Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 250808 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 408 AM EDT FRI JUL 25 2014 .SYNOPSIS... A STALLED FRONTAL BOUNDARY ACROSS PORTIONS OF THE FORECAST AREA ON FRIDAY...WILL DISSIPATE BY SATURDAY. HIGH PRESSURE WILL FOLLOW AND BRING HOT...HUMID AND SULTRY CONDITIONS THIS WEEKEND THRU DAYTIME MONDAY. THE NEXT COLD FRONT WILL DROP INTO THE AREA FROM THE NORTHWEST LATE MONDAY...AND TRACK ACROSS AND SOUTH OF THE REGION BY TUESDAY. IN ITS WAKE...COOLER AND DRIER CONDITIONS WILL OVERSPREAD THE AREA FOR THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM FRIDAY...A COLD FRONT WILL MEANDER ACROSS OUR FORECAST AREA THIS MORNING BEFORE BECOMING INTERTWINED WITH THE SEABREEZE BOUNDARY THIS AFTERNOON. THE FRONT IS EXPECTED TO LIFT BACK TO THE NORTH BEFORE DISSIPATING TONIGHT. SHOWERS AND SOME THUNDERSTORMS WERE STILL ONGOING VERY EARLY THIS MORNING. THIS CONVECTION SHOULD TEND TO BECOME MORE SPARSE THROUGH DAYBREAK...EXCEPT ACROSS THE WATER. THE AIRMASS TODAY WILL NOT BE AS MOIST OR AS UNSTABLE AS ON THU. IN FACT WITH TIME...THE MID LEVELS WILL DRY OUT...FIRST ACROSS INLAND COMMUNITIES AND THEN AT THE COAST LATER THIS AFTERNOON. AS THIS DRIER AIR ARRIVES...PRECIPITABLE WATER VALUES WILL DROP FROM NEAR 2 INCHES THIS MORNING TO NEAR AN INCH AND THREE-QUARTERS DURING THE AFTERNOON. MIXED LAYER CAPE VALUES WILL GENERALLY BE IN THE RANGE OF 1000 TO 1500 J/KG. THE FLOW ALOFT WILL BE WEAKER THAN ON THU AND FROM THE WEST. HOWEVER...A SURFACE FRONT WILL BE IN THE AREA TODAY AND A SEABREEZE BOUNDARY WILL DEVELOP THIS AFTERNOON. ALSO...A MID-LEVEL TROUGH WILL BE JUST UPSTREAM TODAY...MOVING ACROSS THE AREA TONIGHT. THUS ALTHOUGH THE COVERAGE AND INTENSITY OF THE SHOWERS AND THUNDERSTORMS SHOULD BE LESS THAN ON THU...WE DO EXPECT MAINLY SCATTERED CONVECTION WITH PERHAPS A GREATER EMPHASIS ACROSS OUR SOUTHERN AND COASTAL ZONES WHERE DEEPER MOISTURE WILL HANG ON LONGEST. THE DAY WILL BEGIN CONSIDERABLY COOLER THAN 24 HOURS AGO. HIGHS TODAY WILL BE AROUND 90...WITH MORE LOWER 90S ACROSS THE PEE DEE REGION AND MORE UPPER 80S ALONG THE IMMEDIATE COAST. DEWPOINTS WILL ALSO BE A LITTLE LOWER AND THIS WILL KEEP THE AFTERNOON HEAT INDEX UNDER 100 DEGREES IN MOST PLACES. THE SOUTH SANTEE RIVER AREA HAS THE HIGHEST RISK OF EXPERIENCING A HEAT INDEX OF 100 DEGREES THIS AFTERNOON. ANY CONVECTION STILL AROUND LATER IN THE AFTERNOON WILL COME TO AN END THIS EVE AS THE AIRMASS SHOULD STABILIZE RATHER QUICKLY WITH PRONOUNCED DRYING TAKING PLACE IN THE WAKE OF THE UPPER TROUGH. IN FACT SKIES ARE EXPECTED TO BECOME PARTLY CLOUDY TO MOSTLY CLEAR TONIGHT. WINDS WILL BE LIGHT. GIVEN THE GROUND WILL STILL BE WET IN MANY PLACES...PATCHY TO PERHAPS AREAS OF FOG MAY DEVELOP AS TEMPS COOL TO NEAR THE DEWPOINTS...LOWER TO MID 70S. