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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 082011
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
311 PM EST SUN DEC 8 2013

.SYNOPSIS...
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CHILLY AND DAMP CONDITIONS WILL PERSIST THROUGH TONIGHT. TOMORROW WILL
BRING A WARMUP ESPECIALLY ALONG THE COAST. TUESDAY SHOULD ALSO BE MILD
AS A COLD FRONT WILL MOVE THROUGH LATER IN THE DAY...AGAIN MAINLY NEAR
THE COAST. COOLER WEATHER WILL THEN RETURN TUESDAY NIGHT AND REMAIN THROUGH
THE WEEK.
-- End Changed Discussion --

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
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AS OF 3 PM SUNDAY...COLD AND OVERCAST CONDITIONS BLANKETED THE
FORECAST AREA THIS AFTERNOON WITH UPPER 30S PRESENTLY ACROSS THE
NORTHERN AND WESTERN DEEP INTERIOR TO THE MIDDLE 40S ALONG AND
NEAR THE COAST. INCREASING BOUNDARY LAYER SW WIND FLOW OVERNIGHT
WILL BEGIN TO SCOUR AND EAT AT THE UPPER PORTIONS OF THE SHALLOW
COLD AIR HIGH PRESSURE WEDGE. AS THE BREAKDOWN PROCESS OF THE
WEDGE UNFOLDS LATE TONIGHT...OVER-RUNNING AND WARM-FRONTAL TYPE
PROCESSES SHOULD GEAR-UP...BRINGING AN AREAL COVERAGE INCREASE
IN -DZ/FG WITH PATCHY LIGHT RAIN IN THE MIX. IT SHOULD BE NOTED
THE WEDGE ALTHOUGH INCREASINGLY SHALLOW...WILL LIKELY SURVIVE
TONIGHT AND NE WIND-SPEEDS ALTHOUGH TRENDING DOWNWARD SHOULD
PREVAIL MOST IF NOT ALL OF THE NIGHT/NEAR TERM PERIOD BEFORE TRULY
TURNING SW AT THE SURFACE INTO THE DAY ON MONDAY. HAVE HELD THE
PROBABILITY OF PCPN IN THE SCATTERED CATEGORY BELOW LIKELY SINCE
MEASURABLE RAINFALL IS NOT A SLAM DUNK EVERYWHERE OVERNIGHT BUT
OCCASIONAL DRIZZLE WILL BE RETAINED IN THE ZONES...FOR WIDESPREAD
TRACE -DZ OCCURRENCES.

ATYPICAL TEMPERATURE CURVES AFTER 6Z/1AM...WILL LIKELY RISE A FEW
DEGREES FOLLOWING A COUPLE DEGREE DROP IN THE EVENING...AND MAY
VERY WELL WARM UP SEVERAL DEGREES INTO DAYBREAK MONDAY AS SW FLOW
OFF THE SURFACE INTENSIFIES. WARM-UPS HOWEVER WILL BE SLOW BUT IT
DOES APPEARS MINIMUM TEMPERATURES WILL BE REALIZED WELL BEFORE
DAYBREAK ON MONDAY...LIKELY AFTER MIDNIGHT BUT BEFORE 8Z/3AM.
-- End Changed Discussion --

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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AS OF 3 PM SUNDAY...A BIT OF A TRICKY FORECAST FOR MUCH OF THE
PERIOD. PROBABLY THE BIGGEST BUST POTENTIAL IS WITH RESPECT TO
MONDAY HIGH TEMPS. COOL AIR WEDGE INITIALLY TO BE FIRMLY IN PLACE
ALBEIT TO A DEPTH OF JUST 600FT...WITH A VERY SHARP INVERSION
THROUGH ABOUT 1200 FT. IN FACT THE WEDGE MAY HOLD THROUGH MUCH OF
THE MORNING HOURS KEEPING TEMPERATURES RISING ONLY VERY SLOWLY. THIS
WILL BE MOST PRONOUNCED FURTHER INLAND. THE WRF HANGS ON TO THE
WEDGE LONGER THAN THE GFS...AND THE SLOWER MODEL ENDS UP BEING MORE
CORRECT A VAST MAJORITY OF THE TIME. EVEN SO...THE LATER DAY
BREAKING OF THE WEDGE OVER FAR NWRN ZONES WILL KEEP HIGHS CLOSER TO
CLIMO WHILE AREAS ALONG THE MORE IMMEDIATE COAST WARMS UP INTO THE
LOW 70S. WHEN AND WHERE THE WEDGE BREAKS HOWEVER WILL LEAD TO LARGE
JUMPS IN TEMPS DUE TO THE SHALLOWNESS AND STRENGTH OF THE INVERSION.
POPS ARE ALSO RATHER PERPLEXING ON MONDAY...DESPITE THE FACT THAT A
WARM FRONT WILL BE LIFTING THROUGH MODELS ARE SHOWING LITTLE TO NO
ASCENT THROUGH THE COLUMN. ADDITIONALLY...THE MID LEVELS WILL HAVE
DRIED OUT QUITE A BIT WHILE THE LOW LEVELS REMAIN DAMP. DRIZZLE
SEEMS A BIT MORE LIKELY THAN MEASURABLE RAINFALL. NOT SO ON MONDAY
NIGHT HOWEVER AS THE MOISTURE DEEPENS AND A COLD FRONT APPROACHES
FROM THE NW. MODEL TIMING DIFFERENCES WITH THIS FRONT CONTINUE
ALTHOUGH THEY ARE SOMEWHAT DIMINISHED. PREFER THE SLIGHTLY SLOW GFS
AS THE BOUNDARY IS WELL ALIGNED WITH THE DEEP LAYER FLOW AND THUS
WILL HAVE NO LARGE SOUTHWARD PUSH. A FLAT WAVE DEVELOPING IN THE LEE
OF THE MOUNTAINS WILL ALSO SLOW THE PROGRESS SOMEWHAT. ASSUMING THIS
IS CORRECT THE FRONT WILL ENTER NWRN ZONES BY 18Z AND PROBABLY CLEAR
THE AREA 3 TO 4 HOURS LATER. THIS WILL MEAN THAT TUESDAY AFTERNOON
HIGHS WILL SHOW A CONSIDERABLE GRADIENT FROM NRN TO SRN ZONES JUST
AS THEY SHOULD ON MONDAY. STRONG COOL AND DRY AIR ADVECTION UNDERWAY
BY TUESDAY EVENING BRINGING CLEARING SKIES AND NIGHTTIME LOWS BACK
IN THE 30S.
-- End Changed Discussion --

