Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 251154
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
654 AM EST SUN JAN 25 2015

.SYNOPSIS...
A STRONG COLD FRONT WAS RUSHING SOUTHEAST DOWN TO NEAR ROUTE 80 AT
DAYBREAK AND WILL SLIDE DOWN INTO A LATE DAY POSITION FROM THE
DELMARVA WEST INTO LOW PRESSURE OVER THE LOWER OHIO VALLEY. THAT
LOW WILL REACH THE NORTH CAROLINA COAST MONDAY MORNING THEN TURN
NORTH NORTHEAST INTENSIFYING VERY RAPIDLY AS IT NEARS CAPE COD
TUESDAY. HIGH PRESSURE FOLLOWS BY LATE WEDNESDAY, THEN ANOTHER LOW
WILL REDEVELOP ON THE NEXT COLD FRONTAL PASSAGE OFF THE MID ATLANTIC
COAST LATE THURSDAY AND FRIDAY. HIGH PRESSURE FOLLOWS SATURDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS THE LOW PRESSURE FROM YESTERDAY PULLS FARTHER TO OUR NORTHEAST AN
ARCTIC-TYPE COLD FRONT PUSHES THROUGH OUR REGION THIS AFTERNOON.
WATER VAPOR IMAGERY THIS MORNING SHOWS ONE TROUGH AXIS TO OUR
NORTHEAST WHILE ANOTHER SHORTWAVE AXIS PUSHES THROUGH THE GREAT
LAKES...THIS IS DRIVING THE ARCTIC FRONT TODAY. WAY BACK ACROSS THE
NORTHERN PLAINS IS THE ENERGY THAT WILL BE THE DRIVING FORCE FOR THE
CLIPPER SYSTEM LATE TONIGHT AND THEN THE MUCH LARGER COASTAL
NOR`EASTER EXPECTED ON MONDAY-TUESDAY.

OVERALL A DRY AND TRANQUIL DAY IS EXPECTED ACROSS THE REGION. THE
AFOREMENTIONED FRONT WILL SLIP THROUGH THE REGION BY THIS AFTERNOON
USHERING IN A COOLER AIRMASS. THE MORNING STRATOCU SHOULD LIFT AND
MIX OUT A LITTLE AS THE DAY WEARS ON. DECENT DOWNSLOPING COMPONENT
SHOULD ALLOW HIGHS TO REACH CLOSE TO 40F THIS AFTERNOON, SLIGHTLY
WARMER SOUTH AND EAST OF PHILLY, AHEAD OF THE FRONTAL PASSAGE.
BEHIND THE FRONT WEAK MID-LEVEL WARM AIR ADVECTION OCCURS TO OUR
SOUTHWEST AS MORE MOISTURE AND CLOUDS ADVECT IN BEGINNING LATER THIS
EVENING.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM MONDAY/...
BROAD SCALE SURFACE LOW PRESSURE, RIDING ALONG THE SAGGING COLD
FRONT LATER THIS EVENING, WILL PASS TO OUR SOUTH TONIGHT. HIGH
PRESSURE TO OUR NORTH WITH WEAK MID-LEVEL RIDGING WILL ALLOW FOR THE
MID-LEVEL SHORTWAVE DRIVING THE SURFACE LOW TO DEEPEN AND TAKE MORE
OF A NEGATIVE TILT TONIGHT. STRENGTHENING WAA, IN RESPONSE TO THIS
PROCESS, WILL OCCUR ACROSS OUR REGION AS A LIGHT SNOW SHOULD BREAK
OUT FROM WEST-EAST. ONSET TIMING IS STILL A BIT OF A QUESTION BUT A
MAJORITY OF THE HI-RES GUIDANCE IS SHOWING THE INCREASING CHANCES
DURING THE LATE EVENING. PTYPE SHOULD NOT BE MUCH OF AN ISSUE EXCEPT
ACROSS OUR EXTREME SOUTHERN ZONES AS LOW-LEVEL TEMPERATURES STRUGGLE
TO TRANSITION COLDER (BELOW 0C) JUST AHEAD OF THE APPROACHING
LOW...WAA SHOULD KEEP A RAIN/SNOW MIX SOUTH OF DOVER WHILE NORTHWARD
IS ALL SNOW.

