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-- Discussion containing changed information from previous version are highlighted. --
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/...
-- Changed Discussion --
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.
-- End Changed Discussion --

&&

.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...
-- Changed Discussion --
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.
-- End Changed Discussion --

&&

.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