Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 181740 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 140 PM EDT THU SEP 18 2014 .SYNOPSIS... HIGH PRESSURE WILL EXTEND DOWN INTO THE CAROLINAS FROM THE NORTH PROVIDING FALL-LIKE WEATHER FOR THE REMAINDER OF THE WEEK. THE NEXT COLD FRONT WILL MOVE THROUGH ON TUESDAY FOLLOWED BY COOL AND DRY HIGH PRESSURE THROUGH THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1100 AM THURSDAY...SCATTERED TO NUMEROUS SHOWERS AND SOME THUNDERSTORMS PERSIST OFFSHORE. THE VERY ISOLATED SHOWERS THAT WERE AROUND FOR MOST OF THE MORNING...FROM LBT TO CPC HAVE DISSIPATED. STRATUS WAS ERODING...BUT A SIGNIFICANT BATCH REMAINED AND EXTENDED INTO THE CKI AREA LATE THIS MORNING. HIGH PRESSURE WILL PROVIDE A LITTLE MORE SUBSIDENCE AS COMPARED TO WED AS IT CONTINUES TO SLOWLY BUILD SOUTHWARD. A VERY WEAK MID-LEVEL SHORTWAVE TROUGH EMBEDDED IN WNW FLOW WILL MOVE ACROSS THE FORECAST AREA THIS AFTERNOON AND THIS COULD MODESTLY ENHANCE LIMITED LIFTING PROCESSES. INSTABILITY IS NOT AS HIGH AS ON WED...WITH MIXED LAYER CAPE VALUES EXPECTED TO REACH UP TO AROUND 1500 J/KG THIS AFTERNOON. DOWNDRAFT CAPE VALUES STILL REMAIN SIGNIFICANT AND SO ANY STRONG CONVECTION THAT DOES DEVELOP WILL HAVE THE POTENTIAL TO PRODUCE GUSTY WINDS. HIGHER RESOLUTION MODELS ARE INDICATING THE FIRST ACTIVITY THIS AFTERNOON WILL DEVELOP ALONG CONVERGENT SEABREEZE BOUNDARY. INCLUDE 20 TO 30ISH POPS INTO EARLY EVE THROUGHOUT. CONVECTION WILL QUICKLY DIMINISH WITH LOSS OF HEATING THIS EVE. HOWEVER...CONVECTION WILL AGAIN BLOSSOM ACROSS THE WARM ATLANTIC WATERS TONIGHT...SOME OF WHICH MAY SCRAPE THE IMMEDIATE COAST AFTER MIDNIGHT. HIGHS TODAY WILL BE MAINLY IN THE LOWER 80S. OVERNIGHT LOWS WILL AGAIN BE IN THE LOWER TO MID 60S...PERHAPS UPPER 60S AT THE BEACHES. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 300 AM THURSDAY...SURFACE HIGH OVER NEW ENGLAND WILL WEDGE DOWN THE COAST FRI AND SAT...MAINTAINING LOW CLOUDS AND PRECIP CHANCES. NEITHER DAY LOOKS LIKE IT WILL BE A CLASSIC "WEDGE" DAY AS MID LEVEL PROGRESSIVE FLOW OVER NEW ENGLAND WILL BE QUICK TO PUSH THE PARENT HIGH OFF THE COAST. THAT SAID THERE WILL BE AN ABUNDANCE OF LOW LEVEL MOISTURE AND STRONGER NORTHEAST FLOW DOES START TO DEVELOP ON SAT. OF THE 2 DAYS FRI APPEARS TO BE THE DAY WHERE PRECIP IS A LITTLE MORE LIKELY. DEEPER MOISTURE IS PRESENT...PRECIPITABLE WATER VALUES DECREASE BY ABOUT HALF AN INCH FROM FRI INTO SAT...AND LOW LEVEL CONVERGENCE IS A BIT STRONGER. ONLY POTENTIAL HITCH FOR THE SAT FORECAST IS DEVELOPMENT OF WEAK LOW ALONG FRONT STALLED OFF THE COAST. MOST OF THE GUIDANCE KEEPS THIS LOW SOUTHEAST OF THE AREA BUT IF IT DEVELOPS CLOSER TO THE COAST PRECIP CHANCES WOULD BE INCREASED. CLOUD COVER 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 WEDNESDAY/... AS OF 300 AM THURSDAY...NEXT WEEK BEGINS UNSETTLED WITH HIGH PRESSURE WEDGING IN FROM THE NORTH AND LOW PRESSURE PASSING OFF THE SOUTHEAST COAST. DURING SUN THE LOW WILL LIFT NORTHEAST ALONG THE FRONT STALLED OFF THE COAST...BUT HOW FAR OFF THE COAST AND AT WHAT STRENGTH REMAIN CRUCIAL DETAILS. THE LATEST GFS/ECMWF ARE A LITTLE CLOSER TO THE COAST WITH THE FRONT/LOW ON SUN BUT STILL KEEP THE BULK OF THE PRECIPITATION OFF THE COAST. THERE IS LIKELY TO BE A VERY SHARP POP/SKY GRADIENT ON THE WEST SIDE OF THE LOW GIVEN THE TIGHT MOISTURE GRADIENT. FOR NOW HAVE NOT MADE MUCH IN THE WAY OF CHANGES TO THE INHERITED SUN POP FORECAST. REGION WILL START TO DRY OUT LATER SUN WITH SOUTHWEST TO NORTHEAST CLEARING AS THE LOW LIFTS NORTHEAST. LOW EXITS NORTHEAST LATE SUN WITH BRIEF PERIOD OF SOUTHWEST FLOW SUN NIGHT AND MON AS THE NEXT COLD FRONT APPROACHES. THIS WILL BRIEFLY