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 330 AM FRIDAY...MODELS CONTINUE WITH THE ONGOING LONGWAVE UPPER PATTERN THIS PERIOD...WITH TROFFING ALOFT ACROSS THE EASTERN 1/3RD OF THE U.S. AND RIDGING ALOFT FOR THE WESTERN 2/3RDS OF THE U.S. THE UPPER TROF AXIS...NOT AS AMPLIFIED AS WAS EARLIER IN THE WEEK...IS PROGGED TO A POSITION JUST OFF THE CAROLINA COASTS...BASICALLY ALONG THE EASTERN SEABOARD. AT THE SFC...MODELS INDICATE THE SFC FRONT WILL DECAY ACROSS THE AREA ON SATURDAY. THIS WILL LEAVE THE FA UNDER WEAK RIDGING FROM THE ATL WATERS...AND THE FORMATION OF THE PIEDMONT TROF ACROSS THE CENTRAL CAROLINAS DURING SATURDAY. FOR SUNDAY THRU SUNDAY NIGHT...THE MODELS REMAIN IN GOOD AGREEMENT WITH THE AMPLIFICATION OF BOTH THE UPPER TROF OVERHEAD...AND THE UPPER RIDGING THAT IS CURRENTLY AFFECTING THE WESTERN 2/3RDS OF THE U.S. A S/W TROF IS PROGGED TO DIVE OUT OF CENTRAL CANADA EARLY SUNDAY...AND BASICALLY AID IN THE AMPLIFICATION PROCESS OF THE FLOW ALOFT ACROSS THE CONTERMINOUS U.S. AT THE SFC...THE WEAK RIDGING FROM OFF THE COAST WILL GET SHUNTED SOUTH OF THE AREA. THE PIEDMONT SFC TROF WILL GAIN SOME STRENGTH AS MODELS CONTINUE WITH THE TIGHTENING OF THE GRADIENT ASSOCIATED WITH THE PIEDMONT TROF. THIS PERIOD WILL BE HIGHLIGHTED BY THE 3HS...HAZY HOT AND HUMID. VERY LITTLE IN THE WAY OF CONVECTION IS EXPECTED EXCEPT FOR ISOLATED CHANCES ALONG THE SEA BREEZE BOUNDARY...AND ANY CONVECTION THAT DRIFTS TO THE FA AFTER FIRING UP ALONG THE PIEDMONT TROF. THUS 20-30 POPS ARE THE HIGHEST WILL GO THIS PERIOD. OVERALL...WARMER TEMPS ALOFT AS WELL AS SUBSIDENCE ALOFT...WILL BOTH AID IN KEEPING A LID ON CONVECTION THIS WEEKEND. VARIOUS MODEL MOS GUIDANCE DOES PAINT WIDESPREAD 90+ DEGREE TEMPS FOR SATURDAY...AND EVEN HOTTER ON SUNDAY. HAVE GONE ALONG WITH THESE NUMBERS ESPECIALLY WITH THE DECENT W-NW DOWNSLOPE FLOW ALOFT. IN FACT...HEAT ADVISORY CRITERIA WILL LIKELY BE MET ON SUNDAY WITH HIGHS WELL INTO THE 90S ALONG WITH HUMIDITY LEVELS HAVING INCHED BACK UPWARDS. THUS THE 2 COMBINED PROVIDE FORECAST HEAT INDICES REACHING A WIDESPREAD 104-106 DEGREES ACROSS THE FA. