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000
FXUS61 KPHI 080910
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
410 AM EST SUN DEC 8 2013

.SYNOPSIS...
HIGH PRESSURE CONTINUES TO MOVE THROUGH THE REGION TODAY AND WILL
PUSH INTO NEW ENGLAND BY THIS EVENING. A LOW PRESSURE SYSTEM WILL
MOVE THROUGH THE GREAT LAKES REGION ON TODAY AND MONDAY, DRAGGING A
COLD FRONT THROUGH OUR AREA LATE MONDAY. MEANWHILE, A LOW PRESSURE
SYSTEM WILL DEVELOP AND MOVE UP ALONG THE MIDDLE ATLANTIC COAST ON
MONDAY. A SECONDARY FRONT WILL MOVE THROUGH THE REGION LATE TUESDAY
INTO WEDNESDAY. HIGH PRESSURE WILL THEN BUILD INTO THE REGION FROM
THE WEST ON WEDNESDAY BEFORE SHIFTING EAST OF THE AREA AT THE END OF
THE WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HIGH PRESSURE OVER THE REGION EARLY WILL MOVE NE DURG THE DAY.  AS
IT DOES, AN AREA OF LOW PRESSURE WILL APPROACH FROM THE OH VLY AND
BRING PRECIP TO THE REGION.  SRN AND WRN SECTIONS WILL SEE PRECIP
FIRST AND IT WILL THEN SPREAD NEWD.  THE HIGH TO THE N AND NELY
FLOW WILL KEEP COLD AIR STREAMING INTO THE AREA IN WHAT LOOKS TO BE
A GOOD COLD AIR DAMMING SITUATION.  THIS TIME OF YEAR, THE COLD AIR
GENERALLY WINS.  DURG THE DAY THE PRECIP WILL BE GENLY SNOW
EVERYWHERE, EXCEPT FOR THE EXTREME SE.  THERE ARE NO CHANGES TO THE
ADVISORIES ATTM AND JUST SOME MINOR TWEAKS TO THE SNOW/ICE NUMBERS.
THE OVERALL FCST RATIONALE REMAINS THE SAME.  TEMPS WILL REMAIN
STEADY.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
HOWEVER, AS WAA INCREASES THRU THE NIGHT, THE PRECIP WILL BEGIN TO
MIX AND EVENTUALLY CHANGE TO ALL RAIN FROM SE TO NW.  THE GFS IS THE
WARMEST/FASTEST MDL WITH THIS TRANSITION.  THE NAM/WRF AND ECMWF ARE
A BIT SLOWER BUT STILL HAVE THE CHANGEOVER REACHING THE I-95
CORRIDOR SHORTLY AFTER MIDNIGHT.  FURTHER AND W, THE WINTRY PRECIP
WILL HANG ON LONGER.  CURRENT THINKING IS THE GFS IS TOO WARM/TOO
QUICK WITH THE TRANSITION.

IT IS STILL PSBL THERE COULD BE A PD OF FZRA ALG THE I-95 CORRIDOR,
BUT CONFIDENCE IS LOW ON THIS OCCURRENCE SO NO HEADLINES ARE BEING
ISSUED FOR NOW.  IF THE GFS IS CORRECT, THEY WILL LIKELY NOT BE
NEEDED.  IF MORE SLEET OCCURS IN THE TRANSITION, THEY MAY NOT BE
NEEDED EITHER.  BY MON MRNG, ALL BUT THE FAR N AND W SHOULD BE
RAIN.

TEMPS WILL RISE OVERNIGHT AS THE WAA KICKS IN.  THIS IS DEFINITELY A
TRICKY TEMP DAY (AND NIGHT) AND A COUPLE OF DEGREES MAKES A WORLD OF
DIFFERENCE!

