The National Weather Service confirmed touchdowns of one tornado Friday and three on Saturday in northern Illinois and northwest Indiana, as thunderstorms and waves of rain with a possibility of flash flooding are expected again this week.

       One tornado, rated EF-1, occurred in Danforth in Iroquois County on Friday with estimated winds of 95 mph. Three tornadoes, all rated EF-0, were reported in Dyer, Indiana, Crete and Chatsworth with winds of 75 mph, according to Brian Leatherwood of the weather service’s Chicago-area office.

       Scattered thunderstorms, heavy downpours and possible flooding are expected Monday afternoon, with a flash flood watch for areas in northern Illinois and northwest Indiana until Tuesday evening.

       The National Weather Service issued a severe thunderstorm warning Monday afternoon for southeastern Cook County and northern Lake County, Indiana, until 3:45 p.m., including parts of Chicago, Orland Park, Tinley Park and Hammond, Indiana.

       A severe thunderstorm warning was also in effect for areas in northwest Will County, after a severe storm with 60 mph wind gusts was spotted on radar near Crest Hill and Lockport, according to the weather service.

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       The flash flood danger comes from precipitation over the past few days, Leatherwood said.

       “The ground, presently, is very moist. We’re anticipating that it wouldn’t take much rain that falls to saturate the ground,” Leatherwood said.

       Limited thunderstorms are expected to continue throughout the week, until Friday.

       Patterns of thunderstorms and downpours like this are expected in the summertime, Leatherwood said.

       “It’s pretty typical,” Leatherwood said. “We do have rainy Junes and things start slacking off in July, it’s nothing unusual.”

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       The weather service recommends people move indoors when they hear thunder and urges people not to drive on flooded roads.

       The weather service didn’t immediately post details on damage seen from the four tornadoes. It said that while Saturday’s storms produced the first tornado warning issued for downtown Chicago since June 23, 2010, no tornado developed from the storms that hit the city.

       The strongest of the four tornadoes, the one Friday in Danforth, reached a peak wind speed estimated at 95 mph, according to the weather service. The Chatsworth storm hit 80 mph, the Dyer-Schererville storm hit 75 mph and the Crete storm peaked at 70 mph, according to weather service estimates.

       For more details and an updated forecast, check the Tribune’s weather page.

       Check back for updates.

       nagupta@chicagotribune.com

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