MESOSCALE PRECIPITATION DISCUSSION 0358
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
443 PM EDT MON JUN 25 2018

AREAS AFFECTED...CENTRAL & EASTERN SC/SOUTHERNMOST NC

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

VALID 252042Z - 260242Z

SUMMARY...THUNDERSTORMS ARE STARTING TO INCREASE IN COVERAGE AHEAD
OF AN INCOMING BAND OF THUNDERSTORMS.  HOURLY TOTALS TO 2.5" WITH
LOCAL AMOUNTS TO 5" ARE FORECAST.

DISCUSSION...CONVECTION IS INCREASING SOUTH OF AN MCV MOVING
ACROSS SOUTHERN VA AND AHEAD OF AN INCOMING CONVECTIVE LINE
SPAWNED BY ANOTHER MCV ACROSS EASTERN KY. A COUPLE OVERSHOOTING
TOPS ARE EVIDENT ON RECENT GOES-16 "VEGGIE BAND" IMAGERY.
PRECIPITABLE WATER VALUES OF 1.8-2.1" EXIST HERE PER RECENT GPS
DATA.  EFFECTIVE BULK SHEAR IS APPROACHING 25 KTS PER SPC
MESOANALYSIS, WHICH COULD LEAD TO TRAINING BANDS WITHIN A FLOW
PATTERN WHICH IS FAIRLY UNIDIRECTIONAL OUT OF THE WEST PER THE
MORNING MHX/MOREHEAD CITY NC SOUNDING. ML CAPE VALUES ARE
1500-4000 J/KG.

CONVERGENT FLOW AT 850 HPA IS EXPECTED TO FURTHER CONCENTRATE
CONVECTION OVER THE NEXT SEVERAL HOURS, WHICH COULD LEAD TO SOME
CELL TRAINING.  AS THE THUNDERSTORM LINE MOVES OUT OF THE
APPALACHIANS INTO THE PIEDMONT AND AN OUTFLOW BOUNDARY APPROACHES
FROM THE SOUTH, CELL COLLISIONS APPEAR LIKELY WHICH WOULD AMP UP
HOURLY RAIN TOTALS.  THE MESOSCALE GUIDANCE SHOWS A GOOD SIGNAL
FOR LOCAL AMOUNTS IN THE 4-5" RANGE THROUGH 03Z.  THE HOURLY
PROBABILITIES OF 1"+ WITH THE HREF MEMBERS MAXIMIZES IN THE 22-01Z
PERIOD.  THE GFS-BASED GALVEZ-DAVISON INSTABILITY INDEX IMPLIES
THE GREATEST CELL COVERAGE IS LIKELY AROUND 03Z.  FLASH FLOOD
GUIDANCE VALUES ARE RELATIVELY MODEST HERE, WHICH COULD LEAD TO A
FEW POCKETS OF FLASH FLOODING DURING THE NEXT SIX HOURS.

ROTH

ATTN...WFO...CAE...CHS...GSP...ILM...MHX...RAH...

ATTN...RFC...SERFC...

LAT...LON   35107889 34807799 34517730 34057779 33797798
            33777859 33197913 32817963 33248028 33488105
            34628192 34768176 34998085 35057986