Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 200530 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 130 AM EDT WED MAY 20 2015 .SYNOPSIS...
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LOW PRESSURE WILL DEVELOP ALONG A LINGERING FRONTAL BOUNDARY TODAY...PUSHING OFFSHORE LATE THURSDAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTH FRIDAY...BRINGING DRIER AIR INTO THE REGION OVER THE WEEKEND. THE HIGH WILL MOVE OFFSHORE SUNDAY INTO MONDAY BRINGING A RETURN IN HUMIDITY THROUGH EARLY NEXT WEEK.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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AS OF 130 AM WEDNESDAY...DYNAMICS FROM A SMALL AND POTENT MID- LEVEL VORT SPINNING ACROSS THE FAR EASTERN PORTIONS OF THE ILM CWA AT THE MOMENT...WILL PUSH OFF THE ILM NC COAST SHORTLY TAKING THE CURRENT PCPN WITH IT. AT THIS POINT...THE NEXT POSSIBLE ROUND OF PCPN WILL BE ASSOCIATED WITH THE DYNAMICS ACCOMPANYING THE APPROACH AND PASSAGE OF A SFC COLD FRONT BY OR JUST AFTER DAYBREAK WED. LATEST SURROUNDING AND UPSTREAM 88DS INDICATE PCPN QUITE ISOLATED ALONG AND AHEAD OF THE APPROACHING COLD FRONT. 20 POPS AT MOST WILL BE ADVERTISED FOR LATER THIS EVENING AND OVERNIGHT. THE CAA AFTER THE PASSAGE OF THE COLD FRONT LATE TONIGHT WILL BE RATHER WEAK. AS A RESULT... TONIGHTS MIN TEMPS WILL ONLY BE 2 TO 5 DEGREES COOLER FROM THE PREVIOUS NIGHT.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/... AS OF 300 PM TUESDAY...COLD FRONT SHOULD BE ALIGNED JUST SOUTH OF LOCAL FORECAST AREA ALONG SC COAST EXTENDING NORTHEAST INTO THE ATLANTIC WED MORNING...AS SHORTWAVE EXITS FARTHER OFF THE COAST. THIS WILL LEAVE A FAIRLY ZONAL WESTERLY FLOW ALOFT WITH SOME SUBSIDENCE AND DRY AIR THROUGH THE MID LEVELS. WEAK HIGH PRESSURE WILL BUILD IN FROM THE NORTH WITH DRIER AIR BUT WITHOUT MUCH OF PUSH...THE BOUNDARY WILL LINGER NEAR OR JUST SOUTH OF FORECAST AREA ON WED AS IT WEAKENS. A LARGE VARIATION IN PCP WATER WILL EXIST FROM NORTH TO SOUTH WITH VALUES LESS THAN AN INCH OVER NORTHERN CAROLINA COUNTIES AND GREATER THAN 1.5 INCHES OVER COASTAL SC. THEREFORE EXPECT DRIER WEATHER WITH LOWER DEWPOINTS TO THE NORTH AND GREATER AMOUNTS OF SUNSHINE WHILE THE SOUTH CAROLINA COAST WILL HAVE BETTER CHC OF CLOUDS AND CONVECTION. OVERALL EXPECT CONVECTION TO BE MORE ISOLATED ON WED AND CONFINED MAINLY ALONG SC COAST NEAR FRONT OR ALONG SEA BREEZE BOUNDARY. LOWER DEWPOINT AIR WILL MAKE ITS WAY SOUTH WITH TEMPS BACK DOWN CLOSER TO NORMAL OVER NC BUT STILL INTO THE MID TO UPPER 80S MOST PLACES. BY LATE WED A SHORTWAVE WILL MOVE EAST WITH LOW PRESSURE DEVELOPING ALONG THE LINGERING FRONTAL BOUNDARY OVER SC. THIS WILL ALLOW MOISTURE AND BOUNDARY TO RETURN TO THE NORTH AND REMAIN A FOCUS FOR CONVECTION WED NIGHT INTO THURS. AS THIS LOW MOVES EAST ON THURS THE LOCAL AREA WILL SEE PLENTY OF CLOUDS AND MORE WIDESPREAD SHWR/TSTM ACTIVITY. TEMPERATURES WILL BE IN THE MID 80S ONCE AGAIN AS MOISTURE RETURNS NORTH. