Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 232350 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 750 PM EDT TUE SEP 23 2014 .SYNOPSIS... A COASTAL TROUGH JUST OFFSHORE WILL BRING ABUNDANT RAINFALL TO THE AREA TODAY THROUGH WEDNESDAY...ALONG WITH WELL BELOW NORMAL TEMPERATURES. RAINFALL CHANCES WILL DIMINISH LATER IN THE WEEK. A WARMING AND DRYING TREND IS EXPECTED OVER THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 300 PM TUESDAY...UPPER LOW HAVING DEVELOPED ACROSS THE SC- GA AREA...IS PROGGED TO WEAKEN AS IT DRIFTS SLOWLY TO THE NE BY THE MODELS. AT THE SFC...A COASTAL TROF/FRONT IS POISED TO REMAIN EAST OF THE FORECAST AREA WITH OVERRUNNING STRATIFORM LIGHT RAINS RULING THE PCPN FIELD ACROSS THE FA THRU TONIGHT. DYNAMICS FROM THIS UPPER LOW INCLUDING MID- LEVEL VORTS/IMPULSES ROTATING AROUND AND THRU THE UPPER LOW...WILL PROVIDE ADDITIONAL MEANS OF SYNOPTIC/MESOSCALE LIFT. OVERALL...WILL KEEP CATEGORICAL POPS JUST AT THE IMMEDIATE COAST...WITH A DECLINING TREND AS 1 PROGRESSES INLAND. USING THE I-95 CORRIDOR AS A DIVIDING LINE BETWEEN THE BEST/HIGHER POP CHANCES EAST TO THE COAST...AND JUST A CHANCE ALONG AND WEST OF THE I-95 CORRIDOR. THE COASTAL TROF/FRONT TO REMAIN JUST OFFSHORE AND WILL BE A FOCUS FOR THUNDERSTORM ACTIVITY OVER THE ATLANTIC WATERS DUE TO THE INCREASED INSTABILITY. LAND AREAS WILL PRIMARILY HAVE STRATIFORM TYPE LIGHT RAINS TO DOMINATE. HAVE CLOSED THE DIURNAL RANGE WITH TODAYS HIGHS AND TONIGHTS LOWS GIVEN THE LACK OF INSOLATION AND TEMPERATURE RISE TODAY.
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&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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AS OF 300 PM TUESDAY...UNSETTLED WEATHER CONTINUES INTO THE SHORT TERM...ESPECIALLY ON WEDNESDAY AS A LOW PRESSURE CENTER FORMS JUST OFFSHORE ALONG A STALLED FRONTAL BOUNDARY/COASTAL TROUGH. GUIDANCE IN GOOD AGREEMENT ON THE GENERAL SCENARIO FOR WEDNESDAY WITH A STRONG HIGH PRESSURE CENTER MOVING EAST ACROSS NEW ENGLAND AS THE COASTAL TROUGH SHARPENS AND THE LOW CENTER FORMS OFFSHORE. PLENTIFUL MOISTURE WILL CONTINUE TO BE ADVECTED IN...ESPECIALLY AT THE LOW LEVELS. RESULTING OVER-RUNNING SCENARIO WILL KEEP IN THE STRONG LIKELIHOOD OF RAIN ALONG THE COAST WITH LESSER CHANCES INLAND. COOL EASTERLY FLOW AND EXTENSIVE CLOUD COVER WILL KEEP DAYTIME TEMPERATURES WELL BELOW NORMAL WITH HIGHS ONLY IN THE LOWER TO MID 70S MOST PLACES. LOWS WEDNESDAY NIGHT WILL HOVER RIGHT AROUND 60. THURSDAY A LITTLE LESS CERTAIN BUT WILL LIKELY BE LESS WET THAN WEDNESDAY AS THE OFFSHORE LOW PULLS AWAY WELL TO THE NORTHEAST. DRYER AIR WILL ADVECT IN ALOFT...BUT THE LOWEST LEVELS MAY REMAIN NEARLY SATURATED WITH P/W VALUES IN THE 2 INCH RANGE. THE PROXIMITY OF THE STILL-STALLED OFFSHORE FRONT WILL BE KEY TO THE AMOUNT OF RAIN WE WILL SEE AND ON THIS POINT MODELS DIFFER. BEST I CAN SAY WITH REASONABLE CONFIDENCE IS THAT EXTENSIVE CLOUD COVER WILL CONTINUE ALONG WITH THE CHANCES FOR RAIN...ESPECIALLY ALONG THE COAST. HOWEVER...LACKING THE THE STRONGER LOW LEVEL FORCING THAT WE HAVE FOR WEDNESDAY...EXPECT LOWER POPS AND QPF TOTALS.
