The National Weather Service issued a hazardous weather outlook Saturday for a large area of northern Illinois and Indiana, with a possibility of severe tornadoes Sunday.
The forecast for Sunday includes a cold front moving through the area, possibly in the middle of the Bears-Ravens football game at Soldier Field.
Severe thunderstorms are expected to develop in front of the cold front, with possible damaging winds of more than 70 mph, heavy rain, quarter-size hail and also a chance of tornadoes. Immediately behind the cold front could be winds that gust as high as 45 mph.
Temperatures in Northwest Indiana could drop 30 degrees from a daytime high of about 68 shortly after noon Sunday to dawn Monday.
In outlooks issued Saturday, the NWS upped the probable severity of the storms forecast for Sunday. That included boosting the maximum wind speeds to more than 70 mph from 60 mph and forecasting the possibility of severe tornadoes.
The NWS advises tornadoes have occurred previously in November in the region. Those tornadoes include an F3-level one that hit Lake County late in the afternoon on Nov. 12, 1965. An F3 tornado is on the upper end of the Fujita scale used to measure a tornado's ferocity. An F3 can pack winds up to 165 mph.
On Saturday night, scattered thunderstorms were forecast. But the most severe weather is not expected until early Sunday morning.
The hazardous weather outlook includes Lake, Porter, Newton and Jasper counties in Indiana, and Cook and Will counties in Illinois, among others.
Rainfall totals spanning for the weekend should exceed an inch.