Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 190541 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 141 AM EDT FRI SEP 19 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD INTO THE CAROLINAS FROM THE NORTH AS LOW PRESSURE DEVELOPS OFF THE SOUTHEAST COAST AND MOVES NORTHWARD INTO THE WEEKEND. A COLD FRONT WILL MOVE ACROSS THE AREA MONDAY NIGHT FOLLOWED BY COOL AND DRY HIGH PRESSURE DURING THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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AS OF 1:45 AM FRIDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: LOWER DEWPOINTS ARE PRESSING SOUTHWARD INTO OUR NE ZONES THIS EVENING AS SURFACE HIGH PRESSURE RIDGES SOUTHWARD. THIS FEATURE WILL TIGHTEN THE LOCAL PRESSURE GRADIENT WHICH WILL INCREASE ONSHORE WINDS OVERNIGHT...HIGHEST ALONG THE COAST WHERE MIXING WILL BE MUCH MORE VIGOROUS. EVEN AT 2Z/10P ENE GUSTS TO 20 MPH WERE COMMON ALONG BOTH THE SC AND NC COASTS. THE SLIGHT DRY AIR INTRUSION WILL HINDER SHOWER DEVELOPMENT OVER MUCH OF NC BUT FURTHER SOUTH OVERNIGHT MENTIONABLE POP VALUES WILL BE RETAINED DUE TO STRONGER LOW-LEVEL CONVERGENCE...DEEPER MOISTURE AND MORE PARCEL BUOYANCY IN THE LOWER TROPOSPHERE. MINIMUM TEMPS MAY REQUIRE ADJUSTMENTS NEAR THE IMMEDIATE COAST WHERE MOUNTING WINDS WILL LIKELY KEEP TEMPS LEVELED-OFF AND ELEVATED COMPARED TO INTERIOR LOCATIONS MORE DECOUPLED FROM THE BOUNDARY LAYER FLOW. 1500 FOOT PATCHY STRATUS MAY FORM LATE BUT WINDS SHOULD KEEP FOG AND MIST FROM GAINING A SUBSTANTIAL AND MENACING FOOTHOLD TONIGHT.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/... AS OF 300 PM THURSDAY...HIGH PRESSURE WILL RIDGE DOWN THROUGH THE INLAND CAROLINAS IN A TYPICAL WEDGE-LIKE FASHION WHILE LOW PRESSURE OFF THE SOUTHEAST COAST STRENGTHENS AS IT TRACKS NORTHWARD FRI THROUGH SATURDAY. THE MID TO UPPER TROUGH PULLS OFF TO THE NORTHEAST LEAVING A WEAKNESS IN THE MID TO UPPER LEVELS OVER GA/SC COAST. THE SFC LOW WILL TRACK NORTH REACHING EAST OF THE CAPE FEAR COAST BY SAT NIGHT. THE INCREASING E-NE FETCH AHEAD OF THE SYSTEM SHOULD AFFECT MAINLY COASTAL SECTIONS WITH CLOUDS AND POSSIBLE SHOWERS. THE NAM CONTINUES TO BE MUCH SLOWER WITH THE EVOLUTION OF THIS LOW...NOT REACHING THE CAPE FEAR COAST UNTIL LATE SUNDAY. THEREFORE KEEPING A MORE EASTERLY FETCH...BEING MORE AGGRESSIVE WITH ITS ONSHORE PUSH OF MOISTURE WITH PCP WATER VALUES UP TO 1.8 INCHES OVER PORTIONS OF LOCAL FORECAST AREA FRI INTO SAT. THE GFS HOLDS THE MOISTURE CLOSER TO THE COAST IN A TIGHTER MORE NE FLOW AROUND THE LOW WITH MOIST AIR IN A TIGHTER GRADIENT BETWEEN THE COAST AND INLAND. WILL NEED TO WATCH HOW THIS LOW EVOLVES AS IT MAY EVEN TAKE ON SOME TROPICAL CHARACTERISTICS OVER THE NEXT COUPLE OF DAYS. FOR NOW WILL MAINTAIN MAINLY SHALLOW MOISTURE WITH CLOUDS AND PCP CONFINED CLOSER TO THE COAST AND SPREADING NORTHWARD AS LOW APPROACHES. AS WINDS STRENGTHEN THERE MAY BE INCREASED CONVERGENCE AND MORE WIDESPREAD SHWR CHANCES BUT UNCERTAINTY EXISTS AS TO HOW FAST AND HOW CLOSE TO COAST THE LOW WILL MOVE AND THEREFORE WILL KEEP BRUNT OF ACTIVITY ALONG AND OFF SHORE. CLOUD COVER MAINLY ALONG THE COAST AND EAST-NORTHEAST FLOW WILL KEEP HIGH TEMPERATURES NEAR TO SLIGHTLY BELOW CLIMO THROUGH THE PERIOD. LOWS WILL END UP NEAR TO SLIGHTLY ABOVE CLIMO...A COMBINATION OF CLOUD COVER AND LINGERING LOW LEVEL MOISTURE. