Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 141049 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 650 AM EDT SUN SEP 14 2014 .SYNOPSIS... UNSETTLED WEATHER WITH PERIODS OF HEAVY RAINFALL WILL CONTINUE THROUGH MONDAY AS A STALLED FRONT WAVERS NEAR THE AREA. A STRONGER COLD FRONT WILL CROSS THE REGION ON TUESDAY. CANADIAN HIGH PRESSURE WILL BUILD DOWN THE COAST BEHIND THIS COLD FRONT...BRINGING COOLER AND DRIER WEATHER FOR THE MIDDLE AND LATTER PARTS OF THE UPCOMING WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 400 AM SUNDAY...LAST MINUTE CHANGES TO THE ISSUANCE OF A NEW AND RE-CONFIGURED FLOOD WATCH FOR THE ILM CWA. THE COLD FRONT HAS MADE A DECENT PUSH SOUTHWARD ACROSS PORTIONS OF THE FORECAST AREA EARLY THIS MORNING AND LOOKS TO HAVE STALLED ONCE AGAIN ACROSS THE ILM SC COUNTIES FOR THE TIME BEING. 88D RADAR AND SFC OBS TRENDS HAVE IDENTIFIED A MINI-DRY SURGE PUSHING SOUTH ACROSS THE NORTHERN TIER OF THE ILM CWA. THIS HAS PUSHED 60S SFC DEWPOINTS...WITH 50S DEWPOINTS JUST OUTSIDE OF THE FA. AS A RESULT OF THE DRY AIR INFILTRATION...THE DEEPEST MOISTURE HAS ALSO BEEN PUSHED SOUTHWARD. THIS LATEST UPDATE HAS RESULTED IN A RE-HASHING OF THE CURRENT FLOOD WATCH. HAVE DROPPED 6 OF THE NORTHERN-MOST COUNTIES OF THE ILM CWA FROM THE WATCH...AND CONTINUED THE REMAINING ILM COUNTIES THROUGH MIDNIGHT TONIGHT. THE ALREADY SATURATED AREAS WITHIN THE FLOOD WATCH HAVE THE POTENTIAL TO FLOOD FROM RAINFALL AMOUNTS THAT NORMALLY WOULD NOT. ISENTROPIC LIFT MAY BECOME MORE INVOLVED NORTH OF THE COLD FRONT TODAY...WITH ELEVATED CONVECTION FURTHER INCREASING NORTH OF THE FRONT. AM SOMEWHAT CONFIDENT THAT THE ELEVATED AND DEEPEST CONVECTION WILL OCCUR ACROSS THE COUNTIES WITHIN THE WATCH AREA RATHER THAN OUTSIDE IT. OVERALL...THE WATCH AREA COULD OBSERVE AN ADDITIONAL 1 TO 2 INCHES OF RAIN THROUGH MIDNIGHT TONIGHT. AS FOR TEMPS...STAYED CLOSER TO A BLEND OF THE NAM AND GFS MOS GUIDANCE...WITH A SLIGHT LOWER TREND NORTH OF THE COLD FRONT DUE TO THE CURRENT MINI DRY SURGE. THE FA WILL CONSIST OF NEAR CATEGORICAL POPS ALONG AND SOUTH OF THE COLD FRONT...WITH CHANCE TO LIKELY NORTH OF THE FRONT. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 AM SUNDAY...COLD FRONT STALLED TO THE SOUTH WILL LIFT BACK TO THE NORTH AS A WARM FRONT DURING MONDAY...CONTINUING THE UNSETTLED WEATHER BUT WITH WARMER TEMPERATURES EXPECTED. AS THE FRONT LIFTS BACK TO THE NORTH...WAA WILL FOLLOW AND HIGHS MONDAY WILL LIKELY RISE TO SEASONABLE VALUES FINALLY...WITH LOW-TO-MID 80S EXPECTED...WARMEST SOUTH. THIS WARMTH WILL GO SOMEWHAT UNREALIZED HOWEVER...AS