Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 250857
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
357 AM EST TUE NOV 25 2014

.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE REGION TODAY FROM THE SOUTHWEST.
THEN, A STORM IS EXPECTED TO DEVELOP OFF THE SOUTHEASTERN UNITED
STATES TONIGHT AND STRENGTHEN AS IT MOVES NORTHEASTWARD. THIS
SYSTEM WILL IMPACT OUR REGION ON WEDNESDAY BEFORE REACHING THE
CANADIAN MARITIMES ON THANKSGIVING MORNING. A LARGE ARE OF HIGH
PRESSURE WILL THEN BUILD IN FROM THE CENTRAL PART OF THE NATION
FOR FRIDAY THROUGH SATURDAY BEFORE IT MOVES OFFSHORE ON SUNDAY. A
COLD FRONT ASSOCIATED WITH AN AREA OF LOW PRESSURE IN EASTERN
CANADA WILL CROSS THE REGION SUNDAY OR MONDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A COLD FRONT CONTINUES TO SLIDE CLOSER TO THE COAST. ONCE IT MOVES OFF
SHORE, IT SHOULD STALL. WHERE EXACTLY IT WILL STALL WILL HAVE AN
IMPACT ON RAIN CHANCES FOR COASTAL LOCATIONS IN SOUTHERN DE AND NJ.
FOR NOW HAVE ONLY INCLUDED SLIGHT CHANCE AND LOW END CHANCE MENTION
ON LAND AS THERE IS A RATHER ROBUST SOUTHWESTERLY LOW LEVEL JET
BEHIND THE FRONT. THOUGH NOT THE MOST DRAMATIC TEMPERATURE GRADIENT
WITH A FALL COLD FRONT, TEMPERATURES TODAY ARE EXPECTED TO BE ABOUT
15 DEGREES LOWER THAN YESTERDAY, BUT STILL ABOVE NORMAL.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TODAY/...
EXPECTING THE COASTAL LOW TO LIFT NORTHEAST ALONG THE STALLED FRONT
THROUGH THE OVERNIGHT HOURS, AND WILL BE OFF SHORE OF THE CAROLINAS
BY EARLY WEDNESDAY MORNING. AS IT DOES LIFT NORTH THROUGH THE NIGHT,
EXPECT TO SEE PRECIPITATION ASSOCIATED WITH THE LOW BEGIN TO MOVE
INTO OUR REGION AFTER MIDNIGHT. FOR THE MOST PART HOWEVER, THROUGH
THIS PERIOD, GIVEN THE STRAIGHT ON SHORE FLOW, IT SHOULD BE RAIN.
THE ONE EXCEPTION IS IF...AND THAT IS A BIG IF...THE PRECIPITATION
CAN REACH THE HIGHER TERRAIN OF THE POCONOS AND NW NJ THROUGH THE
OVERNIGHT HOURS. HOWEVER, EVEN IN THAT CASE, WITH THE CENTER OF THE
LOW STILL SO FAR AWAY, DO NOT EXPECT SIGNIFICANT PRECIP AMOUNTS, AND
THUS DO NOT EXPECT SIGNIFICANT ACCUMULATING SNOW BEFORE SUNRISE.

&&

.LONG TERM /TONIGHT THROUGH MONDAY/...
...WE CONTINUE TO TRACK A STORM WHICH WILL IMPACT THE BUSY TRAVEL
TIME ON WEDNESDAY...

MODEL GUIDANCE HAS COME INTO MUCH BETTER AGREEMENT OVERALL ON THE
EVOLUTION OF A STORM WHICH WILL DEVELOP OFF THE SERN CONUS CST ON
WED THEN TRACK NEWD DURG THE DAY ON WED. HOWEVER, WHILE THERE IS
GOOD AGREEMENT ON THE SYNOPTIC FEATURES, THERE REMAINS SOME
DISAGREEMENT ON THE THERMAL PROFILES AND SOME THE FINER DETAILS,
WHICH COULD PROVE IMPORTANT AS THE EVENT PLAYS OUT.