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 300 PM TUESDAY...THE EXTENDED FORECAST PERIOD SHOULD FEATURE BENIGN WEATHER. SURFACE LOW PRESSURE AND ITS ACCOMPANYING COLD FRONT IS PROGGED BY ALL OF THE 00Z AND 12Z MODELS TO BE OFF THE COAST BY DAYBREAK FRIDAY MORNING. SURFACE HIGH PRESSURE OVER THE GREAT LAKES ON FRIDAY WILL BUILD SOUTHEAST TO THE MID-ATLANTIC COAST SATURDAY NIGHT...AND SHOULD MOVE OFF THE EAST COAST SUNDAY AND MONDAY. TEMPERATURES WILL AVERAGE BELOW NORMAL FRIDAY THROUGH SUNDAY WITH WINDS GENERALLY NORTHEAST OR EASTERLY...BUT WILL WARM QUICKLY MONDAY AND TUESDAY AS THE HIGH MOVES OFFSHORE AND WINDS BECOMING SOUTHERLY. MY FORECAST TEMPS ARE FAIRLY CLOSE TO LATEST MODEL GUIDANCE...EXCEPT MONDAY AND TUESDAY WHERE MY FORECAST HIGHS ARE 2-3 DEGREES ABOVE LATEST MOS NUMBERS IN RECOGNITION OF THE PATTERN THAT OFTEN BRINGS TOASTY TEMPERATURES TO THE INTERIOR COASTAL PLAIN OF THE CAROLINAS. THE UPPER LEVEL PATTERN EXPLAINS WHY MY FORECAST REMAINS A DRY ONE. ZONAL FLOW FRIDAY WILL BECOME INCREASINGLY AMPLIFIED SATURDAY AS A RIDGE AXIS DEVELOPS OVER THE LOWER MISSISSIPPI VALLEY AND SETS UP RESIDENCE ALONG THE SOUTHEAST COAST SUNDAY & MONDAY. FORECAST SOUNDINGS SHOW VERY DRY AIR ABOVE THE BOUNDARY LAYER THROUGH THE PERIOD...WITH A SUBSIDENCE INVERSION CAPPING OFF ANY DAYTIME CUMULUS LONG BEFORE THEY COULD POSSIBLY BECOME SHOWERS. BY TUESDAY IT IS POSSIBLE INCREASING SURFACE THETA-E VALUES COULD POP CONVECTION THROUGH THE WEAKENING SUBSIDENCE INVERSION AS THE RIDGE PUSHES A LITTLE MORE OFFSHORE...BUT I`LL ONLY PUT A 20 POP IN FOR NOW. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
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AS OF 06Z...POTENTIAL FOR MVFR DUE TO FOG AT KILM/KLBT OVERNIGHT. OTHERWISE EXPECT VFR TO PREVAIL THROUGH THE VALID TAF PERIOD AS A COLD FRONT PUSHES THROUGH THE AREA WITH HIGH PRESSURE BUILDING IN TODAY. ISOLATED SHRA/TSRA POSSIBLE THIS AFTERNOON. GIVEN RAINFALL FROM EARLIER TONIGHT...COULD SEE PATCHY AREAS OF FOG...ESPECIALLY AT KILM AND KLBT. OTHERWISE EXPECT VFR TO PREVAIL WITH LINGERING HIGH CLOUDS AND VARIABLE WINDS AOB 5 KTS AS A COLD FRONT PUSHES THROUGH...DROPPING SOUTH OF THE AREA BY MORNING. AFTER DAYBREAK...VFR WILL PREVAIL AS HIGH PRESSURE GRADUALLY BUILDS IN. COULD SEE ISOLATED SHOWERS AND POSSIBLY A THUNDERSTORM WEDNESDAY AFTERNOON...BUT DO NOT ANTICIPATE MUCH COVERAGE OR ANY FLIGHT RESTRICTIONS TO ARISE. NORTH-NORTHEAST WINDS AOB 10 KTS THROUGH THE MORNING HOURS WILL BECOME SOUTHEAST IN THE AFTERNOON...WITH SCT MID TO HIGH CLOUD COVERAGE. INTO THE EVENING HOURS...ANY SHRA/TSRA WILL TAPER OFF GIVING WAY TO VFR WITH LIGHT WINDS. EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS/THUNDERSTORMS POSSIBLE ON THURSDAY. OTHERWISE EXPECT VFR.
