MESOSCALE PRECIPITATION DISCUSSION 0343
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
140 PM EDT SAT JUL 11 2015
 
AREAS AFFECTED...SOUTHEASTERN VA/EASTERN NC/NC OUTER BANKS... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 111739Z - 112224Z
 
SUMMARY...CONVECTION HAS BEGUN TO ERUPT ALONG A SHARP
MOISTURE/INSTABILITY GRADIENT ANCHORING SOUTHEASTERN VA/EASTERN
NC. MORNING SOUNDINGS ACROSS THE REGION SUPPORT TRAINING
CONVECTION WITH HIGH RAINFALL RATES GIVEN ANOMALOUS MOISTURE IN
PLACE.

DISCUSSION...A COMPLEX OF SHOWERS AND THUNDERSTORMS WHICH TRACKED
THROUGH THE MID-ATLANTIC THIS MORNING IS CURRENTLY MOVING TOWARD
THE EASTERN SHORE OF MD. TO THE SOUTH OF THIS PRECIPITATION
SHIELD...NEARLY CLOUD FREE SKIES HAS LED TO AN EXPANSIVE CU FIELD
ACROSS MUCH OF NORTH-CENTRAL NC EASTWARD TOWARD THE OUTER BANKS.
SUCH CONDITIONS HAVE RAISED SURFACE-BASED INSTABILITY VALUES ABOVE
2000 J/KG WITH NO CAPPING. EXPECT THE CONVECTION TO CONTINUE TO
EXPAND IN COVERAGE THROUGHOUT THE PEAK DIURNAL HEATING CYCLE WITH
LOCALLY HEAVY RAINFALL GIVEN PWATS IN THE 1.75 TO 2 INCH RANGE
BASED ON THE GPS DATA. FURTHERMORE...THE 12Z SOUNDING DEPICTED
NEARLY UNIDIRECTIONAL WESTERLY FLOW WHICH MAY RESULT IN
TRAINING/BACKBUILDING IF CONVECTION CAN ALIGN ITSELF ALONG THIS
MEAN FLOW.

THE PAST FOUR CYCLES OF THE HRRR HAVE SHOWN A STEADY INCREASE IN
THE COVERAGE OF DEEP CONVECTION ACROSS THE AFFECTED REGION. THIS
BRINGS THE SOLUTION INTO BETTER AGREEMENT WITH OTHER
CONVECTION-ALLOWING MODELS WHICH DISPLAY A BROAD REGION 1 TO 2
INCHES OF RAINFALL THROUGH 00Z WITH LOCALIZED AMOUNTS APPROACHING
4 INCHES. WHILE FFG VALUES ARE FAIRLY HIGH...THERE ARE POCKETS OF
LOWER VALUES IN NC WHICH SUPPORTS THE THREAT FOR FLASH FLOODING.
OF COURSE ANY CONVECTION WHICH BEGINS TO TRAIN WILL ALSO BE LIKELY
CANDIDATES FOR POSSIBLE FLASH FLOODING. PLEASE VIEW THE LATEST
SPENES FROM NESDIS/SAB FOR ADDITIONAL INFORMATION.



RUBIN-OSTER

ATTN...WFO...AKQ...MHX...RAH...

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

LAT...LON   37167687 36937569 35887515 34447545 34287679 
            35097733 35707828 36687823