Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 191123
AFDILM

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON NC
624 AM EST FRI DEC 19 2014

.SYNOPSIS...
HIGH PRESSURE WILL RIDGE DOWN INTO THE AREA TODAY CREATING ONE
LAST NICE DAY. THIS HIGH WILL WEDGE DOWN THE COAST DURING THE
WEEKEND...WHILE LOW PRESSURE MOVES NEARBY SATURDAY BRINGING RAIN
AND COOL TEMPERATURES. A SECOND LOW PRESSURE WILL BRING MORE
CLOUDS AND RAIN ON MONDAY...ESPECIALLY NEAR THE COAST. A LARGE LOW
PRESSURE REMAINING TO THE WEST WILL DRIVE A STRONG COLD FRONT
THROUGH THE CAROLINAS ON WEDNESDAY. COLD AND DRY WEATHER IS
EXPECTED FOR CHRISTMAS DAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...NO CHANGES TO THE FORECAST WITH THE LATEST
UPDATE. PREVIOUS DISCUSSION FOLLOWS:

SEASONAL TEMPERATURES IN STORE TODAY AND TONIGHT AS THE SOUTHEAST
EXTENSION OF A HIGH CENTERED OVER THE GREAT LAKES REGION CONTINUES
A COOL NORTH TO NORTHEAST FLOW OVER THE EASTERN CAROLINAS. MODEL
CONSENSUS...WITH A BIAS TOWARDS THE BETTER-PERFORMING GFS
MOS...GIVES US HIGHS IN THE MID TO UPPER 50S MOST PLACES AND
OVERNIGHT LOWS IN THE MID TO UPPER 30S.

MODEL SOUNDINGS AND SATELLITE LOOPS SHOW THAT MAINLY CIRRUS OF
VARYING EXTENT AND THICKNESS ALONG WITH SOME MID-LEVEL CLOUDS WILL
CONTINUE TO STREAM OVERHEAD EARLY THIS MORNING AND INTO THE DAYLIGHT
HOURS. HOWEVER...EXTENSIVE BREAKS IN THIS COVER WILL LEAD TO AMPLE
SUNSHINE INTO THE AFTERNOON HOURS. CLOUD COVER WILL LOWER AND
THICKEN OVERNIGHT AS A SYSTEM EMERGING FROM THE GULF OF MEXICO
APPROACHES FROM THE SW. CHANCES FOR LIGHT RAIN WILL INCREASE FROM
THE SW AFTER MIDNIGHT AS THIS SYSTEM MOVES CLOSER...ALTHOUGH AT THIS
STAGE ANY ACCUMULATIONS ARE EXPECTED TO BE NIL TO MINIMAL.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 330 AM FRIDAY...WET AND RAW SATURDAY STILL ON TAP AS A RATHER
QUICK-HITTING LOW PRESSURE SYSTEM MOVES OVERHEAD. A PERIOD OF DEEP
ISENTROPIC LIFT WILL STILL OCCUR OVER THE AREA THE FIRST HALF OF
SATURDAY...BUT GUIDANCE CONTINUES TO BACK OFF ON STRENGTH AND
DURATION OF THIS FORCING. THE ECMWF IS NOW REALLY THE ONLY GUIDANCE
SHOWING A VERY HEAVY RAINFALL EVENT...AND THUS WILL LEAN ON THE
DRIER HIGH RES SREF AS WELL AS THE GFS GUIDANCE. THIS SUGGESTS THE
HIGHEST QPF WILL OCCUR OVER SOUTHERN PORTIONS OF THE CWA AS THE
SYSTEM RACES EAST...AND DRYING BEGINS IN THE COLUMN AS EARLY AS
SUNSET ON SATURDAY. WHILE TOTAL QPF WILL NOT BE VERY
IMPRESSIVE...STILL FEEL CATEGORICAL POP IS WARRANTED...AND WITH THE
WEDGE OF HIGH PRESSURE REMAINING IN PLACE WILL KEEP HIGHS ONLY IN
THE UPPER 40S MOST PLACES AWAY FROM THE GRAND STRAND AND SOUTH
SANTEE RIVER AREAS. LOWS SATURDAY NIGHT WILL BE A BIT ABOVE CLIMO
NORMS...SLIGHTLY BELOW 40 INLAND...TO AROUND OR JUST ABOVE 40 AT THE
COAST...AS CLOUDS LIMIT TOTAL COOLING.

