Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 090248 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1048 PM EDT TUE JUL 8 2014 .SYNOPSIS... HIGH PRESSURE WILL ONCE AGAIN BRING HEAT ON WEDNESDAY. RAIN CHANCES INCREASE ON THURSDAY WITH THE APPROACH OF A COLD FRONT. THIS FRONT WILL STALL OVER THE REGION ON FRIDAY AND WASH OUT ACROSS THE AREA OVER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 1030 PM TUESDAY...ONLY SIGNIFICANT CHANGE TO THE FORECAST WAS TO ADD A 20-30 PERCENT CHANCE OF SHOWERS EXTENDING FROM DARLINGTON...FLORENCE AND BENNETTSVILLE EASTWARD ACROSS DILLON AND LUMBERTON TO ELIZABETHTOWN. CLOUD BASES ARE VERY HIGH...8000 TO 9000 FEET...AND SOUNDINGS INDICATE A LOT OF DRY AIR LURKING ABOVE 1300-14000 FEET. THIS LEAVES ONLY A NARROW VERTICAL GROWTH ZONE FOR THE SHOWERS TO DEVELOP WITHIN. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS... HIGH PRESSURE COVERING ALMOST THE ENTIRE ATLANTIC OCEAN IS EXTENDING A RIDGE AXIS WESTWARD ACROSS THE BAHAMAS...FLORIDA...AND THE NORTHERN GULF OF MEXICO. WESTERLY MID-LEVEL FLOW ACROSS THE SOUTHERN APPALACHIANS HAS PRODUCED A LEE-SIDE TROUGH OVER THE INTERIOR CAROLINAS. THESE TWO FEATURES ARE COMBINING TO PRODUCE A STRONG SOUTHWEST WIND ACROSS THE COASTAL PLAIN AND NEARSHORE WATERS.. RECENT GUSTS HAVE BEEN MEASURED AS HIGH AS 29 MPH AT WRIGHTSVILLE BEACH...31 MPH IN WILMINGTON...AND 32 MPH IN NORTH MYRTLE BEACH. ALTHOUGH SURFACE WINDS SHOULD LOSE THEIR GUSTINESS LATER THIS EVENING...A HEALTHY FLOW JUST ABOVE THE SURFACE SHOULD PREVENT MUCH OF A RADIATIONAL INVERSION FROM DEVELOPING WITH PLENTY OF TURBULENCE CONTINUING WITHIN THE BOUNDARY LAYER. MORE ON THIS IN A BIT. THE SEABREEZE MADE EXCELLENT PROGRESS INLAND TODAY AND IS APPROACHING LUMBERTON...MARION...AND SOUTHERN FLORENCE COUNTY AT THE CURRENT TIME. DEWPOINTS WEST OF THE SEABREEZE BOUNDARY MIXED DOWN INTO THE UPPER 50S WHILE TO THE EAST DEWPOINTS ARE IN THE LOWER TO MIDDLE 70S. THIS HUMID MARINE AIR SHOULD SPREAD WEST OF INTERSTATE 95 AFTER SUNSET WITH A MUGGY NIGHT EXPECTED ACROSS THE AREA. DESPITE STEEP LAPSE RATES ALOFT AND PLENTY OF ELEVATED INSTABILITY OVERNIGHT...THERE APPEARS TO BE NO TRIGGER FOR CONVECTION...SO OUR DRY FORECAST WILL CONTINUE. THIS IS THE SECOND NIGHT OF ESSENTIALLY THE SAME AIRMASS AND WIND/WEATHER CONFIGURATION...WHICH MEANS CHECKING LAST NIGHT`S MODEL PERFORMANCE SHOULD GIVE A GOOD IDEA ABOUT TONIGHT. OBSERVED MOS BIASES IN LOW TEMPERATURES LAST NIGHT: GFS NAM WILMINGTON -5 -3 FLORENCE -3 -2 N. MYRTLE BEACH -6 -4 MYRTLE BEACH -4 -3 LUMBERTON -5 -2 ELIZABETHTOWN -3 -2 WHITEVILLE -4 -3 DARLINGTON -3 0 APPLYING A CORRESPONDING UPWARD CORRECTION TO TONIGHT`S GFS AND NAM