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000
FXUS62 KILM 111133
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
633 AM EST WED DEC 11 2013

.SYNOPSIS...
HIGH PRESSURE WILL SETTLE OVER THE AREA TODAY THROUGH FRIDAY.
THE WEEKEND IS LOOKING MORE AND MORE UNSETTLED AS A STORM SYSTEM
TRACKS ACROSS THE SOUTHEAST. COOLER AND DRIER CONDITIONS ARE
EXPECTED EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 6:30 AM WEDNESDAY...NO CHANGES TO THE FORECAST WITH THE
LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS:

COOL AND DRY CONDITIONS WILL PREVAIL TODAY AS ARCTIC HIGH PRESSURE
CENTERED OVER THE DEEP SOUTH BUILDS EAST ACROSS THE CAROLINAS.
MODEL SOUNDINGS SHOW A VERY DRY AND STABLE COLUMN WITH P/W VALUES
ONLY IN THE 0.15 INCH RANGE FOR THE DAYLIGHT HOURS. THIS WILL LEAD
TO AMPLE SUNSHINE...WITH THE EXCEPTION OF SOME PASSING CIRRUS AS
INDICATED ON THE LATEST IR SATELLITE LOOPS. MODEL CONSENSUS HAS
MAXIMUM TEMPERATURES IN THE LOWER TO MID 50S...WHICH IS 5 TO 8
DEGREES BELOW NORMAL.

A REINFORCING SURGE OF COLD AIR OVERNIGHT WILL FOLLOW THE PASSAGE OF
A CLIPPER SYSTEM NOW RACING SOUTHEAST ACROSS THE NATIONS MIDSECTION.
SYSTEM WILL COME THROUGH MOSTLY DRY WITH NO PRECIPITATION...AND ONLY
AN INCREASE IN MID AND HIGH LEVEL CLOUDINESS. LOWS WILL CONTINUE TO
RUN BELOW NORMAL...FROM THE UPPER 20S WELL INLAND TO THE MID 30S AT
THE BEACHES. THIS IS ABOUT 4 TO 7 DEGREES BELOW NORMAL.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 3 AM WEDNESDAY...SURFACE HIGH CONTINUES TO BUILD IN FROM THE
WEST ON THU WITH COLD ADVECTION CONTINUING INTO THE AFTERNOON.
LITTLE CHANGE IN PARTIAL THICKNESS VALUES DURING THU INDICATES THE
STRENGTH OF THE COLD AIR WHICH WILL BE ABLE TO OFFSET ANY AIR MASS
MODIFICATION DUE TO SUNNY SKIES. TEMPS WILL REMAIN BELOW CLIMO WITH
HIGHS STRUGGLING TO REACH 50 ACROSS MUCH OF THE AREA. SURFACE RIDGE
AXIS WILL BE BASICALLY OVERHEAD THU NIGHT INTO FRI SETTING UP WHAT
SHOULD BE A GOOD RADIATIONAL COOLING EVENT. BOUNDARY LAYER FLOW
PROGGED TO QUITE WEEK AND WITH DEEP DRY AIR LOWS WELL INTO THE 20S
ARE EXPECTED.

SURFACE HIGH IS SHIFTED OFF THE COAST BY PROGRESSIVE FLOW
ALOFT...ENDING UP EAST OF HATTERAS FRI EVENING. RETURN FLOW WILL
DEVELOP AS THE HIGH EXITS EAST BUT TEMPERATURES WILL BE SLOW TO
RESPOND. HIGHS WILL REMAIN BELOW CLIMO FRI. ANOTHER POTENTIAL
STICKING POINT IS A COASTAL TROUGH EXPECTED TO DEVELOP LATE FRI OR
FRI NIGHT. AS THIS FEATURE DEVELOPS RETURN FLOW WILL BACK TO
EASTERLY...MAINLY FRI NIGHT. ABUNDANT SUNSHINE WILL BE PRESENT FRI
BUT DO EXPECT AN INCREASE IN HIGH CLOUD LATE IN THE DAY AS MOISTURE
AHEAD OF A SYSTEM FOR THE WEEKEND SPREADS OVER THE SOUTHEAST.

