-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPHI 120224
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
924 PM EST WED DEC 11 2013

.SYNOPSIS...
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A REINFORCING COLD FRONT FROM THE GREAT LAKES WILL MOVE THROUGH
OVERNIGHT. HIGH PRESSURE WILL THEN BUILD ACROSS THE NORTHEAST
FRIDAY INTO SATURDAY AND MOVE NORTHEAST INTO THE CANADIAN
MARITIMES BY SUNDAY. A LOW PRESSURE SYSTEM FROM THE SOUTHWEST WILL
MOVE EAST OVER THE LOWER MISSISSIPPI VALLEY SATURDAY BEFORE
TURNING NORTHEAST WHERE IT WILL STRENGTHEN OFF THE MID ATLANTIC
COAST SUNDAY. THIS STORM WILL THEN QUICKLY MOVE INTO THE CANADIAN
MARITIMES BY MONDAY ALLOWING HIGH PRESSURE TO BUILD INTO THE AREA.
A POSSIBLE QUICK CLIPPER SYSTEM ON TUESDAY WILL BE FOLLOWED BY
HIGH PRESSURE WHICH WILL BEGIN TO PUSH IN AGAIN WEDNESDAY.
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&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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ESTF UPDATE DROPPED TEMPERATURES A BIT OVER THE NEXT COUPLE OF
HOURS BASED ON CURRENT CONDITIONS. OVERNIGHT SOME CLOUDINESS ALONG
WITH AN EXPECTED INCREASE OF WINDS MAKES TEMPERATURE ADJUSTMENTS
SLIGHTLY LESS CONFIDENT. WE DID LOWER THEM A BIT TO MAKE THEM
FLOW FROM CURRENT READINGS. WE ADDED SOME FLURRIES WEST BASED ON
OBSERVATIONS IN WESTERN PA. THE LATEST HRRR AND RAP DONT SEEM TO
IMPRESSED BY IT, BUT SNOW THAT IS REACHING THE GROUND (EVEN IF ITS
NOT GOING TO BE AT .01 W/E) IS SLIGHTLY GREATER THAN THEIR
EXPECTATIONS.

A MAINLY DRY COLD FRONT AND ASSOCIATED SHORT WAVE/VORTICITY IMPULSE
ARE EXPECTED TO CROSS THE AREA OVERNIGHT TONIGHT. THIS SHOULD
BRING AN INCREASE IN CLOUD COVER TO MUCH OF THE AREA OVERNIGHT,
AND WITH A LIMITED AMOUNT OF MOISTURE, A FEW ISOLATED SNOW
SHOWERS/FLURRIES ARE POSSIBLE ACROSS OUR NORTHERN AND WESTERN
AREAS. ANY SNOW THAT DOES FALL SHOULD BE RELATIVELY LIGHT,
ALTHOUGH A COATING IS POSSIBLE, MAINLY FOR OUR HIGHEST ELEVATIONS.

IT WILL CONTINUE TO REMAIN COLD, ESPECIALLY WITH THE SNOW COVER
ACROSS THE AREA. WINDS MAY INCREASE TOWARD DAYBREAK BEHIND THE
FRONTAL BOUNDARY, WHICH COMBINED WITH THE WINDS WILL CREATE LOW
WIND CHILL TEMPERATURES. WIND CHILLS SHOULD DROP TO THE SINGLE
DIGITS TO LOW TEENS FOR MOST AREAS, WITH SOME MINUS SINGLE DIGITS
ACROSS OUR HIGHER ELEVATIONS.
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&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
A DRY, COLD, BREEZY DAY IS EXPECTED FOR THURSDAY. THE
AFOREMENTIONED COLD FRONT WILL PUSH OFFSHORE EARLY IN THE MORNING,
WHILE HIGH PRESSURE BEGINS TO PUSH IN FROM THE WEST. THIS WILL
ALLOW WEST-NORTHWESTERLY WINDS TO INCREASE ACROSS THE AREA.
MEANWHILE, THICKNESSES WILL LOWER ACROSS THE AREA AS A TROUGH
ALOFT SWINGS ACROSS THE AREA. THIS WILL KEEP TEMPERATURES QUITE
COLD, AND WITH THE BREEZY WINDS, WIND CHILLS WILL REMAIN LOW FOR
THE DAY. WIND CHILLS WILL GENERALLY BE IN THE TEENS, WITH SOME
SINGLE DIGITS POSSIBLE, MAINLY FOR HIGHER ELEVATIONS. NO
PRECIPITATION IS EXPECTED AS DRIER AIR ALOFT MOVES ACROSS THE
AREA, ALTHOUGH AN INCREASE IN CLOUD COVER IS POSSIBLE DURING THE
DAYTIME.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
THE LARGE-SCALE PATTERN FOR THE EXTENDED PERIOD CONTINUES TO
FEATURE A LONG-WAVE TROF OVER THE CENTRAL/EASTERN U.S. WITH SHRTWV
FEATURES MOVING THROUGH IT. TEMPERATURES WILL BE BELOW NORMAL AND
PRECIP WILL BE MOSTLY LACKING EXPCEPT FOR THE WEEKEND STORM SYSTEM
DISCUSSED BELOW. IN GENERAL THE WPC GUIDANCE WAS FOLLOW FOR
POPULATING THE LONGER-TERM GRIDS.

