Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 052121 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 421 PM EST THU MAR 5 2015 .SYNOPSIS... A POWERFUL COLD FRONT WILL BRING SHARPLY COLDER TEMPERATURES BEGINNING THIS EVENING. THERE IS A CHANCE OF SOME LIGHT FROZEN PRECIPITATION FRIDAY MORNING. THE WEEKEND WILL FEATURE SLOWLY MODERATING TEMPERATURES. THE SLOW WARMUP WILL CONTINUE NEXT WEEK WITH SHOWERS POSSIBLE. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS OF 330 PM...AT THE MOMENT...88D RADAR INDICATES A FINE LINE STRETCHING FROM CAMP LEJEUNE WEST TO THE CITY OF DILLON. ALONG AND JUST AFTER THE PASSAGE OF THIS FINE LINE...AKA THE COLD FRONT...IS WHERE SYNOPTIC DRIVEN WIND GUSTS UP TO 50 MPH WILL AND HAVE BEEN OCCURRING. FROM DILLON SOUTHWEST ACROSS FLORENCE TO OLANTA...SOME WEAK CONVECTION IS INJECTING SOME OF ITS JUICE TO THE STRONG WIND FIELD ASSOCIATED WITH THE PASSAGE OF THE COLD FRONT. AGAIN AND OVERALL...THE FA WILL BE SUBJECTED TO 35 TO 50 MPH WIND GUSTS ALONG AND JUST AFTER THE COLD FRONTAL PASSAGE. BY EVENING...THE COLD FRONT IS PROGGED TO BE SITUATED ALONG OR JUST OFF THE CAROLINA COASTS. THE FA WILL BE SUBJECTED TO 20 TO AS MUCH AS 40+ DEGREE TEMPERATURE SWINGS WITHIN A 30 MINUTE THRU 1 HOUR TIME-LINE AS A RESULT OF THE INJECTING ARCTIC AIRMASS ACROSS THE REGION. AFTER FROPA...THE FA WILL BE SUBJECTED TO A TIGHTENING SFC PG DUE TO THE APPROACH OF A 1040+ MB SFC HIGH...AND EXCELLENT COLD AIR ADVECTION IE. THE ARCTIC AIR MASS. ALL PRECIPITATION ASSOCIATED WITH THE COLD FRONTAL PASSAGE IS ACTUALLY LOCATED BEHIND THE FRONT. DECENT LIFT AND OVERTURNING OF THE ATM IN THE LOWER LEVELS AS THE SHALLOW BUT INTENSE ARCTIC AIRMASS PUSHES TO AND OFF THE COAST THIS EVENING AND OVERNIGHT. THE MOISTURE FEED IE. LATEST WATER VAPOR LOOPS...ACCESSES THE GULF OF MEXICO AND `EVEN AS FAR WEST AS THE PACIFIC OCEAN. HOWEVER...VARIOUS MODELS WANT TO THIN/SCOUR OUT THIS MOISTURE DURING THE PRE-DAWN FRI HOURS AS IT MOVES FURTHER AWAY FROM THESE MOISTURE SOURCES AS THE UPPER WINDS BECOME MORE WESTERLY. AS THE MOISTURE THINS OUT...SO DOES THE CHANCE FOR RAIN LET ALONE ANY WINTRY PCPN. AT THIS POINT...VARIOUS MODEL SOUNDINGS INDICATE A RATHER DEEP SFC BASED SUB-32 COLD LAYER THAT EXTENDS UPWARDS OF 3500-5000 FT DURING THE MID TO LATE PRE-DAWN FRI HOURS. THE ONCE AVBL MOISTURE IS NO LONGER. AND THUS...COULD ONLY INDICATE A SMALL THREAT FOR LIGHT FREEZING RAIN OR DRIZZLE PRIOR TO THE OVERALL PCPN ENDING. IF ENOUGH MOISTURE WERE AVBL THRU THE ATM COLUMN... SLEET WOULD HAVE BEEN THE NEXT CHOICE FOR POSSIBLE WINTRY PCPN. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... AS OF 300 PM THURSDAY...WINTER WILL MAKE AN APPEARANCE THROUGH THE SHORT TERM AS ARCTIC HIGH PRESSURE BUILDS INTO THE CAROLINAS. WHILE WELL BELOW NORMAL TEMPERATURES ARE A CERTAINTY FOR FRIDAY AND SATURDAY...WHAT IS UNCERTAIN IS WHETHER ANY PRECIP WILL LINGER FRIDAY MORNING...POTENTIALLY AS A WINTRY TYPE. COLD FRONT WILL BE WELL OFFSHORE FRIDAY MORNING...BUT SOME RESIDUAL LOW-LEVEL MOISTURE WILL PERSIST IN THE COLUMN FOR THE FIRST FEW HOURS OF FRIDAY. GUIDANCE HAS BACKED OFF CONSIDERABLY ON AMOUNT OF MOISTURE LEFT IN THE COLUMN...AND SREF PROBABILITIES ARE LESS THAN MENTIONABLE. FOR THIS