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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AS OF 3 PM SUNDAY...CONFIDENCE REMAINS ON THE LOW SIDE FOR THE
PERIOD WITH MEDIUM RANGE GUIDANCE SHOWING LITTLE RUN TO RUN
CONSISTENCY. BROAD MID LEVEL TROUGHING OVER THE CONUS WILL PERSIST
THROUGH NEXT WEEK BUT WILL BECOME FLATTER LATER IN THE WEEK. EARLY
IN THE PERIOD FRONT STALLED OFF THE COAST MAY MOVE CLOSER TO THE
AREA AS A WEAK SURFACE WAVE MOVES NORTHEAST ALONG THE BOUNDARY. HAVE
LOW CONFIDENCE IN THIS BUT WILL CARRY SLIGHT CHC POP FOR EASTERN
HALF OF FORECAST AREA WED NIGHT INTO THU AS THERE COULD BE A BRIEF
PERIOD OF ISENTROPIC LIFT COMBINED WITH AN INCREASE IN MOISTURE.

HIGH PRESSURE BUILDS IN BEHIND THE EXITING WAVE WITH THE AREA DRYING
OUT THU AND FRI AS MUCH DRIER AIR MASS MOVES IN. ALTHOUGH PLENTY OF
SUNSHINE IS EXPECTED THU AND FRI NORTHERLY FLOW WILL KEEP
TEMPERATURES BELOW CLIMO.

THE WEEKEND BRINGS ANOTHER LOW CONFIDENCE EVENT WITH THE GUIDANCE
SHOWING A WEAK COASTAL TROUGH SAT. THE TROUGH MAY OR MAY NOT MOVE
ONSHORE SAT NIGHT AHEAD OF A SOUTHERN STREAM SYSTEM ARRIVING LATE
SAT NIGHT OR SUN. HAVE HIGHER CONFIDENCE IN THE COASTAL TROUGH
DEVELOPING GIVEN THE SURFACE HIGH SHIFTING OFF THE COAST FRI INTO
SAT BUT LESS CONFIDENCE IN IT MOVING ONSHORE. THE WEAK SOUTHERN
STREAM SYSTEM REMAINS AN ENIGMA AT THIS POINT WITH VERY LITTLE
AGREEMENT BETWEEN THE GFS...ITS ENSEMBLE MEMBERS...AND THE ECMWF.
THINK SOMETHING WILL BE THERE BUT HAVE LITTLE CONFIDENCE ON THE
PARTICULARS. HIGH TEMP FORECAST FOR SUN QUITE NICELY SUMS UP THE
RANGE OF SOLUTIONS LATE IN THE PERIOD. GFS SOLUTION WOULD PRODUCE
HIGHS IN THE LOW TO MID 70S WITH ECMWF SOLUTION PRODUCING HIGHS IN
THE LOW TO MID 40S. UNTIL THE PICTURE BECOMES CLEARER SEE NO REASON
TO MAKE CHANGES LATE IN THE PERIOD.
-- End Changed Discussion --

&&

.AVIATION /18Z SUNDAY THROUGH THURSDAY/...
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AS OF 18Z...WEDGE WILL LIKELY REMAIN IN PLACE THROUGH MUCH OF THE
FORECAST PERIOD. HIGH CONFIDENCE FOR IFR CONDITIONS THIS
AFTERNOON...POSSIBLY BECOMING VLIFR TONIGHT. THE WARM AIR WILL START
TO OVERRIDE THE WEDGE LATE TONIGHT. THE RISING DEWPOINTS COUPLED WITH
DIURNAL AFFECTS SHOULD BE A GOOD RECIPE FOR DENSE FOG TONIGHT. WOULD
NOT BE SURPRISED TO SEE SOME M1/4SM ESPECIALLY OVER THE SOUTHERN
TERMINALS. MONDAY...DENSE FOG WILL LINGER THROUGH MID MORNING AT THE
COASTAL TERMINALS...LIFTING AS WINDS SHIFT TO THE SOUTHWEST AS THE
WEDGE ERODES. INLAND TERMINALS MAY SEE LIFR/IFR CONDITIONS THROUGH
THE END OF THE FORECAST PERIOD AS THE WEDGE IN TYPICAL FASHION WILL
BE STUBBORN TO RETREAT.
-- End Changed Discussion --

&&

.MARINE...

