A severe thunderstorm watch was issued for Jasper and Newton counties in Indiana and Ford and Iroquois counties in Illinois until 7 p.m.
Scattered showers became more numerous during the late morning and were expected to continue into the early afternoon, as a cold front sweeps across the area, meteorologist Greg Dutra said.
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There is a chance some storms could become severe in northwest Indiana; the main threat would be high winds, but a brief tornado cannot be ruled out, Dutra said.
If severe storms do occur, they will quickly exit the area.
Much cooler air is behind the front, with highs almost 20 degrees cooler than normal.