REASON HAVE CUT BACK POP TO SILENT FOR ALL BUT THE IMMEDIATE BEACHES...AND EVEN THERE ONLY A SCHC IS WARRANTED FOR A COUPLE OF HOURS FRIDAY MORNING. THIS PRECIP MAY BE A BIT OF IP/ZR BUT NO IMPACTS ARE ANTICIPATED FROM ANY WINTRY PRECIP. THEREAFTER...RAPID DRYING OCCURS AND AMPLE SUNSHINE WILL ENVELOP THE AREA FRIDAY AFTN. EVEN WITH FULL MARCH SUN...TEMPS ON FRIDAY WILL RISE ONLY INTO THE MID/UPR 30S - A FULL 25-30 DEGREES BELOW NORMAL! HIGH PRESSURE BUILDS TOWARDS THE AREA FRIDAY CAUSING CAA TO WEAKEN...AND A VERY COLD NIGHT IS EXPECTED AS THE DRY COLUMN AND WEEK WINDS SUPPORT STRONG LONGWAVE COOLING. GUIDANCE HAS COOLED A BIT...AND WE MAY APPROACH RECORD LOWS FRIDAY NIGHT (20 AT WILMINGTON AND 20 AT FLORENCE). CURRENT FORECASTS ARE JUST ABOVE THESE NUMBERS...BUT AN EXCEEDINGLY COLD NIGHT IS EXPECTED. A WARMER DAY EXPECTED SATURDAY AS THE AIRMASS BEGINS TO MODIFY...BUT TEMPS WILL STAY ABOUT 10 DEGREES BELOW NORMAL EVEN BENEATH THE INCREASING MARCH SUN ANGLE. HIGH PRESSURE SHIFTS OFFSHORE LATE SATURDAY ALLOWING FOR WARM RETURN FLOW TO DEVELOP. THIS WILL KEEP MINS MUCH WARMER SATURDAY NIGHT THAN FRIDAY NIGHT...SO WHILE STILL EXPECTING BELOW NORMAL VALUES FOR LOWS...MOST OF THE AREA WILL REMAIN JUST ABOVE FREEZING. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 330 PM THURSDAY...MEDIUM RANGE GUIDANCE IS SHOWING A SPLIT FLOW DEVELOPING AS THE MAIN BELT OF WESTERLIES JOGS TO THE NORTH WITH A WEAKER SOUTHWEST FLOW OVER THE SOUTHERN U.S. SURFACE FEATURES INCLUDE A WEAK AND DRY BACKDOOR FRONT SUNDAY WITH A BROAD BAROCLINIC ZONE ALIGNED OFFSHORE. THIS IS WHAT REMAINS OF OF THE ARCTIC FRONT THAT MOVES ACROSS LATER TODAY. BEYOND THIS WEAK HIGH PRESSURE WILL PREVAIL AT THE SURFACE BUT POPS WILL REMAIN IN THE FORECAST DUE TO MID AND UPPER LEVEL INFLUENCES. WITH THE WEAK FORCING...CONFIDENCE IS LOWER THAN USUAL BUT FOR NOW WE HAVE THE HIGHEST POPS...CHANCE VALUES FOR TUESDAY AND THURSDAY WHEN THE FORCING IS SLIGHTLY BETTER. TEMPERATURE TRENDS SHOW A LITTLE BELOW NORMAL FOR DAYTIME HIGHS BUT OVERNIGHT LOWS...MODERATED QUITE A BIT BY THE MOISTURE...WELL ABOVE NORMAL WITH 45-50 DEGREES. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... AS OF 18Z...A MIXTURE OF VFR/MVFR EXPECTED THROUGH THE AFTERNOON AS LOWER CIGS MOVE IN ASSOCIATED WITH AN APPROACHING COLD FRONT...WITH THE EXCEPTION OF MVFR/IFR AT KCRE DUE TO LINGERING SEA FOG. AS THE COLD FRONT PUSHES THROUGH...BEHIND IT CONDITIONS WILL DETERIORATE TO MVFR/IFR DUE TO LOW CIGS...AREAS OF FOG...AND RAINFALL. CONDITIONS IMPROVE TO VFR LATE INTO FRIDAY MORNING. LATEST SATELLITE IMAGERY DEPICTS INCREASING CLOUDS ACROSS THE FORECAST AREA THIS AFTERNOON JUST AHEAD OF AN APPROACHING COLD FRONT...CREATING WIDESPREAD VFR/MVFR...WITH THE EXCEPTION OF KCRE WHERE LINGERING SEA FOG HAS ALLOWED FOR IFR TO PERSIST. SOUTH-SOUTHWEST WINDS AOB 20 KTS WITH GUSTS UP TO 30 KTS EXPECTED BOTH AHEAD OF THE COLD FRONT WHICH WILL PUSH THROUGH LATER TODAY. BEHIND THE FRONT...EXPECT GUSTY WINDS TO BECOME NORTHERLY WITH MVFR/IFR DUE TO RAIN...LOW CIGS...AND AREAS OF FOG...TONIGHT THROUGH THE OVERNIGHT HOURS. TOWARDS MORNING...PRECIPITATION WILL TAPER OFF WEST TO EAST...BUT WILL NOTE THAT BEFORE PRECIPITATION MOVES OUT OF THE COASTAL AREAS