Flash flood watch issued for Chicago area ahead of Tuesday thunderstorms

A flash flood watch was issued for the Chicago area as two rounds of thunderstorms were expected to move through the region on Tuesday.

Isolated or scattered “non-severe” thunderstorms were expected Tuesday morning, according to a hazardous weather outlook from the National Weather Service. A second round of storms will form over eastern Iowa Tuesday afternoon and could spread east into northern Illinois throughout the evening.

The evening storms “will be capable of being severe with strong winds and possibly some hail being the main threats,” the weather service said. Winds could reach 60 to 70 mph and hail up to the size of a quarter could develop.

A flash flood watch was in effect for north central and northeast Illinois from 1 p.m. to 1 a.m. Wednesday, the weather service said. Rivers and streams in the area are running high and the ground remains moist from recent rainfall, so any additional rain could quickly turn into runoff.

Another flash flood watch was in effect on Friday, when the CTA Yellow Line was halted for nearly two hours because of water on the tracks in north suburban Skokie.

Chicago has seen more rain since May 1 this year than the same period in any year since 1871, when officials started keeping records.

A high of 79 degrees is forecast for Tuesday and Wednesday before temperatures start to climb again at the end of the week, according to the weather service. Thursday was expected to see a high of 88, while temperatures on Friday and Saturday could reach 95. The humidity could make it feel like 110 degrees on Friday, while the heat index on Saturday could reach 109.