-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 160523
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1223 AM EST MON DEC 16 2013

.SYNOPSIS...
HIGH PRESSURE WILL BUILD FROM THE WEST...BRINGING DRY AND COOL
CONDITIONS INTO MONDAY. A DRY COLD FRONT WILL CROSS THE AREA
TUESDAY NIGHT...REINFORCING RAIN-FREE AND SEASONABLY COOL WEATHER
THROUGH MID WEEK. A WARMING TREND IS EXPECTED LATE WEEK IN ADVANCE
OF AN APPROACHING LOW PRESSURE SYSTEM INTO NEXT WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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AS OF 1230 AM MONDAY...NO SIGNIFICANT UPDATES WERE NEEDED TO THE
FORECAST EXCEPT RIGHT ALONG THE BEACHES WHERE OFFSHORE WINDS
OVERNIGHT SHOULD ADVECT COLD AIR TO THE DUNES AND BEYOND. DOWNWARD
ADJUSTMENTS TO FORECAST LOWS HAVE BEEN MADE HERE. PREVIOUS
DISCUSSION FROM 1020 PM FOLLOWS...

NEARLY A FULL LATITUDE UPPER TROF AFFECTING THE EASTERN 2/3RDS OF
THE U.S. TONIGHT. THE UPPER TROF AXIS WILL REMAIN WEST OF THE ILM
CWA...WHILE STRONG SW FLOW ALOFT CONTINUES WITH MAINLY THIN JET
STREAM CI AFFECTING THE EASTERN ONE THIRD OF THE ILM CWA AS WELL AS
THE ADJACENT COASTAL WATERS. DO NOT EXPECT ANY OF THE CLOUDINESS
AFFECTING THE WINDWARD SIDE OF THE APPALACHIANS TO MOVE ACROSS THESE
MOUNTAINS AND TO THE FA. THE GENERAL TREND VIA SAT IMAGERY...THESE
CLOUDS HAVE BEEN SCOURING OUT AFTER PUSHING ACROSS THE SPINE OF THE
APPALACHIAN MOUNTAINS AND DOWNSLOPE THE LEEWARD SIDE OF THE
APPALACHIANS. BROAD CENTER OF SFC HIGH PRESSURE ACROSS THE GULF
COAST STATES WILL RIDGE TO THE ILM CWA OVERNIGHT. LOOK FOR SFC WINDS
TO LIKELY DECOUPLE...ESPECIALLY AWAY FROM THE IMMEDIATE COAST...AS
THE SFC BASED INVERSION BECOMES BETTER ESTABLISHED OVERNIGHT.
CURRENT MIN TEMP FORECAST OF 30 TO 35 LOOKS ON TARGET.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
AS OF 3 PM SUNDAY...FAIR AND SEASONABLE CONDITIONS ON TAP BOTH
MONDAY AND TUESDAY WITH MAX/MIN TEMPERATURES RUNNING VERY CLOSE TO
CLIMATE STANDARDS FOR MIDDLE DECEMBER. SURFACE HIGH PRESSURE WILL
NOT FULLY BUILD INTO THE AREA UNTIL TUE...IN WAKE OF A CLIPPER
TYPE SYSTEM THAT SWINGS THROUGH MID-ATLANTIC TUESDAY...SWEEPING
A MOISTURE-STARVED FRONTAL SYSTEM ACROSS THE EASTERN CAROLINAS
THAT WILL REINFORCE DRY CONDITIONS INTO MID WEEK.