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 300 PM THURSDAY...BIGGEST QUESTION MARK DURING THE EXTENDED INVOLVES A LOW PRESSURE MOVING ALONG THE COAST SUNDAY. GFS/CMC/NAM SUGGEST THAT A HYBRID/WARM-CORE LOW PRESSURE SYSTEM WILL BE JUST OFF THE NC COAST SUNDAY MORNING...WHILE THE ECMWF SHOWS BARELY A TROUGH MOVING TO THE NORTHEAST. TIMING DIFFERENCES EXIST...AS THE NAM IS QUITE SLOW COMPARED TO THE OTHER GUIDANCE...AND IS LIKELY TOO SLOW SINCE ANY LOW PRESSURE SHOULD BE PICKED UP AND SLUNG TO THE NE BY A SECONDARY TROUGH DROPPING INTO THE GREAT LAKES. THE GFS SEEMS TO BE A CONSISTENT COMPROMISE...AND IS FAVORED FOR THE EXTENDED. THIS SUGGESTS THAT WHILE RAPID DRYING WILL OCCUR DURING SUNDAY...THE FIRST PART OF THE DAY WILL BE CLOUDY AND POSSIBLY UNSETTLED WITH SHOWERS...ESPECIALLY ALONG THE COAST. AS THIS SYSTEM PULLS AWAY...RAPID DRYING WILL OCCUR AND THE SECOND HALF OF SUNDAY WILL BE SUNNY WITH SEASONABLE TEMPERATURES. A VERY BRIEF PERIOD OF WAA DEVELOPS LATE SUNDAY INTO MONDAY BEFORE A STRONGER COLD FRONT CROSSES THE CAROLINAS LATE MONDAY. THIS FRONT NOW LOOKS TO BE MOISTURE STARVED DUE TO SUCH A BRIEF PERIOD OF MOIST ADVECTION AHEAD OF IT...AND THUS ONLY A SCHC OF SHOWERS IS EXPECTED WITH SOME ENHANCED CLOUD COVER. THIS WILL RAPIDLY CLEAR AND DRY BY TUESDAY...AND SOME BEAUTIFUL FALL WEATHER WILL OVERSPREAD THE REGION WITHIN CANADIAN HIGH PRESSURE FROM LATE TUESDAY THROUGH THE REST OF THE PERIOD. HIGHS AND LOWS ARE EXPECTED TO BE A FEW DEGREES BELOW CLIMO...BUT LOW HUMIDITY AND LOTS OF SUNSHINE WILL PRODUCE GREAT WEATHER AS THE CALENDAR TICKS OFFICIALLY INTO ASTRONOMICAL FALL. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/...
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AS OF 06Z...THE RADAR SHOWS SOME NOCTURNAL SHOWER ACTIVITY OVER THE COASTAL WATERS...BUT RIGHT NOW NO THREAT TO ANY TAF SITES. COULD SEE AREAS OF MVFR CIGS DEVELOP EARLY THIS MORNING...PARTICULARLY ALONG THE COAST WHERE 2-3KFT MARINE STRATOCU MAY CLIP KCRE/KMYR WITHIN THE LOW LEVEL E-NE FLOW. SOME MVFR CIGS COULD ALSO DEVELOP INLAND AROUND AND JUST AFTER DAYBREAK. WINDS ARE TOO STRONG FOR ANY FOG CONCERNS TONIGHT. EASTERLY FLOW WILL STRENGTHEN ON FRI AS CANADIAN HIGH PRESSURE CONTINUES BUILDING SOUTHWARD INTO THE CAROLINAS. EAST WINDS 10-15 KT WITH HIGHER GUSTS...ESPECIALLY AT THE COASTAL TERMS...WILL PREVAIL DURING THE DAY. AN UPPER DISTURBANCE MAY HELP TO SPARK SOME SHOWER ACTIVITY IN THE AFTN. FOR NOW...WILL MAINTAIN VCSH FOR OUR SOUTHERN TERMINALS AS THIS IS WHERE THE BEST MOISTURE/LIFT IS EXPECTED. WINDS WILL DIMINISH TO NORTHEAST AOB 10 KT DURING THE EVENING HOURS. EXTENDED OUTLOOK...CHANCE OF SHOWERS ALONG THE COAST SAT. GUSTY NORTHEAST WINDS SAT WILL BECOME NORTHWEST ON SUN AS LOW PRESSURE WELL OFFSHORE MOVES UP THE EAST COAST. VFR ON MON/TUE.
