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000
FXUS61 KPHI 182354
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
654 PM EST WED DEC 18 2013

.SYNOPSIS...
A HIGH PRESSURE WILL MOVE FROM THE TENNESSEE VALLEY OFF THE
CAROLINA COASTLINE TONIGHT AND THURSDAY. A FRONTAL BOUNDARY THEN
WILL SLOWLY APPROACH THE REGION FROM THE NORTHWEST ON FRIDAY.
THIS FRONTAL BOUNDARY WILL BE LOCATED FROM NEW ENGLAND INTO THE
OHIO VALLEY THROUGH THE WEEKEND WITH SEVERAL WAVES OF LOW PRESSURE
TRAVELING NORTHEAST ALONG IT. THE FRONTAL BOUNDARY WILL MOVE EAST
OF THE REGION GIVING WAY TO HIGH PRESSURE ON MONDAY. THE HIGH
PRESSURE SYSTEM WILL BE OVERHEAD THROUGH WEDNESDAY.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
THROUGH TONIGHT...PATCHY SC CLOUDINESS AND GUSTY W-NW WINDS 20-25
KT OF THIS AFTN WILL DISSIPATE-SUBSIDE AFTER SUNSET. THEN CLEAR
TONIGHT WITH SOME CIRRUS TOWARD MORNING. VERY GOOD RADIATIONAL
COOLING AS BL WINDS ARE FCST UNDER 15 KT PERMITTING EASY DECOUPLING.
FCST HOURLY TEMPS MAY NOT BE GOING DOWN FAST ENOUGH THIS EVENING
OVER THE SNOW PACK IN THE NW NJ VALLEYS.

GUIDANCE HAS BEEN MUCH TOO WARM OVER THE THICK SNOWPACK OF NE NJ
AND PTNS OF E PA THE PAST TWO NIGHTS...IN SOME CASES 10 TO 15 DEGREES
TOO WARM. THE ECMWF 2M TEMPS WERE MUCH MUCH BETTER THAN NCEP GUIDANCE.
THE 12Z/18 ECMWF 2M TEMP GUIDANCE HAS 2M TEMPS DOWN ABOUT 11F IN
NW NJ TONIGHT. FCST MINS UP THERE ARE ABOUT 5 DEGREES BELOW THE
COLDEST OF THE 12Z/18 NCEP MOS GUIDANCE AND STILL THINK THAT IS
TOO WARM FOR THE SUSSEX COUNTY TO SOMERVILLE AREAS AS WELL WEST TO
KABE AND KRDG. THIS IS MUCH MUCH CLOSER TO THE 00Z/18 ECMWF MOS
TEMPERATURE GUIDANCE...FCSTG CLOSE TO 10F IN SUSSEX COUNTY NJ.

SNOWCOVER OVER S DELAWARE HAS DISAPPEARED FAST TODAY SO THERE WAS
LITTLE MODIFICATION OF THE 12Z/18 NCEP MOS GUIDANCE.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
DRY WARM AIR ADVECTION WITH SW WIND GUSTING TO AT LEAST 15 KT IN THE
AFTN... THICK CIRRUS AT TIMES BUT AVERAGING PARTLY TO MOSTLY SUNNY.
IN THESE SITUATIONS...THE MOS GUIDANCE MAY BE LINKED TOO MUCH TO
THE COOLER SKIN TEMP OF THE SNOWCOVER AND HAVE CHOSEN TO FCST THE
WARMEST OF AVBL MOS GUIDANCE IN THE I95 CORRIDOR AND A 50 50 BLEND
OF THE GUIDANCE OVER THE SNOW COVER OF NW NJ AND NE PA.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
***RECORD WARMTH POTENTIAL SUNDAY***