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
THINGS SHOULD BEGIN TO WIND DOWN BY MONDAY MORNING WITH JUST A FEW
ISSUES LEFT LINGERING ACROSS THE POCONOS IN TERMS OF ICING, THOUGH
WE MIGHT BE A COUPLE HOURS TOO LONG ON THIS. OTHERWISE RAIN WILL
CONTINUE TO OVERSPREAD FROM THE SOUTH-SOUTHWEST AS THE COASTAL WAVE
CONTINUES ITS NORTHWARD PROGRESS PASSING JUST OFF THE DELMARVA
COAST. A WEAK COLD FRONT WILL THEN PUSH IN FROM THE WEST AND
EFFECTIVELY PUT AN END TO PRECIPITATION BUT IN DOING SO COLDER AIR
BEGINS TO FILTER BACK INTO THE REGION.

MODELS CONTINUE TO SHOW A DISCONTINUITY WITH EACH OTHER IN TERMS OF
THE FINAL WAVE ON TUESDAY...DOES IT SKIRT BY TO OUR SOUTH OR HAVE
ENOUGH LATITUDE TO BRUSH BY OVERHEAD. UPPER LEVEL SUPPORT IN TERMS
OF THE RIGHT ENTRANCE TO THE STRONG JET AND WEAK Q-VEC CONVERGENCE
COUPLED WITH WEAK FGEN IN THE 700-500MB LAYER, SHOULD ALLOW FOR SOME
MORE MOISTURE TO BE SQUEEZED OUT ACROSS AT LEAST THE SOUTHERN HALF
OF THE CWA TUESDAY AFTERNOON. THERMAL PROFILES WILL BE CONDUCIVE FOR
ALL SNOW TO FALL THOUGH THE ONE MAJOR QUESTION BECOMES HOW MUCH
ENERGY IS STILL LEFT IN THE MID-LEVELS. BY TUESDAY THE MID-LEVEL
ENERGY BECOMES VERY STRUNG OUT AND MAY HAVE GIVEN ALL IT CAN SO
ONLY TIME WILL TELL IN THE AFTERMATH OF TONIGHTS SYSTEM TO SEE IF IF
CAN RECOVER. SPEAKING OF SNOWFALL, NOT EXPECTING MUCH IN THE WAY OF
ACCUMULATION THOUGH SOME OF THE MODELS ARE TRYING TO SHOW A QUICK
BURST TUESDAY AFTERNOON WITH DECENT DENDRITIC GROWTH POSSIBLE WITH
UPWARDS OF AN INCH IN SPOTS...MOST SOUTH AND EAST OF PHILLY.

WITH THE FINAL WAVE GONE, HIGH PRESSURE WORKS BACK IN ON WEDNESDAY
AND TEMPERATURES PLUMMET TO WELL BELOW SEASONAL AVERAGES...THROUGH
AT LEAST THE END OF THE WORK WEEK. A SLIGHT MODERATION IS EXPECTED
BY SATURDAY AS THE FLOW BEGINS TO VEER SLIGHTLY TOWARDS THE
WEST-SOUTHWEST. THE NEXT POTENTIAL SYSTEM LOOKS TO SKIRT BY THE
COAST SATURDAY NIGHT INTO SUNDAY THROWING SOME MOISTURE BACK ACROSS
THE REGION.

&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

THE PD STARTS OUT VFR, BUT THEN THINGS DETERIORATE AS HIGH PRESSURE
MOVES TO THE NE AND A WK AREA OF LOW PRESSURE MOVES ACROSS FROM THE
OH VLY.  THIS LOW WILL BRING AN ASSORTMENT OF PRECIP TO THE REGION.

VIRTUALLY EVERYONE WILL START OFF AS SNOW THIS AFTN.  THE SRN AND
ERN SECTION WILL CHANGE TO RAIN FAIRLY QUICKLY AND THE CHANGEOVER
WILL OCCUR MORE SLOWLY N AND W.  FOR THE I-95 CORRIDOR ARPTS,
CURRENT THINKING IS IT SHOULD BE AROUND MIDNIGHT A BIT AFTER.  FOR
KABE AND KRDG IT WILL BE IN WELL AFTER MIDNIGHT.  OF COURSE, WITH
THIS TYPE OF PRECIP, THERE WILL BE MVFR AND EVEN IFR CONDS (MAINLY
FOR CIGS) AND THESE REDUCED CONDS WILL THEN PERSIST FOR THE
REMAINDER OF THE TAF PD.