THERE IS A POTENTIAL FOR SOME ICE PELLETS TOWARDS THE END OF THE TAF PERIOD. HOWEVER...GIVEN LOWER CONFIDENCE HAVE NOT INTRODUCED IN GOING FORECAST ATTM. AFTER 12Z...ANTICIPATE RAINFALL CHANCES TO BE MINIMAL WITH CONDITIONS GRADUALLY IMPROVING TO VFR AND AND EXTENDED OUTLOOK...IFR CONDITIONS POSSIBLY INTO FRIDAY ALONG THE COAST. OTHERWISE EXPECT VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 330 PM THURSDAY...THE SEA FOG WILL CONTINUE TO BE A PROBLEM UP UNTIL THE PASSAGE OF THE ARCTIC FRONT LATER THIS AFTERNOON AND EARLY EVENING. THERE-AFTER...THE AVBL PARAMETERS TO CONTINUE THE EXISTENCE OF SEA FOG CEASES. THE PASSAGE OF THE ARCTIC FRONT ACROSS THE AREA WATERS WILL BECOME A NEMESIS TO MARINERS...LET ALONE THE DIRECTION CHANGE...THE WIND GUSTS AFTER THE WIND SHIFT WILL BRIEFLY REACH 30 TO 40 KT BEFORE SETTLING BACK DOWN TO A SYNOPTIC DRIVEN NORTHERLY WIND AT 20-30 KT WITH GUSTS UP TO 35 KT FOR THE REMAINDER OF THE OVERNIGHT. SIGNIFICANT SEAS WILL BUILD TO 4 TO 9 FT. LOWEST ALONG THE IMMEDIATE COAST...HIGHEST THE OUTER WATERS OFF CAPE FEAR...AND OFF FROM THE MOUTH OF WINYAH BAY. LOCALLY PRODUCED WIND DRIVEN WAVES WILL DOMINATE THE SIGNIFICANT SEAS...WITH DOMINATING PERIODS AROUND 7 SECONDS. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 300 PM THURSDAY...ARCTIC COLD FRONT WILL BE WELL OFFSHORE FRIDAY MORNING...BUT A TIGHT GRADIENT WILL REMAIN OVER THE WATERS AND THE GALE WARNING CURRENTLY IN PLACE WILL PERSIST THROUGH 10AM FOR NORTH WINDS GUSTING ABOVE 34 KTS. WINDS BEGIN TO EASE THEREAFTER...BUT WILL ONLY SLOWLY FALL THROUGH FRIDAY...REMAINING 15-20 KTS INTO SATURDAY MORNING. THESE CONTINUED STRONG NORTH WINDS WILL KEEP WAVE HEIGHTS ABOVE 6 FT ALL OF FRIDAY...AND AN SCA WILL BE NEEDED ONCE THE GALE WARNING DROPS. HIGH PRESSURE WILL MOVE TOWARDS...AND THEN OVER...THE WATERS ON SATURDAY BEFORE DRIFTING OFFSHORE SATURDAY NIGHT. THIS WILL DRIVE PRIMARILY LIGHT AND VARIABLE WINDS SATURDAY AND SATURDAY NIGHT...EVENTUALLY TAKING ON A PREDOMINANT SW DIRECTION LATE. WAVE HEIGHTS WILL FALL STEADILY ON SATURDAY...LEVELING OFF AT 1-2 FT TOWARDS THE END OF THE PERIOD. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 330 PM THURSDAY...A RATHER WEAK PRESSURE PATTERN WILL CONTINUE THROUGH THE PERIOD. THIS LEADS TO MODEST WIND FIELDS AND SIGNIFICANT SEAS. WITH WEAK HIGH PRESSURE TO THE WEST...NORTHWEST AND AN OLD BOUNDARY LINGERING OFFSHORE WIND DIRECTIONS WILL BE MOSTLY NORTHEAST. SPEEDS WILL DISPLAY SOME VARIATION BUT OVERALL A RANGE OF 10-15 KNOTS SHOULD BE GOOD. SIGNIFICANT SEAS WILL START OFF VERY LOW...1-2 FEET SUNDAY AND INCREASE MONDAY AND TUESDAY AS WINDS HOVER AROUND THE HIGHER END OF THE RANGE FOR SEVERAL PERIODS. COULD EVEN SEE SMALL CRAFT CONDITIONS TUESDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...DENSE FOG ADVISORY UNTIL 6 PM EST THIS EVENING FOR SCZ054-056. NC...DENSE FOG ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ106-108- 110. MARINE...DENSE FOG ADVISORY UNTIL 6 PM EST THIS EVENING FOR AMZ250-252- 254-256. GALE WARNING FROM 9 PM THIS EVENING TO 10 AM EST FRIDAY FOR AMZ250-252-254-256. && $$ SYNOPSIS...JDW NEAR TERM...DCH SHORT TERM...JDW LONG TERM...SHK AVIATION...MRR

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