829
AWUS01 KWNH 270605
FFGMPD
OHZ000-TNZ000-KYZ000-INZ000-ILZ000-MOZ000-ARZ000-271200-
MESOSCALE PRECIPITATION DISCUSSION 0537
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
204 AM EDT SAT JUN 27 2026
AREAS AFFECTED...SOUTHEAST MISSOURI THROUGH EASTERN KENTUCKY
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 270603Z - 271200Z
SUMMARY...EXPANDING SHOWERS AND THUNDERSTORMS WITH RAINFALL RATES
OF 1-2"/HR ARE EXPECTED OVERNIGHT. REPEATING ROUNDS OF CONVECTION
COULD CAUSE 3-4" OF RAIN WITH LOCALLY HIGHER AMOUNTS LEADING TO
INSTANCES OF FLASH FLOODING.
DISCUSSION...THE REGIONAL RADAR MOSAIC HAS SHOWN A SLOW UPTICK IN
HIGH REFLECTIVITY ABOVE 40DBZ THE PAST FEW HOURS FOR PARTS OF
SOUTHERN IN ASSOCIATED WITH INTENSIFYING CONVECTION. AT THE SAME
TIME, LIGHTNINGCAST PROBABILITIES HAVE STEADILY INCREASED AND
EXPANDED, WITH AREAS ABOVE 30% NOW WIDESPREAD FROM EASTERN MO
THROUGH CENTRAL KY. TOGETHER, THIS INDICATES THAT THE ENVIRONMENT
IS BECOMING INCREASINGLY SUPPORTIVE FOR EXPANDING AND INTENSIFYING
CONVECTION WITH RAIN RATES ABOVE 1"/HR AS REFLECTED BY RECENT
HOURLY MRMS MEASUREMENTS.
THE ENVIRONMENT IS STEADILY BECOMING MORE CONDUCIVE TO
INTENSIFYING THUNDERSTORMS. PWS AS MEASURED BY GPS HAVE SURGED TO
1.9-2.1 INCHES, WELL ABOVE THE 90TH PERCENTILE AND APPROACHING
DAILY RECORDS, WITH CONTINUED MOIST ADVECTION ON A SWLY 850MB LLJ
OF 25-30 KTS AS MEASURED VIA REGIONAL VWPS. AT THE SAME TIME,
MUCAPE HAS SLOWLY CLIMBED TO ABOVE 1000 J/KG IN RESPONSE TO THE
THERMODYNAMIC ADVECTION PROVIDED VIA THIS LLJ, CREATING THE
FAVORABLE ENVIRONMENT SUPPORTING THE ONGOING ACTIVITY. FORCING FOR
ASCENT IS SLOWLY INTENSIFYING AS WELL THANKS TO BROAD ISENTROPIC
UPGLIDE OF THE LLJ ATOP A SURFACE TROUGH, AIDED BY CONVERGENCE
ALONG THE NOSE OF THIS LLJ, AND AT LEAST MODEST RRQ DIFFLUENCE
ALOFT SUPPORTING BOTH SYNOPTIC AND MESOSCALE LIFT. A SHORTWAVE
EXITING FROM MO WILL ALSO PROVIDE LOCALLY ENHANCED ASCENT, WHILE
ALSO FORCING SUBTLE ACCELERATION OF THE INFLOW/WAA/THERMODYNAMIC
ADVECTION.
TOGETHER, THIS SUGGESTS THAT THUNDERSTORM COVERAGE WILL EXPAND
RAPIDLY IN THE NEXT FEW HOURS WITHIN THIS WAA, AND THIS IS
SUPPORTED BY RECENT RUNS OF THE HRRR AND RRFS. MUCH OF THIS
ACTIVITY IS PROGGED TO DEVELOP TO THE SW OVER MO/IL AND THEN LIFT
ENE ON 0-6KM MEAN WINDS AROUND 20 KTS. HOWEVER, REGENERATING CELLS
ARE LIKELY WITHIN THE WAA, AND CORFIDI VECTORS FALLING TO 5-10 KTS
AND BECOMING INCREASINGLY ANTI-PARALLEL TO THIS MEAN WIND SUGGEST
BACKBUILDING AND REPEATING OF HEAVY RAIN RATES ARE EXPECTED. THESE
RAIN RATES, WHICH ARE ANTICIPATED TO BE 1-2"/HR, IF NOT LOCALLY
HIGHER, WILL CONTRIBUTE TO TOTAL RAINFALL ACCUMULATION OF 3-4",
WITH HIGHER AMOUNTS POSSIBLE (10-30% CHANCE OF 5"). THIS RAIN
FALLING ATOP VULNERABLE SOILS DUE TO RECENT HEAVY RAIN AND THE
RESULTING EXTREMELY COMPROMISED FFG (AS LOW AS 0.25-0.75"/3HRS)
WILL LIKELY CREATE INSTANCES OF FLASH FLOODING INTO THE MORNING
HOURS.
WEISS
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...ILN...ILX...IND...JKL...LMK...LSX...LZK...MEG...
PAH...RLX...SGF...
ATTN...RFC...MSR...ORN...TIR...NWC...
LAT...LON 39288556 39098392 38668328 38078308 37788345
37558437 37328566 36998688 36788797 36428898
36088982 35989042 36159081 36569121 36979128
37559116 38199068 38558986 38808877 39158717
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