Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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FXUS61 KPHI 151618
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1118 AM EST MON DEC 15 2014

.SYNOPSIS...
HIGH PRESSURE EXTENDING OVER MUCH OF THE EASTERN UNITED STATES WILL
GRADUALLY MOVE EAST AND OFFSHORE LATER TONIGHT. A WARM FRONT IS
EXPECTED TO LIFT NORTH THROUGH THE AREA TUESDAY, FOLLOWED BY A COLD
FRONT TUESDAY NIGHT INTO WEDNESDAY. HIGH PRESSURE TO OUR WEST WILL
THEN SLOWLY BUILD EASTWARD INTO OUR REGION THROUGH THE END OF THE
WORK WEEK. BY SATURDAY, A LOW PRESSURE SYSTEM IS FORECAST TO
APPROACH THE AREA FROM THE SOUTHWEST, EVENTUALLY EMERGING OFF THE
EAST COAST SUNDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
NO SIGNIFICANT CHANGES TO THE FORECAST SO FAR TODAY. ONLY SOME
MINOR HOURLY GRID CHANGES MADE.

THE CLOUD COVER WHERE IT IS CURRENTLY LOCATED WILL LIKELY REMAIN
IN PLACE AS MOISTURE REMAINS TRAPPED UNDERNEATH THE LOW LEVEL
INVERSION. IT IS QUITE POSSIBLE, WITH THE RIDGING NEARLY OVERHEAD
THIS AFTERNOON, THAT THE INVERSION WILL LOWER THROUGHOUT THE DAY
AND THE CEILINGS WILL LOWER WITH TIME. THE LOWERING INVERSION WILL
ALSO HAVE AN EFFECT ON THE HIGHS FOR TODAY. AS WE LOWER THE BASE
OF THE INVERSION WE WILL NOT BE ABLE TO MIX AS HIGH AS YESTERDAY
AND THEREFORE WILL END UP COOLER THAN YESTERDAY.

FOR HIGHS TODAY WE USED A HEAVIER WEIGHTING OFF THE MAVMOS THOUGH
DID ADD IN A MINIMAL AMOUNT OF THE METMOS. IT SHOULD BE NOTED THAT
THE MET HAD HIGHS ACROSS THE REGION THAT WERE COOLER THAN THE EARLY
MORNING HOURLY OBSERVATIONS.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
HIGH PRESSURE OVERHEAD SO NO MEASURABLE PRECIPITATION IS EXPECTED.
IT IS POSSIBLE THAT AS WE BEGIN TO DEVELOP AN SOUTH-SOUTHEASTERLY
FLOW  FLOW VERY LATE TONIGHT THERE COULD BE SOME PATCHY DRIZZLE
AHEAD OF THE APPROACHING COLD FRONT...MOSTLY CONFINED TO OUR WESTERN
ZONES WITH GENTLE UPSLOPE FLOW. OTHERWISE WE WILL REMAIN CLOUDY WITH
TEMPERATURES SLIGHTLY BELOW AVERAGE.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
THE START OF THE LONG TERM WILL FEATURE SURFACE HIGH PRESSURE AND A
MID-LEVEL RIDGE PASSING JUST OFFSHORE, WITH A LOW PRESSURE SYSTEM
TRACKING ACROSS THE GREAT LAKES AND ITS ASSOCIATED FRONTAL
BOUNDARIES MOVING OVER OUR REGION TUESDAY INTO WEDNESDAY. THEN, A
RELATIVE LULL IS EXPECTED FOR THE AREA THROUGH THE REST OF THE WORK
WEEK AS HIGH PRESSURE TO THE WEST SLOWLY BUILDS EASTWARD. THE NEXT
MORE SIGNIFICANT SYSTEM LOOKS TO APPROACH AND PASS OFF THE EAST
COAST NEXT WEEKEND, POTENTIALLY BRINGING MIXED PRECIP TO OUR AREA.