CLOUDS LOWER LATE FRI NIGHT AS COASTAL TROUGH MOVES TO THE COAST. AT
THE SAME TIME WEAK ISENTROPIC LIFT IN THE PRESENCE OF INCREASING LOW
LEVEL MOISTURE MAY GENERATE SOME LIGHT RAIN ACROSS THE AREA. GIVEN
THAT VERY DRY AIR WILL BE IN PLACE BEFORE THE EVENT UNFOLDS WILL
MAINTAIN INHERITED SLIGHT CHC POP FOR MOST OF THE AREA. NOT PLANNING
ON AN INCREASE IN POP AS GUIDANCE IS SOMETIMES IS TOO QUICK TO ERODE
THE DRY LOW LEVEL AIR. CLOUD COVER AND INCREASED BOUNDARY LAYER FLOW
WILL KEEP LOWS NEAR TO SLIGHTLY ABOVE CLIMO FRI NIGHT.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 3 AM WEDNESDAY...PERIOD BEGINS WITH SOUTHERN STREAM SYSTEM
MOVING ACROSS THE GULF STATES. THE SHORTWAVE REMAINS POSITIVELY
TILTED KEEPING THE SURFACE LOW WEAKER AND FAST MOVING. COASTAL
TROUGH/WARM FRONT LIFTS NORTH OF THE AREA SAT AS THE SURFACE LOW
PASSES WEST OF THE AREA. SEVERAL FACTORS SUGGEST SAT AFTERNOON
THROUGH SAT NIGHT COULD BE QUITE WET. DEEP SOUTHWEST FLOW WILL PUMP
PLENTY OF MOISTURE INTO THE REGION. PRECIPITABLE WATERS REACH 1.5
INCH SAT AND EXCEED 1.7 INCH SAT NIGHT. FLOW ALOFT IS STRONGLY
DIVERGENT AND FORECAST SOUNDINGS DEPICT SOME ELEVATED INSTABILITY.
NOCTURNAL TIMING IS LESS THAN IDEAL BUT CONVERGENCE ALONG THE STRONG
COLD FRONT THAT WILL MOVE OFF THE COAST SUN MORNING MAY BE ABLE TO
OFFSET THE LACK OF SURFACE BASED INSTABILITY.

CONFIDENCE IS INCREASING FOR SAT AND SAT NIGHT SO AN INCREASE IN POP
IS WARRANTED. HOWEVER...THERE REMAINS SOME DIFFERENCE BETWEEN THE
MEDIUM RANGE GUIDANCE. THE GFS/CMC ARE IN FAIRLY GOOD AGREEMENT BUT
THE ECMWF DEPICTS LESS AMPLIFICATION OF THE MID LEVEL PATTERN SAT
NIGHT AND SUN. THIS WOULD KEEP THE COLD FRONT STALLED CLOSER TO THE
COAST A BIT LONGER. THE DIFFERENCES ARE NOT HUGE BUT ENOUGH TO PUT
SUN/SUN EVE FORECAST IN QUESTION. FOR NOW WILL MAINTAIN INHERITED
LOW CHC/SLIGHT CHC POP SUN AND DRY FORECAST SUN NIGHT.

DRY HIGH PRESSURE BUILDS IN BEHIND THE COLD FRONT FOR THE START OF
NEXT WEEK. A WEAK FRONT MOVES ACROSS THE AREA TUE BUT ITS PASSAGE
WILL BE MAINLY A WIND SHIFT. ZONAL MID LEVEL FLOW WILL KEEP COLDEST
AIR NORTH OF THE AREA WITH TEMPERATURES A LITTLE BELOW CLIMO AS THE
PERIOD ENDS.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AS OF 12Z...VFR WILL PREVAIL THROUGH THE VALID PERIOD. EXPECT PLENTY
OF SUNSHINE TODAY AS DRY HIGH PRESSURE BUILDS INTO THE MID-ATLANTIC.
NORTHEAST WINDS AOB 8 KTS TODAY WILL BECOME LIGHT AND VARIABLE LATER
THIS AFTERNOON. SOUNDINGS INDICATE THE AIR MASS WILL BE TOO DRY FOR
ANY FOG CONCERNS TONIGHT. LOOK FOR ANOTHER NORTHERLY SURGE AFTER 09Z
THURSDAY...WITH CALM WINDS BECOMING N-NW AROUND 5 KTS BY DAYBREAK.

