Strong storms bringing heavy rainfall to the Chicago area Sunday night could cause flash flooding, according to the National Weather Service.
Beginning Sunday afternoon, showers and thunderstorms are expected to develop across northwest and north central Illinois ahead of an approaching low pressure system, according to the weather service. The showers and thunderstorms will likely persist into Monday morning while slowly moving east.
A flash flood watch is in effect from 7 p.m. Sunday through Monday morning for all Chicago-area counties, according to the weather service. These slow-moving thunderstorms could drop between 1 and 3 inches of rainfall, and flooding of creeks, streams and low-lying areas is possible.
Sunday will reach a high in the mid- to upper-70s but drop to the mid-50s or lower-60s when thunderstorms roll in during the afternoon, forecasters said. Chance of precipitation is 100 percent.
While thunderstorms are still likely Monday morning, this will taper off to a chance of showers by afternoon. Monday's high temperatures are expected to be in the upper 60s.