THURSDAY NIGHT THROUGH SATURDAY NIGHT: A FRONTAL BOUNDARY WILL BE
MOVING CLOSER TO THE REGION TO ALLOW FOR AN INCREASE OF CLOUDS ON FRIDAY.
A SHOWER OR TWO CAN NOT BE RULED OUT ACROSS NORTHWESTERN SECTIONS OF
THE CWA BUT LEFT IT IN THE CHANCE CATEGORY THROUGH SATURDAY NIGHT. MAY
HAVE TO WATCH TO SEE IF WE GET ANY ADVECTION FOG FORM OVER THE
SNOWCOVER AS WELL FRIDAY MORNING. HOWEVER SOUTHERLY WINDS SHOULD
BEGIN TO INCREASE DURING THE DAY WHICH WOULD BURN OFF ANY FOG. GOOD
AGREEMENT IN THE MODELING WITH REGARDS TO FRONTAL POSITION. STUCK
CLOSE TO A MAV/MET BLEND FOR TEMPERATURES AND WINDS. USED THE 09Z
SREF AS A BASIS FOR QPF IN THE FRIDAY AND SATURDAY PERIODS.


SUNDAY AND SUNDAY NIGHT: THE BOUNDARY IS LIKELY TO MOVE NORTH OF THE
REGION AS A WARM FRONT WITH THE COLD FRONT STILL WELL WEST OF OUR
REGION. THIS ALLOWS US TO BE WELL ENTRENCHED IN THE WARM SECTOR WITH
STRONG SOUTHWESTERLY WINDS. 850 MB TEMPS NEAR 16C COUPLED WITH THIS
STRONG FLOW SUGGEST HIGHS SUNDAY MAY REACH 70 DEGREES ACROSS A GOOD
PORTION OF THE AREA. WENT A BIT WARMER THAN THE RAW ECMWF MODELED TWO
METER TEMPERATURES ACROSS THE REGION. NEEDLESS TO SAY THIS WILL
LIKELY BREAK MANY LATE DECEMBER HIGH TEMPERATURE RECORDS. PLEASE SEE
CLIMATE SECTION BELOW. TIMING DIFFERENCES WITH THE MODELS ARE RATHER
SMALL WITH THE FRONTAL PASSAGE FOR SUNDAY NIGHT ATTM. A LINE OF
GUSTY SHOWERS MAY ACCOMPANY THE FRONT ORGANIZED BY AMPLE SHEAR AND A
POWERFUL LLJ. THOUGH INSTABILITY IS LIKELY TO BE VERY LIMITED. THIS
SET-UP IS SIMILAR TO WHAT WE HAD A FEW TIMES THIS FALL AND WILL BE
WATCHED CLOSELY WITH FURTHER UPDATES.

MONDAY: A NON-DIURNAL TREND WITH TEMPERATURES MAY VERY WELL OCCUR.
THOUGH WILL WAIT FOR MORE CONFIRMATION ON THE FRONTAL TIMING BEFORE
GOING AWAY FROM A DIURNAL TREND. THE CURRENT TIMING ALLOWS FOR
CLEARING CONDITIONS THROUGHOUT THE DAY. WINDS SHOULD ALSO SHIFT TO
THE WEST BUT WILL STILL BE BREEZY AS THE LOW DEPARTS. MOST ELEMENTS
FAIRLY CLOSE TO WPC GUIDANCE.

TUESDAY AND WEDNESDAY: QUIET AND COOLER WEATHER EXPECTED WITH HIGH
PRESSURE OVER THE REGION FOR THE HOLIDAY. DID NOT DEVIATE MUCH FROM
WPC.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

REST OF THIS AFTERNOON...VFR SCT TO BRIEFLY BKN CLOUDS AOA 4000 FT
WITH THE BKN SKYCOVER RESTRICTED TO KABE AND KRDG AND MAYBE KTTN.
WNW WIND GUSTS 20 TO 25 KT.

TONIGHT...VFR WITH SOME CIRRUS LATE. WIND BECOMES LIGHT W OR SW
DURING THE NIGHT.

THURSDAY...VFR WITH VARYING AMTS OF CIRRUS AOA 20000 FT. SW WINDS
GUSTS AROUND 15 KT IN THE AFTN.

OUTLOOK...

