MESOSCALE PRECIPITATION DISCUSSION 0432
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
520 PM EDT SUN JUL 02 2017

AREAS AFFECTED...CENTRAL/SOUTHEAST TN...NORTHEAST AL AND NORTHWEST
GA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 022115Z - 030115Z

SUMMARY...SLOW-MOVING CLUSTERS OF THUNDERSTORMS WITH INTENSE
RAINFALL RATES WILL FOSTER SOME ADDITIONAL CONCERNS FOR FLASH
FLOODING THROUGH THE EARLY EVENING HOURS.

DISCUSSION...A CLUSTER OF RELATIVELY COLD-TOPPED BY RATHER
SLOW-MOVING THUNDERSTORMS OVER PARTS OF NORTH-CENTRAL TN IS SEEN
ATTEMPTING TO DROP SOUTHEASTWARD WHILE ALSO TAKING ADVANTAGE OF A
VERY MOIST AND UNSTABLE AIRMASS. MLCAPE VALUES OF OVER 1500 J/KG
AND PWATS OF CLOSE TO 2 INCHES IS PRODUCING AN ENVIRONMENT
CONDUCIVE FOR RAINFALL RATES OF UP TO 2.5 INCHES/HR.

THE ACTIVITY IS BEING FOSTERED BY CLOSE PROXIMITY OF AN OLD
FRONTAL ZONE NEAR THE KY/TN BORDER AND WITH THE POOLING OF
FAVORABLE THERMODYNAMICS ALONG AND SOUTH OF IT. MEANWHILE...THE
EXPERIMENTAL GOES-16 0.64 MICRON/VIS IMAGERY IS SHOWING AN MCV
OVER NORTHERN AL ADVANCING EASTWARD WHICH IS HELPING TO FACILITATE
CLUSTERS OF CONVECTION APPROACHING NORTHEAST AL AND DOWNWIND
ACROSS SOUTHEAST TN AND NORTHWEST GA AT THIS TIME.

SOME OF THESE AREAS HAVE SEEN SOME RELATIVELY HEAVY RAINFALL OF
LATE...AND SO THE ADDITIONAL RAINFALL THREAT THROUGH THE EARLY
EVENING HOURS WILL AT LEAST LOCALLY BE FALLING ON RATHER MOIST
SOIL CONDITIONS WHICH WILL ENHANCE THE RUNOFF POTENTIAL.

EXPECT AS MUCH AS 2 TO 4 INCHES OF RAIN WITH ISOLATED HEAVIER
AMOUNTS. THE RAINFALL AMOUNTS MAYBE LOCALLY HEAVIER ACROSS AREAS
OF NORTH-CENTRAL TN AND CLOSE TO THE NASHVILLE AREA WHERE
CONVECTION RECENTLY HAS BEEN MORE ORGANIZED. SOME FLASH FLOODING
WILL BE POSSIBLE AND ESPECIALLY IN AND AROUND THE MORE URBANIZED
ENVIRONMENTS.

ORRISON

ATTN...WFO...BMX...FFC...HUN...LMK...MRX...OHX...PAH...

ATTN...RFC...LMRFC...OHRFC...SERFC...

LAT...LON   36828656 36648547 36368481 36028440 35268418
            34328434 33868551 33908648 34428669 34948657
            35618703 36078740 36638729