438
AWUS01 KWNH 120712
FFGMPD
VAZ000-OHZ000-TNZ000-KYZ000-INZ000-121311-
MESOSCALE PRECIPITATION DISCUSSION 1020
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
311 AM EDT WED AUG 12 2026
AREAS AFFECTED...IN INTO EASTERN TN
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 120711Z - 121311Z
SUMMARY...A BROADENING AREA OF THUNDERSTORMS IN EASTERN IN IS
EXPECTED TO SHIFT SOUTH-SOUTHEAST WITH TIME. HOURLY RAIN AMOUNTS
TO 2.5" WITH ADDITIONAL LOCAL TOTALS TO 5" SHOULD CAUSE AT LEAST
SCATTERED OCCURRENCES OF FLASH FLOODING.
DISCUSSION...A BROADENING AREA OF ELEVATED CONVECTION EXISTS
ACROSS EASTERN IN AT THE PRESENT TIME TO THE EAST OF AN OUTFLOW
BOUNDARY/THERMAL GRADIENT ACROSS CENTRAL AND EASTERN IL. IT HAS
DEVELOPED QUICKER THAN THE MESOSCALE GUIDANCE HAS SUGGESTED AND
ALSO HAS EXTENDED MORE SOUTHWARD THAN FORECAST. IT IS WITHIN AN
AREA OF MOISTURE GRADIENT WHICH EXTENDS SOUTH FROM MICHIGAN AND
WITHIN A REGION OF CONFLUENT WESTERLY FLOW AT 850 HPA. HOURLY
RAIN AMOUNTS PER RADAR IMAGERY HAVE BROACHED 2" AT TIMES.
PRECIPITABLE WATER VALUES OF ~1.8" LIE WEST OF THE COMPLEX. MU
CAPE IS 3000-4000 J/KG ACROSS CENTRAL IN. EFFECTIVE BULK SHEAR OF
~30 KTS HAS ORGANIZED THE BAND.
THE 00Z HREF, OTHER THAN BEING A LITTLE SLOW IN ITS SOUTHWARD
ADVANCE, HAS DONE A GOOD JOB DEPICTING THE EVOLUTION OF THIS
COMPLEX THUS FAR, SO USED IT TO DEFINE THE MPD REGION, ACCOUNTING
FOR THE HOUR OF SLOWNESS NOTED THROUGH 07Z. THE COMPLEX IS
EXPECTED TO MOVE SOUTH-SOUTHEAST WITH TIME WITH CONVECTION FORWARD
PROPAGATING WITHIN AN AREA OF DIFLUENT 1000-500 HPA THICKNESS AS
INSTABILITY ACROSS KY CONTINUES TO MARCH EASTWARD UNTIL ITS
ARRIVAL. HOURLY RAIN AMOUNTS TO 2.5" WITH LOCAL AMOUNTS OF 5" ARE
EXPECTED LOCALLY. FLASH FLOOD GUIDANCE IS LOW AS RECENT RAINS
HAVE PARTIALLY TO COMPLETELY SATURATED SOILS IN THIS AREA. DUE TO
THIS, CHOSE THE LIKELY CATEGORY. FLASH FLOODING OCCURRENCES ARE
EXPECTED TO BE AT LEAST SCATTERED IN NATURE ACROSS THE DISCUSSION
AREA.
ROTH
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...ILN...IND...IWX...JKL...LMK...MRX...OHX...
ATTN...RFC...ORN...TIR...NWC...
LAT...LON 41038630 40928513 38888358 36138330 35748519
38868613 40238655
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