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NEAR TERM /UNTIL 6 AM MONDAY MORNING/...

AS OF 3 PM SUNDAY...PERSISTENT AND MODERATE NE WINDS HAVE AIDED
IN ELEVATED SEAS ALL DAY...AND ACROSS THE OUTER WATERS WE STILL
HAVE SEAS IN EXCESS OF 6 FT. FRYING PAN SHOALS THIS HOUR REPORTED
NE WIND GUSTS TO 24 KT AND 7 FOOT SEAS. FOR THIS REASON WE HAVE
EXTENDED THE ADVISORY FLAGS UNTIL 600 PM TO ALLOW SEAS A BIT MORE
TIME TO RECOVER AS WINDS GRADUALLY EASE. AN EXERCISE CAUTION
STATEMENT HOWEVER MAY BE NEEDED AFTER 600 PM SINCE IMPROVEMENT
WILL BE SLOW TO PLAY OUT. THE SEA SPECTRUM WILL BE COMPRISED MOSTLY
OF NE WAVES 4-6 FEET EVERY 6-7 SECONDS...DAMPENING TO 3-5 FT
TONIGHT. NO TSTMS EXPECTED ON THE 0-20NM WATERS BUT DRIZZLE AND
PATCHY FOG/MIST WILL REDUCE VISIBILITIES BELOW 2NM AT TIMES AND
THIS INCLUDES THE INLAND WATERWAYS AND INLETS/ENTRANCES AS WELL.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 3 PM SUNDAY...THE COLD AIR WEDGE THAT HAD BRINGING THE
NORTHERLY FLOW WILL ERODE FROM SE TO NW ON MONDAY. THIS SHOULD
HAPPEN QUITE READILY OVER THE WATERS BUT MAY BE MORE SLUGGISH AND
PROBLEMATIC TO FORECAST OVER LAND. AS SUCH A LIGHT SOUTHERLY FLOW
WILL JUST BE GETTING ESTABLISHED OVER THE WATERS EARLY IN THE
PERIOD. THE REST OF THE DAY WILL BRING A SLIGHT VEER AND INCREASE
IN THE SPEEDS AS THE BOUNDARY MOVES FURTHER INLAND...POSSIBLY
ENOUGH FOR A 15 TO 20KT FCST BY LATER IN THE DAY. A COLD FRONT AND
FLAT WAVE OF LOW PRESSURE APPROACHING FROM THE NW WILL INCREASE
THE GRADIENT ACROSS THE WEST ATLANTIC BUT GENERALLY EAST OF THE 20
NM FORECAST ZONES. EVEN SO...EVEN BY LATER MONDAY SEAS MAY MANAGE
TO BUILD TO 3 TO 5 FT RANGE WITH THE HIGHER VALUES FOUND WELL
OFFSHORE DUE TO THE LARGELY COAST-PARALLEL WIND DIRECTION. COLD
FRONT BRINGS A SHARP VEER TO NRLY WINDS TUESDAY EVENING ALTHOUGH
THE SPEED OF THE BOUNDARY IS A LITTLE BIT UNCERTAIN...WITH SOME
GUIDANCE BEING FASTER THAN CURRENT FCST.

LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 3 PM SUNDAY...NORTH TO NORTHEAST FLOW WILL PERSIST FOR MUCH OF
THE PERIOD THOUGH SPEEDS REMAIN A QUESTION. PERIOD BEGINS WITH
SPEEDS 15 TO 20 KT BUT DROPPING TO 10 TO 15 KT BY MIDDAY AS GRADIENT
RELAXES. SPEEDS START TO INCREASE WED NIGHT INTO THU AS SURFACE WAVE
MOVES NORTHEAST ALONG A STALLED FRONT. GRADIENT TIGHTENS UP AS THE
WAVE PASSES WITH SPEEDS INCREASING TO CLOSE TO 20 KT AND BECOMING
MORE NORTHERLY. GRADIENT RELAXES AND SPEEDS DROP TO 10 TO 15 KT THU
NIGHT AND FRI AS WAVE EXITS AND CENTER OF HIGH MOVES TO THE NC
COAST. SEAS 3 TO 5 FT FOR MUCH OF THE PERIOD WILL DROP TO 2 TO 4 FT
ON FRI.
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&&

.ILM WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
SC...NONE.
NC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR AMZ250-
     252-254-256.
-- End Changed Discussion --

&&

$$
SYNOPSIS...MBB
NEAR TERM...MJC
SHORT TERM...MBB
LONG TERM...III
AVIATION...MJC/DL