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 300 PM THURSDAY...MID LEVEL TROUGH WILL DOMINATE MUCH OF THE PERIOD KEEPING TEMPERATURES ACROSS THE REGION BELOW CLIMO. THE EXCEPTION WILL BE ON SUN WITH MID LEVEL RIDGE TO THE WEST EXTENDING EAST. 850 TEMPS WILL FLIRT WITH 20-22C WHICH SHOULD PRODUCE HIGHS IN THE MID TO UPPER 90S. DESPITE THE HOT TEMPS DO NOT THINK THERE WILL BE MUCH CONVECTION AROUND. WESTERLY MID LEVEL FLOW AND SUBSIDENCE ON THE RIDGES PERIPHERY WILL KEEP MID LEVELS DRY. CANNOT RULE OUT ISOLATED CONVECTION...ESPECIALLY LATER IN THE DAY ASSOCIATED WITH THE PIEDMONT TROUGH BUT SEE NO REASON TO GO ABOVE INHERITED SILENT POP. COLD FRONT MOVES INTO THE AREA LATE MON...PUSHED BY IMPRESSIVE MID LEVEL TROUGH. DOES NOT LOOK LIKE MON WILL BE AS HOT AS SUN GIVEN INCREASED MID LEVEL MOISTURE AND MORE WIDESPREAD CONVECTION LATER IN THE DAY...JUST AHEAD OF THE FRONT. SHOULD THE FRONT BE DELAYED A BIT MON COULD END UP AS HOT AS SUN GIVEN 850 TEMPS HANGING IN THE LOW 20C RANGE FOR MUCH OF THE DAY. LATER MON INTO TUE WILL BE THE MOST ACTIVE PART OF THE PERIOD CONVECTIVELY SPEAKING AND WILL MAINTAIN INHERITED HIGH CHC POP. MID LEVEL TROUGH AXIS WILL REMAIN WEST OF THE AREA THROUGH THE PERIOD WITH THE FRONT STALLING NOT TOO FAR OFF THE COAST. INITIALLY MID LEVELS ARE DRY BUT INCREASING MOISTURE ALOFT WILL RESULT IN A SLOW INCREASE IN POP THROUGH THE MIDDLE OF NEXT WEEK. TEMPS WILL RUN A LITTLE BELOW CLIMO LATE IN THE PERIOD. && .AVIATION /07Z FRIDAY THROUGH TUESDAY/... AS OF 06Z...ISOLATED TO SCATTERED SHOWERS WILL REMAIN IN THE VICINITY OFF THE TAF SITES THROUGH 10Z OR SO. MVFR/IFR IS POSSIBLE DUE TO PATCHY FOG ESPECIALLY INLAND TERMINALS. BEST CONFIDENCE OF TEMPO LIFR WILL BE AT KLBT. VFR EXPECTED ALL TERMINALS 12-13Z WITH LIGHT SW-WNW WINDS AT THE COASTAL TERMINALS AND WNW-N WINDS AT KFLO. WINDS BECOME SE-SW AT THE COASTAL TERMINALS LATE MORNING. SHRA/TSRA POSSIBLE AGAIN BY 18Z WITH BEST CONFIDENCE OF TS OCCURRENCE AT THE COASTAL TERMINALS. CONVECTION DISSIPATES IN THE EVENING WITH WINDS BECOMING LGT/VRBL. EXTENDED OUTLOOK...SHOWERS/TSTMS/TEMPO MVFR POSSIBLE SUNDAY AND MONDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM FRIDAY...A FRONT SHOULD BE NEAR THE WATERS THIS MORNING AND THEN BECOME INTERTWINED WITH THE SEABREEZE THIS AFTERNOON BEFORE LIFTING NORTH AND DISSIPATING TONIGHT. PRIOR TO DAYBREAK...SUSTAINED WIND SPEEDS WILL RANGE FROM 10 TO 15 KT. WINDS WILL BE 10 KT OR LESS FOR THE REMAINDER OF THE PERIOD. THE DIRECTION WILL BE MAINLY FROM THE WSW OR SW THROUGH DAYBREAK AND MAY BECOME LIGHT AND VARIABLE FOR A TIME THIS MORNING. A S TO SW WIND DIRECTION IS EXPECTED THIS AFTERNOON. SW WINDS SHOULD RETURN TONIGHT. SEAS WILL BE HIGHEST NEAR DAYBREAK...UP TO 4 TO 5 FT. SEAS WILL BE SUBSIDING THEREAFTER... REACHING TO 2 TO 3 FT THIS AFTERNOON AND 2 FT TONIGHT. