MESOSCALE PRECIPITATION DISCUSSION 0129
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
912 PM EDT SAT MAY 05 2018

AREAS AFFECTED...SOUTHERN WV...FAR EASTERN KY/TN...FAR SOUTHWEST
VA

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

VALID 060115Z - 060500Z

SUMMARY...CONVECTION TRACKING OVER AREAS THAT RECEIVED HEAVY
RAINFALL DURING THE AFTERNOON AND EVENING COULD RESULT IN A FLASH
FLOOD THREAT THROUGH THE LATE EVENING.

DISCUSSION...REGIONAL RADARS SHOWED A LARGE AREA OF MODERATE TO
HEAVY RAINFALL EXTENDING ACROSS MUCH OF KY/EASTERN TN INTO
WV/WESTERN VA EARLY THIS EVENING. EMBEDDED WITHIN THE MODERATE TO
HEAVY RAINFALL WERE LINES OF CONVECTION...CONCENTRATED MAINLY OVER
FAR EASTERN TN INTO SOUTHEAST WV/FAR WESTERN VA. THE 00Z RNK
SOUNDING SHOWED SBCAPE VALUES NEAR 1000 J/KG IN THIS AIRMASS. A 20
TO 30 KNOT LOW LEVEL SOUTH SOUTHEAST FLOW CONTINUES TO PUMP 1.25
INCH PRECIPITABLE WATER AIR OVER THIS AREA.

CONVECTION OVER SOUTHEAST WV AND PORTIONS OF EASTERN TN IS TAKING
ADVANTAGE OF THE INSTABILITY AND MOISTURE TO PRODUCE HOURLY
RAINFALL RATES NEAR 1.50 INCHES...WITH THE HIGHEST VALUES OVER
WASHINGTON COUNTY TN. 00Z SOUNDINGS ACROSS THE OH VALLEY AND
INTERIOR MID ATLANTIC SHOWED SOME DRY AIR IN THE MID LEVELS...AND
THE HCA PRODUCT FROM KFCX SHOWED INDICATIONS OF HAIL...SO SOME OF
THESE RATES COULD BE HAIL CONTAMINATED.

A SHORT WAVE OVER WESTERN AND CENTRAL TN WILL PROVIDE INCREASING
SYNOPTIC SCALE LIFT OVER THE REGION INTO THE EARLY MORNING HOURS.
HOWEVER...INSTABILITY IS EXPECTED TO CONTINUE TO WANE DURING THIS
TIME...AS THE BEST INSTABILITY REMAINS SOUTH OF A QUASI STATIONARY
FRONT EXTENDING INTO SOUTHWEST VA. THROUGH 06/03Z OR SO...THE
COMBINATION OF RESIDUAL INSTABILITY AND LIFT ASSOCIATED WITH THE
SHORT WAVE COULD PRODUCE LOCAL RAINFALL AMOUNTS OF 1.00 TO 2.00
INCHES) WHICH IS SUPPORTED BY THE MOST RECENT HRRR AND
EXPERIMENTAL HRRR). THE HIGHEST AMOUNTS ARE EXPECTED OVER 
SOUTHERN WV INTO A PORTION OF EASTERN TN.

SOME OF THESE AREAS RECEIVED BETWEEN 2.00 AND 2.50 INCHES OF
RAINFALL (BASED ON THE KRLX STORM TOTAL RAINFALL IMAGE) THIS
AFTERNOON AND EVENING...WITH THE HIGHEST AMOUNTS OVER SOUTHEAST
WV. THE ADDITIONAL RAINFALL COULD RESULT IN AN ADDITIONAL FLASH
FLOOD THREAT INTO THE LATE EVENING... AFTER WHICH TIME THE
REMAINING INSTABILITY IS EXPECTED TO BECOME EXHAUSTED.

SINCE THERE IS SOME QUESTION ABOUT THE AREAL EXTENT OF ADDITIONAL
CONVECTION OVER THESE AREAS...FLASH FLOODING IS ONLY CONSIDERED
POSSIBLE.

HAYES

ATTN...WFO...GSP...JKL...MRX...RLX...RNK...

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

LAT...LON   38768027 38427970 36748124 36228189 36008256
            36118303 36718306 37578254