MOS OUTPUT SUGGESTS LOWS WILL HAVE CONSIDERABLE TROUBLE FALLING BELOW 80 IN MYRTLE BEACH...NORTH MYRTLE BEACH...AND SOUTHPORT. THIS MAKES SENSE GIVEN THE MARINE AIR TEMPERATURES AND THE AMOUNT OF WIND EXPECTED OVERNIGHT. TURBULENCE INDUCED BY 1000 FOOT WINDS OF 25-30 KNOTS VERSUS SURFACE WINDS FALLING TO 6-12 KNOTS SHOULD KEEP THE SURFACE FROM DECOUPLING THERMALLY FROM THE REST OF THE ATMOSPHERE. MY FORECAST LOWS ARE NEAR 80 FOR MOST OF THE BEACH COMMUNITIES... WITH MID 70S FARTHER INLAND ALONG INTERSTATE 95.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 PM TUESDAY...SHARPENING PIEDMONT TROUGH TO BE THE FOCUS FOR SCATTERED CONVECTION ON WEDNESDAY...MAINLY OVER NW ZONES. SLIGHTLY DRY MID LEVEL AIR AND A BIT MORE FLOW THAN TYPICAL JULY HAS MADE FOR A SMALL BUT NONZERO SEVERE WEATHER THREAT. TEMPERATURES SIMILAR TO TODAY INLAND...AND A LITTLE HOTTER THAN TODAY ALONG THE COAST WITH A PINNED SEA BREEZE. POPS APPEAR TO LINGER INTO WEDNESDAY NIGHT AS MOISTENING PROCESS CONTINUES AND WEAK SHORTWAVES RIPPLE ACROSS THE REGION. PIEDMONT TROUGH LINGERS INTO THURSDAY...POSSIBLY IN A WEAKENING STATE. MID LEVEL FLOW HOWEVER BECOMES MORE SUPPORTIVE OF AREA-WIDE CONVECTION AS CYCLONIC FLOW AND HEIGHT FALLS IMPINGE UPON THE AREA WITH EMBEDDED SHORTWAVES CONTINUING. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 330 PM TUESDAY...THE PERIOD WILL BEGIN WITH A STALLED AND DISSIPATING FRONT OVER THE EASTERN CAROLINAS ON FRIDAY. DEEPER MOISTURE WILL ACCOMPANY THIS FEATURE...AS FORECAST SOUNDINGS DEPICT PWAT VALUES IN THE 1.7-1.8 INCH RANGE ACROSS THE AREA ON FRIDAY AFTERNOON. THIS WARRANTS ABOVE NORMAL POPS FOR FRIDAY...GRADUALLY DIMINISHING OVER THE WEEKEND AS UPPER TROUGHING GIVES WAY TO WEAK RIDGING OVER OUR AREA. WE COULD STILL SEE ISOLATED TO SCATTERED DIURNAL CONVECTION ALONG MESOSCALE FEATURES LIKE THE SEA BREEZE THIS WEEKEND...BUT OVERALL FORCING WILL BE LIMITED. POPS GRADUALLY RAMP UP AGAIN ON MONDAY AND TUESDAY AS A PRE-FRONTAL SURFACE TROUGH DEVELOPS AND MOISTURE DEEPENS AHEAD OF ANOTHER COLD FRONT THAT APPROACHES FROM THE NORTHWEST. HIGH TEMPS WILL REMAIN NEAR NORMAL THROUGH THE PERIOD...RANGING FROM UPPER 80S AT THE BEACHES TO LOWER 90S INLAND. STRENGTHENING S-SW FLOW THROUGH EARLY NEXT WEEK COULD ACTUALLY KEEP THE BEACHES A LITTLE BELOW NORMAL AS THE SEA BREEZE GETS AN EARLIER PUSH ACROSS OUR COASTAL LOCATIONS. CLOUD COVER AND PERSISTENT ONSHORE FLOW WILL KEEP LOWS IN THE LOW TO MID 70S THROUGH THE PERIOD. && .AVIATION /00Z WEDNESDAY THROUGH SATURDAY/... AS OF 00Z...EXPECT VFR THROUGH THE VALID TAF PERIOD AS HIGH PRESSURE REIGNS OVER THE AREA...WITH ISOLATED SHRA/TSRA POSSIBLE WEDNESDAY. QUIET CONDITIONS ON TAP