MESOSCALE PRECIPITATION DISCUSSION 0368
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
453 PM EDT WED JUN 27 2018

AREAS AFFECTED...CENTRAL AND EASTERN TN

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

VALID 272100Z - 280100Z

SUMMARY...CONVECTION TRAINING OVER AREAS THAT RECEIVED HEAVY
RAINFALL EARLIER COULD POSE A FLASH FLOOD THREAT INTO THE EARLY
EVENING.

DISCUSSION...REGIONAL RADARS SHOWED CONVECTION DROPPING SOUTHEAST
ACROSS CENTRAL TN...RIDING ALONG AN INSTABILITY AXIS EXTENDING
FROM WEST CENTRAL KY INTO NORTHERN GA. WHILE THIS ACTIVITY IS
MAINLY OUTFLOW DRIVEN...THE KOHX RADAR SHOWED HOURLY RAINFALL
RATES NEAR 2.00 INCHES OVER JACKSON COUNTY TN.

THE CONVECTION IS HEADING FOR A PORTION OF NORTH CENTRAL TN THAT
RECEIVED BETWEEN 2.00 AND 4.00 INCHES OF RAINFALL (BASED ON THE
KOHX RADAR) FROM EARLIER CONVECTION. THE ADDITIONAL HEAVY
RAINFALL...EVEN WITH CONVECTION THAT IS PROGRESSIVE...COULD RESULT
IN A FLASH FLOOD THREAT UNTIL THIS CONVECTIVE COMPLEX DROPS OUT OF
THE AREA.

FURTHER EAST ACROSS EASTERN TN...THE AIRMASS HAS NOT BEEN
OVERTURNED BY EARLIER CONVECTION...AS EVIDENCED BY MUCAPE VALUES
BETWEEN 500-1000 J/KG. WITH DEEP MOISTURE IN PLACE (PRECIPITABLE
WATER VALUES REMAIN NEAR 2.00 INCHES), CONVECTION DEVELOPING OVER
EASTERN TN COULD PRODUCE HOURLY RAINFALL RATES BETWEEN 1.50 AND
2.00 INCHES (AS EVIDENCED BY THE MOST RECENT HRRR RUNS). THE
LATEST HRRR/EXPERIMENTAL HRRR SOLUTIONS INDICATED THE POTENTIAL
FOR LOCAL 2.00/3.00 INCH RAINFALL AMOUNTS OVER SOUTHEAST TN.

THE EASTERN TN CONVECTION IS ALSO EXPECTED TO BE PROGRESSIVE...SO
THE FLASH FLOOD THREAT OUTSIDE OF AREAS THAT RECEIVED EARLIER
HEAVY RAINFALL COULD BE SOMEWHAT LIMITED. HOWEVER...GIVEN THE DEEP
MOISTURE IN PLACE...THE THREAT FOR FLASH FLOODING IS EXPECTED TO
CONTINUE INTO EARLY EVENING... BEFORE THE PASSAGE OF SHORT WAVE
ENERGY AND WANING INSTABILITY LESSEN THE THREAT.

HAYES

ATTN...WFO...GSP...HUN...JKL...LMK...MRX...OHX...

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

LAT...LON   36768596 36228249 35518251 35118361 35118364
            35108445 35078571 35338716 36248768