Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 221958 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 358 PM EDT MON SEP 22 2014 .SYNOPSIS...
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AN UPPER LEVEL LOW DEVELOP ACROSS THE AREA TONIGHT THROUGH THE MIDWEEK PERIOD. LIGHT STRATIFORM RAINS WILL BECOME THE MAINSTAY ACROSS THE EASTERN CAROLINAS THROUGH THE MID TO POSSIBLY LATE WEEK PERIOD. A STALLED AND INVERTED COASTAL TROF/FRONT WILL REMAIN OVER THE ADJACENT ATLANTIC WATERS DURING THIS PERIOD KEEPING THE THREAT FOR CONVECTION OVER LAND TO A MINIMUM. A WARMING AND DRYING TREND IS EXPECTED BY THE UPCOMING WEEKEND.
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&& .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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AS OF 300 PM MONDAY...THE COLD FRONT CONTINUES TO DROP SOUTH AS DEWPOINTS ARE NOW IN THE UPPER 50S ACROSS MOST AREAS. ANY SHOWERS ASSOCIATED WITH THE BOUNDARY HAVE DISSIPATED FOR THE MOST PART AT LEAST FOR THE MOMENT. THIS LULL IN ACTIVITY WILL CONTINUE FOR THE NEXT FEW HOURS BEFORE THE DEEP MID LEVEL TROUGH ACROSS THE APPALACHIANS DROPS FURTHER SOUTH AND CLOSES OFF. SEVERAL FACTORS SEEM TO HAVE COME TOGETHER TO FORECAST A WET OVERNIGHT PERIOD FOR THE EASTERN THIRD OF THE CWA. FIRST THERE IS A DECENT PLUME OF MOISTURE EMANATING FROM THE GULF OF MEXICO VIA WATER VAPOR. SECOND...THE OMEGA WILL COME IN SEVERAL FORMS THROUGH A DEEP LAYER. STARTING AT THE LOWEST LEVELS...SOME MODEST ISENTROPIC LIFT EXISTS IN THE 209-300K LAYER. MOVING UP...SOME MID LEVEL FRONTOGENESIS EVIDENT IN THE 700-500MB LAYER. DIFLUENCE EXISTS AT THE 500MB LAYER AND FINALLY...A STRONG JET AT 300MB WILL MOVE UP THE COAST AND THE FAVORABLE REGIONS WILL MOVE ACROSS THE COASTAL AREAS. LONG STORY SHORT...I HAVE INCREASED POPS TO LIKELY FOR THESE AREAS. QPF AMOUNTS MAY ECLIPSE ONE HALF INCH ESPECIALLY SOUTHERN AND EXTREME COASTAL AREAS BUT WILL OTHERWISE END UP BETWEEN ONE TENTH INLAND TO ONE HALF ELSEWHERE. I HAVE MADE A FEW ADJUSTMENTS FOR THE AFTERNOON TEMPERATURES TO ADDRESS THE CLOUD COVER COOLED READINGS BUT OVERNIGHT LOWS REMAIN ON TRACK FOR LOWER 60S ALONG THE COAST TO UPPER 50S NORTHWEST.