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&& .MARINE...
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NEAR TERM /THROUGH TONIGHT/... AS OF 1:45 AM FRIDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: WILL NEED TO TAKE A CLOSER LOOK AT POTENTIAL OF AN EXERCISE CAUTION STATEMENT AS WINDS HOLD NEAR 20 KT INTO EARLY FRIDAY. SEAS HOLDING AT 4 FEET BUT NOT GOING TO TAKE TOO MUCH MORE WIND TO REACH 5 FT. STRONG HIGH PRESSURE WILL BUILD SOUTHWARD AND INCREASE NE-ENE WINDS INTO EARLY FRIDAY. SEAS OF 3 TO 4 FT MAY SEE A 4-5 FT RANGE EARLY FRIDAY...HIGHEST OFFSHORE AND NORTH OF CAPE FEAR. SEAS SHOWING WANING SWELL FROM EDOUARD OF 1-2 FEET EVERY 10-11 SECONDS BUT BUILDING E WAVES 3-4 FT EVERY 5-6 SECONDS. A FEW SHOWERS OR AN ISOLATED TSTMS IS POSSIBLE ON THE 0-20 NM WATERS OVERNIGHT AS NIGHT-TIME INSTABILITY RISES. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 300 PM THURSDAY...WINDS WILL WILL INCREASE THROUGH FRI IN PINCHED GRADIENT FLOW BETWEEN WEDGE OF HIGH PRESSURE INLAND AND LOW PRESSURE DEVELOPING OFF THE SOUTHEAST COAST. NE WINDS WILL INCREASE UP TO 20 KT WITH HIGHER GUSTS THROUGH FRI INTO FRI NIGHT. AS NE WINDS INCREASE THROUGH FRI...SEAS WILL REACH SCA THRESHOLDS INTO FRI EVE...ESPECIALLY NORTH OF CAPE FEAR...BUILDING TO 4 TO 6 FT. SEAS WILL REMAIN LOWER CLOSE TO THE COAST SOUTH OF CAPE FEAR WHERE NE FLOW IS BLOCKED. HIGH PRESSURE WILL WEAKEN INLAND AS HIGH SHIFTS FARTHER OFF THE NEW ENGLAND COAST LOSING ITS GRIP. THIS SHOULD HELP GRADIENT WINDS TO DIMINISH AND SEAS TO LOWER THROUGH SATURDAY...BUT AS LOW MOVES NORTHWARD CLOSER TO THE LOCAL WATERS...NE WINDS SHOULD INCREASE ONCE AGAIN...POSSIBLY REACHING SCA THRESHOLDS ONCE AGAIN. LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 300 PM THURSDAY...LOW PRESSURE WILL BE MOVING UP THE COAST ON SUNDAY...AND WILL BE JUST OFFSHORE...EAST OR NORTHEAST...OF THE WATERS TO START THE PERIOD. THIS LOW WILL MOVE AWAY DURING SUNDAY...WITH WINDS BACKING FROM NE TO NW...AND THEN WEST BY MONDAY MORNING. STILL SOME UNCERTAINTY INTO THE STRENGTH AND TRACK OF THIS LOW PRESSURE...BUT ATTM IT LOOKS LIKE IT WILL BE WEAK ENOUGH AND FAR ENOUGH OFFSHORE TO KEEP WINDS TO 15 KTS OR LESS REGARDLESS OF DIRECTION ON SUNDAY. SEAS WILL FEATURE HIGHLY VARIABLE DIRECTIONS ON SUNDAY WHICH WILL MAKE A CONFUSED SPECTRUM...BUT WAVE HEIGHTS WILL FALL FROM 3-5 FT EARLY TO 2-3 FT BY MONDAY MORNING. OF COURSE...IF THIS LOW PRESSURE BECOMES STRONGER OR MOVES CLOSER...CONDITIONS COULD END UP BEING WORSE THAN CURRENTLY FORECAST. A BRIEF PERIOD OF W/SW WINDS MONDAY WILL QUICKLY BECOME NW BEHIND A COLD FRONT WHICH WILL CROSS THE WATERS LATE IN THE DAY...FOLLOWED BY A NE SURGE ON TUESDAY WITH WINDS AGAIN RISING TO 15 KTS. LOW-AMPLITUDE SEAS OF 1-2 FT MONDAY WILL RISE SLOWLY DURING TUESDAY AS THE NE WINDS INCREASE...BECOMING 3-5 FT LATE IN THE PERIOD.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...RGZ NEAR TERM...REK/RJD SHORT TERM...RGZ LONG TERM...JDW AVIATION...BJR MARINE...REK/RJD/JDW/RGZ

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