082
AWUS01 KWNH 280820
FFGMPD
VAZ000-NCZ000-TNZ000-KYZ000-INZ000-ILZ000-MOZ000-281400-
MESOSCALE PRECIPITATION DISCUSSION 0544
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
418 AM EDT SUN JUN 28 2026
AREAS AFFECTED...FAR EASTERN MISSOURI SOUTHEAST THROUGH EASTERN
TENNESSEE
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 280818Z - 281400Z
SUMMARY...SHOWERS AND THUNDERSTORMS WILL EXPAND AND TRAIN
SOUTHEAST THROUGH THE MORNING. RAINFALL RATES OF 1-2"/HR ARE
EXPECTED, LEADING TO A CORRIDOR OF 2-4" OF RAIN WITH LOCALLY
HIGHER AMOUNTS POSSIBLE. THIS WILL LIKELY LEAD TO INSTANCES OF
FLASH FLOODING.
DISCUSSION...THE REGIONAL RADAR MOSAIC EARLY THIS MORNING SHOWS
RAPIDLY EXPANDING CONVECTION ORGANIZING ALONG A LINE FROM NEAR ST.
LOUIS, MO SOUTHEAST TO NEAR KNOXVILLE, TN. THIS CONVECTION IS
INTENSIFYING ALONG A WEAK SURFACE TROUGH AND AIDED BY IMPRESSIVE
ASCENT DOWNSTREAM OF A CONVECTIVELY INDUCED SHORTWAVE LIFTING
THROUGH WESTERN KY, WHICH IS OVERLAPPING THE ISENTROPIC ASCENT
DRIVEN BY THE 30 KT WSW 850MB LLJ. THIS LLJ IS ALSO ADVECTING
ELEVATED THERMODYNAMICS (PWS OVER 2" AND MUCAPE 1000-2000 J/KG)
NORTHEASTWARD TO SUPPORT HEAVY RAIN RATES. RECENT HOURLY RAINFALL
MEASURED VIA MRMS HAS BEEN AS HIGH AS 1.5" IN PARTS OF EASTERN TN.
THE HIGH-RES CAMS ARE STRUGGLING WITH THE CURRENT EVOLUTION, BUT
THE MOST RECENT HRRR HAS FINALLY STARTED TO CAPTURE THE ONGOING
CONVECTION. REGARDLESS OF THE CAM OUTPUT, THERE IS HIGH CONFIDENCE
THAT CONVECTION WILL CONTINUE TO BLOSSOM AS EVIDENCED BY A STEADY
SURGE IN COVERAGE AND PROBABILITY WITHIN THE LIGHTNINGCAST
PRODUCT. AS THE LLJ IS EXPECTED TO ONLY GRADUALLY VEER THROUGH
MORNING, IT WILL MAINTAIN POTENT THERMODYNAMIC ADVECTION TO
SUPPORT REGENERATING AND INTENSIFYING THUNDERSTORMS. DESPITE
MODEST CAM AGREEMENT, HREF AND REFS PROBABILITIES FOR 1"/HR
(2"/HR) RAIN RATES INCREASE TO 50-70% (10-20%) THROUGH MORNING.
THESE STORMS ARE EXPECTED TO TRAIN SW TO NE ALONG THE WEAK SURFACE
BOUNDARY THANKS TO NEARLY PARALLEL MEAN 0-6KM WINDS, WITH THE
VEERING OF THE LLJ CAUSING CORFIDI VECTOR COLLAPSE TO AROUND 5 KTS
SUGGESTING AN INCREASED RISK FOR BACKBUILDING INTO THE GREATER
INSTABILITY. TOGETHER, THIS POSES A STRONG TRAINING MECHANISM TO
CREATE CORRIDORS OF RAINFALL EXCEEDING 3" (40% CHANCE) WITH
ISOLATED TOTALS APPROACHING 5" POSSIBLE (10-20% CHANCE).
TRAINING OF THESE INTENSE RAIN RATES WILL POSE A FLASH FLOOD RISK
FOR THE NEXT SEVERAL HOURS. HOWEVER, THIS THREAT IS MADE EVEN
GREATER BY EXTREMELY VULNERABLE SOILS DUE TO RECENT HEAVY
RAINFALL. 3-HR FFG IS AS LOW AS 0.25" IN SOME AREAS, AND BROADLY
LESS THAN 1", FOR WHICH THE HREF INDICATES HAS A 60-80% CHANCE OF
EXCEEDANCE. ADDITIONALLY, THIS REGION HAS SENSITIVE TERRAIN THAT
MAKES IT EVEN MORE VULNERABLE TO FLASH FLOODING, SO ANY TRAINING
DURING THE NEXT SEVERAL HOURS WILL LIKELY RESULT IN FLASH FLOOD
IMPACTS.
WEISS
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...GSP...ILX...IND...JKL...LMK...LSX...MRX...OHX...
PAH...
ATTN...RFC...KRF...MSR...ORN...TIR...NWC...
LAT...LON 39478970 39148851 38598654 38218526 37868440
37108305 36518268 35958281 35568340 35448436
35898580 36658734 37248886 37909025 38959173
39429135
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page