FOR TUESDAY, A WARM FRONT IS FORECAST TO APPROACH OUR REGION FROM
THE SOUTHWEST AND SLOWLY LIFT NORTHWARD THROUGH THE DAY. THE EARLY
PART OF THE DAY SHOULD BE MAINLY DRY FOR THE MORNING COMMUTE AS THE
MODELS HAVE BEEN TRENDING SLOWER WITH THE APPROACH OF THE FRONT AND
THE ASSOCIATED LIFT AND ONSET OF PRECIP. BY MID-MORNING, WE DO
INTRODUCE CHANCE POPS ACROSS OUR WESTERN AND SOUTHERN ZONES FOR RAIN
SHWRS, AND WE STEP-UP POPS INTO THE LIKELY CATEGORY FOR TUESDAY
AFTERNOON AND EVENING FOR THE FORECAST AREA. WITH THE LATER ONSET OF
PRECIP INTO THE REGION, THERE NO LONGER LOOKS TO BE ANY P-TYPE
ISSUES AT THE START OF THIS EVENT AS TEMPERATURES WILL HAVE WARMED,
WITH RAIN EXPECTED AT THE ONSET. INTO TUESDAY NIGHT, WE TRIM BACK
POPS TO CHANCE AND THEN SLIGHT CHANCE INTO THE OVERNIGHT HOURS, AS
MOST OF THE LIFT AND MOISTURE WITH THE APPROACHING COLD FRONT LOOKS
TO PASS BY TO OUR NORTH. QPF AMOUNTS INTO TUESDAY NIGHT WILL BE
PRETTY LIGHT, AND WHILE TEMPERATURES FOR THE MOST PART ARE EXPECTED
TO REMAIN ABOVE FREEZING THROUGH THE NIGHT, THERE COULD BE SOME
MIXING OF SNOW WITH RAIN BEFORE THE PRECIP TAPERS OFF, MAINLY FOR
PORTIONS OF NORTHWEST NJ AND INTO THE POCONOS.

WHILE SOME IMPROVEMENT IS EXPECTED FOR OUR REGION INTO WEDNESDAY AS
A BROAD AREA OF SURFACE HIGH PRESSURE STRETCHING ACROSS THE PLAINS
AND MIDWEST SLOWLY STARTS TO BUILD EASTWARD, LINGERING SURFACE AND
UPPER LOW PRESSURE LOOK TO HANG AROUND TO OUR NORTHEAST. WHILE WE
ARE ANTICIPATING A MAINLY DRY WEDNESDAY WITH MIXED CLOUDS AND SUN,
SOME ISOLATED TO SCATTERED RAIN/SNOW SHWRS CANNOT BE RULED OUT FOR
THE HIGHER TERRAIN OF OUR NORTHWEST ZONES, ESPECIALLY IN THE
ANTICIPATED WEST-NORTHWEST FLOW. THROUGH THE END OF THE WORK WEEK
THEN, FAIRLY QUIET WEATHER IS EXPECTED AS THE PREVIOUSLY MENTIONED
BROAD HIGH PRESSURE GRADUALLY PROGRESSES EASTWARD. MIXED SUN AND
CLOUDS ARE EXPECTED FOR THE MOST PART THROUGH THURSDAY AND FRIDAY
WITH NEAR TO BELOW AVERAGE TEMPERATURES; ALTHOUGH, SOME FLURRIES
CANNOT BE RULED OUT IN THE CONTINUED NORTHWEST FLOW FOR THE POCONOS,
ESPECIALLY ON THURSDAY.