WIDESPREAD CLOUD COVER WILL INHIBIT MUCH SUNSHINE...AND SHOWERS AND TSTMS WILL BE SCATTERED THROUGHOUT THE DAY. PWATS RISE TO 2.25 INCHES LATE MONDAY...AND EXPECT ANOTHER DAY OF SCATTERED-TO-WIDESPREAD CONVECTION WITH PERIODS OF HEAVY RAINFALL. BEST CHANCE OF HEAVY RAINFALL WILL ACTUALLY BE LATE MONDAY INTO TUESDAY...AS THE FRONT THEN GETS PUSHED BACK TO THE SOUTHEAST ONE LAST TIME AS A STRONGER COLD FRONT...WITH DRY/COOL ADVECTION INCREASING BEHIND THIS BOUNDARY DURING TUESDAY. BEST CHANCE FOR SHOWERS WILL BE EARLY TUESDAY BEFORE A BREAK IS EXPECTED LATE. ALTHOUGH SUNSHINE WILL INCREASE ON TUESDAY...AN HIGH TEMPS MAY BE REACHED EARLIER THAN TYPICAL AHEAD OF THE CAA...WITH MID 80S AGAIN EXPECTED BEFORE COOLING LATE IN THE AFTN. MINS MONDAY NIGHT WILL BE VERY WARM...LIKELY AROUND 70...BEFORE DROPPING TO THE MID 60S TUESDAY NIGHT. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 300 AM SUNDAY...GFS HAS COME MORE IN LINE WITH THE STEADY ECMWF IN ITS EVOLUTION FOR LATE NEXT WEEK REGARDING A STALLED COLD FRONT OFFSHORE. AS A DEEP UPPER TROUGH AMPLIFIES ACROSS THE EAST...COOL CANADIAN SURFACE HIGH PRESSURE RIDGES DOWN THE COAST...AND THESE TWO FEATURES PUSH TUESDAYS COLD FRONT WELL OFFSHORE BY WEDNESDAY. THIS FRONT WILL EVENTUALLY STALL...AND IT APPEARS A WAVE OF LOW PRESSURE WILL DEVELOP ALONG IT...BUT IT LOOKS TO BE JUST DISTANT ENOUGH TO KEEP THE AREA DRY (FOR A CHANGE). WILL CONTINUE WITH SCHC POP ALONG THE COAST...BUT CONTINUE THE INHERITED TREND OF RAMPING DOWNWARD THROUGH LATE NEXT WEEK...AS A PERIOD OF FALL-LIKE WEATHER ENVELOPS THE CAROLINAS WITH SLIGHTLY BELOW SEASONABLE TEMPS AND LOW HUMIDITY. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/...
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AS OF 12Z...WEDGE IS MUCH MORE IMPRESSIVE THAN EXPECTED...AND HAS PUSHED FARTHER SOUTH THAN ANTICIPATED. MOST OF THE PRECIP TODAY MAY BE QUITE LIGHT...MORE OF AN OVERRUNNING SITUATION. RAINFALL COULD STILL BE HEAVY AT TIMES OVER THE SOUTHERN THIRD OF THE CWA...DUE TO THE PROXIMITY OF THE FRONT. POST FRONTAL IFR CEILINGS WILL LIFT TO MVFR BY MID MORNING...WITH A RATHER BRISK NORTHEAST WIND. BECOMING VFR BY EARLY AFTERNOON...CONTINUING THROUGH THE END OF THE FORECAST PERIOD. EXTENDED OUTLOOK...CHANCE OF AFTERNOON SHOWERS/TSTMS AND TEMPO MVFR THROUGH TUESDAY. EXPECT MAINLY VFR WEDNESDAY AND THURSDAY.