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&& .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 300 PM TUESDAY...WEDGE OF HIGH PRESSURE WILL RUN DOWN THROUGH THE INLAND CAROLINAS WHILE A COASTAL TROUGH LINGERS JUST OFF SHORE THROUGH MUCH OF THE WEEKEND. THE MID TO UPPER LOW WHICH PLAGUED THE EAST COAST THROUGH THE FIRST HALF OF THE WEEK WILL ACTUALLY ROTATE AROUND FROM THE OFF SHORE MID ATLANTIC WATERS DOWN TOWARD THE OFF SHORE WATERS OF HATTERAS. THIS MAY NUDGE THE COASTAL TROUGH TO THE SOUTH ALLOWING FOR SOME DRYING OVER THE CAPE FEAR REGION FRI INTO THE WEEKEND. THE NAM SHOWS COASTAL TROUGH PUSHING INLAND ON FRI AND PRODUCING A WETTER FORECAST THROUGH FRI AFTN WHILE THE ECMWF AND GFS KEEP TROUGH FARTHER OFF SHORE ALLOWING FOR A DRIER FORECAST. LOOKS LIKE WE SHOULD BE ABLE TO PULL OFF A DRY WEEKEND BUT THE PATTERN REMAINS QUITE MESSY LEAVING A BROAD RIDGE OVER THE EASTERN CONUS UNTIL SHORTWAVE DIGS DOWN BY SUN NIGHT INTO MONDAY AND UPPER LOW TAKES SHAPE OVER THE GULF COAST. THIS TROUGH SHOULD MOVE THROUGH MONDAY BRINGING A DEEPER DRIER FLOW BY TUES. OVERALL WILL GO WITH MORE OPTIMISTIC FORECAST FOR THE WEEKEND BUT NOT OVERLY CONFIDENT AS TO HOW MUCH SUN WE WILL SEE...ESPECIALLY ALONG THE COAST. INLAND AREAS HAVE A MUCH BETTER SHOT OF MORE SUNSHINE THROUGH THE PERIOD. A COOLER NORTHERLY FLOW WILL EXIST THROUGH MUCH OF THE PERIOD ALTHOUGH IT LIGHTENS UP QUITE A BIT THROUGH THE WEEKEND. CURRENT THINKING IT THAT THE CLOUDS SHOULD KEEP OVERNIGHT LOWS ABOVE NORMAL WHICH SHOULD HELP TO GIVE TEMPS A HEAD START IN THE MORNING AND PLACES WITH SUNSHINE SHOULD SEE TEMPS AROUND NORMAL FOR AFTN HIGHS...AROUND 80. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
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AS OF 00Z...LIGHT RAIN WILL CONTINUE THIS TAF VALID PERIOD WITH BRIEF PERIODS OF MODERATE SHOWERS AT THE COASTAL TERMINALS. NW-NE WINDS 5-15 KT...HIGHEST AT THE COASTAL TERMINALS DECREASING WED AFTERNOON. MODERATE TO HIGH CONFIDENCE MVFR WILL OCCUR AT THE COASTAL TERMINALS THROUGH SUNRISE. IFR COULD OCCUR ASSOCIATED WITH HEAVIER SHOWERS BUT SHOULD BE BRIEF DUE TO RAPID MOVEMENT OF INDIVIDUAL CELLS. IFR MAY BECOME MORE LIKELY AS EARLY AS THE PRE-DAWN HOURS...BUT MORE LIKELY AFTER SUNRISE AS RAIN SATURATES THE LOW LEVEL AIRMASS UPSTREAM. AT KFLO/KLBT VFR EXPECTED THROUGH SUNRISE. MVFR BECOMES MORE LIKELY AS EARLY AS THE PRE-DAWN HOURS...BUT MORE LIKELY AFTER SUNRISE. IFR WILL BE MORE LIKELY IN THE LATE AFTERNOON AS RAIN SATURATES THE LOW LEVEL AIRMASS UPSTREAM BUT CONFIDENCE IS LOW. EXTENDED OUTLOOK...PERIODS OF RAIN AND MVFR/IFR CONDITIONS EXPECTED THROUGH THURSDAY. CHANCE OF SHOWERS FRIDAY...MAINLY ALONG THE COAST. VFR ON SATURDAY AND SUNDAY.