THE NEXT SYSTEM ON THE HORIZON TO WATCH AT THE VERY END OF THE LONG
TERM PERIOD WILL BE A DEVELOPING LOW PRESSURE SYSTEM AROUND THE GULF
COAST STATES LATE FRIDAY INTO SATURDAY. THERE CONTINUES TO BE MUCH
UNCERTAINTY AT THIS TIME WITH THIS SYSTEM BETWEEN THE GFS, ECMWF,
AND OTHERS REGARDING THE STRENGTH OF AN INCOMING SHORTWAVE AND ITS
INTERACTION WITH THE DEVELOPING SURFACE LOW ACROSS THE DEEP SOUTH.
IN ADDITION, THE TRACK AND INTENSITY OF THIS LOW PRESSURE INTO
SATURDAY AND SUNDAY CONTINUES TO BE HIGHLY UNCERTAIN, AND THE LATEST
MODEL GUIDANCE STILL RAISES MORE DIFFERENCES RATHER THAN
SIMILARITIES. THE ECMWF OVERALL DEVELOPS A MORE INTENSE LOW PRESSURE
THAT REMAINS FARTHER SOUTH, TRACKING FROM THE GULF COAST REGION TO
THE CAROLINAS THROUGH THE COURSE OF SATURDAY. THIS STRONG LOW
PRESSURE IS THEN PROGGED TO EMERGE JUST OFF THE EAST COAST AROUND
THE VIRGINIA TIDEWATER AREA SATURDAY NIGHT AND THEN TRACK
EAST-NORTHEAST OUT TO SEA THROUGH SUNDAY. THE GFS AT THIS TIME
DEVELOPS A MUCH WEAKER SYSTEM THAT TAKES MORE OF AN INLAND TRACK,
WITH A WEAKER LOW EMERGING OFF THE SOUTHERN MID ATLANTIC COAST AND
TRACKING MORE DIRECTLY EASTWARD OUT TO SEA. FACTORING IN THE CMC
MODEL AND VARIOUS ENSEMBLE DATA, WE HAVE TAKEN A MIDDLE OF THE ROAD
APPROACH WITH REGARDS TO THE TRACK AND INTENSITY OF THE DEVELOPING
LOW PRESSURE AND HOW THESE FACTORS WILL ULTIMATELY AFFECT PRECIP
TIMING AND PRECIP TYPE FOR OUR REGION SATURDAY AND SUNDAY. WE MOSTLY
TOOK A BLEND OF WPC GUIDANCE WITH CONTINUITY FOR TEMPS/WINDS/POPS
AND WILL LOOK TO FUTURE MODEL RUNS FOR MORE SIMILARITIES AND
AGREEMENT WITH THE DEVELOPMENT OF THIS SYSTEM.

&&

.AVIATION /16Z MONDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

TODAY...MVFR. WE COULD BE SOCKED IN ALL DAY WITH A 1500 TO 2500
FOOT DECK PLAGUING THE REGION. LIGHT NORTHWESTERLY WINDS WILL KEEP
COOL, MOIST AIR FLOWING IN FROM THE GREAT LAKES REGION.

TONIGHT...HIGH PRESSURE WILL SLIDE OVERHEAD TONIGHT ALLOWING WINDS
TO DROP OFF, GOING CLAM IN A LOT OF PLACES. MORE MOISTURE SHOULD
ADVECT IN FROM THE EAST AS A WEAK ONSHORE FLOW DEVELOPS. MVFR OR
POSSIBLY LOWER WILL BE AROUND.

OUTLOOK...
TUESDAY...MVFR CONDITIONS TO START THE DAY, BUT IFR CONDITIONS MAY
SET IN AS RAIN SHWRS DEVELOP ACROSS THE REGION.

WEDNESDAY...POSSIBLE MVFR CONDITIONS TO START, WITH IMPROVEMENT BACK
TO VFR EXPECTED BY MIDDAY TO AFTN.

THURSDAY AND FRIDAY...VFR CONDITIONS WITH NORTHWEST WINDS.

&&

.MARINE...
TODAY - TONIGHT...SUB-SCA CONDITIONS EXPECTED WITH LIGHT NORTHERLY
WINDS, AROUND 10 KNOTS. SEAS WILL REMAIN AROUND 2 FEET.

OUTLOOK...
TUESDAY...SUB-ADVISORY CONDITIONS ARE EXPECTED.

WEDNESDAY AND THURSDAY...WHILE SEAS ARE EXPECTED TO REMAIN BELOW SCA
LEVELS, NORTHWEST WIND GUSTS COULD REACH THE SCA THRESHOLD OF 25
KNOTS AT TIMES.

FRIDAY...MOSTLY SUB-ADVISORY CONDITIONS ARE EXPECTED. SOME NORTHWEST
WIND GUSTS COULD STILL BE IN THE 20 PLUS KNOT RANGE, THOUGH.

&&

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

&&

$$
SYNOPSIS...KLINE
NEAR TERM...HEAVENER/ROBERTSON
SHORT TERM...HEAVENER
LONG TERM...KLINE
AVIATION...HEAVENER/KLINE
MARINE...HEAVENER/KLINE







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