IT CONTINUES TO APPEAR AS THE AREAS N AND W OF PHILADELPHIA HAVE
THE BEST SHOT OF SEEING SIGNIFICANT SNOW, WHICH WILL IMPACT
TRAVEL. SRN AND ERN AREAS WILL LIKELY STAY ALL OR MOSTLY RAIN,
SOME OF WHICH COULD BE HEAVY AT TIMES. THE POTENTIAL FOR SOME
PONDING OF RAIN ON ROADWAYS AND POOR DRAINAGE AREAS IS POSSIBLE IN
THESE LOCATIONS.

THE BIGGEST QUESTION MARK IS WHAT HAPPENS ALONG THE I-95 CORRIDOR.
TEMPS LOOK MARGINAL. CERTAINLY ABOVE FREEZING AT THE START OF THE
EVENT, COOLING DURING IT, BUT HOW MUCH. MODEL GUID VARIES AS TO
WHAT DEW POINTS WILL BE, AND HENCE WHEN THE PRECIP START WHERE THE
WET BULB ZERO WILL BE. A DEGREE OR TWO CAN MAKE A WORLD OF
DIFFERENCE HERE.

ADDITIONALLY, IT WAS QUITE WARM ON MONDAY AND WILL BE FAIRLY WARM
TODAY SO THE GROUND HAS IS WARM WHICH MAY NEGATE SOME ACCUMS,
ESPECIALLY AT THE ONSET ON ROADWAYS ETC, UNLESS THE SNOW COMES
DOWN HEAVY.

THE ECMWF WAS OUT AHEAD OF THIS SYS (NO SURPRISE!). WHILE THE
OTHER MDLS OFFERED VARIOUS SOLNS OVER THE COURSE OF THE LAST FEW
DAYS, THE ECMWF ALWAYS HAD A ROBUST SYS AND NEVER WAVERED MUCH
FROM ITS TRACK. HOWEVER, IT HAS ALSO CONSISTENTLY BEEN WARMER AS
WELL, WHICH IS DIFFICULT TO IGNORE.

SO, ULTIMATELY IT REMAINS TO BE SEEN WHAT WILL WIN OUT IN THIS
AREA. THERE IS ALSO THE POTENTIAL FROM THE I-95 CORRIDOR N AND W
FOR SOME MESOSCALE BANDING WHICH COULD INCREASE ANY SNOWFALL
RATES, BUT THIS IS OFTEN DIFFICULT TO PREDICT MORE THAN A FEW
HOURS IN ADVANCE, AND AMOUNTS CAN VARY WIDELY BETWEEN THOSE AREAS
UNDER A BAND AND THOSE WHICH ARE NOT.

WITH THE MRNG PKG, ALL HEADLINES WILL BE LEFT IN PLACE UNCHANGED.
THE MOST LIKELY PLACES TO REACH HEADLINE CRITERIA WOULD BE EXTREME
NRN NJ AND THE POCONOS. THE FURTHER S ONE GETS IN THE WATCH,
CONFIDENCE FALLS QUICKLY, BUT WILL WAIT OTHER GUIDANCE BEFORE
MAKING OTHER CHANGES TO HEADLINES. ULTIMATELY, SOME OF THE WATCH
WILL PROBABLY BECOME WARNINGS, SOME MAY BECOME ADVISORIES AND SOME
MAY BE DROPPED.

ALSO, WHEN PRECIP BEGINS ON WED, IT WILL LIKELY BE RAIN VIRTUALLY
EVERYWHERE AND WILL MIX AND CHANGE FROM NW TO SE, WHICH OF COURSE
IS HIGHLY DEPENDENT ON TEMPS. FURTHERMORE, LTST GUID INDICATES
THAT ALL PRECIP WILL BE ENDING DURG WED EVE. THE COMBINATION OF
ALL OF THESE FACTORS CAME UP WITH SLIGHTLY LOWER SNOW TOTALS THIS
MORNING.

