Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 010012 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 812 PM EDT TUE SEP 30 2014 .SYNOPSIS... HIGH PRESSURE RIDGING SOUTH ACROSS THE AREA WILL MOVE OFFSHORE THURSDAY AND THURSDAY NIGHT. A STRONG COLD FRONT WILL MOVE ACROSS THE AREA LATE FRIDAY NIGHT. DRY AND COOL HIGH PRESSURE WILL FOLLOW FOR THE WEEKEND AND PERSIST INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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AS OF 730 PM TUESDAY...SOME TRAPPED LOW LEVEL MOISTURE UP TO 6K FT WILL BE ENOUGH FOR SCATTERED STRATOCU CLOUDS OVERNIGHT...MAINLY ALONG THE IMMEDIATE COASTLINE...WITH PARTLY CLOUDY THE WORSE CASE SCENARIO FOR SKY CONDITIONS. MODELS SHOW A WEAK MID-LEVEL S/W OR IMPULSE APPROACHING FROM THE NW DURING THE PRE-DAWN WED HRS. THE DYNAMICS AND MOISTURE ACCOMPANYING IT WILL RESULT IN HIGH STRATOCU OR LOW ALTO-CU CLOUDS AS WHAT IS CURRENTLY OCCURRING WELL UPSTREAM FROM US. WILL KEEP THE BULK OF THESE CLOUDS JUST OUTSIDE THE ILM CWA AT DAYBREAK WED. HAVE HIT THE FOG A LITTLE HARDER...MAINLY TO OCCUR FROM 06Z THROUGH AN HOUR OR 2 AFTER DAYBREAK. FOR THE NEXT UPDATE...WILL DETERMINE WHETHER DENSE FOG MAY BECOME AN ISSUE WITH ALOT DEPENDING ON HOW STRONG AND WIDESPREAD RADIATIONAL COOLING CONDITIONS BECOME. A SOMEWHAT SOFT PRESSURE PATTERN AND RELAXED GRADIENT WILL RESULT WITH CALM WINDS ESPECIALLY AWAY FROM THE IMMEDIATE COAST...WHICH WILL AID THE FOG ISSUE INLAND. PREVIOUS DISCUSSION............................................ AS OF 300 PM TUESDAY...SEASONABLE WEATHER EXPECTED THROUGH THE PERIOD WITH A PLEASANTLY MILD EVENING YIELDING TO A TYPICAL LATE SEPTEMBER NIGHT. A BIT OF A BREEZE LEADING UP TO SUNSET ESPECIALLY ALONG THE COAST DUE TO WAVE OF LOW PRESSURE RUNNING ALONG THE WELL OFFSHORE FRONTAL BOUNDARY. HOWEVER AFTER SUNSET RADIATIONAL COOLING WILL SET UP A SURFACE-BASED COOLING LAYER THAT WILL INHIBIT MIXING AND WINDS SHOULD DROP OFF. A CONTINUATION OF THE LESSENING OF WIND OVERNIGHT MAY LEAD TO SOME CALM WINDS INLAND DURING THE PREDAWN HOURS. SOME PATCHY FOG EXPECTED IN THESE AREAS WITH SOME MUCH MORE MINOR VISIBILITY RESTRICTION POSSIBLE ALONG THE COAST. WIDESPREAD OR DENSE FOG NOT ANTICIPATED AT THIS TIME.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... AS OF 300 PM TUESDAY...SURFACE RIDGE OF HIGH PRESSURE WILL CONTINUE ACROSS THE AREA...MOVING OFFSHORE LATER THURSDAY AND THURSDAY NIGHT. BUILDING RIDGE ALOFT WILL BE MOST AMPLIFIED THURSDAY...THEN MOVING OFFSHORE ON FRIDAY. A VERY WEAK UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE AREA WEDNESDAY NIGHT AND THURSDAY MORNING...BUT THIS SHOULD NOT BE ENOUGH TO INTRODUCE ANY MENTION OF PRECIPITATION. PERHAPS A LITTLE MORE IN THE WAY OF CLOUDS...BUT WILL MAINTAIN A DRY FORECAST. RISING HEIGHTS AND SUNSHINE WILL BRING THE WARMEST TEMPS OF THE WEEK AND EXPECT THURSDAY AFTERNOON WILL BE THE WARMEST. LOWER TO MID 80S BOTH DAYS. A SEABREEZE EACH AFTERNOON WILL KEEP HIGHS AT THE BEACHES AROUND 80. LONGER NIGHTS AND A RATHER DRY COLUMN SHOULD ALLOW LOWS TO DROP TO THE LOWER TO MID 60S. A FEW LOCATIONS WELL INLAND...WHERE RADIATIONAL COOLING IS MAXIMIZED...MAY DROP TO THE UPPER 50S WEDNESDAY NIGHT. GRADIENT MAY BEGIN TO INCREASE THURSDAY NIGHT AS UPSTREAM TROUGH BEGINS TO APPROACH. