows in case a warning is issued.
- Keep a weather radio or smartphone alerts active to receive timely warnings and updates.
- Secure outdoor objects that could become projectiles in strong winds, and avoid driving through flooded roadways.
- Prepare an emergency kit with water, nonperishable food, flashlights, and a first-aid kit.
- If you hear a tornado warning, move to a windowless interior room on the lowest level of your building and protect yourself under sturdy furniture.
Why this matters for science and public safety
From a meteorological standpoint, the situation highlights how evolving atmospheric cap dynamics and low-pressure systems interact to produce high-impact weather.
Mesoscale boundaries like warm fronts and drylines also play a crucial role in these events.
For public safety, clear, timely communication about risk levels and expected hazards is essential.
Actionable steps help reduce injuries and damage when severe thunderstorms unfold across urban and rural communities.
Here is the source article for this story: Hail, tornadoes possible across Upper Midwest ahead of multi-day severe weather threat taking aim at 70M+