SUMMARY...TRAINING RAINFALL WITH RATES OF 1-2 IN/HR SHOULD SLOWLY ADVANCE FROM SRN WI INTO NRN IL THROUGH 12Z. AN ADDITIONAL 2-4 INCHES WILL BE POSSIBLE THROUGH 14Z ALONG WITH POSSIBLE FLASH FLOODING. DISCUSSION...09Z RADAR IMAGERY SHOWED SEVERAL SMALLER CORES OF CONVECTION CONTAINING 1-2 IN/HR RAIN RATES EMBEDDED WITHIN A LARGER SWATH OF PRECIPITATION EXTENDING FROM THE SRN MN/WI BORDER TO NRN IL. THIS REGION OF ELEVATED CONVECTION CONTINUES TO BE ROOTED BETWEEN 700-800 MB...OCCURRING 50-100 MILES NORTHEAST OF A SLOW MOVING SURFACE WARM FRONT ANALYZED NW TO SE THROUGH ERN IA INTO CNTRL IL AT 09Z. RECENT VAD WIND PLOTS FROM KMPX AND KARX SHOWED WLY 700 MB FLOW OF 40-50 KT WHICH CONTINUED TO SUPPLY AMPLE MOISTURE AND INSTABILITY INTO THE CONVECTIVE COMPLEX. EXPERIMENTAL GOES 16 INFRARED IMAGERY OVER THE PAST FEW HOURS HAS SHOWN BURSTS OF COLDER CLOUD TOPS ORIGINATING NEAR THE SRN MN/WI BORDER AND PROPAGATING SEWD INTO SRN WI AND RECENTLY INTO NRN IL. GAUGE AND RADAR ESTIMATES HAVE PLACED 4-7 INCHES OF RAIN OVER THE PAST 12 HOURS ALONG AND JUST EAST OF THE MISSISSIPPI RIVER INTO WRN WI. THE ENTIRE COMPLEX OF RAIN HAS BEEN TRANSLATING SEWD AHEAD OF AN 850 MB COLD FRONT WHICH EXTENDED FROM THE CNTRL U.P. OF MICHIGAN INTO SRN MN BASED ON VAD WIND PLOTS AND RAP ANALYSES AT 09Z. RAINFALL WILL END FROM NW TO SE AHEAD OF THIS STEADILY MOVING BOUNDARY INTO THE REMAINDER OF THE MORNING. MID-UPPER LEVEL DIFFLUENT FLOW WILL REMAIN IN PLACE OVER FAR SRN WI AND NRN IL HELPING TO SUPPORT VERTICAL MOTIONS IN THE PRESENCE OF PRECIPITABLE WATER VALUES NEARING 2 INCHES ALONG THE IA/WI BORDER. WITH LOW LEVEL INFLOW REMAINING STEADY-STATE AND AN ESTIMATED 500-1000 J/KG MUCAPE AVAILABLE FROM WRN WI INTO NRN IL...PER 08Z SPC MESOANALYSIS PAGE...1-2 IN/HR RAINFALL RATES APPEAR LIKELY TO CONTINUE OVER THE NEXT 2-4 HOURS ALONG WITH POSSIBLE FLASH FLOODING.
BULLETIN – IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Chicago/Romeoville Il
348 AM CDT THU JUL 20 2017
The National Weather Service in Chicago has issued a
* Severe Thunderstorm Warning for…
Northeastern Ogle County in north central Illinois…
Northwestern De Kalb County in north central Illinois…
Winnebago County in north central Illinois…
Boone County in north central Illinois…
* Until 430 AM CDT
* At 347 AM CDT, severe thunderstorms were located along a line
extending from near Durand to near German Valley, moving east at 35
HAZARD…60 mph wind gusts and nickel size hail.
IMPACT…Expect damage to roofs, siding, and trees.
* Locations impacted include…
Rockford, Belvidere, Loves Park, Machesney Park, South Beloit,
Rockton, Rockford Airport, Roscoe, Poplar Grove, Byron, Cherry
Valley, Winnebago, Pecatonica, Kirkland, Durand, Capron, Kingston,
Stillman Valley, Timberlane and Caledonia.
Including the following interstates…
I-39 between mile markers 110 and 123.
I-90 between mile markers 1 and 2, and between mile markers 50 and
For your protection move to an interior room on the lowest floor of a
LAT…LON 4249 8871 4203 8877 4216 8956 4220 8954
4220 8940 4250 8940
TIME…MOT…LOC 0847Z 284DEG 29KT 4247 8928 4222 8944