THURSDAY NIGHT AND FRIDAY...MOSTLY VFR. CHANCE OF MVFR CONDITIONS
NORTHWEST DUE TO CLOUDS AND SHOWERS. POSSIBLE PATCHY FOG IN THE
MORNING MAINLY FOR AREAS NW OF PHL. SOUTHWEST WIND GUSTS
INCREASING TO AROUND 15 KNOTS IN THE AFTERNOON.

FRIDAY NIGHT AND SATURDAY...MAINLY VFR. SOME MVFR CONDITIONS IN
SHOWERS WITH A GREATER CHANCE/CONFIDENCE NORTHERN AIRPORTS.

SATURDAY NIGHT THROUGH SUNDAY NIGHT...PREDOMINATELY MVFR. IFR AT TIMES IN
LOW CLOUDS AND PCPN. STRONG GUSTY SOUTHWEST WINDS POTENTIALLY
EXCEEDING 20 KTS FROM THE SOUTHWEST.

MONDAY: MVFR CONDITIONS IMPROVING TO VFR WITH ANY SHOWERS ENDING.

&&

.MARINE...
THE ADVISORY FOR THE NORTHERN HALF OF THE ATLANTIC COASTAL WATERS
WAS EXTENDED THROUGH THURSDAY. WINDS REMAIN GUSTY AROUND 25 KNOTS
AT BUOY 44065 AND SHOULD CONTINUE FOR A FEW MORE HOURS. THERE
COULD BE A LULL IN GUSTS OVERNIGHT, BEFORE INCREASING AGAIN
THURSDAY MORNING.

THE ADVISORY FOR THE SOUTHERN HALF OF THE ATLANTIC COASTAL WATERS
AND THE DELWARE BAY IS NOW IN EFFECT STARTING AT 8 AM THURSDAY AND
RUNS THROUGH THE DAY THURSDAY. WINDS REMAIN BELOW 25 KNOTS THIS
EVENING AND SHOULD REMAIN THROUGH THE NIGHT BEFORE INCREASING
AGAIN ON THURSDAY MORNING.

OUTLOOK...
SCA CONDITIONS ARE LIKELY ATTM FROM FRIDAY MORNING THROUGH SATURDAY
MORNING THEN AGAIN FROM 00Z SUNDAY THROUGH 12Z TUESDAY MAINLY FROM
SEAS. WINDS WILL APPROACH GALE FORCE FOR A TIME SUNDAY AFTERNOON AND
EARLY EVENING.

&&

.CLIMATE...
DAILY RECORD MAX TEMPERATURES THAT ARE VULNERABLE TO BE EXCEEDED.

12/21 KGED 65-1956  POR BACK TO 1949

12/22

KACY 65-1998        POR BACK TO 1874
KPHL 64-1998        POR BACK TO 1872
KILG 64-1998, 1984  POR BACK TO 1894
KABE 61-1998        POR BACK TO 1922
KTTN 64-1998        POR BACK TO 1865
KGED 68-1949        POR BACK TO 1949
KRDG 61-1998, 1949  POR BACK TO 1869
KMPO 58-1990        POR BACK TO 1901


FOR THE MONTH WE`VE TAKEN A LOOK AT THE RECORDS AND FOR THE TIME
BEING WE WILL ONLY LIST THE VULNERABLE SHORT PERIOD OF RECORD
KGED 77 SET 12/1991. THE MONTHLY RECORDS FOR ALL OUR CWA LONG TERM
CLIMATE STATIONS ARE IN THE 70S AND IN MOST CASES FEATURED THE
PERIOD OF 12/4-7 1998. THE MPO ALL TIME DECEMBER RECORD IS 66.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 8 AM TO 6 PM EST THURSDAY FOR ANZ430-
     431-452>455.
     SMALL CRAFT ADVISORY UNTIL 6 PM EST THURSDAY FOR ANZ450-451.

&&

$$
SYNOPSIS...DRAG/GAINES
NEAR TERM...DRAG
SHORT TERM...DRAG
LONG TERM...GAINES
AVIATION...DRAG/GAINES
MARINE...ROBERTSON/DRAG/GAINES
CLIMATE...DRAG/MEOLA