Flooding possible as snow melts, heavy rain moves in; Flood Watch issued
Update 7AM CST…
The Flood Watch for rapid rises and potential flooding on Chicago-area rivers and streams due to heavy rains continues in effect from this Monday evening through Tuesday night. Waves of showers and embedded thunderstorms are expected to surge over the Chicago area moving from southwest to northeast during the next 24 to 48 hours with rainfall totals on the order of 2 to 4-inches at many locations by the time a cold front sweeps through – rain ending from the west Tuesday night. Note the Flood Watch depicted in dark green on the highlighted map extends north into southern Wisconsin and Lower Michigan and east into Indiana.
As the intensifying center of low pressure moves east-northeast over Iowa today with the associated warm front shifting north over our area, temperatures here will warm into the upper 40s north to lower 60s south. The combination of gusty southwest winds, mild temperatures and occasional heavy rains will melt the existing snow cover, and in the process develop spotty dense fog which could create visibility of less than a quarter-mile.
The rapid runoff due to frozen soils will cause localized pooling of water and flooding of low-lying flood-prone area. Rivers should rise with flooding possibly complicated by ice break-up jamming. Flooding will probably continue into the mid-latter part of the week on some of the rivers/streams.
CHICAGO — A Flood Watch issued by the National Weather Service is in effect for the entire Chicago area beginning Monday evening and running through Tuesday night.
A slow-moving low pressure system is forecast to consolidate and intensify over Iowa in the next 24 to 36 hours, tracking east-northeast through northern Illinois and southern Wisconsin.
A series of showers and embedded thunderstorms are expected to develop to our south and surge north through our area beginning Monday morning and continue in waves through Monday and Tuesday into Wednesday morning.
Temperatures will rise into the 60’s at least over portions of the Chicago area Monday and Tuesday, and that along with the periodic heavy rains will quickly melt the existing snow cover. The resulting runoff should cause rapid rises on area rivers and streams and ice jam breakups are also a concern with widespread flooding possibly developing and extending for some time after the rains have ended.