NO MAJOR FLY-IN-THE-OINTMENTS ANTICIPATED TO SPOIL A FAIR AND DRY
WEATHER REGIME...BUT TO NOTE THAT A FEW H6/15KFT CLOUDS PERHAPS
MONDAY AFTERNOON WILL PASS EAST OVERHEAD IN ZONAL FLOW AT THE
BASAL PORTIONS OF A BROAD UPPER TROUGH OVER THE EASTERN CONUS.
MODERATE BOUNDARY LAYER WIND FLOW DURING THIS PERIOD WILL LIKELY
PREVENT BOUTS OF SIGNIFICANT FOG FORMATION.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 3 PM SUNDAY...TEMPERATURES TAKE A SMALL HIT BACK TOWARDS
CLIMO OR EVEN A FEW DEGREES SHY ON WEDNESDAY AS HIGH PRESSURE
BUILDS INTO THE OHIO VALLEY ALLOWING SOME COOLER AIR TO BLEED INTO
THE CAROLINAS BY THE START OF THE PERIOD. THIS AIRMASS TRANSLATES
OFF THE COAST BY THURSDAY AND A WEAK COASTAL TROUGH DEVELOPS AND
SOUTHERLY FLOW WILL DEVELOP ABOVE THE SURFACE LAYER. CLOUDS MAY
INCREASE SLIGHTLY AND TEMPS RETURN TO ABOVE NORMAL BY ABOUT A
CATEGORY. MORE ROBUST WARM ADVECTION ENSUES ON FRIDAY AS THE HIGH
MOVES EVEN FURTHER OFF THE COAST AND LOW LEVEL FLOW STRENGTHENS IN
RESPONSE TO AN APPROACHING COLD FRONT. HOW THE REST OF THE PERIOD
PANS OUT IS A TOUGH CALL. MODELS GOING BACK AND FORTH ON SOUTHERN
BRANCH SYSTEM OVER BAJA CA...AND WHEN/WHETHER IT PROGRESSES
EASTWARD AND PHASES WITH THE BROAD TROUGHINESS OF THE NRN BRANCH.
COMPLICATING FACTOR IS THE POSSIBILITY OF THE 00Z ECMWF WHICH
ALTHOUGH DOES SHOW PHASING ALSO HINTS THAT THE RIDGE IN THE
BAHAMAS HOLDS. CONTRAST THIS WITH SOLUTIONS LIKE THE GFS WHICH
WHEN IT WOULD SHOW PHASING IT PROGGED A PROGRESSIVE SOLUTION AND A
WET WEEKEND IN THE SOUTHEAST...SUPPORTED BY THE MORE RECENT 12Z
ECMWF. IF NOTHING ELSE, THE STRENGTH OF THE JET COMING OFF OF
JAPAN MAKES THE MORE PROGRESSIVE SOUTHERN BRANCH SOLUTIONS MORE
PLAUSIBLE AS IT SHOULD GET KICKED EASTWARD. ADDITIONALLY WHENEVER
A MODEL HINTS THAT A RIDGE HOLDS ITS GROUND AND SHUNTS ENERGY OVER
THE TOP OF IT THIS TOO IS ALWAYS AN APPEALING SOLUTION. THAT SAID
WILL SHOW A CONTINUATION OF VERY MID WEATHER LATE IN THE PERIOD
BUT ALSO VERY MINOR RAIN CHANCES IN LIGHT OF THE DEGREE OF
UNCERTAINTY.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
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AS OF 06Z...HIGH PRESSURE WILL CONTINUE TO BUILD IN...WITH WEAK COLD
AIR ADVECTION OVERNIGHT. DEWPOINTS WILL FALL INTO THE 20S BY MORNING
WITH LITTLE TO NO FOG EXPECTED. LBT MAY SEE A BRIEF PERIOD OF MVFR
VISIBILITIES...BUT CONFIDENCE IS RATHER LOW. AFTER DAYBREAK...A NICE
AVIATION DAY WITH NEARLY CLEAR SKIES AND LIGHT WINDS. A WEAK
SEABREEZE IS POSSIBLE ALONG THE COAST DURING THE AFTERNOON.

EXTENDED OUTLOOK...VFR EXPECTED THROUGH LATE THIS WEEK.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 AM MONDAY...CHANGES WITH THIS EARLY-MORNING UPDATE
INCLUDE CUTTING SEA HEIGHT FORECASTS BY ONE FOOT AND WIND SPEED
FORECASTS BY 3-5 KNOTS BASED ON LATEST OBSERVATIONS FROM OUR TWO
DATA BUOYS NEAR CAPE FEAR. THESE DOWNWARD CHANGES ALSO APPEAR TO BE
NEEDED OUT BEYOND SUNRISE INTO MONDAY MORNING. PREVIOUS DISCUSSION
FROM 1020 PM FOLLOWS...