THE AFOREMENTIONED STORM MOVES OUT WED NIGHT AND AND A DRY FCST IS
EXPECTED BY THE TIME EVERYONE SITS DOWN FOR TURKEY.  HIGH PRESSURE
WILL BUILD IN FROM THE MIDDLE OF THE COUNTRY FOR FRI THRU EARLY
SUN WHICH WILL YIELD CONTINUED DRY WX AND A WARMING TREND, AS THE
HIGH MOVES EWD BY SUN AND SWLY FLOW RETURNS.

LOW PRES WILL MOVE ACRS ERN CANADA ON SUN AND ITS ASSOCD CDFNT WILL
CROSS THE REGION SUN NIGHT OR ERLY MON, BRINGING ANOTHER SHOT OF
PRECIP, MAINLY IN THE FORM OF RAIN. GUID IS NOW SUGGESTING THAT A
WAVE COULD FORM ON THIS FRONT ON MON, WHICH WOULD LINGER PRECIP CHCS.




&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

VFR CONDITIONS SHOULD CONTINUE THROUGH AT LEAST 00Z. THROUGH THIS
TIME, EXPECT ONLY HIGH CLOUDS WITH CEILINGS ABOVE 10000 FT AGL. THE
ONE EXCEPTION TO THIS IS KMIV AND POSSIBLY KACY, WHICH COULD SEE
TRANSIENT CLOUDS BETWEEN 2000 AND 3000 FT AGL THROUGH 12Z. WESTERLY
WINDS COULD GUST TO 20KT AT TIMES THROUGH THE DAY.

AFTER 00Z...CEILINGS SLOWLY START TO LOWER. MOST TAF SITES FROM THE
DELAWARE RIVER VALLEY AND FURTHER WEST (KPHL, KILG, KPNE, KTTN,
KABE, AND KRDG) WILL LIKELY SEE CEILINGS STAY IN THE VFR RANGE
THROUGH 12Z. AT KMIV AND KACY HOWEVER, THEY COULD SEE MVFR CEILINGS
MOVE IN BETWEEN 06 AND 12Z. IN ADDITION TO LOWER CEILINGS, AREAS OF
-RA COULD BEGIN TO MOVE IN AFTER 00Z AS WELL. HOWEVER, IT IS
UNLIKELY THAT ANY TAF SITES WILL BE AFFECTED BEFORE 06Z, AND
UNLIKELY THAT ANY OF THE INLAND TAF SITES WILL SEE ANY BEFORE 12Z.
IF RA DOES MOVE IN, COULD SEE VISIBILITIES REDUCED TO MVFR AT TIMES.

OUTLOOK....
WED AND WED EVENING... A VERY BUSY TRAVEL DAY, AND UNFORTUNATELY A
TIME WHICH WILL BE IMPACTED BY A COASTAL STORM. THIS STORM WILL BRING
WIDESPREAD MVFR AND IFR CONDS, MAINLY WITH CIGS BUT SOME VSBY
RESTRICTIONS AS WELL, ESPECIALLY IN THOSE AREAS THAT SEE SNOW OR
HVY RAIN.

FOR NRN AND WRN AREAS (KABE/KRDG)...MOSTLY SNOW IS EXPECTED. ALONG
THE I-95 CORRIDOR, THE PRECIP WILL START OFF AS RAIN, WITH TEMPS
ABV FREEZING THEN WILL MIX WITH SNOW AND CHANGE OVER AT SOME POINT
WED AFTN OR EVE BEFORE ENDING. FOR SRN AND ERN AREAS PRECIP WILL
BE MOSTLY OR ALL RAIN. WIND WILL GUST IN THE 15 TO 25 KT RANGE AS
WELL, MAINLY FROM THE N. PRECIP SHUD END DURG WED EVE.

CONFIDENCE IS HIGH ABOUT THE EVENT, BUT LOW ABOUT PRECIP TYPE ALG
THE I-95 CORRIDOR.

THU...CONDS RETURN TO VFR AND WINDS SHIFT TO WESTERLY OR
NORTHWEST. THERE COULD BE BRIEF MVFR CONDITIONS IN SCATTERED SNOW
SHOWERS LATER THURSDAY MAINLY JUST N OF KRDG AND KABE. WINDS MAY
GUST TO 25 KT.

