786
AWUS01 KWNH 272137
FFGMPD
INZ000-ILZ000-MOZ000-280200-
MESOSCALE PRECIPITATION DISCUSSION 0142
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
537 PM EDT MON APR 27 2026
AREAS AFFECTED...CENTRAL AND NORTHEAST IL...FAR NORTHEAST MO...FAR
NORTHWEST IND...
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 272140Z - 280200Z
SUMMARY...ELEVATED CONVECTION WITH CAPABILITY OF 1.5"/HR RATES AND
TOTALS UP TO 2.5" DUE TO SHORT-TERM REPEATING ACROSS RECENTLY
SATURATED/LOW FFG SOILS POSE POSSIBLE LOCALIZED FLASH FLOODING
RISK, ESPECIALLY NEAR PRONE URBAN CENTERS.
DISCUSSION...GOES-WV SHOWS SHORTWAVE AT THE BASE OF MEAN LONGWAVE
TROUGH OVER THE NEB/IA/MO/KS INTERSECTION LIFTING NORTHEAST
PROVIDING SOLID DPVA ALONG AND DOWNSTREAM IN NORTHERN MO. LOW
LEVEL JET RESPONSE HAS BEEN TO LIFT THE OLD OUTFLOW BOUNDARY/FRONT
NORTHWARD OVER THE LAST FEW HOURS WITH SOLID BOUNDARY LAYER WAA
CONFLUENT ALONG THE UPWIND EDGE OF A OLD SURFACE PRESSURE
TROUGH/CONVERGENCE AXIS FROM KEOKUK NORTH THROUGH SW WI. AS SUCH,
THETA-E ASCENT ALONG WITH SOME INSOLATION RECOVERY OVER CENTRAL IL
HAS SEEN A NARROW WEDGE OF INCREASING MLCAPE TO 2000-2500 J/KG
INTO FAR NE MO ALONG THE PRESSURE TROUGH BUT WELL AHEAD OF THE
APPROACHING COLD FRONT. SOUTHEASTERLY SURFACE FLOW WITH TDS IN
THE THE LOW 60S COMBINED WITH THE SOUTHERLY 925-850MB PROVING
SUFFICIENT MOISTURE FLUX AS WELL TO FEED DEVELOPING THUNDERSTORMS
ALONG THIS AXIS.
HI-RES CAMS INCLUDING THE 18Z NAM-NEST HAVE SHOWN A STEADY
INCREASING TREND TO CONVECTIVE VIGOR AND COVERAGE INTO CENTRAL IL
TOWARD THE EVENING. RATES OF 1-1.5"/HR ARE EXPECTED GIVEN THE
STRENGTHENING MOISTURE FLUX CONVERGENCE IN THE SHARPENING
DEFORMATION ZONE/NORTH OF THE MAIN FRONT AHEAD OF THE HEIGHT-FALL
MAXIMUM. CELLS WILL BE FASTER MOVING ALONG THE NOSE OF THE 110KT
JET STREAK BUT SHOULD BE ALIGNED FOR AN HOUR OR SO, BEFORE
EASTWARD PROPAGATION STOPS THE SHORT-TERM TRAINING. SHORT-TERM
TOTALS SHOULD BE 1-1.5" BUT IN THESE STREAKS OF SHORT-TERM CORE
TRAINING (ESPECIALLY OVER THE NEXT FEW HOURS), A SPOT OR TWO OF
2.5" COULD BE POSSIBLE. OVERALL, THE GROUNDS HAD LOWER FFG DUE TO
HIGHER SEASONAL RAINS, BUT THIS MORNING'S MCS HELPED TO SATURATE
THE UPPER SOILS, SO CAPACITY IS SLIGHTLY REDUCED. FFG VALUES OF
1-1.5"/HR AND LESS THAN 2"/3HR (ESPECIALLY FURTHER SOUTH ACROSS
CENTRAL IL) REMAIN POSSIBLE TO BE EXCEEDED OVER THE NEXT FEW
HOURS. ADDITIONALLY, THERE IS A LOWER POSSIBILITY THAT CELLS MAY
MAINTAIN OR BUILD FAR ENOUGH NORTH BEFORE THE HEIGHT-FALLS/COLD
FRONT WASH OVER THAT SUB-URBAN AND SOUTHERN CHICAGOLAND MAY SEE
THESE QUICK HITTING SUB-HOURLY 1"+ TOTALS, WHICH HAS TYPICALLY
BEEN AN ISSUE FOR URBAN FLOODING AS WELL.
GALLINA
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...DVN...ILX...IND...IWX...LOT...LSX...
ATTN...RFC...MSR...TIR...NWC...
LAT...LON 42058784 41588676 40918642 40278668 39628790
39538839 39449018 39319217 40639101 41588936
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