FXUS61 KPHI 010354
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1054 PM EST MON NOV 30 2009

.SYNOPSIS...
HIGH PRESSURE WILL BUILD IN BEHIND THE DEPARTING COLD FRONT
OVERNIGHT TONIGHT. THE HIGH WILL RECEDE EAST BEGINNING TUESDAY
NIGHT. LOW PRESSURE WILL DEVELOP OVER THE GULF REGION ON TUESDAY
NIGHT AND THEN LIFT NORTHEAST. THE LOW LIKELY WILL PASS TO OUR
WEST LATE WEDNESDAY NIGHT OR EARLY THURSDAY AND THEN CONTINUE
NORTHEAST. HIGH PRESSURE WILL BUILD SLOWLY TOWARD THE AREA
BEGINNING FRIDAY, ALTHOUGH LOW PRESSURE MAY DEVELOP OFF THE
SOUTHEAST COAST AND LIFT BY WELL TO OUR NORTH OVER THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
THE SHOWERS ASSOCIATED WITH THE SURFACE FRONT ARE OFF THE COAST
NOW AND A REFRESHING NORTHWEST WIND KICKED IN BUT WILL SETTLE DOWN
IN A COUPOLE HOURS. REMAINDER OF THE NIGHT WILL FEATURE SOME
CLOUDS AS A SECOND SHORT WAVE PUSHES ACROSS THE REGION BY MORNING.
 

REGIONAL RADAR IMAGERY AND OBSERVATIONS SHOW LAKE EFFECT SNOW
SHOWERS FORMING IN WESTERN AND CENTRAL PENNSYLVANIA OFF OF LAKE
ERIE. AS THESE SHOWERS HEAD FURTHER EAST THEY WILL BEGIN TO RUN
INTO DRIER, WARMER AIR AND FALL APART, SO NOT EXPECTING THESE TO
AFFECT OUR REGION.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
WE END THE LOW CHANCE POPS IN THE NORTHWEST /RAIN AND/OR SNOW
SHOWERS/ ONCE THE SHORT WAVE MOVES BY, AND THEN HIGH PRESSURE IS
THE MAJOR INFLUENCE THROUGH TUESDAY NIGHT. THE STAT GUIDANCE MAXES
ON TUESDAY WERE IN VERY GOOD AGREEMENT WITH CONTINUITY, AND SO
ALL WERE ACCEPTED. WE ARE WORKING UNDER THE ASSUMPTION THAT THERE
WON'T BE A LOT OF HIGH CLOUDS ON TUESDAY NIGHT, AND SO WE CONTINUE
TO UNDERCUT STAT GUIDANCE ON TUESDAY NIGHT AS WINDS WILL DIMINISH
ON TUESDAY AND BECOME LIGHT ON TUESDAY NIGHT. 

THE MODELS BEGIN TO DIVERGE ON WEDNESDAY. THE NAM IS THE SLOWEST
WITH ADVANCING FORCING FROM THE LOW. THE GFS IS STRONGEST WITH THE
SURFACE LOW, AS IT SEEMS TO HAVE A CONSIDERABLY STRONGER UPPER JET
THAT IT IS LATCHING ONTO. WE HAVE GONE WITH THE ECMWF, WHICH IS
FASTER THAN THE NAM AND NOT SO ROBUST AS THE GFS. THIS STILL
BRINGS GOOD I300 ISENTROPIC INTO AT LEAST THE SOUTHWESTERN PART OF
THE AREA BY 00Z THURSDAY, WHICH CONTINUES THE GENERAL TREND OF
BEING SOMEWHAT QUICKER WITH THIS SYSTEM. WE BRING THE CHANCE OF
RAIN FURTHER NORTH THAN WE HAVE BEEN CARRYING. WE LEANED ON THE
COOLER MAV GUIDANCE AS WE THINK THE NAM /UPON WHICH THE MET
GUIDANCE IS BASED/ IS TOO SLOW. 

ON WEDNESDAY NIGHT, WE MAY SEE A JET ABOVE THE SURFACE IN EXCESS
OF 50 KNOTS WITH STRONG ISENTROPIC LIFT, Q-VECTOR CONVERGENCE
ALOFT AND LOWER LEVEL FRONTOGENESIS. H8 DEW POINTS LOOK LIKE THEY
WILL EXCEED 10 DEG C. THERE IS A CHANCE WE WILL BE BRUSHED WITH
SOME ELEVATED INSTABILITY, AND THERE MAY BE CSI WITH THIS SYSTEM
ALSO. SINCE THE SURFACE SYSTEM PASSES WELL TO OUR WEST, WE EXPECT
A DECENT RAIN EVENT FROM THIS. WE CONTINUE OUR MENTION OF THIS
SYSTEM IN THE HWO, AND WE HAVE REFRESHED THE PNS ISSUED
PREVIOUSLY. REGARDING TEMPERATURES, WE RAISE GUIDANCE BECAUSE OF
THE STRONG SOUTHERLY WIND AT H925 TO THE POINT WHERE THEY BARELY
DIFFER FROM WEDNESDAY MINS.  

