MESOSCALE PRECIPITATION DISCUSSION 0430
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
718 AM EDT THU JUL 07 2016
 
AREAS AFFECTED...WESTERN KY...CENTRAL AND NORTHERN TN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 071115Z - 071515Z
 
SUMMARY...LIFE-THREATENING FLASH FLOODING CONTINUES ACROSS
PORTIONS OF WESTERN KY AND NORTHERN TN THIS MORNING. ADDITIONAL
HEAVY RAINS ARE EXPECTED FOR THE NEXT FEW HOURS...WITH IMPROVING
CONDITIONS ANTICIPATED BY LATE MORNING.

DISCUSSION...A CLASSIC BACKBUILDING AND TRAINING CONVECTIVE EVENT
CONTINUES EARLY THIS MORNING ACROSS PORTIONS OF WESTERN KY AND
DOWN INTO NORTHERN TN WHICH HAS LED TO AN EXTREME FLASH FLOOD
EVENT. A VERY MOIST AND UNSTABLE AIRMASS FACILITATED BY A WESTERLY
LOW LEVEL JET OF 40 TO 45 KTS CONTINUES TO INTERACT WITH THE
SOUTHWEST FLANK OF A SLOWLY DEPARTING SHORTWAVE TROUGH EXTENDING
FROM THE OH RIVER SOUTH ACROSS KY AND INTO NORTHERN TN. IN
FACT...THERE IS A CLOSED LOW CIRCULATION SEEN IN THE 850/700 MB
LAYER OVER CENTRAL KY...AND THIS IS ALLOWING FOR THE PERSISTENCE
OF A CONFLUENT LOW/MID LEVEL FLOW REGIME OVER WESTERN KY AND DOWN
ACROSS NORTHERN AND CENTRAL TN.

THE CONVECTION CONTINUES TO DEVELOP WITHIN A WELL-DEFINED NW/SE
ORIENTED INSTABILITY GRADIENT...WITH THE LATEST RAP ANALYSIS
SHOWING MLCAPE VALUES OF OVER 1500 J/KG STILL POOLED FROM
SOUTHEAST MO DOWN ACROSS WESTERN TN. PWATS OVER THE AREA ARE ON
THE ORDER OF 1.8 TO 2 INCHES...WHICH CONTINUES TO FAVOR EFFICIENT
RAINFALL PROCESSES LEADING TO HEAVIER RAINFALL RATES.

THE CLOUD TOPS HAVE STARTED TO WARM A TAD OVER THE LAST COUPLE OF
HOURS...AND THERE SHOULD BE A TENDENCY THROUGH MID TO LATE MORNING
FOR THE CONVECTION TO WEAKEN AS THE LOW LEVEL JET WEAKENS...AND
ESPECIALLY AFTER 12Z. HOWEVER...AT THIS POINT...ANY ADDITIONAL
RAINFALL WILL EXACERBATE ONGOING FLASH FLOODING PROBLEMS.
ADDITIONAL RAINFALL IS EXPECTED TO BE ON THE ORDER OF 2 TO 3
INCHES THROUGH 15Z. WILL CONTINUE TO MONITOR.

WPC

ATTN...WFO...MEG...MRX...OHX...PAH...

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

LAT...LON   37098867 36888794 36478672 36188491 35848435 
            35418453 35448548 35748680 36368817 36718865 
            36958876