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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AS OF 300 PM MONDAY...PATTERN ALOFT TO BECOME SOMEWHAT OF A BOTTLE NECK ACROSS THE AREA. MODELS IN UNISON WITH THE DEVELOPMENT OF A CLOSED UPPER LOW ACROSS THE CAROLINAS ON TUESDAY...AND WILL PERSIST ACROSS THE FA THRU WEDNESDAY. POSITIONING OF THIS CLOSED LOW ACROSS WESTERN CAROLINAS WILL RESULT IN S GOOD FEED OF MOISTURE FROM THE ATLANTIC AND TO A LESSER DEGREE FROM THE GULF OF MEXICO. AT THE SFC...STRONG 1035+ MB HIGH CENTERED OVER THE NE STATES WILL RIDGE DOWN THE EAST COAST. JUST OFFSHORE AND LINING UP NEARLY PARALLEL TO THE CAROLINA COASTLINE SOUTH OF CAPE HATTERAS...WILL LIE A COASTAL TROF/FRONT. DURING THIS SHORT TERM PERIOD...DO NOT ANTICIPATE THIS BOUNDARY MOVING ONSHORE VIA MODEL CONSENSUS. WILL BE LOOKING AT OVERRUNNING OR ISENTROPIC LIFT ACROSS THE FA WHICH WILL PRODUCE STRATIFORM-TYPE LIGHT RAINS. A SHARP GRADIENT WILL EXIST WITH RESPECT TO THE MOISTURE DISTRIBUTION ACROSS THE FA...WITH THE HEAVIEST PCPN LIKELY TO OCCUR EAST OF THE I-95 CORRIDOR TO THE IMMEDIATE CAROLINA COASTS. THE POSITIONING OF THIS UPPER LOW ACROSS THE WESTERN AND CENTRAL CAROLINAS WILL DETERMINE WHETHER ADDITIONAL HEAVIER PCPN WILL GET PUSHED INLAND. HAVE INDICATED AN ISOLATED THUNDERSTORM POSSIBLE FOR ANY ELEVATED CONVECTION THAT HOLDS TOGETHER AS IT DEVELOPS IN THE VICINITY OF THE COASTAL FRONT AND PUSHES ONSHORE. AS FOR MAX/MIN TEMPS TUESDAY THRU WEDNESDAY...HAVE LEANED TOWARD THE COOLER GFS MOS GUIDANCE DUE TO CLOUDINESS AND ONGOING PCPN THREAT AS WELL AS THE PRESENT STRONG NE FLOW ACROSS FA THRUOUT THIS PERIOD.
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&& .LONG TERM /THURSDAY THROUGH MONDAY/...
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AS OF 300 PM MONDAY...COOL AIR WEDGE PLUS A COASTAL TROUGH SPELLS SOME RATHER UNSETTLED AND PROBABLY PRETTY COOL WEATHER THURSDAY AND FRIDAY. IN FACT THE MOS GUIDANCE NUMBERS MAY BE SHOWING THEIR BIAS TOWARDS CLIMO THAT INCREASES WITH TIME SINCE THEY PORTRAY TEMPS NEAR CLIMO BOTH DAYS...WHILE KEEPING HIGHS NEAR 70 TOMORROW IN A SIMILAR AIRMASS OFFERING UP CLOUDS AND RAIN. WILL KEEP FORECAST CLOSER TO CURRENT VALUES OF MID 70S FOR HIGHS. RAIN CHANCES WILL BE MOST FOCUSED ALONG THE COAST BOTH DAYS IN PROXIMITY TO THE TROUGH AND DEEPEST MOISTURE AND THE GFS HAS NOW BACKED OFF ALMOST COMPLETELY WITH INLAND PENETRATION OF QPF. THIS IS NOW SUPPORTED BY THE GEM AND SO MAY NEED TO BE REEVALUATED. MID LEVEL RIDGING STRENGTHENS ACROSS THE EASTERN U.S. SUPPRESSING THE DEEP MOISTURE OFF TO OUR SOUTH LIKELY LEADING TO A RAIN-FREE WEEKEND. WHILE THE SENSE OF LOW LEVEL THERMAL ADVECTION OVER THE WEEKEND WILL TECHNICALLY BE NEUTRAL OR EVEN WEAKLY COOL THE RETURN OF SUNSHINE WILL FAVOR SEASONABLE TEMPERATURES DURING THE DAY. THE LESSER CLOUD COVER MEANWHILE COULD BRING SOME COOLER NIGHTS WHEN COMPARED TO EARLIER IN THE PERIOD.