RAIN ENDS FROM SOUTHWEST TO NORTHEAST ON THURSDAY, AND GUIDANCE
MAXES WERE ACCEPTED.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THE CHANGE THAT HAS BEGUN IN THE OVERALL WESTERN HEMISPHERIC WEATHER 
PATTERN ARRIVES IN OUR CWA DURING THIS PERIOD. A VIGOROUS MJO WAVE 
WHICH HELPED SET IT IN MOTION IS STILL ALIVE AND NOW A NEGATIVE EPO 
AND POSITIVE PNA TELECONNECTION PATTERN AS ITS BY PRODUCT WILL LEAD 
TO COLDER WEATHER FOR US. 

IN TERMS OF SENSIBLE WEATHER IT SHOULD AVERAGE COLDER THAN NORMAL 
THROUGH THE LONG TERM WITH A CHANCE AT MEASURABLE PRECIPITATION ON 
OR ABOUT DECEMBER 5TH. 

THURSDAY NIGHT SHOULD BE COLDER AND DRIER. THERE MIGHT BE SOME 
LINGERING FLURRIES IN THE POCONOS PENDING HOW LONG THE LAKE EFFECT 
CONTINUES. FOR NOW WE DID NOT INCLUDE IT.

A FAIR DAY IS THEN EXPECTED FOR FRIDAY WITH HIGH PRESSURE TRYING TO 
BUILD IN FROM SOUTHWEST. THE TROF ALOFT THOUGH IS STILL POSITIVE 
TILTED AND THUS THE COLDER AIR WILL ONLY SLOWLY BE MOVING OUR WAY. 
THIS MAY BE THE WARMEST DAY OF THE LONG TERM.

THE WEATHER THEN GETS A BIT MORE INTERESTING FOR SATURDAY AND SINCE 
THERE HAS BEEN SOMETHING MAGICAL ABOUT DECEMBER 5TH (IT SNOWED ON 
DECEMBER 5TH IN 2002, 3, 5 & 7 TU MATT) THIS DECADE ITS WORTH PAYING 
ATTENTION. ALL OF THE MODELS HAVE HAD A WAVE OF LOW PRESSURE SYSTEM 
DEVELOPING ALONG THE BAROCLINIC ZONE OFFSHORE FOR A COUPLE OF DAYS. 
UP TO THE 12Z RUN TODAY THE DEVELOPMENT WAS TOO FAR OFFSHORE TO 
AFFECT US. WITH THE 12Z RUN TODAY ALL OF THE MODELS HAVE SHIFTED THE 
SURFACE LOW FARTHER TO THE NW (THE PARALLEL GFS MOST NOTABLY) AND 
ALSO SHARPENED THE TROF. WE HAVE BEEN DOWN THIS ROAD BEFORE AS TO 
HOW FAR DOES THE LOW BACK AND WITH 5 DAYS TO GO AND THE TRIGGERING 
SHORT WAVE JUST ENTERING NORTHERN CANADA, THERE IS STILL UNCERTAINTY 
TO THE DETAILS.

FOR NOW WE HAVE ADDED CHANCE POPS TO SATURDAY DAY WHICH AS OF TODAY 
HAS MUCH TO DO WITH THE JET STREAK (TU OKX AND GH) AND THE NEGATIVE 
TILT SHORT WAVE AS WITH THE OFFSHORE SURFACE LOW ITSELF. STAY TUNED.

THE REST OF THE LONG TERM APPEARS DRY BUT COLD AS THE AFOREMENTIONED 
TROF MOVES THROUGH AND THEN ALLOWS THE HIGH PRESSURE SYSTEM TO BUILD 
INTO THE EASTERN CONUS.

&&

.AVIATION /04Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, 
KMIV, KACY AND SURROUNDING AREAS.

SOME MVFR SC CEILING SHOULD LINGER FOR A COUPLE OF HOURS AFTER
THE RAIN ENDS FROM TIME TO TIME, BUT AFTER THAT THE MODELS ARE
CONTINUING TO FORECAST RAPID CLEARING WITH NOT MANY CLOUDS DURING
THE SECOND HALF OF THE NIGHT. WE HAVE KEPT THE LOSS OF CEILINGS AT
AROUND 06Z OVERNIGHT.

THERE SHOULD BE ENOUGH OF A WIND TO PREVENT FOG FROM FORMING
TOWARD MORNING. A GOOD VFR DAY IS FORECAST FOR TUESDAY. THE
MODELS ARE SHOWING A BIT OF MOISTURE AROUND 4500 FT, BUT IT
APPEARS TOO LIMITED TO CARRY AS A CIG IN A PREVAILING GROUP. THERE
SHOULD BE SOME WIND GUSTS TO AROUND 20 KT FROM THE WEST, BUT
WINDS WILL DECOUPLE QUICKLY TOWARD EVENING AND MOST OF THE SC OR
CU CLOUDS SHOULD DISSIPATE BY THEN.