CONTINUED DIMINISHING WIND SPEEDS...AND SUBSIDING SIGNIFICANT
SEAS...WILL HIGHLIGHT THE OVERNIGHT PERIOD. THE SFC PRESSURE PATTERN
AND LOOSENING GRADIENT ILLUSTRATE NW-N WINDS WILL RUN AT 10 TO 15
KT...POSSIBLY UP TO 20 KT OFF CAPE FEAR AND OFF CAPE ROMAIN.
MILDER/WARMER SSTS IN THE 60S AND LOWER 70S AT THESE LOCATIONS WILL
ENABLE THE STRONGER WINDS ALOFT TO MIX DOWN TO THE OCEAN SFC.
SIGNIFICANT SEAS OF 2 TO 5 FT WILL OCCUR OVERNIGHT...WITH THE HIGHER
SEAS ACROSS THE OUTER WATERS OFF CAPE FEAR AND NORTH OF CAPE ROMAIN.
THE SOUTHERLY WIND DRIVEN PSEUDO-SWELL EXHIBITING 6 TO 8
SECONDS...WILL DOMINATE THE SEAS SPECTRUM.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 3 PM SUNDAY...MANAGEABLE MARINE CONDITIONS EXPECTED THIS
PERIOD ALTHOUGH WE WILL SEE SW-WSW WINDS PICK UP ON TUESDAY AS A
DRY COLD FRONT SWEEPS ACROSS THE REGION. THIS MAY REQUIRE EXERCISE
CAUTION OR EVEN ADVISORY HEADLINES TUESDAY AFTERNOON AND EVENING.
SINCE THE WIND TRAJECTORY WILL HAVE A WESTERLY COMPONENT TO IT
DURING THE HIGHEST WIND-SPEEDS...THE ROUGHEST SEAS WILL REMAIN
OFFSHORE COMPARED TO INSHORE. THE WAVE SPECTRUM WILL FEATURE SE
WAVES 2 FEET EVERY 8 SECONDS BOTH DAYS...WITH BUILDING SW WAVES OF
TUESDAY IN 4-6 SECOND INTERVALS. NO TSTMS OR SEA-FOG EXPECTED
MONDAY OR TUESDAY.

LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 3 PM SUNDAY...NORTHWESTERLY WINDS TO ABATE WEDNESDAY AS THE
DAY WEARS ON AS POST-FRONTAL GRADIENT EASES. LANDMASS WAVE
SHADOWING IN SUCH A COAST-PERPENDICULAR FLOW WILL PRECLUDE ANY
ADVISORIES OR CAUTIONARY HEADLINES. WEDNESDAY NIGHT WILL FEATURE
THE MINIMAL WIND AND SEAS OF THE LONG TERM AS THE HIGH PASSES BY
JUST TO OUR NORTH. THEREAFTER A SOUTHERLY COMPONENT WILL BE
PREDOMINANT IN THE FLOW AS HIGH PRESSURE MOVES FURTHER AND FURTHER
OUT TO SEA. THE NEAR STEADY STATE OF THE FETCH WILL CAUSE A SLOW
INCREASE IN WAVE HEIGHT EVEN AS THE DOMINANT PERIOD MAY DROP
SLIGHTLY. COLD FRONT APPROACHING FROM THE NW TIGHTENS THE GRADIENT
FRIDAY NIGHT AND FLAGS MAY BE NEEDED AS 6 FT SEAS INTRODUCED TO
PART IF NOT THE ENTIRE AREA.
-- End Changed Discussion --

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
NC...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...SHK
NEAR TERM...DCH/TRA
SHORT TERM...SHK
LONG TERM...MBB
AVIATION...HDL/TRA