RESIDUAL LOW LEVEL MOISTURE REMAINS ON SUNDAY...BUT LACK OF FORCING
SHOULD KEEP SUNDAY DRY...ALBEIT WITH PARTLY TO AT TIMES MOSTLY
CLOUDY SKY CONDITIONS AND CONTINUED COOL TEMPS IN THE LOW 50S. THIS
DRYING COULD BE SHORT LIVED HOWEVER...AS RESIDUAL BAROCLINIC
INSTABILITY OFFSHORE IN CONJUNCTION WITH ANOTHER MID-LEVEL ENERGY
IMPULSE MAY SPAWN ANOTHER LOW PRESSURE OFFSHORE SUNDAY NIGHT.
AGAIN...ECMWF AND GFS DIFFER HIGHLY...BUT THE GFS HAS SUPPORT FROM
THE CMC/SREF/NAM AND IS FAVORED. ADDITIONALLY...THE FASTER SOLUTION
MAKES SENSE BASED OFF PROGRESSIVE FLOW AND CONTINUED PACIFIC JET
ENERGY AS NOTED BY WPC. THUS...WHILE WILL NOT SHOW POP/QPF AS
SIGNIFICANT AS INDICATED BY THE GFS/NAM...WILL BRING A RETURN OF QPF
TO THE AREA SUNDAY NIGHT AND KEEP LOWS WELL ABOVE NORMAL A DEGREE OR
TWO EITHER SIDE OF 40.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 330 AM FRIDAY...WELL AFTER MUCH OF DECEMBER WAS RATHER QUIET
LOCALLY...PATTERN TAKES A DECIDEDLY MORE ACTIVE TURN DURING THE LAST
FULL WEEK OF THE MONTH. MONDAY WILL BE WET AGAIN AS LOW PRESSURE
DEVELOPS ALONG THE STALLED BAROCLINIC BOUNDARY OFFSHORE...AND SLINGS
RAIN BACK INTO THE CAROLINAS. THE GFS REMAINS A STRONG OUTLIER IN
TERMS OF QPF...BUT THE NAM/SREF/CMC HAVE BEEN TRENDING WETTER...AND
MOIST ADVECTION IS PRETTY SIGNIFICANT...SO A BUMP TO LIKELY POP IS
WARRANTED. CONTINUING TO FAVOR THE GFS IN THE EXTENDED...MONDAY
NIGHT AND THE FIRST HALF OF TUESDAY LOOK TO FEATURE A BRIEF RESPITE
FROM THE RAIN ALTHOUGH SHOWERS ARE STILL POSSIBLE IN AN ISOLATED
NATURE.

THEREAFTER...A POTENT STORM SYSTEM LOOKS MORE LIKELY TO DEVELOP AS
THE MID-LEVEL FLOW BUCKLES IN RESPONSE TO STRONG RIDGING ACROSS THE
WESTERN CONUS. AS A DEEP TROUGH DIGS ACROSS THE EAST...STRONG
CYCLOGENESIS WILL OCCUR AND MOVE FROM THE GULF COAST UP INTO THE OH
VLY. THERE IS GOOD AGREEMENT THAT THE SURFACE LOW WILL REMAIN WELL
WEST OF THE LOCAL CWA...BUT DEEP MOIST ADVECTION WILL FUNNEL
TREMENDOUS MOISTURE INTO THE CAROLINAS AND PERIODS OF HEAVY RAINFALL
OR EVEN TSTMS WILL BE POSSIBLE AS THE COLD FRONT SWINGS ACROSS THE
AREA ON WEDNESDAY. THE CURRENT SETUP COULD SUPPORT SOME STRONGER
STORMS TUE/WED...BUT ITS STILL A BIT FAR OUT TO REALLY DETERMINE
THIS POTENTIAL...WHICH IS MADE EVEN TOUGHER BY THE MODEL
DISAGREEMENT. STILL...IT IS SOMETHING THAT BEARS WATCHING EARLY NEXT
WEEK...ESPECIALLY WITH WEDNESDAY BEING A BIG TRAVEL DAY.