FOR THE AREA TONIGHT AS FEW/SCT MID TO HIGH LEVEL CLOUDS PUSH ACROSS PORTIONS OF THE AREA. SOUTHWEST WINDS ALONG THE COAST REMAIN AROUND 15 KTS WITH GUSTS AROUND 25 KTS...WHICH WILL CONTINUE FOR THE NEXT FEW HOURS...BEFORE SUBSIDING TO AROUND 10 KTS THROUGH THE OVERNIGHT HOURS. INTO WEDNESDAY MORNING VFR WILL PREVAIL WITH WEST-SOUTHWEST WINDS INCREASING TO 10 KTS INLAND...UP TO 15 KTS ALONG THE COAST WITH HIGHER GUSTS. ISOLATED TO SCATTERED CONVECTION IS POSSIBLE BEGINNING AS SOON AS EARLY AFTERNOON...CONTINUING THROUGH THE END OF THE VALID TAF PERIOD. EXTENDED OUTLOOK...EXPECT VFR TO PREVAIL THROUGH THE EXTENDED PERIOD. CHANCE SHRA/TS/TEMPO MVFR LATE WEDNESDAY THROUGH SUNDAY. BEST COVERAGE OF SHRA/TS THURSDAY AND FRIDAY. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM TUESDAY...HIGH PRESSURE COVERING MOST OF THE ATLANTIC OCEAN IS EXTENDING A RIDGE AXIS WESTWARD ACROSS FLORIDA AND THE NORTHERN GULF OF MEXICO. A LOW PRESSURE TROUGH ACROSS THE INTERIOR CAROLINAS IS COMPRESSING THE PRESSURE GRADIENT...CREATING STRONG SOUTHWEST WINDS ACROSS THE COASTAL WATERS. LATE THIS EVENING WINDS ARE NEAR 20 KNOTS WITH GUSTS STILL IN THE 25-28 KNOT RANGE AT SEVERAL STATIONS ALONG THE COAST. STRONG WINDS IN THE LOWEST 2500 FEET OF THE ATMOSPHERE WILL CONTINUE THROUGH THE NIGHT...WITH SURFACE WIND SPEEDS AVERAGING 20 KNOTS. SEAS HAVE BUILT TO 5 FEET AT THE NEARSHORE WRIGHTSVILLE BEACH BUOY...AND ONLY A SMALL ADDITIONAL INCREASE IS EXPECTED OVERNIGHT AS SEAS ARE NEARLY FULLY DEVELOPED FOR THIS WIND SPEED AND DIRECTION. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 PM TUESDAY...MODERATE SOUTHWESTERLY BREEZES ON WEDNESDAY AND SOME AREAS MAY NEED CAUTIONARY HEADLINES...MAINLY NORTHERLY ZONES WHERE SEAS MAY BE AVERAGING 4 TO 5 FT. PIEDMONT TROUGH HELPING TO KEEP THE GRADIENT ON THE STRONG SIDE LOSES MUCH OF ITS IDENTITY HEADING INTO THURSDAY. THE RESULTING RELAXATION OF THE FLOW WILL ALLOW SEAS TO DROP 1 FT SOUTH...AND PERHAPS 1-2 FT OVER NRN ZONES. NO HEADLINES EXPECTED ON THURSDAY. LONG TERM /FRIDAY THROUGH SUNDAY/... AS OF 330 PM TUESDAY...SOUTH-SOUTHWEST WINDS WILL PERSIST THROUGH THE LONG TERM PERIOD...AROUND 10 KTS ON FRIDAY INCREASING TO 10-15 KTS ON SATURDAY AND 15 KTS BY SUNDAY. EXPECT 2 TO 3 FT SEAS FRIDAY AND SATURDAY WITH THE PRIMARY CONTRIBUTOR BEING S-SW 4-6 SECOND WIND WAVES. SEAS WILL BUILD TO 3-4 FT AS THE WINDS INCREASE ON SUNDAY... WITH MORE REGULAR 4 FT SEAS IN THE OUTER WATERS. NO SCEC CONDITIONS ARE FORECAST DURING THE FRIDAY-SUNDAY PERIOD ATTM.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...TRA SHORT TERM...MBB LONG TERM...BJR AVIATION...SGL

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