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 300 PM TUESDAY...A STRONG COLD FRONT WILL MOVE ACROSS THE AREA LATE FRI NIGHT. AHEAD OF THE FRONT INCREASING SOUTHWEST FLOW WILL PUSH TEMPERATURES INTO THE LOW TO MID 80S. DESPITE DEWPOINTS IN THE MID TO UPPER 60S THE LACK OF INSTABILITY AND SHEAR AHEAD OF AND ALONG THE FRONT WILL LIMIT CONVECTION. STILL THINK ISOLATED THUNDER IS POSSIBLE WITH FROPA BUT STRONG TO SEVERE CONVECTION SEEMS UNLIKELY. STORMS THAT DO DEVELOP WILL HAVE THE ABILITY TO PRODUCE DECENT RAINFALL GIVEN PRECIPITABLE WATER VALUES EXCEEDING 2 INCHES...BUT STORM MOTION WILL BE AROUND 15 MPH SO FLOODING IS NOT A CONCERN. THE AIR MASS FOLLOWING THE COLD FRONT IS LOOKING MORE INTERESTING WITH SIGNIFICANT HEIGHT AND 850 TEMP DROPS FOR THE WEEKEND. 850 TEMPS DROP FROM AROUND 16C LATE FRI NIGHT TO AS LOW AS 4C BY SUN MORNING. GFS/ECMWF SHOW DECENT COLD SURGE ARRIVING DURING THE DAY SAT. TIMING IS STILL A BIT UNCERTAIN AND WILL PLAY A LARGE ROLE IN DETERMINING HIGHS SAT. TEMPS RISE INITIALLY SAT MORNING THEN START FALLING DURING THE MIDDAY EARLY AFTERNOON PERIOD AS THE COLDER AIR ARRIVES. COLD ADVECTION CONTINUES SAT NIGHT WITH TEMPS DROPPING INTO THE UPPER 40S/LOWER 50S IF 850 TEMPS AND PARTIAL THICKNESS VALUES ARE TO BE BELIEVED. TEMPS CONTINUE BELOW CLIMO SUN/SUN NIGHT WITH LOWS AGAIN FLIRTING WITH UPPER 40S AND LOWER 50S...DUE TO RADIATIONAL COOLING AS OPPOSED TO COLD ADVECTION. DEEP DRY AIR WILL KEEP SKIES MOSTLY CLOUD FREE AND ALL BUT RULE OUT PRECIP CHANCES. TEMPERATURES CLIMB BACK NEAR CLIMO MON WITH DEVELOPMENT OF SOUTHERLY FLOW. ANOTHER COLD FRONT DROPS INTO THE REGION TUE BUT THE CORE OF THE COLD AIR PASSES OFF TO THE NORTHWEST TUE AS THE CENTER OF THE HIGH MOVES OVERHEAD. FRONT LACKS MOISTURE AS WELL AS STRONG FORCING AND ITS PASSAGE MAY END UP BEING LITTLE MORE THAN AN INCREASE IN CLOUD COVER. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... AS OF 00Z...CURRENT TAFS WILL BE TWEAKED FOR CLOUD COVER/WINDS FOR THE EVENING PERIOD...OTHERWISE NO MAJOR CHANGES EXPECTED. VFR THIS EVENING. MODERATELY GOOD SETUP FOR FOG OVERNIGHT. SURFACE MOISTURE IS LIMITED AND VERY NEAR THE SURFACE WITH VERY DRY AIR ALOFT. WINDS AT THE BOUNDARY LAYER WILL BE LIGHTEST INLAND TERMINALS...THUS BEST CONFIDENCE FOR IFR/LIFR WILL BE AT KLBT AND KFLO. CANNOT RULE OUT IFR/LIFR AT THE COASTAL TERMINALS...ESPECIALLY KCRE...BUT BELIEVE THERE A BIT MORE WIND TO CONTEND WITH AT THE SURFACE AND ALOFT AND WILL CONTINUE TO INDICATE MVFR. SINCE FOG SHOULD BE SHALLOW IT SHOULD MIX OUT FAIRLY QUICKLY AFTER SUNRISE... 