-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPHI 032047
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
347 PM EST TUE DEC 3 2013

.SYNOPSIS...
-- Changed Discussion --
A WEAK HIGH PRESSURE SYSTEM OVER THE SOUTHEASTERN UNITED STATES WILL
MOVE OFFSHORE TONIGHT AND WEDNESDAY. A WEAK WARM FRONT WILL MOVE
THROUGH THE FORECAST AREA WEDNESDAY NIGHT AND THURSDAY MORNING. A
STRONG LOW PRESSURE SYSTEM REACHING JAMES BAY CANADA THURSDAY WILL
SEND A COLD FRONT ACROSS OUR AREA FRIDAY MORNING. WEAKER LOW
PRESSURE SYSTEMS SHOULD FORM ALONG THE COLD FRONTAL BOUNDARY AS IT
SLOWLY SAGS SOUTH FRIDAY NIGHT AND SATURDAY. A STRONG HIGH PRESSURE
SYSTEM WILL BUILD EASTWARD AND BECOME ANCHORED IN NEW ENGLAND BY
SUNDAY MORNING. A LOW PRESSURE SYSTEM FORMING IN THE WESTERN
GULF OF MEXICO IS FORECAST TO REACH THE OHIO VALLEY SUNDAY NIGHT
AND THE SAINT LAWRENCE VALLEY ON MONDAY. ANOTHER LOW PRESSURE
SYSTEM SHOULD FORM ALONG ITS WARM FRONT EAST OF DELMARVA SUNDAY
NIGHT AND TRACK NORTHEAST AND BECOME THE PRIMARY LOW EARLY NEXT
WEEK. ANOTHER WEAK WAVE OF LOW PRESSURE SHOULD THEN RIDE ALONG ITS
COLD FRONTAL BOUNDARY AND PASS EAST OF THE AREA ON TUESDAY.
-- End Changed Discussion --

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
-- Changed Discussion --
LOW PRESSURE WELL OFF THE ATLANTIC CST WILL CONTINUE TO MOVE NEWD
AWAY FROM THE REGION.  AS IT DOES, WEAK HIGH PRESSURE WILL BUILD IN
THROUGH TONIGHT.  LTST STLT IMAGERY SHOWED A GENLY CLEAR SKY OVER
THE AREA AND  WITH A GENL W TO SW FLOW ALOFT, TEMPS HAVE REBOUNDED
NICELY THIS AFTN INTO THE 50S IN MANY AREAS.  EXPECT TEMPS TO FALL
INTO THE 30S IN MOST LOCALES TONIGHT. WITH WK SFC FLOW AND NEAR CALM
WIND.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
-- Changed Discussion --
LOW PRESSURE WILL MOVE FROM THE CNTRL PLAINS TO NR THE GRTLKS ON WED
AND BRING A WK WMFNT THRU THE REGION.  TEMPS WILL ONCE AGAIN MAKE IT
INTO THE 50S ACRS THE REGION.  THE MAV AND MET ARE ABOUT 5 DEGREES
APART AND SOME OF THIS VARIANCE IS BASED ON CLOUD COVER.  FOR NOW,
WILL SPLIT THE DIFF.  THE FLOW IS ALSO MORE WLY THAN SWLY AND STILL
FAIRLY LIGHT.
-- End Changed Discussion --

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
-- Changed Discussion --
A VERY ACTIVE LONG TERM PERIOD IS EXPECTED FOR OUR CWA WITH A COUPLE
OF SHOTS AT MIXED PRECIPITATION AND PUTTING TO BED FOR A WHILE ANY
LINGERING CONCERNS ABOUT DROUGHT. THE GFS AND WRF-NMMB
INITIALIZATION LOOKED PRETTY GOOD, BUT AS NOTED IN THE PMDHMD,
BOTH MODELS ARE TRENDING TOWARD THE NON-US MODELING CONSENSUS AND
IN GENERAL WE USED ABOUT A 3 TO 6 HR SLOWER VERSION OF THE CURRENT
GFS RUN.

WEDNESDAY NIGHT STARTS SIMPLE ENOUGH AS A WEAK WARM FRONT IS
FORECAST TO START MOVING NORTH THROUGH THE AREA. THE FORECAST
SOUNDINGS STRONGLY SUGGEST DRIZZLE. THERE IS ALSO POSSIBLY SOME
LIGHT RAIN EARLIER AS A SHORT WAVE IS PREDICTED TO MOVE THROUGH.
GREATER CONFIDENCE FARTHER NORTH IN OUR CWA. GIVEN THE EXPECTED
CLOUD COVER AND WEAK SOUTHERLY FLOW, WE DID NOT LOWER MIN TEMPS
MUCH AND LEANED TOWARD THE WARMER NAM MOS.

