Wednesday night’s thunderstorms, not only produced severe weather, with numerous reports of damaging winds and hail, but it also targeted many areas, with blinding and flooding rainfall, with totals exceeding two and locally three inches in many locations.
Tonight, another round of heavy rain is possible, likely affecting locations from extreme northern Illinois north into southern Wisconsin and west into Iowa.
Here is the latest discussion on the heavy rain potential from the Weather Prediction Center.
MESOSCALE PRECIPITATION DISCUSSION 0124 NWS WEATHER PREDICTION CENTER COLLEGE PARK MD 503 PM EDT THU MAY 03 2018 AREAS AFFECTED...EXTREME EASTERN NEB...IA...SOUTHEAST MN...SOUTHERN WI...FAR NORTHERN IL CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE VALID 032100Z - 040300Z May 3 4pm-10pm SUMMARY...SHOWERS AND THUNDERSTORMS WILL BE EXPANDING IN COVERAGE AS LOW PRESSURE APPROACHES FROM THE SOUTHWEST. THE WET ANTECEDENT CONDITIONS MAY RESULT IN SOME FLASH FLOODING CONCERNS THROUGH THE LATE EVENING HOURS. DISCUSSION...THE LATE-AFTERNOON GOES-16 AIRMASS RGB IMAGERY SHOWS THE CLASSIC SIGNATURE OF A DEVELOPING MID LEVEL DEFORMATION ZONE AHEAD OF AN APPROACHING PV ANOMALY ASSOCIATED WITH A STRONG SHORTWAVE TROUGH. ENHANCED MID LEVEL FORCING/DPVA ASSOCIATED WITH THIS WILL INTERACT WITH MOIST SOUTHERLY FLOW AHEAD OF A DEEPENING WAVE OF LOW PRESSURE TO PROMOTE AN EXPANDING AREA OF HEAVY SHOWERS AND THUNDERSTORMS NEAR AND TO THE NORTH OF A WARM FRONT SLOWLY ADVANCING NORTHEAST ACROSS THE MIDWEST. IN FACT...THE LATEST HRRR GUIDANCE FAVORS THE DEVELOPMENT OF A 40 TO 50 KT S/SW LOW LEVEL JET ACROSS THE MID MS VALLEY BETWEEN 00Z AND 03Z WHICH WILL INTERCEPT THE AFOREMENTIONED FRONT AND FAVOR STRENGTHENING LOW LEVEL MOISTURE AND INSTABILITY TRANSPORT FOR MORE ORGANIZED AND LOCALLY FOCUSED CONVECTIVE GROWTH JUST NORTH OF THE FRONT WHERE DEEP LAYER SHOULD BE MAXIMIZED. ALREADY A NOSE OF MLCAPE VALUES OF 500 TO 1000 J/KG HAS NOSED UP ACROSS NORTHWEST MO AND INTO SOUTHERN IA AND IS HELPING TO ALLOW CONVECTION TO BREAK OUT BACK ACROSS FAR EASTERN NEB AND WESTERN IA AT THIS TIME. EXPECT RAINFALL RATES OF AS MUCH AS 1.5 INCHES/HR AND STORM TOTAL AMOUNTS THROUGH 03Z OF AS MUCH AS 2 TO 4 INCHES WITH ISOLATED HEAVIER AMOUNTS NOT OUT OF THE QUESTION. GIVEN THE WET ANTECEDENT CONDITIONS...SOME FLASH FLOODING WILL BE POSSIBLE.