CHICAGO — With periods of heavy rain expected to continue, the Flash Flood Watch through Saturday morning has been extended to include all but northernmost counties (green-shaded area on the headlined map). This Watch may well have to be extended time-wise through the weekend.
The nearly stationary upper-air pattern over the U.S. remains unchanged with a low pressure trough over the plains bookended by high pressure ridging along the east and west coasts. Moisture-laden southwest flow will continue with embedded short-wave low pressure disturbances triggering mainly nighttime Mesoscale Convective Systems that will spread waves of showers and thunderstorms over our area.
Thursday night’s complex produced rainfall totals generally in the 0.50 to 2-inch-plus range. While showers could occur at any time under the current weather regime, the next surge of widespread rains will most likely occur again later Friday night into Saturday morning.
The National Weather Prediction Center has included the entire Chicago area in a Slight Risk for Excessive rainfall causing flash-flooding for the 24-hour periods ending 7AM CDT Saturday and Sunday mornings (yellow-shaded areas on maps below). The National Storm Prediction Center has our area in a Marginal Risk for severe storms with the main risk damaging winds during the same 24-hour periods.
For the latest weather updates, go to wgnv.com/weather.