Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 211503
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
1003 AM EST SUN DEC 21 2014

.SYNOPSIS...
A WEDGE OF HIGH PRESSURE WILL KEEP CLOUDS AND RAIN CHANCES IN THE
FORECAST TODAY. RAIN CHANCES INCREASE ON MONDAY AS LOW PRESSURE
MOVES ALONG THE COAST. THE WEATHER WILL REMAIN UNSETTLED TUESDAY
BUT GROW A BIT MORE SEASONABLE. A STRONG COLD FRONT WILL BRING
SHOWERS AND MAYBE THUNDERSTORMS WEDNESDAY INTO WEDNESDAY NIGHT.
SUNSHINE FINALLY RETURNS ON CHRISTMAS DAY WHILE IT TURNS COOLER.
DRY AND FAIRLY SUNNY WEATHER SHOULD LAST INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 10 AM SUNDAY...EASTWARD MOVEMENT OF WEAK SURFACE WAVE ALONG
FRONT STALLED OVER NORTHERN FLORIDA HAS SHIFTED THE AREA OF WEAK
ISENTROPIC LIFT...AND ASSOCIATED PRECIP...OFF THE COAST. THE LOSS
OF LIFT ALONG WITH A SOUTHWARD PUSH OF COOLER/DRIER AIR WILL WORK
TO BREAK UP LOW CLOUD THIS MORNING. SKIES WILL NOT FULLY CLEAR
OUT BUT THERE WILL BE GLIMPSES OF SUN DURING THE LATE MORNING AND
EARLY AFTERNOON HOURS. LATER TODAY CLOUD COVER STARTS TO INCREASE
AHEAD OF THE NEXT WAVE EMERGING FROM THE GULF. THIS WAVE IS
STRONGER THAN THE PREVIOUS ONE AND WILL HELP PULL DEEPER MOISTURE
AND THE STALLED BOUNDARY FARTHER NORTH. AS THIS HAPPENS ISENTROPIC
LIFT INCREASES WITH LIGHT RAIN TO THE AREA LATER THIS AFTERNOON
AND EVENING. ALTHOUGH DO EXPECT TO SEE SOME BREAKS OF SUN DO THINK
THIS WILL BE LIMITED OVERALL WITH MINIMAL IMPACT ON TEMPS. KNOCKED
HIGHS DOWN A FEW DEGREES BUT DEPENDING ON TENACITY OF CLOUD COVER
FURTHER REDUCTION MAY BE REQUIRED.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 3 AM SUNDAY...CLOUDS HANG TOUGH MONDAY TO KEEP TEMPS BELOW
CLIMATOLOGY ONCE AGAIN AS SURFACE WEDGE OF HIGH PRESSURE RIDGES IN
FROM POINTS NORTH. FRONTAL BOUNDARY STALLED WELL OFFSHORE AND IT
WILL HAVE A WAVE OF LOW PRESSURE RIDGE UP ALONG OUR LATITUDE LATE IN
THE DAY. AS THIS OCCURS SOME AREAS MAY EXPERIENCE SOME WEAK
ISENTROPIC UPGLIDE THAT LEADS TO SOME LIGHT RAIN. WITH THIS FORCING
VERY WEAK AND MOISTURE CONFINED TO RELATIVELY LOW LEVELS
NON-MEASURABLE SPRINKLES SEEM JUST AS LIKELY AS MEASURABLE RAINFALL
ESPECIALLY INLAND. THE WEDGE STARTS TO BREAK DOWN ON TUESDAY AND THE
UPPER PATTERN WILL REALLY BE AMPLIFYING. THIS WILL CERTAINLY LEAD TO
A MILDER AFTERNOON BUT THE INCREASED MOISTURE ADVECTION WILL KEEP
THE SKY CLOUDY. RAIN CHANCES WILL ALSO INCREASE FAIRLY
RAPIDLY...MORESO FROM MOISTURE ADVECTION RATHER THAN FORCING LEADING
TO ASCENT. IN FACT IN SUCH A SITUATION MODELS ARE OFTEN A BIT FAST
ON ADVECTING MEASURABLE RAINFALL AND SO THERE MAY BE A FEW
RAIN-FREE HOURS EARLY TUESDAY.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 3 AM SUNDAY...WEDNESDAY PROBABLY REPRESENTS THE BEST RAIN
CHANCES THAT THE AREA HAS SEEN AND POSSIBLY WILL SEE FOR QUITE SOME
TIME. HIGHLY AMPLIFIED PATTERN TO DRIVE A COLD FRONT THROUGH BY
WEDNESDAY NIGHT. THE AMPLITUDE OF THE SYSTEM WILL BE SUCH THAT IT
WILL SCOOP UP PLENTY OF GULF MOISTURE. IN THE WAKE OF THIS SYSTEM
CHRISTMAS IS SHAPING UP TO BE RATHER BRISK AND COOLER BUT WILL AT
LEAST FEATURE A RETURN OF SUNSHINE WHICH BY THEN WILL HAVE BEEN
ABSENT FOR SEVERAL DAYS. THIS COOL HIGH THEN WEAKENS AND MOVES INTO
THE REGION BY FRIDAY WHICH SHOULD SHUT OFF THE COOL ADVECTION.
SATURDAY MAY BE EITHER SEASONABLE OR A FEW DEGREES WARMER AS ANOTHER
COLD FRONT APPROACHES FROM THE NW.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
AS OF 12Z...CIGS HAVE IMPROVED TO VFR THIS MORNING...BUT AT
KFLO/KLBT OCCASIONALLY VSBYS HAVE LOWERED TO MVFR IN BR. WITH A
SHARP COASTAL TROUGH JUST OFFSHORE LOW VFR/HIGH MVFR CIGS WILL
REMAIN A GOOD POSSIBILITY THROUGH THIS AFTERNOON. WEAK ISENTROPIC
LIFT WILL PRODUCE LIGHT RAIN TODAY. AS THE PRECIPITATION INCREASES
IN COVERAGE/INTENSITY AND FURTHER MOISTENS THE LOW LEVELS...CIGS
WILL EVENTUALLY LOWER TO MVFR THIS EVENING AND TO IFR BY MIDNIGHT.
COULD HAVE SOME TEMPO MVFR VSBYS MID/LATE AFTERNOON BUT NOT IN TAFS
ATTM.