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&& .MARINE...
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NEAR TERM /THROUGH TONIGHT/... AS OF 130 AM WEDNESDAY...THE REMAINDER OF THIS EVENINGS SFC PRESSURE PATTERN TO YIELD SW TO WSW WIND DIRECTIONS. A MODEST SFC PG WILL YIELD 10 TO AROUND 15 KT FOR WIND SPEEDS. AS THE COLD FRONT APPROACHES AND PUSHES ACROSS THE AREA WATERS DURING THE PRE- DAWN WED AND EARLY DAYTIME MORNING WED HOURS...WINDS WILL SLOWLY VEER TO THE NW-N BY DAYBREAK...AND NE-ENE BY LATE DAYTIME MORNING WED. NOT MUCH OF A COOL SURGE EXPECTED AFTER THE PASSAGE OF THIS FRONT...AND THEREFORE HELD SPEEDS IN THE 10-15 KT RANGE. SIGNIFICANT SEAS WILL RANGE BETWEEN 2 AND 3 FEET...WITH A SOLID 3 FT ACROSS THE WATERS FROM CAPE FEAR TO LITTLE RIVER INLET DUE TO THE SW-W WIND DIRECTION AND THE BETTER FETCH. THE SIG. SEAS WILL BE A COMBINATION OF A PSEUDO ESE GROUND SWELL AT 1.0 TO 1.5 FT AT 8-9 SECOND PERIODS...AND...2 TO 3 FT WIND DRIVEN WAVES AT 4 SECOND PERIODS. SPECTRAL DENSITY CHARTS FOR VARIOUS BUOYS INDICATE NEARLY EQUAL ENERGY BEING PRODUCED VIA THE GROUND SWELL VS WIND WAVES. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 300 PM TUESDAY...COLD FRONT WILL BE JUST SOUTH OF LOCAL WATERS ON WEDNESDAY EXTENDING FROM SOUTH CAROLINA E-NE INTO THE ATLANTIC. OVERALL EXPECT WEAK PRESSURE GRADIENT WITH NORTHERLY WINDS LESS THAN 15 KTS. LOW PRESSURE WILL DEVELOP ALONG THE FRONT TO THE SOUTH AND WILL MOVE EAST THROUGH THURS. EXPECT VARIABLE WINDS AND TIGHTENING GRADIENT AS BOUNDARY SHIFTS NORTH BEFORE LOW PUSHES EAST OVERNIGHT THURS. WINDS WILL INCREASE UP TO 15 KTS THROUGH WED NIGHT INTO THURS. SEAS OF 1-2 FEET INITIALLY WILL INCREASE TO 2-4 FEET WED NIGHT INTO THURS. LONG TERM /FRIDAY THROUGH SUNDAY/... AS OF 300 PM TUESDAY...LOW PRESSURE AND ITS ASSOCIATED SURFACE COLD FRONT SHOULD BE OFFSHORE BY DAYBREAK FRIDAY MORNING. HIGH PRESSURE OVER THE GREAT LAKES WILL PUSH A SURGE OF SLIGHTLY COOLER AIR SOUTHWARD...WITH A 15-KNOT NE BREEZE EXPECTED FRIDAY. THE HIGH WILL MOVE DOWN TO THE MID-ATLANTIC COAST SATURDAY NIGHT...THEN SHOULD PUSH OFFSHORE FOR SUNDAY AND MONDAY. DRY WEATHER IS FORECAST THROUGH THE PERIOD. SEAS ARE LIKELY TO BE LARGEST AND CHOPPIEST ON FRIDAY BUT EVEN HERE WE`RE ONLY TALKING 3 FEET INSIDE 20 MILES FROM SHORE. DIMINISHING WINDS EARLY NEXT WEEK SHOULD ALLOW SEAS TO SUBSIDE TO AROUND 2 FEET.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...DCH/8 SHORT TERM...RGZ LONG TERM...TRA AVIATION...SGL/8

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