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&& .AVIATION /19Z MONDAY THROUGH SATURDAY/... AS OF 18Z...A COLD FRONT WILL CONTINUE TO DROP SOUTHWARD...WITH NORTH NORTHEAST WINDS AT ALL TERMINALS. PATCHY LIGHT RAIN MAY BE REPLACED WITH HEAVIER CONVECTION...MAINLY ALONG THE EXTREME SOUTHEASTERN PORTION OF THE CWA...POSSIBLY AFFECTING THE MYRTLES. PREDOMINATELY MVFR CONDITIONS IN THE SHOWERS. TONIGHT...ACTIVITY DIMINISHING WITH CONTINUED NORTHEAST FLOW. THE NAM IS VERY PESSIMISTIC WITH REGARD TO CEILINGS...BRINGING EVERYONE DOWN TO IFR. FELL THIS IS WAY OVERDONE AT THE JUNCTION...BUT KEEP AN OPEN MIND. TUESDAY...A LOW FORMS ALONG THE FRONT AND TRIES TO WAVE THE FRONT BACK ONSHORE...HOWEVER FEEL MOST OF THE MOISTURE WILL STAY OFFSHORE AT THIS TIME. EXTENDED OUTLOOK...UNSETTLED WEATHER THROUGH THE PERIOD...MAINLY ALONG THE SOUTHEAST COAST OF THE CWA WITH PERIODS OF RAIN/SHOWERS AND INTERMITTENT MVFR/IFR CONDITIONS. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM...THE COASTAL WATERS WILL CONTINUE TO SEE WINDS INCREASE IN MAGNITUDE AND MAINTAIN A NORTHERLY COMPONENT THROUGH TUESDAY MORNING. CURRENTLY...WINDS ARE FROM THE NORTH ABOUT 10-12 KNOTS. AS HIGH PRESSURE SHIFTS ACROSS THE OHIO VALLEY THE GRADIENT WILL GRADUALLY INCREASE TO SEE A ROBUST 15 KNOTS. THE DIRECTION WILL SHIFT A BIT TO THE NORTHEAST AS WELL. SIGNIFICANT SEAS WILL SLOWLY BUILD FROM AROUND THE CURRENT 2-3 FEET TO 3-4 FEET. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 300 PM MONDAY...STRONG SFC HIGH CENTERED OVER THE NE STATES...WILL RIDGE DOWN THE EASTERN SEA BOARD THRU THIS PERIOD. AT THE SAME TIME...A COASTAL TROF/FRONT WILL MANIFEST ITSELF DURING THIS PERIOD. MODELS KEEP THIS BOUNDARY JUST OFFSHORE FROM THE CAROLINAS COASTLINES. THIS WILL RESULT IN A PINCHED SFC PG ACROSS THE LOCAL WATERS FOR AN EXTENDED PERIOD OF TIME. THIS WILL PRODUCE NE TO ENE 15 TO 25 KT WINDS...WITH FEW GUSTS UP TO 30 KT. SOMEWHAT TOO EARLY FOR THE DAYSHIFT...WILL LET EITHER THE EVENING OR OVERNIGHT SHIFT PUT UP THE EXTENDED SCA. SIGNIFICANT SEAS WILL BUILD AND HOLD IN THE 3 TO 7 FOOT RANGE DEPENDING ON ONES LOCATION IN RELATION TO THE COASTLINE CONFIGURATION. OVERALL...SIG SEAS WILL BECOME MAINLY A FUNCTION OF NE TO ENE WIND WAVES EXHIBITING 5 TO 6 SECOND PERIODS. AN UNDERLYING 1-3 FOOT GROUND SWELL AT 8+ SECOND PERIODS WILL ALSO REMAIN PRESENT. LONG TERM /THURSDAY THROUGH FRIDAY/... AS OF 300 PM MONDAY...A PINCHED NORTHEASTERLY GRADIENT WILL KEEP THE REGION VERY CLOSE TO THE CUSP OF SCEC HEADLINES VS SMALL CRAFT ADVISORY. THE MORE SERIOUS LATTER HEADLINE APPEARS IN THE OFFERING FOR THE EARLIER PART OF THE PERIOD WHILE CONDITIONS MAY DROP DOWN TO SCEC COME SATURDAY. THIS WOULD BE IN RESPONSE TO A BUILDING MID LEVEL RIDGE AND A SLIGHT SOUTHWARD PUSH OF THE MAIN AXIS OF SURFACE HIGH PRESSURE. THERE WILL BE A LONG PERIOD NE SWELL THAT WILL COEXIST WITH THE WIND WAVES...BUT BOTH WILL ALSO EXPERIENCE SOME SHADOWING LOCALLY OFF OF HATTERAS.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...DCH NEAR TERM...SHK SHORT TERM...DCH LONG TERM...MBB AVIATION...SHK/DL

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