ALLOW TEMPERATURES ABOVE CLIMO...LIKELY THE ONLY TIME DURING THE PERIOD. GFS/ECMWF CONTINUE TO ADVERTISE A LATE MON OR EARLY TUE FROPA...LIKELY ACCOMPANIED BY CONVECTION. FRONT WILL BE ACCOMPANIED BY A NARROW BAND OF DEEPER MOISTURE ALONG WITH DIVERGENCE ALOFT AND THE POTENTIAL FOR SHORTWAVE TROUGH ENHANCEMENT. FROPA TIMING SHOULD ALSO PROVIDE SOME DIURNAL INSTABILITY. WILL INCREASE POP TO CHC MON AND MON NIGHT. MID LEVEL TROUGH PUSHES THE FRONT OFF THE COAST FOR TUE/WED WITH COLD ADVECTION DEVELOPING AS ANOTHER CANADIAN HIGH BUILDS IN. DEEP DRY AIR AND WEST TO NORTHWEST FLOW ALOFT WILL WORK TO KEEP THE REGION DRY TUE/WED. SURFACE HIGH WILL SHIFT FROM OVER THE GREAT LAKES TUE INTO THE NORTHEAST AS THE PERIOD ENDS. THIS MAY LEAD TO ANOTHER WEDGE EVENT FOR THE MIDDLE OF NEXT WEEK. ALOFT THE 5H TROUGH WEAKENS BUT REMAINS IN PLACE THROUGH THE END OF THE PERIOD. && .AVIATION /18Z THURSDAY THROUGH MONDAY/... AS OF 18Z...WEAK HIGH PRESSURE IS AFFECTING THE TERMINALS WITH A FRONT WELL TO THE SOUTH. COASTAL TERMINALS ARE VFR EXCEPT TEMPO MVFR HAS OCCURRED AT KMYR/KCRE OVER THE PAST SEVERAL HOURS. SHOWERS ARE OCCURRING ALONG A RESULTANT BOUNDARY NEAR KCRE/KMYR. VFR IS EXPECTED AT ALL TERMINALS THROUGH THIS EVENING...EXCEPT EARLY THIS AFTERNOON TEMPO MVFR WILL POTENTIALLY OCCUR AT KCRE/KMYR WITH SHOWER ACTIVITY. ISOLATED SHOWERS ALSO POSSIBLE LATER THIS AFTERNOON AND EARLY THIS EVENING NEAR KLBT...BUT CONFIDENCE IS LOW. SHOWER ACTIVITY SHOULD DISSIPATE DURING THE EVENING BUT WILL CONTINUE OFFSHORE OVERNIGHT. OVERNIGHT THERE IS INCREASING CONFIDENCE MVFR CONDITIONS WILL OCCUR. MVFR COULD CONTINUE INTO THE MID-MORNING HOURS AS ISOLATED SHOWERS DEVELOP TERMINAL-WIDE. EXTENDED OUTLOOK...VFR FRIDAY AFTERNOON WITH ISOLATED SHOWERS AND THUNDERSTORMS. RAIN/TEMPO MVFR COASTAL AREAS SAT...WITH GUSTY NORTHEAST WINDS TERMINAL-WIDE EXPECTED SAT/SUN AS A LOW PRESSURE AREA MOVES NORTHEAST ALONG THE COAST. VFR SUN. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1100 AM THURSDAY...NORTHEAST WINDS UP TO 10 TO 15 KT WILL COMBINE WITH EDOUARD RESIDUAL EASTERLY SWELL OF 11 TO 13 SECONDS TO PRODUCE 2 TO 4 FT SEAS. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 300 AM THURSDAY...HIGH PRESSURE BUILDING DOWN THE COAST AND FRONT STALLED EAST OF THE WATERS WILL MAINTAIN EAST TO NORTHEAST FLOW WITH SPEEDS APPROACHING 20 KT AT TIMES. DEVELOPING LOW ALONG THE STALLED FRONT WILL ENHANCE THE GRADIENT DURING THE SECOND HALF OF THE PERIOD AND SPEEDS LATE SAT AND SAT NIGHT COULD APPROACH 25 KT. CONTINUED STRONG NORTHEAST FETCH WILL BUILD SEAS TO 3 TO 5 FT LATER FRI AND SAT WITH AN OUTSIDE SHOT AT 6 FT NORTH OF CAPE FEAR. SCEC OR SCA HEADLINES MAY BE REQUIRED FOR AT LEAST A PORTION OF THE PERIOD. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 300 AM THURSDAY...NORTHEAST FLOW WILL TOP OUT AROUND 15 KT SUN AS WEAK LOW PASSES EAST OF THE WATERS. WINDS WILL BACK TO SOUTHWEST IN THE WAKE OF THE LOW WITH SPEEDS UNDER 10 KT SUN NIGHT AS THE GRADIENT REMAINS WEAK. COLD FRONT APPROACHES FROM THE NORTHWEST MON...TIGHTENING THE GRADIENT A LITTLE AND INCREASING WIND SPEEDS. COLD FRONT CROSSES THE WATERS LATE IN THE PERIOD BUT GRADIENT BEHIND THE FRONT IS INITIALLY WEAK AND COLD ADVECTION IS DELAYED. COLDER AIR ARRIVES AS THE PERIOD ENDS...GIVING A LATE BUMP TO NORTHWEST FLOW. SEAS 3 TO 5 FT AT THE START OF THE PERIOD WILL SUBSIDE TO 2 TO 3 FT LATER SUN AND MON. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...COASTAL FLOOD ADVISORY FROM 5 PM THIS AFTERNOON TO 8 PM EDT THIS EVENING FOR NCZ107. MARINE...NONE. && $$ NEAR TERM...RJD SHORT TERM...III LONG TERM...III AVIATION...MRR/RJD

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