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM TUESDAY...THE COASTAL WATERS WILL REMAIN WEST OF THE INVERTED COASTAL TROF/FRONT DURING THIS RAIN EVENT. A PINCHED GRADIENT WILL DEVELOP BETWEEN THE STRONG RIDGING DOWN THE EAST COAST AND THE INVERTED SFC TROF/FRONT. THIS HAS ALREADY RESULTED WITH NE WINDS HAVING INCREASED TO SCA VALUES...ALONG WITH BUILDING SIGNIFICANT SEAS. SEAS COULD PEAK AROUND 8 FT FOR THE WATERS OFF CAPE FEAR...AND OFF FROM THE MOUTH OF WINYAH BAY. DOMINANT PERIODS WILL HOVER AT 5 TO 6 SECONDS INDICATIVE OF WIND DRIVEN WAVES THE DOMINANT WAVE TYPE. AS FOR PCPN...MAINLY STRATIFORM LIGHT RAINS TO FALL ACROSS THE ILM WATERS. INCLUDED ISOLATED CONVECTION AT BEST DUE TO THE CLOSE PROXIMITY OF THE COASTAL TROF/FRONT...BUT AT THIS POINT DO NOT EXPECT THIS CONVECTION TO PUSH ONSHORE...JUST AFFECT THE ILM WATERS AS IT WEAKENS WHILE MOVING WESTWARD. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 300 PM TUESDAY...A LOW PRESSURE CENTER WILL FORM ALONG A STALLED FRONT EITHER OVER OR IN THE VICINITY OF THE WATERS. THIS WILL KEEP WINDS LIGHT AND VARIABLE AT TIMES OVER OUR NC WATERS...AND IN A MORE GENERALLY NORTHERLY DIRECTION FOR OUR SC WATERS. AS THE LOW PULLS AWAY TO THE NE ON THURSDAY WE WILL SEE WINDS GRADUALLY BECOMING NORTHEASTERLY THROUGHOUT BY THE OVERNIGHT HOURS. MOST SIGNIFICANT IMPACT ON MARINE OPERATIONS WILL ACTUALLY BE THE EXTENSIVE RAINFALL GENERATED BY THIS LOW OVER THE COASTAL WATERS. EXPECT THE SMALL CRAFT ADVISORY IN EFFECT AT THE BEGINNING OF THE PERIOD TO LAPSE ON WEDNESDAY MORNING AS SEAS DECAY BELOW 6 FT. EXPECT SEAS TO RUN IN THE 2 TO 4 FT RANGE FROM WEDNESDAY EVENING THROUGH THURSDAY. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 300 PM TUESDAY..WEDGE OF HIGH PRESSURE WITH A PERSISTENT NORTHERLY FLOW UP TO 15 TO 20 KTS...BUT COASTAL TROUGH SHOULD WEAKEN AND SHIFT SOUTH LEAVING LIGHTER WINDS BY THE END OF THE WEEKEND. SHOULD BE SAFE WITH PRECAUTIONARY STATEMENT THROUGH FRI INTO SAT BUT MAY REACH SCA THRESHOLDS FRI NIGHT...BEFORE SEAS SUBSIDE IN LIGHTER WINDS BY THE END OF THE WEEKEND. && .ILM WATCHES/WARNINGS/ADVISORIES...
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SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR AMZ250-252- 254-256.
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&& $$ SYNOPSIS...REK NEAR TERM...DCH SHORT TERM...REK LONG TERM...RGZ AVIATION...MRR MARINE...DCH/REK/RGZ

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