OUTLOOK...
HIGH PRESSURE MOVING IN FROM THE WEST WILL SUPPLY US WITH VFR
CONDITIONS TUESDAY INTO WEDNESDAY. A STORM SYSTEM IS THEN FORECAST
TO DEVELOP ALONG THE GULF COAST AND HEAD NORTHEAST. THE CURRENT
TRACK WILL KEEP THE LOW INLAND, CROSSING THE TENNESSEE AND OHIO
VALLEYS BEFORE REACHING NEW ENGLAND THURSDAY. RAIN IS FCST TO SPREAD
ACROSS THE AREA FROM SW TO NE LATER WEDNESDAY INTO WEDNESDAY 
NIGHT AND CONTINUE INTO EARLY THURSDAY. RAINFALL AMOUNTS COULD BE
MODERATE TO HEAVY AT TIMES AND A RUMBLE OF THUNDER CAN NOT BE RULED
OUT, ESPECIALLY SOUTHERN SECTIONS. CIGS AND VSBY ARE EXPECTED TO
BE RESTRICTED AND WINDS COULD BECOME QUITE GUSTY. THE STORM WILL
MOVE AWAY TO THE NORTHEAST THURSDAY NIGHT WITH GUSTY NORTHWEST
WINDS IN ITS WAKE. HIGH PRESSURE WILL MOVE IN FRIDAY INTO
SATURDAY.

&&

.MARINE...
A COLD FRONT WILL BE MOVING ACROSS THE MARINE AREA LATE THIS
AFTERNOON INTO THIS EVENING. WEST TO SOUTHWEST WINDS AHEAD OF THE
FRONT WILL SWING AROUND TO WEST TO NORTHWEST BEHIND THE FRONT.
GUSTS TO BETWEEN 25 AND 30 KT ARE EXPECTED OVERNIGHT BUT WILL
GRADUALLY DROP OFF TOWARD DAYBREAK. THE SMALL CRAFT ADVISORY WILL
REMAIN IN EFFECT UNTIL 6 AM ON OUR OCEAN WATERS AND ON THE LOWER
DELAWARE BAY. WAVE HEIGHTS AROUND 5 FT WILL SLOWLY SUBSIDE LATE
TONIGHT AND TUESDAY. HIGH PRESSURE, WITH SUB ADVISORY CONDITIONS,
GRADUALLY BUILDS IN TUESDAY INTO WEDNESDAY. THEN A STRONGER STORM
IS FORECAST TO DEVELOP ALONG THE GULF COAST AND HEAD NORTHEAST.
THE CURRENT TRACK FOR THIS SYSTEM WILL KEEP IT INLAND, CROSSING
THE TENNESSEE AND OHIO VALLEYS BEFORE REACHING NEW ENGLAND THURSDAY.
THIS IS EXPECTED TO BE A STRONG MOISTURE-LADEN SYSTEM DUE TO THE
UPPER AIR SUPPORT AND ITS GULF ORIGINS. SOUTHEAST WINDS WILL BE
INCREASING LATE WEDNESDAY INTO WEDNESDAY NIGHT. THESE WINDS WILL
PRODUCE INCREASING SEAS AS WELL. ADVISORIES OR WARNINGS WILL
PROBABLY BE NEEDED WITH THIS SYSTEM. IN ADDITION, POUNDING WAVES
OF 6 TO 8 FEET IN THE SURF COULD PRODUCE SOME BEACH EROSION
WEDNESDAY NIGHT. WITH THE FULL MOON OCCURRING WEDNESDAY, ASTRONOMICAL
TIDES WILL BE QUITE HIGH. THE ONSHORE FLOW LATE WEDNESDAY INTO
WEDNESDAY NIGHT IS EXPECTED TO PRODUCE INCREASING TIDAL DEPARTURES
AND SOME MINOR TIDAL FLOODING MAY OCCUR AROUND THE TIME OF HIGH TIDE
THURSDAY MORNING. WE WILL CONTINUE TO MONITOR THIS DEVELOPING
SITUATION AS IT DRAWS CLOSER IN TIME. ALL MARINE INTERESTS SHOULD
CHECK THE NATIONAL WEATHER SERVICE WEBSITE OR LISTEN TO NOAA WEATHER
RADIO ALL HAZARDS FOR THE POSSIBLE ISSUANCE OF ADVISORIES OR
WARNINGS.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST TUESDAY FOR ANZ431-450>455.

&&

$$
SYNOPSIS...EBERWINE/HEAVENER
NEAR TERM...EBERWINE/HEAVENER
SHORT TERM...DELISI
LONG TERM...GIGI
AVIATION...GIGI/RPW
MARINE...RPW