EXTENDED OUTLOOK...RAIN LIKELY MON WITH MVFR/IFR CIGS AS A COASTAL
TROUGH PERSISTS OFFSHORE. SHOWERS/TEMPO MVFR EXPECTED TUE/WED AHEAD
OF A STRONG COLD FRONT. GUSTY WINDS WED/THU BEFORE AND AFTER FROPA.
THU WILL BE VFR AT ALL TERMINALS.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 10 AM SUNDAY...SCEC WILL CONTINUE FOR ALL ZONES TODAY. FLOW
REMAINS NORTHEASTERLY WITH WATERS IN PINCHED GRADIENT BETWEEN HIGH
BUILDING DOWN THE COAST AND FRONT/WAVES PASSING SOUTH OF THE
AREA. THE PINCHED GRADIENT WILL KEEP NORTHEAST FLOW BETWEEN 15 TO
20 KT THIS AFTERNOON AND FOR MUCH OF TONIGHT. SEAS WILL RUN 4 TO
5 FT IN WATERS OPEN TO NORTHEAST FETCH. WATERS SHELTERED FROM
NORTHEAST FLOW WILL RUN CLOSER TO 3 TO 4 FT.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 3 AM SUNDAY...NE WINDS ON MONDAY WILL VEER SLIGHTLY ON
TUESDAY AS A WEDGE OF HIGH PRESSURE OVER LAND WEAKENS. MONDAY WILL
ALSO BRING ABOUT 5KT OF HIGHER WIND SPEED AT TIMES AS LOW PRESSURE
MOVES UP ALONG A FRONTAL BOUNDARY OFF THE COAST. TUESDAY NIGHT THE
FLOW WILL VEER AGAIN MORE DECIDEDLY AS THE APPROACH OF A COLD
FRONT AND DYNAMIC UPPER SYSTEM APPROACH. WINDS WILL ALSO INCREASE
LATE TUESDAY NIGHT ABOVE THE BOUNDARY LAYER...THOUGH COOL SSTS MAY
TEMPER THE INCREASE IN WINDS SOMEWHAT AT THE SURFACE EARLY IN THE
NIGHT. THIS EFFECT HOWEVER WILL BE OVERWHELMED TOWARDS THE END OF
THE PERIOD BY THE OVERALL INCREASE IN MOMENTUM OF THE ATMOSPHERE
AND A SMALL CRAFT ADVISORY WILL BE NEEDED.

LONG TERM /WEDNESDAY THROUGH THURSDAY/...
AS OF 3 AM SUNDAY...STRONGLY FORCED COLD FRONT APPROACHING ON
WEDNESDAY AND SOLID SMALL CRAFT ADVISORY IN EFFECT. SUSTAINED GALE
FORCED WINDS WILL BE LURKING NOT TOO FAR ABOVE THE SURFACE AND AS
THE EVENT GETS CLOSER ATTENTION WILL SHIFT TO HOW DEEP MOMENTUM
TRANSFER OVER THE COOL SSTS WILL BE. SHOULD MIXING OVERWHELM THE
STABILIZING EFFECT OF THE COOL WATERS THEN WINDS MAY BE HIGHER THAN
CURRENTLY FORECAST, ALTHOUGH SURFACE GALES STILL SEEM RATHER
UNLIKELY. SHARP VEER WED NIGHT WITH FROPA AND BOUNDARY LAYER WIND
SPEEDS DROP OFF CONSIDERABLY BY THURSDAY.

&&

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

&&

$$
SYNOPSIS...MBB
NEAR TERM...III
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...MRR





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