THE WIND WILL GENLY BE NE LESS THAN 10 KTS.

OUTLOOK...
MONDAY...STILL EXPECTING AN MVFR/IFR DAY AS RAIN CONTINUES TO
OVERSPREAD FROM THE SOUTH-SOUTHWEST. A COASTAL LOW PRESSURE WILL
PASS BY HEADING TOWARDS NEW ENGLAND AND MAY HELP TO KEEP A
PREDOMINANT EASTERLY FLOW ACROSS THE REGION THROUGH THE MORNING
HOURS AND THEN AS THE LOW MOVES AWAY WE BACK TOWARDS THE WEST. RAIN
SHOULD BEGIN TO COME TO AN END DURING THE EVENING HOURS.

TUESDAY...ONE FINAL WAVE OF LOW PRESSURE MAY IMPACT THE REGION
DURING THE DAY PROVIDING MVFR/IFR SNOW. NOT QUITE SURE HOW FAR
INLAND THE PRECIPITATION WILL FALL BUT HIGHER CONFIDENCE AT THIS
POINT IS FROM MIV AND ACY...MAYBE THE I-95 CORRIDOR. OTHERWISE WE
WILL BE VFR.

WEDNESDAY - THURSDAY...VFR.

&&

.MARINE...
HIGH PRESSURE WILL MOVE TO THE NE AS A WK LOW PRESSURE SYS MOVES IN
FROM THE OH VLY.  THIS FEATURE WILL BRING PRECIP TO THE AREA AND
WILL MOVE OFFSHORE OFF SRN NJ/DELMARVA TONIGHT.  AS A RESULT, THE
SCA CURRENTLY IN EFFECT FOR THE SRN WATERS WILL REMAIN IN EFFECT
UNCHANGED.  ATTM, IT DOES NOT APPEAR ANY ADDITIONAL FLAGS WILL BE
NEEDED FURTHER N.

OUTLOOK...
MONDAY...LINGERING SMALL CRAFT ISSUES POSSIBLE AS THE COASTAL WAVE
PULLS FURTHER NORTH WITH SEAS AND WINDS BEGINNING TO RELAX BY LATE
IN THE DAY.

TUESDAY AND WEDNESDAY...A FAIRLY TIGHT GRADIENT WILL EXIST FOR THE
TUESDAY THROUGH WEDNESDAY TIME FRAME WITH WINDS PICKING UP OUT OF
THE WEST OR NORTHWEST. WE COULD NEAR GALES ACROSS THE NORTH FOR A
BRIEF TIME PERIOD WEDNESDAY MORNING BUT CONFIDENCE IS RATHER LOW
RIGHT NOW. CONFIDENCE IS HIGH THAT A SMALL CRAFT WILL BE NEEDED FOR
THAT TIMEFRAME.

THURSDAY...WINDS AND SEAS WILL SUBSIDE BELOW SMALL CRAFT ADVISORY
LEVELS AS HIGH PRESSURE BUILDS ACROSS THE REGION.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 5 AM EST
     MONDAY FOR PAZ060>062.
     WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 3 AM EST
     MONDAY FOR PAZ101>106.
     WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 AM EST
     MONDAY FOR PAZ054-055.
NJ...WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 5 AM EST
     MONDAY FOR NJZ007-008.
     WINTER WEATHER ADVISORY FROM 2 PM THIS AFTERNOON TO 3 AM EST
     MONDAY FOR NJZ009.
     WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 7 AM EST
     MONDAY FOR NJZ001.
DE...NONE.
MD...WINTER WEATHER ADVISORY FROM 9 AM THIS MORNING TO 6 PM EST
     THIS EVENING FOR MDZ008-012-015-019-020.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR
     ANZ452>455.

&&

$$
SYNOPSIS...HEAVENER/MEOLA
NEAR TERM...NIERENBERG
SHORT TERM...NIERENBERG
LONG TERM...HEAVENER
AVIATION...HEAVENER/NIERENBERG
MARINE...HEAVENER/NIERENBERG/MEOLA