Sunday, September 2, 2018

Heavy Rainfall and Localized Flash Flooding Possible through Monday Morning

Over the past 24-36 hours, radar estimates of 3-6 inches of rain has fallen over parts of northern Illinois, with an additional 1-2 inches falling Sunday evening and night.  Flash Flood Watches continue for parts of northern Illinois until Monday.

(8:05:23 PM) nwsbot: Local Storm Report by NWS DVN: 4 NNE Stockton [Jo Daviess Co, IL] trained spotter reports HEAVY RAIN of M1.14 INCH at 08:01 PM CDT -- 3 hour rainfall total. 6.39 inches has fallen in the last 36 hours.

A line of thunderstorms extending from near Elkhorn, WI to Forreston, IL will continue to move east around 30-35 mph.  Non-severe at the moment, but gusty winds will be felt ahead of the main line.  These storms have been very efficient at producing heavy rainfall, as seen with the storm report below.  Biggest threats remain heavy rainfall, followed by a lower end strong wind threat through Sunday evening.

 (6:47:22 PM) nwsbot: Local Storm Report by NWS DVN: Freeport [Stephenson Co, IL] trained spotter reports HEAVY RAIN of M1.00 INCH at 06:46 PM CDT -- 30 minute rainfall.

A Flash Flood Watch has been issued once again for the following counties in Illinois: Jo Daviess, Carroll, Whiteside, Stephenson, Winnebago, Ogle, Boone and McHenry.  While most of Sunday afternoon was dry and warm, thunderstorms are increasing in coverage from the northwest.  Storms over northeast Iowa and southwest Wisconsin were severe, producing damaging wind gusts, but locally our overall severe threat remains low.  A few of the stronger storms could produce locally strong winds, but heavy rainfall remains the biggest concern.

Thunderstorms Saturday night produced anywhere from one to three inches of rain.  An additional one to three inches of rain could occur between Sunday evening and early Monday morning.  A lot of rain soaked areas had quite a bit of standing water from Saturday night's thunderstorms and will likely experience more through Monday.  Localized flash flooding is possible.

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