A “gusty line of showers” was likely to move into the Chicago area Monday evening, with the potential to bring isolated lightning, brief downpours and wind gusts as strong as 40 to 50 mph, according to the National Weather Service.
Earlier in the day, forecasters had warned storms could also bring an isolated tornado, large hail and stronger wind gusts.
“While not the primary hazard, a brief tornado cannot be ruled out. The severe threat may diminish” as the storm moves into northwest Indiana, according to the weather service.
Most of northern Illinois could see heavy downpours, lightning strikes and some high winds, but the highest chance for more severe weather was expected to be outside the immediate Chicago area, forecasters said midday.
Hail and “a tornado or two” were more likely in an area mostly south of Interstate 80, stretching from Kankakee west toward Ottawa, with the southwest tip of Will County expected to be in the higher-risk zone, according to the weather service.
Storms Monday evening in central Illinois, near Springfield and Decatur, brought reports of hail and “brief tornado touchdowns,” the weather service in Lincoln reported.
Forecasters earlier said the thunderstorms could be “strong to severe,” and suggested residents of northern Illinois should have two methods for receiving severe weather notifications, one of which ideally would include a battery-operated radio or charged cellphone in case the power goes out as a result of the weather or tree limbs were downed by the powerful wind gusts.
According to the weather service, the adverse weather was likely to move into northern Illinois between 4 and 10 p.m. The system would approach from the west and was likely to affect outlying suburbs to the west and north before the more immediate Chicago area.
In the 8 to 10 p.m. range, areas such as DeKalb, Ottawa and Rockford were expected to clear up, while Chicago and northwest Indiana would still be in the storm’s path, according to an approximate timeline graphic released by meteorologists.
Light rain could persist Tuesday, particularly in the morning.
“Isolated thunderstorms are possible on Tuesday and again Thursday afternoon,” according to the weather service.
After a daytime high temperature approaching the mid- to upper 70s Monday, the rest of the week could “then trend cooler,” meteorologists said.
Tuesday, Wednesday and Thursday all are forecast to have a high temperature in the low 50s to low 60s. Overnight temperatures could drop as low as the upper 30s.
Visit the Tribune’s weather page for more information and check back for updates.