EXTENDED OUTLOOK...VFR THROUGH FRIDAY. INCREASING CLOUDS SATURDAY
WITH SHOWERS/MVFR SATURDAY INTO SUNDAY.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 6:30 AM WEDNESDAY...NO CHANGES TO THE FORECAST WITH THE
LATEST UPDATE. RELEVANT PORTION OF PREVIOUS DISCUSSION FOLLOWS
BELOW:

EXPECT CONTINUED NORTHEASTERLY WINDS TODAY...GENERALLY IN THE 10 TO
15 KT RANGE...AS COOL AND DRY HIGH PRESSURE BUILDS IN FROM THE WEST.
SEAS WILL RANGE FROM 3 TO 5 FT INITIALLY BUT WILL SUBSIDE TO 2 TO 4
FT BY THIS AFTERNOON. WINDS WILL BACK TO THE N AND NW AFTER MIDNIGHT
AS A DRY COLD FRONT MOVES ACROSS THE WATERS...WITH SEAS FURTHER
SUBSIDING TO 2 TO 3 FT.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 3 AM WEDNESDAY...NORTHWEST FLOW WILL GRADUALLY DECREASE THU
INTO THU NIGHT...DROPPING FROM 15 TO 20 KT THU TO 10 TO 15 KT THU
NIGHT. WINDS WILL VEER TO NORTH AND THEN NORTHEAST THU NIGHT INTO
FRI AS SURFACE HIGH MOVES TO THE NC COAST. GRADIENT REMAINS WEAK FRI
AND FRI NIGHT WITH NORTH TO NORTHEAST FLOW 10 KT OR LESS THROUGH THE
END OF THE PERIOD. SEAS 2 TO 4 FT THU WILL DROP TO 2 TO 3 FT LATE
THU NIGHT AND FALL TO 2 FT FRI AND FRI NIGHT.

LONG TERM /SATURDAY THROUGH SUNDAY/...
AS OF 3 AM WEDNESDAY...ANTICIPATE POOR CONDITIONS FOR MUCH OF THE
PERIOD AS SLOWLY INTENSIFYING LOW PRESSURE PASSES TO THE WEST.
SOUTHEAST FLOW OF 15 TO 20 KT SAT WILL APPROACH 20 TO 25 KT SAT
NIGHT AND VEER TO SOUTHWEST AS GRADIENT TIGHTENS. COLD FRONT CROSSES
THE WATERS SUN WITH 15 TO 20 KT WINDS VEERING TO WEST AND EVENTUALLY
NORTHWEST. COLD ADVECTION IS INITIALLY SLOW TO DEVELOP SO WINDS MAY
DROP UNDER 15 KT FOR A PERIOD SUN NIGHT BEFORE RETURNING TO 15 TO 20
KT AS THE PERIOD ENDS. SEAS WILL BUILD ON SAT AS SOUTHERLY FLOW
INCREASES...PEAKING AROUND 5 TO 8 FT LATE SAT AND SAT NIGHT.
DEVELOPMENT OF OFFSHORE WINDS ON SUN WILL HELP KNOCK SEAS BELOW 6 FT
BEFORE THE END OF THE PERIOD...BUT SCA HEADLINES ARE LIKELY TO BE
REQUIRED INTO SUN AFTERNOON.

&&

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

&&

$$

SYNOPSIS...III
NEAR TERM...REK
SHORT TERM...III
LONG TERM...III
AVIATION...BJR
MARINE...REK/III