THE CLOSED LOW CURRENTLY OFF THE SRN CAL COAST IS FORECAST TO BE
EJECTED EWD ACROSS THE SWRN U.S. ON FRIDAY...WITH BOTH THE KICKER
AND KICK-EE CONTINUING EWD ACROSS THE CENTRAL AND ERN U.S. ON SAT
AND SUNDAY. MODELS GENERALLY INCDC THAT LOW/MID LVL WARM
ADVECTION, UPWARD VV AND NEAR-SAT RH WILL ARRIVE OVER THE FCST
AREA EARLY ON SAT MORN. MODEL QPF HANGS BACK A BIT AND MAY BE TOO
SLOW. HAVE INTRODUCED CHC POPS IN THE GRIDS PRIOR TO 12Z ON SAT.
AT THAT TIME TEMPS AT THE SFC AND ALOFT SHOULD BE COLD ENOUGH FOR
SNOW.

WARM ADVCTN WILL INCREASE DURING THE DAY SATURDAY AND THE PRECIP
SHOULD TURN OVER TO RAIN FOR AREAS MAINLY S/E OF PHL. WARM
ADVECTION ABOVE THE SFC WILL CONT SAT NIGHT BUT SUB-FREEZING AIR
AT THE SFC MAY BE HARD TO DISLODGE SAT NIGHT FOR AREAS N/W OF PHL.
THUS A MIXED BAG OF PRECIP IS LIKELY FOR THOSE AREAS. A FEW INCHES
OF SNOW/ICE ACCUMULATION IS POSSIBLE AS THE SFC LOW MOVES NEWD OFF
THE MID-ATLANTIC COAST AND DEEPENS. ALSO THERE IS THE POTENTIAL
FOR FRONTO-GEN TO PLAY HAVOC WITH SNOW AMOUNTS AS IT DID LAST SUNDAY.

MOST PRECIP IS EXPECTED TO BE OVER BY SUNDAY MORNING ALTHO THE
LASTEST ECMWF INDICATES IT MAY HOLD ON THRU PART OF THE DAY. FCST
GRIDS HAVE CHC POPS WITH RW- SOUTHEAST SW- NORHTWEST.

A FAST MOVING CLIPPER SYSTEM ACROSS THE GRTLKS ON TUES COULD BRING
A CHC OF LIGHT SNOW TO NORTHERN AREAS TUE OR TUE NIGHT. OTRW HIGH
PRES WILL PROVIDE FAIR WX WITH MODERATING TEMPS THRU THE MIDDLE OF
NEXT WEEK.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

VFR CONDITIONS EXPECTED THROUGH THE PERIOD. HIGH LEVEL CLOUDS EARLY
TONIGHT, BEFORE LOWER CLOUDS MOVE IN OVERNIGHT WITH A DRY FRONTAL
PASSAGE, BUT STILL VFR. ADDITIONAL CLOUD COVER IS POSSIBLE THURSDAY,
BUT SHOULD REMAIN VFR.

GUSTY WINDS THIS AFTERNOON WILL DROP OFF OVERNIGHT, BEFORE BECOMING
GUSTY AGAIN ON THURSDAY BEHIND THE FRONTAL PASSAGE.

OUTLOOK...
FRIDAY...VFR CONDS WITH WEST WIND AROUND 10 MPH.

SATURDAY AND SUNDAY...CONDS DETERIORATING TO IFR ON SATURDAY WITH
MIXED PRECIP TYPES AND FOG. EAST WINDS AROUND 10 MPH ON SAT WILL
SHIFT TO NW 15 TO 20 MPH ON SUNDAY AS THE STORM MOVES OFFSHORE.
CONDS SHOULD IMPROVE TO VFR AGAIN BY SUNDAY AFTN.

MONDAY...VFR CONDS WITH LIGHT WINDS.

&&

.MARINE...
THE SMALL CRAFT ADVISORY FOR THE NORTHERN WATERS
REMAINS IN EFFECT ALTHOUGH WINDS HAVE DROPPED OFF BELOW ADVISORY
LEVELS FOR NOW. THE WINDS WILL INCREASE LATER THIS EVENING INTO
THE OVERNIGHT HOURS AND CONTINUE INTO THURSDAY. A SMALL CRAFT
ADVISORY HAS BEEN ISSUED OR THE REMAINDER OF THE WATERS, INCLUDING
THE DELAWARE BAY. WINDS ARE EXPECTED TO INCREASE OVERNIGHT BEHIND
THE FRONTAL BOUNDARY, AND CONTINUE INTO THURSDAY.

OUTLOOK...
FRIDAY...SMALL CRAFT ADVISORY CONDITIONS MAY CONTINUE THROUGH
EARLY MORNING BUT WINDS AND SEAS SHOULD SUBSIDE BELOW SCA BY
AFTERNOON.

SATURDAY AND SUNDAY...A STORM IS FORECAST TO DEVELOP OFF OF OUR
COAST LATE SATURDAY INTO SUNDAY THEN MOVE TOWARD THE CANADIAN
MARITIMES. AT LEAST A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED
IN NW WINDS BEHIND THE STORM FROM SUNDAY EVENING INTO MONDAY.

MONDAY...WINDS AND SEAS SHOULD SUBSIDE AS HIGH PRESSURE MOVES OVER
THE AREA.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
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PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST FRIDAY FOR ANZ452>455.
     SMALL CRAFT ADVISORY UNTIL 7 AM EST FRIDAY FOR ANZ450-451.
     SMALL CRAFT ADVISORY FROM 5 AM TO 6 PM EST THURSDAY FOR ANZ430-
     431.
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&&

$$
SYNOPSIS...AMC/GORSE/99
NEAR TERM...GIGI/ROBERTSON
SHORT TERM...ROBERTSON
LONG TERM...AMC
AVIATION...AMC/ROBERTSON
MARINE...AMC/ROBERTSON