MESOSCALE PRECIPITATION DISCUSSION 0679
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
250 PM EDT MON SEP 19 2016
 
AREAS AFFECTED...SOUTHEAST VA...EASTERN NC...FAR NORTHEAST SC 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 191845Z - 200000Z
 
SUMMARY...SLOW-MOVING HEAVY SHOWERS AND THUNDERSTORMS MAY RESULT
IN SOME RUNOFF PROBLEMS THROUGH LATE-AFTERNOON.

DISCUSSION...IR SATELLITE IMAGERY SHOWS COLD CONVECTIVE TOPS
CONTINUING TO DEVELOP AND EVER SO SLOWLY SHIFT SOUTH AND EAST INTO
SOUTHEAST VA AND DOWN THROUGH CENTRAL AND EASTERN PORTIONS OF NC.
A VERY WELL-DEFINED AND CONVECTIVELY ENHANCED SURFACE TROUGH IS
FOCUSED OVER THIS REGION AND IS INTERCEPTING THE VERY MOIST AND
MODERATELY UNSTABLE ATLANTIC INFLOW AROUND THE NORTH SIDE OF THE
POST-TROPICAL REMNANTS OF JULIA WHICH ARE SITUATED OFFSHORE TO THE
SOUTHEAST OF WILMINGTON NC.

LOW LEVEL INFLOW IS ONLY ON THE ORDER OF 10 TO 20 KTS IN OFF THE
ATLANTIC OCEAN...BUT THE CONVECTION THAT IS FOCUSED ALONG THE
BOUNDARY IS VERY SLOW-MOVING AND IS FORECAST TO REMAIN THIS WAY
THROUGH THE BALANCE OF THE AFTERNOON HOURS. LARGER SCALE ASCENT IS
ALSO HELPING TO SUSTAIN THE CONVECTION WITH THE PRESENCE OF
RIGHT-ENTRANCE REGION JET DYNAMICS AHEAD OF AN UPPER TROUGH AND
ALSO A WELL-DEFINED SHORTWAVE APPROACHING THE REGION FROM WESTERN
NC.

VERY HIGH PWATS ARE IN PLACE WITH VALUES AS HIGH AS 2 TO 2.2
INCHES AS PER CIRA TPW/BLENDED-TPW DATA. THE RAINFALL RATES WILL
REMAIN ENHANCED GIVEN THE DEEP WARM/MOIST COLUMN AND ENHANCED
RAINFALL EFFICIENCY. THE HIRES GUIDANCE FROM 12Z IS GENERALLY
UNDERDOING THE CURRENT LEVEL OF CONVECTION AND ASSOCIATED
ORGANIZATION. THE BEST GUIDANCE IF ANYTHING WOULD BE THE 12Z
NSSL-WRF...BUT IT APPEARS TO BE UNDERDONE WITH THE RAINFALL
POTENTIAL THROUGH 00Z GIVEN THE DEGREE OF INSTABILITY POOLED OVER
EASTERN NC AND SOUTHEAST VA WHICH IS AS HIGH AS 2500 J/KG OF
MLCAPE.

EXPECT THERE TO BE SOME CONCERNS FOR FLASH FLOODING AND GENERAL
RUNOFF PROBLEMS THROUGH THE AFTERNOON...WITH RAINFALL RATES AS
HIGH AS 2.5 INCHES/HR...AND STORM TOTAL AMOUNTS THROUGH 00Z AS
HIGH AS 5 INCHES WITH LOCALLY HEAVIER AMOUNTS.

ORRISON

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

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

LAT...LON   37847624 37627565 36637584 35277646 34447718 
            33917785 33787842 33787895 34107949 34327969 
            34677960 35257847 35997785 36717740 37427685