ON THURSDAY, THE GFS IS ALREADY STARTING TO EDGE TOWARD THE FASTER
ENVELOPE OF SOLUTIONS OF BRINGING IN PRECIPITATION LATE SOUTH. WE
HAVE OPTED TO GO WITH A NON-GFS TIMING CONSENSUS FOR AFTERNOON
PCPN CHANCES. IN THE MORNING, THERE STILL MAY BE SOME LEFTOVER
LIGHT RAIN OR DRIZZLE MAINLY NORTH. THE AIR MASS IS UNSEASONABLY
WARM AND SOUNDINGS WOULD SUPPORT MAX TEMPS REACHING INTO THE 60S
AWAY FROM THE HIGHER TERRAIN. THE LOW CLOUDS AND LACK OF DAYLIGHT
MAY TRUMP THIS UP NORTH. REGARDLESS THIS IS ATYPICAL FOR DECEMBER
5TH WHICH SINCE THE START OF THIS CENTURY HAS BEEN A HISTORICALLY
SNOWY DAY.

PCPN CHANCES WILL INCREASE THURSDAY NIGHT AS THE COLD FRONT ENTERS
OUR CWA. GUIDANCE AND OUR POPS FAVOR NORTHWESTERN PARTS OF OUR
CWA VS DELMARVA. ALSO ALL THE MODELS ARE SHOWING INSTABILITY ALOFT
SOUTHEAST, ALTHOUGH TIMING DIFFERENCES FAVOR FRIDAY OVERALL VS
THURSDAY NIGHT. WE ADDED A LOW CHANCE OF THUNDER LATE SOUTHEAST.
WHILE THE FORECAST LLJ IS DECENT, ITS NOT ON THE LEVEL OF THE ONE
PRECEDING THANKSGIVING, SO LESS WIND CONCERNS FOR NOW.

THE BEST CONFLUENCE OF THE JET STRUCTURE AND PVA IS ON FRIDAY WHEN
WE CARRY OUR HIEST POPS. THE GFS IS FASTER THAN THE OTHER MODELS AND
OTS GEFS MEAN AT BRINGING IN COLDER AIR DURING THE DAY AND
ESPECIALLY AT 925MB. WE CONTINUED A SLOWER TREND AND THUS LIMITED
SLEET MENTION (BECAUSE OF THOSE FCST 925MB TEMPS) TO LATE AND JUST
FAR NORTHWEST. MAX TEMPS WILL LIKELY BE DURING THE FIRST HALF OF THE
DAY WITH TEMPERATURES FALLING AS WE GET DEEPER INTO THE COLD AIR.

THE POS TILT TROF CONTINUES TO FAVOR AN ANAFRONTAL LOOK TO THE PCPN
AND LIKELY POPS WERE KEPT THROUGH THE NIGHT. A TRANSITION TO
SLEET AND THEN SNOW WAS SHOWN IN THE GRIDS, ESPECIALLY IN THE
NORTHWESTERN THIRD OF OUR CWA. PLENTY OF MOVING PARTS SO
CONFIDENCE ABOUT PARTICULARS IS LOW. PTYPE CONSIDERATIONS WAS
CLOSEST TO THE ECMWF THERMAL FIELDS WHICH WOULD SUPPORT A MEASURABLE
SNOW NORTHWEST THIRD.

LOW CHANCE POPS (LIQUID) WERE KEPT SATURDAY MORNING FAR SOUTHEAST
BEFORE A STRONG HIGH PRESSURE SYSTEM BUILDS INTO THE NORTHEAST. IT
WILL FEEL LIKE DECEMBER AGAIN AS HIGH TEMPERATURES RETURN TO NORMAL.
IT WILL ALSO BE A COLD NIGHT SATURDAY NIGHT AS THE CANADIAN HIGH
BUILDS INTO NEW ENGLAND.

FOR SUNDAY INTO MONDAY ITS A COLD COLD AND DRY DRY HIGH PRESSURE
SYSTEM.  WHILE IT HAS THAT GOING FOR IT, THERE IS NO 50-50 LOW TO
IMPEDED ITS EXIT NOR WILL IT HAVE A COUPLE OF DAYS TO COLD AIR DAM.
REGARDLESS A 1040 MB HIGH DESERVES RESPECT AND WE HAVE A POTPOURRI
OF PCPN TYPES FORECAST FOR OUR ENTIRE CWA ON SUNDAY DAY AND
TRANSITION OVER TO MAINLY RAIN SOUTHEAST AT NIGHT. THE NORTHWEST PART
OF OUR CWA MAY BE PROBLEMATICAL TO GOING OVER TO PLAIN RAIN. EVEN
IF ITS A PARTING DAMMING SHOT, THE IDEA OF A BAROCLINIC ZONE (AND
SECONDARY LOW) FORMING AT THE COAST IS A LOGICAL CONCLUSION. THIS
WOULD LOCK IN COLDER AIR AT THE SURFACE LONGER NORTHWEST AS THE
SURFACE WINDS WOULD LIKELY BACK TO THE NORTHEAST. MORE ON THIS IN
THE DAYS AHEAD.