14Z AT THE LATEST. VFR EXPECTED THE REMAINDER OF THE DAY WITH LIGHT NE WINDS EXCEPT BECOMING SE AT KCRE/KMYR IN THE AFTERNOON. EXTENDED OUTLOOK...VFR CONDITIONS WILL PREVAIL THROUGH SUN. CHANCE OF SHOWERS/MVFR LATE FRI/EARLY SAT WITH A COLD FRONT. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... AS OF 745 PM TUESDAY...THE NAM REMAINS THE SLOWER AND SLIGHTLY DEEPER WITH THE LOW OFFSHORE FROM THE CAROLINAS...THAT IS PROGGED TO MOVE FURTHER AWAY FROM THE U.S. MAINLAND. AS A RESULT...WILL LEAN TOWARD THE NAM WIND OUTPUT. OVERALL...LOOKING AT NNE-NE WINDS AT 10 KT...TO OCCASIONALLY 15 KT ESPECIALLY IN THE VICINITY OF CAPE FEAR. SIGNIFICANT SEAS WILL RUN MAINLY 2 TO 3 FT...EXCEPT SOME 1 FOOTERS ESPECIALLY SOUTH OF CAPE FEAR TO MYRTLE BEACH WHERE AN OFFSHORE WIND TRAJECTORY RESIDES. WIND DRIVEN WAVES WITH 4 TO 6 SECOND PERIODS WILL DOMINATE THE SIGNIFICANT SEAS. HOWEVER... A 1 FOOT...13-15 SECOND PERIOD...EASTERLY GROUND SWELL HAS BEEN IDENTIFIED BY LOCAL AND VICINITY BUOYS AND WILL PUSH ACROSS THE ILM COASTAL WATERS. PREVIOUS DISCUSSION.................................................. AS OF 300 PM TUESDAY...A SMALL PINCH IN THE GRADIENT FOR MOST OF THE PERIOD AS HIGH PRESSURE BUILDS IN FROM THE N. AT THE SAME TIME LOW PRESSURE WILL BE VERY SLOW TO MOVE NORTHEAST ALONG A FRONTAL BOUNDARY STALLED WELL OFF THE COAST. WIND WILL REMAIN OUT OF THE NORTHEAST AT 10 TO 15 KT FOR MUCH OF THE PERIOD BUT MAY DROP TO JUST 10KT TOWARDS ITS END. AS SUCH ANY 4 FT WAVES SHOULD DROP OFF AND SEAS WILL TEND TO BE CAPPED AT 3 FT. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 300 PM TUESDAY...THE WIND DIRECTION WILL STILL BE NORTH WEDNESDAY MORNING...BUT WINDS WILL VEER TO NORTHEAST DURING THE AFTERNOON. NEAR SHORE...THE SEABREEZE WILL ALLOW WINDS TO BECOME EAST TO SOUTHEAST DURING THE AFTERNOON. A DEVELOPING LAND BREEZE LATE WEDNESDAY NIGHT SHOULD BRING WINDS MORE OFFSHORE. AS HIGH PRESSURE BEGINS TO MOVE OFFSHORE ON THURSDAY...THE WIND DIRECTION WILL BECOME SOUTHERLY AND THEN SOUTHWEST THURSDAY NIGHT. THE WIND SPEEDS SHOULD BE 10 KT OR LESS THROUGH THE PERIOD. SEAS WILL BE 2 FT OR LESS...UP TO 3 FT ACROSS THE OUTER MOST WATERS. LONG TERM /FRIDAY THROUGH SUNDAY/... AS OF 300 PM TUESDAY...INCREASING SOUTHWEST FLOW FRI INTO FRI NIGHT AHEAD OF ADVANCING COLD FRONT WILL LIKELY REQUIRE HEADLINES. WINDS AND SEAS MAY END UP JUST SHORT OF SCA THRESHOLDS BEFORE FRONT ARRIVES BUT AT THE VERY LEAST A SCEC SHOULD BE REQUIRED. ALTHOUGH A STRONG COLD SURGE IS NOT EXPECTED BEHIND THE FRONT THERE WILL BE ENOUGH OF A SURGE TO KICK UP NORTHWEST FLOW LATER SAT AND SAT NIGHT. 15 TO 20 KT IS LIKELY BUT OFFSHORE COMPONENT WILL KEEP SEAS WITHIN 20 NM 2 TO 4 FT AT MOST. GRADIENT RELAXES SUN AS HIGH PRESSURE ALONG THE GULF COAST SHIFTS EAST. NORTHWEST FLOW WILL DROP UNDER 10 KT BY MIDDAY WITH WINDS BACKING TO SOUTHWEST AS THE PERIOD ENDS. SEAS WILL DROP TO 2 FT OR LESS SUN.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...RJD NEAR TERM...DCH/MBB SHORT TERM...RJD LONG TERM...III AVIATION...MRR

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