STRONG CAA AND WILL FOLLOW BEHIND THE STORM SO CHRISTMAS LOOKS
DRY...BUT COLD AND WINDY.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
AS OF 12Z...WEAK LOW PRESSURE IN EASTERN TEXAS WILL SLOWLY DEVELOP
AND MOVE NORTHEAST. AHEAD OF THE SYSTEM WILL BE AN ASSORTMENT OF
CLOUD LAYERS...MAINLY MID AND HIGH CLOUDS AT FIRST. HIGH PRESSURE
WILL TRY TO RIDGE IN AT FIRST...WITH NORTHEAST FLOW EXPECTED. CLOUDS
WILL THICKEN IN THE OVERNIGHT HOURS WITH SOME PRECIP DEVELOPING
TOWARD MORNING AS ISENTROPIC LIFT BECOMES MODERATE. CEILINGS WILL
LOWER BUT WILL LIKELY REMAIN VFR THROUGH THE END OF THE FORECAST
PERIOD.

EXTENDED OUTLOOK...RAIN LIKELY SAT WITH DEVELOPING MVFR/IFR CIGS
POSSIBLY LASTING INTO SUN. CHANCE OF SHOWERS MON AS LOW PRESSURE
MOVES UP THE COAST. SHOWERS POSSIBLE LATE TUE AHEAD OF A STRONG COLD
FRONT.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
AS OF 630 AM FRIDAY...NO CHANGES TO THE FORECAST WITH THE LATEST
UPDATE. PREVIOUS DISCUSSION FOLLOWS:

HIGH PRESSURE CENTERED OVER THE GREAT LAKES WILL MAINTAIN A LIGHT
NORTH TO NORTHEASTERLY FLOW OVER THE WATERS THROUGH THE NEAR TERM.
WINDS WILL STAY IN THE 10 KT RANGE TODAY...INCREASING TO 10 TO 15
KTS OVER OUR SC WATERS OVERNIGHT AS A FRONTAL SYSTEM APPROACHES
FROM THE SW. SEAS WILL STAY IN THE 2 FT RANGE THROUGH THE PERIOD.

SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 330 AM FRIDAY...HIGH PRESSURE WEDGE WILL BE ENTRENCHED ALONG
THE COAST DURING THE WKND...WHILE AN AREA OF LOW PRESSURE MOVES NEAR
THE WATERS ON SATURDAY...WITH A SECOND LOW DEVELOPING OFFSHORE LATE
SUNDAY. THIS LEAVES A PINCHED GRADIENT BETWEEN THE FEATURES...AND NE
WINDS WILL BE PERSISTENT AT 10-15 KTS...AT TIMES HIGHER...THROUGH
THE PERIOD. THESE PERSISTENT NE WINDS WILL DRIVE SEAS TO 2-4 FT MUCH
OF THE WKND...WITH THE EXCEPTION BEING IN THE WAVE SHADOWED REGION
SW OF BRUNSWICK COUNTY...WHERE 1-2 FT SEAS WILL BE MORE COMMON.

LONG TERM /MONDAY THROUGH TUESDAY/...
AS OF 330 AM FRIDAY...NE WINDS TO START THE PERIOD AT 10-15 KTS WILL
BE HIGHLY VARIABLE ON MONDAY AS A LOW PRESSURE MOVES UP THE COAST.
EXPECT WINDS TO VEER THROUGH NEARLY THE ENTIRE COMPASS ON
MONDAY...SETTLING ON NW AT 5-10 KTS MONDAY NIGHT. A BRIEF PERIOD OF
LIGHT WESTERLY WINDS WILL OCCUR TUESDAY MORNING...BUT A LARGE AND
POTENT STORM SYSTEM WILL MOVE WELL WEST OF THE AREA BEGINNING
TUESDAY NIGHT. THIS WILL CAUSE A TIGHT PRESSURE GRADIENT AND SW
WINDS WILL RISE RAPIDLY LATE TUESDAY TO 15-20 KTS. SEAS MONDAY WILL
BE 2-4 FT WITH SEVERAL DIFFERENT WAVE GROUPS IN THE SPECTRUM. WAVE
HEIGHTS FALL TO AROUND 2 FT THE FIRST HALF OF TUESDAY...BEFORE
RISING DRAMATICALLY LATE...AND HEADLINES MAY BE NEEDED BY THE END OF
THE PERIOD.

&&

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

&&

$$

SYNOPSIS...JDW
NEAR TERM...REK
SHORT TERM...JDW
LONG TERM...JDW
AVIATION...43
MARINE...REK/JDW







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