THE PRECIPITATION EVENT SHOULD WIND DOWN A BIT ON MONDAY AND THEN
THERE ARE MODEL DIFFERENCES AS TO HOW QUICKLY THE FRONT MOVES
THROUGH AND THE EFFECTS OF YET ANOTHER SECONDARY LOW AS IT RIDES
ALONG THE FRONT. THIS SECONDARY COULD BRING WINTRY PCPN DEEPER
INTO OUR CWA MONDAY NIGHT OR TUESDAY AGAIN.
-- End Changed Discussion --

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

VFR CONDS ARE EXPECTED FOR MOST, IF NOT ALL OF THE TAF PD.  WK HIGH
PRES ILL BE OVER THE REGION THRU WED.  A WK WMFNT WILL CROSS THE
AREA ON WED AS LOW PRES MOVES FROM THE CNTRL PLAINS TO THE GRTLKS.
A WK W TO NW FLOW WILL CONTINUE TODAY AND BECOME VERY LIGHT TONIGHT.
THIS WILL BE FOLLOWED BY A WEAK SE TO S FLOW ON WED.  OVERALL WIND,
SHOULD BE 5 KTS OR LESS AND COULD BE JUST PLAIN CALM FOR MUCH OF THE
TIME.

THERE IS A CHANCE, MUCH LIKE THIS MRNG, THAT THERE COULD BE SOME
LIGHT HAZE OR FOG OVERNIGHT INTO THE MID MRNG HOURS ON WED.  THIS
COULD REDUCE VSBYS TO MVFR LEVELS BEFORE RETURNING TO VFR BY 15/16Z.

OUTLOOK...
WED NIGHT...MVFR TO IFR CONDITIONS POSSIBLE DUE MAINLY TO LOW
CLOUDS.
THURSDAY...MVFR TO IFR NORTH BECAUSE OF CLOUDINESS, BECOMING VFR
SOUTH.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...PREDOMINATELY MVFR WITH TIMES
OF IFR THURSDAY NIGHT AND FRIDAY AS PRECIPITATION OCCURS. CHANCE OF
LLWS LATE THURSDAY NIGHT. CHANCE OF TSTMS SOUTH LATE THURSDAY NIGHT
AND FRIDAY MORNING. A PROBABLE TRANSITION TO MIXED PCPN NORTHWEST
AIRPORTS FRIDAY NIGHT.
SATURDAY...IMPROVING TO VFR CONDITIONS.
SATURDAY NIGHT...VFR,
SUNDAY...BECOMING MVFR AND POSSIBLY IFR LATE AS A MIXED
PRECIPITATION EVENT IS EXPECTED TO START.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
LOW PRESSURE WAS MOVG AWAY FROM THE CSTL WATERS AND WK HIGH PRESSURE
WAS BUILD IN THRU WED.  THIS WILL KEEP WIND AND SEAS BELOW SCA
CRITERIA THRU THE NEAR AND SHORT TERM PDS.

OUTLOOK...

WEDNESDAY NIGHT AND THURSDAY...SUB SMALL CRAFT ADVISORY CONDITIONS
EXPECTED.
THURSDAY NIGHT THROUGH FRIDAY NIGHT...SMALL CRAFT ADVISORY CONDITIONS
EXPECTED ON THE OCEAN WITH GREATER CONFIDENCE ABOUT SEAS. NEAR SMALL
CRAFT ADVISORY CONDITIONS ON DELAWARE BAY.
SATURDAY AND SATURDAY NIGHT...SUB SMALL CRAFT ADVISORY CONDITIONS ON
DELAWARE BAY AND BORDERLINE SMALL CRAFT ADVISORY CONDITIONS ON THE
OCEAN DUE TO BOTH WINDS AND SEAS.
SUNDAY...GREATER CONFIDENCE ABOUT SMALL CRAFT ADVISORY CONDITIONS
DEVELOPING AS THE DAY CONTINUES, ESPECIALLY ON THE OCEAN.
-- End Changed Discussion --

&&

.TIDES/COASTAL FLOODING...
-- Changed Discussion --
TIDAL FLOODING ISSUES FOR WEDNESDAY MORNING`S HIGH TIDE CYCLE APPEAR
TO BE NEGATED BY THE LACK OF ON-SHORE FLOW. ASTRONOMICAL TIDES ARE
SLIGHTLY LESS THAN TUESDAY MORNING`S AS WE BECOME FURTHER REMOVED
FROM THE NEW MOON. CURRENT FORECASTS SHOW A +0.5 FOOT DEPARTURE FOR
WEDNESDAY MORNING WHICH IS ABOUT HALF OF THE DEPARTURE EXPERIENCED ON
TUESDAY MORNING THAT PRODUCED SOME AREAS OF MINOR TIDAL FLOODING
ALONG THE ATLANTIC COASTLINE. WE DO NOT EXPECT OUR MINOR TIDAL FLOOD
THRESHOLDS TO BE MET FOR AN ADVISORY ISSUANCE AT THIS TIME.
-- End Changed Discussion --

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.

&&

$$
SYNOPSIS...GIGI/O`HARA
NEAR TERM...NIERENBERG
SHORT TERM...NIERENBERG
LONG TERM...GIGI
AVIATION...GIGI/NIERENBERG/O`HARA
MARINE...GIGI/NIERENBERG/O`HARA
TIDES/COASTAL FLOODING...HEAVENER