Tornado outbreak possible in Chicago area Thursday, with highest threat in west suburbs

Another day of severe weather in Chicago is expected Thursday, with a high possibility of a dangerous tornado outbreak in the afternoon and evening.

The Chicago area has been upgraded to a Level 4 out of 5 risk for severe storms. The National Weather Service warns that the threat for tornadoes is notably higher Thursday than typical during severe weather events, and the threat of more dangerous and violent tornadoes is also enhanced. It is very important to be weather aware Thursday, and prepared to seek shelter immediately if a tornado warning is issued when there is potential for violent tornadoes.

This is Chicago's first 4 out of 5 risk since July 15, 2024, when the area saw a record tornado outbreak with 32 touchdowns. This level of risk is typically seen once every two years. 

The biggest threats are for destructive winds, large hail, flash flooding and strong tornadoes. A Flood Watch has been issued for the entire Chicago area and Lake and Porter counties in Indiana until 11 p.m.

A first round of storms is expected from midday to early afternoon, until about 3 p.m., but are likely to be more scattered and significantly less severe. 

Ground stops were issued at both O'Hare and Midway international airports until 1:15 p.m. as the first round of storms began sweeping in.

The much greater danger is in the afternoon and evening, primarily between 4 p.m. and 8 p.m., as heat, humidity, and strong winds in the atmosphere combine to create an environment favorable for significant severe weather.

The worst storms are expected to develop to our west and move into the area between about 4 p.m. and 11 p.m. These storms have the potential to produce damaging winds, large hail, and tornadoes. The greatest risk for tornadoes is between 4 p.m. and 8 p.m.

The National Weather Service said an outbreak of tornadoes should be expected, and will be widespread across the area but with the highest risk in the western suburbs. Thy 

How to stay safe during a tornado warning

The NWS issues a tornado watch when conditions are right for a tornado to form in an area, and a tornado warning when a tornado has been spotted or indicated by radar. 

If a tornado warning is issued for your area, you should take immediate steps to protect yourself, your family and your pets. When a tornado warning is issued:

• Immediately seek shelter in your basement or the lowest floor of your home or building in an interior room without windows. In general, put as many walls between yourself and the outside as possible, and do everything you can to avoid windows.
• In homes or public buildings, if you do not have or have access to a basement, go to a small interior room like a bathroom, closet or interior hallway on the lowest level you can access. Close all doors to the hallway for more protection and if possible get under something sturdy. The National Weather Service advises using things like pillows, blankets and quilts to protect yourself from flying debris, or if you have a motorcycle or bicycle helmet you can wear that.
• If you are in a mobile home, leave in advance of the weather and take shelter for the duration of a storm in a sturdy building. 
• If you are outside, in a vehicle, or don't have access to a sturdy building, get into the nearest ditch, low spot or underground culvert, lay down flat on your belly and cover your head with your hands for protection. Do not take shelter under highway overpasses; tunneling effects can actually increase wind speeds. 
• In general, stay away from doors, windows, outside walls and protect your head. 

It's advisable to keep your phone charged in anticipation of severe weather and put together a small kit with water, flashlights, a radio, and any vital medications in case you need to take shelter for a longer period. Because the risk of wind damage and power outages is so high Thursday, it's also advised 

Chicago area still cleaning up after Wednesday storms

All this is happening on the heels of a day where storms wreaked havoc all around the Chicago area, pulling down trees and power lines and leaving hundreds of thousands of customers without power.

ComEd has reported over 5,600 active outages as of Thursday morning, with nearly 200,000 customers impacted. 

ComEd expected 80% of the outages to be restored by 11 p.m. this coming Saturday.  Customers can check for alerts on the ComEd website.

Meanwhile, large trees came down all around the Chicago area. There were also reports of lightning striking a house in Orland Park, and strong winds tearing parts of a roof off a building in Stickney.

Conditions improve Friday with sunshine returning, as well as lower humidity. The nice weather continues into the weekend. There's an additional chance for thunderstorms late Saturday; those storms could turn severe with hail and wind as the main threats.