MESOSCALE PRECIPITATION DISCUSSION 0141
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
742 AM EDT MON APR 24 2017

AREAS AFFECTED...EXT EASTERN GA...SOUTHEAST NC...SC

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 241145Z - 241745Z

SUMMARY...TRAINING CONVECTIVE BANDS WITH SOME STATIONARY NATURE
CLOSER TO UPPER LOW/PIVOT AXIS IN NW SC/NE GA.

DISCUSSION...GOES-E WV LOOP DENOTES VERY STRONG CONSOLIDATED UPPER
LOW DIGGING INTO SE GA ATTM PROVIDING AN EXPANSIVE REGIME OF
DIFFLUENCE/DIVERGENCE ACROSS THE CAROLINAS PROVIDING EXCELLENT
REGIME TO SUPPORT BROAD SCALE ASCENT FOR LARGE SHIELD OF MODERATE
PRECIPITATION BUT ALSO GOOD EVACUATION FOR EMBEDDED CONVECTIVE
BANDS.  AT THE SURFACE A 1004 LOW SITS NW OF SAVANNAH GA WITH WARM
FRONT HUGGING THE WARM FRONT UP TO THE NC OUTERBANKS...MOISTURE
AND INSTABILITY IS GENERALLY LIMITED TO THE WARM SECTOR THOUGH
MODEST 20-30KT ISENTROPIC ASCENT THAT IS GENERALLY TIGHTENING IN
CONFLUENCES HAS FOCUSED MST FLUX CONVERGENCE TO PRODUCE A LINE OF
CONVECTION (AIDED BY THE WESTERN EDGE OF THE GULF STREAM) ACROSS E
SC AS WELL AS A SECONDARY LINE FORMING FROM NEAR BEAUFORT TO EAST
OF COLUMBIA.  CLOUD BARING FLOW IS GENERALLY UNIDIRECTIONAL NEAR
THE DEVELOPMENT REGION AND FANNING OUT FURTHER NORTH TO THE SC/NC
BORDER...FOCUSING SOME TRAINING ENVIRONMENT AS THE TWO LINES ARE
EXPECTED TO MERGE OVER THE NEXT FEW HOURS IN E SE.  GIVEN
STRENGTHENING DPVA AS WELL AS INCREASING BUT SLOWLY BACKING
SOUTHERLY  FLOW OFF THE ATLANTIC WITH SFC TDS IN THE UPPER 60S TO
NEAR 70...CONTINUED UPSTREAM REDEVELOPMENT IS EXPECTED THROUGH THE
MORNING.  CURRENTLY GIVEN FAIRLY WARM MID-LEVELS LAPSE RATES ARE
MILD LIMITING INSTABILITY TO LESS THAN 1500 J/KG WITH SOME DRY AIR
PRESENT TOO LIMITING RAINFALL EFFICIENCY AS WELL WITH TPWS IN THE
1.4-1.5" NOT FULLY TAPPING THE DEEPER TROPICAL CONNECTION EXPECTED
LATER THIS AFTERNOON...AS SUCH RAINFALL RATES WILL NOT BE WORST
CASE SCENARIO WITH 1HR RATES OF 1.5" MAYBE REACHING 2" IN MERGERS
AND FOR SHORT TIME PERIODS.  STILL...GIVEN THE
ORIENTATION/PERSISTENCE THIS WILL LEAD TO THE POTENTIAL OF SPOT
3-5" TOTALS OVER THE NEXT 6HRS PARTICULARLY FROM SE OF I-77 AND E
OF I-26 PERHAPS AFFECTING SE NC AS WELL...THERE IS FAIRLY GOOD
CONFIDENCE DUE TO STRONG AGREEMENT IN HI-RES CAMS IN THIS SETUP
PRODUCING THESE MAGNITUDES OF RAINFALL THAT FLASH FLOODING IS
CONSIDERED LIKELY THOUGH THE CAMS ARE LESS PRECISE ON THE EXPECTED
LOCATION...IE HOW FAR EAST TOWARD NC BOARDER. 

FURTHER WEST...E GA/W SC.  TROWAL JUST AHEAD OF MAIN HEIGHT
FALLS/TROF DENOTED WELL IN WV CHANNELS ON GOES-16...WILL HAVE A
MORE LIMITED ISENTROPIC ASCENT REGIME THAN FURTHER EAST...YET
GIVEN THE TRACK OF THE UPPER LOW...THE CELL MOTIONS WILL BE FAIRLY
WEAK AND MAY PRESENT SOME STATIONARY NATURE PARTICULARLY LATER
THIS MORNING CLOSE TO THE AUGUSTA REGION.  WHILE THE COVERAGE OF
CONVECTION WILL BE MORE SCATTERED DUE TO THE FURTHER LIMITED
INFLOW/INSTABILITY REGIME...FLASH FLOODING UNDER THESE STATIONARY
CELLS IS POSSIBLE WITH TOTALS OF 1.5-3.5" POSSIBLE.

ALONG THE NC COAST...GREATEST UNCERTAINTY IN HEAVY RAINFALL OVER
THE MORNING HOURS RESIDES ALONG THE WARM FRONT ACROSS NC. STRONG
ONSHORE FLOW AND MODEST INSTABILITY FROM GULF STREAM ENVIRONMENT
WILL BE SUFFICIENT FOR CONVECTION TO DEVELOP...HOWEVER WITH
LIMITED FOCUS CONVECTION MAY BE WEAKER AND MORE BROKEN REDUCING
FLOODING CONCERN IN THE SHORT-TERM.  HOWEVER...IT IS POSSIBLE WITH
SOME FOCUSED FORCING SUCH AS THE LINE CURRENTLY APPROACHING
WILMINGTON NC VICINITY SOME BANDED/TRAINING CONVECTIVE REGIMES MAY
FORM AND POSE THE FLOODING CONCERNS SEEN FURTHER SW IN SC.  STILL
THE RAINFALL THROUGH THE MORNING WILL BE SUFFICIENT TO SET THE
STAGE FOR FURTHER FLOODING CONCERNS LATER THIS AFTERNOON AS THE
TROPICAL MOISTURE AND FORCING IS TAPPED FROM THE SYSTEM OFFSHORE. 


GALLINA

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

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

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            32098065 32258093 32928154 33398261 34088339
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            35138023