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 415 AM SUNDAY...THE POSITIONING OF THE SFC COLD FRONT WILL DETERMINE THE WIND FIELD ACROSS THE LOCAL WATERS. NORTH OF THE FRONT...THE WATERS WILL OBSERVE INCREASING NE WINDS UP TO 15 KT FROM A MINI DRY AIR SURGE RATHER THAN A COOL SURGE. SFC DEWPOINTS IN THE 60S AND EVEN 50S NOT TOO FAR NORTH WILL FURTHER FUEL THIS SURGE. SOUTH OF THE FRONT...LOOKING AT A VARIABLE WIND DIRECTION AT 5 KT OR LESS DUE TO A WEAK AND LOOSE SFC PRESSURE GRADIENT. SIGNIFICANT SEAS SOUTH OF THE FRONT REMAIN QUITE DOCILE WITH 1 TO 2 FEET. THE WATERS EXPERIENCING THE SURGE WILL OBSERVE INCREASING SIG. SEAS...IN THE 2 TO 3 FOOT RANGE...POSSIBLY UP TO 4 FT ACROSS THE WATERS COVERING FRYING PAN SHOALS. AVERAGE PERIODS WILL RUN 3 TO 4 SECONDS...INDICATIVE OF SHORT PERIOD WIND DRIVEN WAVES DOMINATING THE WAVES SPECTRUM. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 AM SUNDAY...NEARLY STATIONARY COLD FRONT WILL WAVER ACROSS THE WATERS EARLY IN THE WEEK...CAUSING WINDS TO EXPERIENCE NEARLY EVERY COMPASS DIRECTION DURING THE PERIOD. INITIALLY...FRONT WILL BE SOUTH OF THE WATERS WITH LIGHT NE WINDS COMMON...BUT THESE WINDS WILL SHIFT THROUGH MONDAY TO BECOME SE AND THEN W/SW BY TUESDAY NIGHT AS THE FRONT LIFTS NORTHWARD. THIS FRONT WILL THEN RETURN AS A REINFORCED COLD FRONT EARLY TUESDAY...CAUSING WINDS TO TURN TO THE NW AND EVENTUALLY NE BY TUESDAY NIGHT. SPEEDS WILL BE LESS THAN 10 KTS REGARDLESS OF DIRECTION...INCREASING ONLY VERY LATE IN THE PERIOD. THESE LIGHT AND HIGHLY VARIABLE WINDS WILL KEEP WAVE HEIGHTS LOW AMPLITUDE MOST OF THE PERIOD...REMAINING 1-3 FT INTO TUESDAY NIGHT. LATE TUESDAY HOWEVER...SOME LONG PERIOD SWELL FROM TROPICAL STORM EDOUARD WILL ARRIVE IN THE COASTAL WATERS...AND WAVE HEIGHTS WILL BEGIN TO BUILD...BECOMING 3-5 FT TUESDAY NIGHT. LONG TERM /WEDNESDAY THROUGH THURSDAY/... AS OF 300 AM SUNDAY...AN EXTENDED PERIOD OF POOR MARINE CONDITIONS MEETING SCA THRESHOLDS BEGINS WEDNESDAY AS AN EXTENDED NE SURGE DEVELOPS WITHIN A PINCHED GRADIENT BEHIND A COLD FRONT...AND INCREASING AMPLITUDE LONG PERIOD SWELL FROM TROPICAL STORM EDOUARD COMBINE. NE WINDS OF 10-15 KTS EARLY WEDNESDAY WILL RISE TO 15-20 KTS LATE WEDNESDAY...AND THEN PERSIST ON THURSDAY...DRIVING A WIND WAVE OF ABOUT 6FT/5SEC INTO THE COASTAL WATERS. THESE WIND WAVES WILL WORK IN TANDEM WITH A 3FT/13SEC SE SWELL TO PRODUCE 4-6 FT WAVES THROUGH MIDDLE AND LATTER PORTIONS OF THE UPCOMING WEEK...CREATING THE EXPECTED LONG-DURATION SMALL CRAFT ADVISORY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...FLOOD WATCH THROUGH THIS EVENING FOR SCZ032-033-039-053>056. NC...FLOOD WATCH THROUGH THIS EVENING FOR NCZ099-107>110. MARINE...NONE. && $$ SYNOPSIS...JDW NEAR TERM...DCH SHORT TERM...JDW LONG TERM...JDW AVIATION...43

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