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 330 AM FRIDAY...FOR SATURDAY...THE AREA WATERS WILL BE UNDER THE INFLUENCE OF A DECAYING FRONTAL BOUNDARY...RESULTING IN MAINLY A VARIABLE WIND DIRECTION FOR MUCH OF THE DAY...AND WITH THE LACK OF ANY GRADIENT...SPEEDS WILL GENERALLY BE 10 KT OR LESS. FOR SUNDAY...THE AMPLIFYING FLOW ALOFT WILL RESULT IN A STRENGTHENING SFC PIEDMONT TROF ACROSS THE CENTRAL CAROLINAS AND THE RIDGING FROM THE BERMUDA HIGH BEING SHUNTED WELL SOUTH OF THE AREA WATERS. THIS WILL PRODUCE A TIGHTENING SFC PG ACROSS THE CAROLINAS INCLUDING THE COASTAL WATERS. THE SFC PRESSURE PATTERN WILL YIELD A SFC SW-WSW WIND DIRECTION...WITH INCREASING SPEEDS SUNDAY INTO SUNDAY NIGHT. SCEC AND/OR SCA CONDITIONS WILL LIKELY BE MET SUNDAY AFTERNOON AND/OR NIGHT. SIGNIFICANT SEAS WILL BE AT THEIR EBB DURING SATURDAY WITH AN ESE- SE 1-3 FOOT GROUND SWELL DOMINATING THE WATERS. THE AFTN/EVENG SEA BREEZE CIRCULATION WILL ADD SOME WIND CHOP NEAR SHORE. FOR SUNDAY...LOOK FOR WIND DRIVEN WAVES TO STEADILY INCREASE IN BOTH HEIGHT AND PERIODS...AND WILL LIKELY BE THE DOMINANT PLAYER IN THE SIGNIFICANT SEAS FORMULA. WILL ADVERTISE 6 FOOTERS ACROSS THE LOCAL WATERS LATE SUNDAY AFTERNOON BUT MORE LIKE SUNDAY NIGHT. .LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 300 PM THURSDAY...MODEST SW FLOW ON SUN WILL INCREASE INTO MON AS GRADIENT TIGHTENS AHEAD OF ADVANCING COLD FRONT. SPEEDS LATER SUN MAY APPROACH SCEC THRESHOLDS AS PIEDMONT TROUGH STRENGTHENS. SCA HEADLINES SEEM CERTAIN FOR AT LEAST MON AND POSSIBLY SUN NIGHT AS PROLONGED STRONG SOUTHWEST FLOW BUILDS SEAS TO 4 TO 6 FT. FRONT MOVES ACROSS THE WATERS MON NIGHT WITH NORTHERLY FLOW DEVELOPING. GRADIENT RELAXES BEHIND THE FRONT AND SPEEDS WILL DROP UNDER 10 KT BY MIDDAY TUE. FRONT ENDS UP STALLED JUST EAST OF THE WATERS WITH THE PROXIMITY TO THE FRONTAL ZONE KEEPING GRADIENT WEAK AND WINDS LIGHT AND VARIABLE. SEAS WILL DROP TO 3 TO 4 FT BEHIND THE FRONT AND BELOW 3 FT BY THE END OF THE PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...DCH NEAR TERM...RJD SHORT TERM...DCH LONG TERM...III AVIATION...RJD

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