ILLINOIS — The National Weather Service’s Storm Prediction Center has placed portions of Illinois under a Slight Risk (Level 2 of 5)for severe thunderstorms Thursday afternoon into early evening.
Forecasters say strong to severe storms are expected to develop across parts of the middle Mississippi Valley, including western, central and southern Illinois, as a powerful storm system moves from the Plains into the Midwest.
Storm Threat Details
According to the outlook, thunderstorms that develop Thursday could produce:
- Damaging wind gusts
- Large hail
- A few tornadoes
A strengthening area of low pressure is forecast to move from the Plains toward the Great Lakes by early Friday. As it approaches Illinois, increasing moisture and daytime heating will help fuel storm development.
Although moisture levels are expected to be somewhat limited for this time of year, cooling temperatures in the mid-levels of the atmosphere and strong wind energy aloft will create favorable conditions for rotating storms. Wind speeds above the surface are expected to exceed 100 mph in some areas, producing strong wind shear — a key ingredient for severe thunderstorms.
Storms are expected to develop first in eastern Missouri and move quickly eastward into Illinois by mid to late afternoon. Some storms may take on a supercell structure, which increases the potential for large hail and tornadoes.
Strong low-level wind shear, particularly near any warm front, could enhance the tornado threat in parts of the state.
Timing and Impacts
The greatest threat in Illinois appears to be Thursday afternoon into early evening, with storms gradually weakening later at night as they push farther east.
Potential impacts include:
- Downed trees and power lines
- Scattered power outages
- Damage to roofs, siding and vehicles from hail
- Isolated tornado damage
Forecasters note that while atmospheric instability will not be extreme, the strong wind dynamics mean even modest storms could intensify quickly.
Possible School Impacts
Because the timing of the storms overlaps with typical school dismissal hours, districts across Illinois may need to monitor conditions closely.
If warnings are issued during dismissal, schools could:
- Hold students in place until storms pass
- Delay bus routes
- Cancel after-school sports and activities
- Consider early dismissal if forecast confidence increases
Additionally, any overnight power outages or storm damage could result in delayed starts or closures Friday morning in affected communities.
Officials encourage residents to stay weather-aware Thursday and ensure they have multiple ways to receive emergency alerts.