FRI THRU SAT...VFR CONDITIONS EXPECTED.

&&

.MARINE...
WINDS AND SEAS WILL BE SLOW TO DECREASE ONCE THE COLD FRONT MOVES
OFF SHORE BY SUNRISE. ONCE WINDS AND SEAS DO FALL BELOW SCA CRITERIA
THIS MORNING ON THE BAY, AND LATE THIS AFTERNOON ON THE ATLANTIC
COASTAL WATERS, THERE WILL BE A BRIEF LULL WITH SUB SCA CONDITIONS
BEFORE NORTHEASTERLY WINDS INCREASE QUICKLY AFTER MIDNIGHT IN
RESPONSE TO THE APPROACHING LOW. BY EARLY TOMORROW MORNING, GALE
CONDITIONS ARE LIKELY ON THE LOWER DELAWARE BAY AND THE ATLANTIC
COASTAL WATERS.

OUTLOOK...
WED...A GALE WARNING HAS BEEN RAISED FOR THE COASTAL WATERS AND
DELAWARE BAY AS AN AREA OF LOW PRESSURE MOVES BU OFFSHORE.

WED NIGHT...GALE CONDITIONS WILL CONTINUE EARLY, THEN SEAS AND
WIND WILL DECREASE AND AND SCA WILL BE LIKELY NEEDED.

THU...WIND AND SEAS CONTINUE TO DIMINISH BUT SCA WILL BE NEEDED
PROBABLY THU AFTN OR EVE.

FRI THROUGH SAT..WIND AND SEAS ARE EXPECTED TO REMAIN BELOW SCA
CRITERIA.

&&

.CLIMATE...

REGARDING THE MIDWEEK COASTAL STORM BRINGING SNOW TO A LARGE
PORTION OF OUR REGION, WE HAVE INCLUDED DAILY SNOWFALL RECORDS
BELOW FOR OUR FOUR PRIMARY CLIMATE SITES THAT HAVE A LONG-STANDING
UNBROKEN PERIOD OF RECORD (POR) WITH RESPECT TO HISTORICAL
SNOWFALL DATA.

DAILY SNOWFALL RECORDS:

NOVEMBER 26TH:               NOVEMBER 27TH:       PERIOD OF RECORD:

ACY: TRACE 1977,1957,1955    1.2 INCHES 1978            1874

PHL: 6.0 INCHES 1898         6.9 INCHES 1949,1938       1872

ILG: 0.1 INCHES 1950         4.5 INCHES 1978            1894

ABE: 1.7 INCHES 1925         7.0 INCHES 1938            1922

OTHER COOPERATIVE SITE SHORTER HISTORICAL RECORD CAN BE FOUND AT
THE NWS MOUNT HOLLY WEBSITE UNDER NOW DATA.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE
     WEDNESDAY NIGHT FOR PAZ054-055.
     WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE
     WEDNESDAY NIGHT FOR PAZ060>062-101-103-105.
     WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE
     WEDNESDAY NIGHT FOR PAZ070-071-102-104-106.
NJ...WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE
     WEDNESDAY NIGHT FOR NJZ001-007-008.
     WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE
     WEDNESDAY NIGHT FOR NJZ009.
     WINTER STORM WATCH FROM WEDNESDAY MORNING THROUGH LATE
     WEDNESDAY NIGHT FOR NJZ010-015.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR
     ANZ450>455.
     GALE WARNING FROM 4 AM TO 10 PM EST WEDNESDAY FOR ANZ431-
     450>455.
     SMALL CRAFT ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
     ANZ430-431.

&&

$$
SYNOPSIS...NIERENBERG
NEAR TERM...JOHNSON
SHORT TERM...JOHNSON
LONG TERM...NIERENBERG
AVIATION...JOHNSON/NIERENBERG
MARINE...JOHNSON/NIERENBERG
CLIMATE...






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