DECENT CONVERGENCE ACROSS OUR CENTRAL ZONES LATE TONIGHT, BOTH
THERMALLY AND DYNAMICALLY. GUIDANCE IS PAINTING A NOSE OF A TENTH OF
LIQUID FROM A PHL/ABE LINE WEST SO THIS IS WHERE WE SHOULD SEE
SLIGHTLY HIGHER SNOW AMOUNTS...ON THE ORDER OF 1-2" IN AND AROUND
PHILLY, 2-3" FARTHER WEST TOWARDS RDG...MESOSCALE BANDING POTENTIAL
ALSO EXISTS ALBEIT NOT NEARLY AS ROBUST AS SATURDAY MORNING.

EVEN THOUGH THIS SNOW WILL AFFECT THE MONDAY MORNING COMMUTE WE DID
NOT WANT TO ADD TO ANY CONFUSION WITH MULTIPLE WINTER WEATHER
HEADLINES DEALING WITH THE SAME EVENT...JUST TWO DIFFERENT PIECES OF
ENERGY. GIVEN WE ARE EXPECTING A MUCH MORE IMPACTFUL STORM BEGINNING
LATER ON MONDAY...SEE LONG TERM DISCO...WE DECIDED TO FORGO AN
ADVISORY BUT MAKE MENTION OF THE EARLY MORNING SNOWFALL IN THE
HWO/WSW PRODUCTS.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
**MAJOR DISRUPTIVE SNOWSTORM POTENTIAL LATE MONDAY INTO TUESDAY
 MORNING PHLLY AREA NEWD TO NEW ENGLAND**

500 MB: A STRONG SHORT WAVE MONDAY MORNING OVER THE CENTRAL APPALACHIANS
INTENSIFIES INTO A CLOSED LOW SOUTH OF LONG ISLAND TUESDAY. RIDGING
IN THE WAKE OF ITS MARITIMES DEPARTURE FOLLOWS TO THE EAST COAST
WEDNESDAY. A SOUTHEASTWARD MOVING SHORT WAVE REACHES THE MID
ATLANTIC COAST FRIDAY WITH A TEMPORARILY FLATTENED WESTERLY FLOW
NEXT WEEKEND.

TEMPERATURES (ENERGY USE): BELOW NORMAL MONDAY THROUGH THURSDAY,
POSSIBLY 5 TO 10 DEGREES BELOW MON-WED;  NEAR NORMAL FRI,  CHILLING
AGAIN SATURDAY.

FORECAST BASIS: UNLESS OTHERWISE NOTED WITHIN THE DAILIES. THIS
FORECAST IS A 50 50 BLEND OF THE 00Z/25 MAV/MET FOR MONDAY-TUESDAY.
THE 00Z/25 MEX MOS WAS APPLIED TUESDAY NIGHT AND WEDNESDAY. THE 05Z/25
WPC D4-8 ELEMENTS OF DEWPOINTS/WIND/SKY/POP/MAX-MIN TEMPS WERE NOT USED
FOR THE LONGER RANGE DUE TO FOCUS ON THE POTENTIALLY VERY HIGH IMPACT
STORM FOR MONDAY NIGHT.

THEREFORE...THERE WAS NO UPDATE OF THE FORECAST BEYOND WEDNESDAY
IN THE EARLY ISSUANCE TODAY.



THE DAILIES...
MONDAY-TUESDAY...WSA IN DIFFERING SEGMENTS TO BE REFINED WHEN
WATCHES CONVERT TO WARNINGS AND OR ADVISORIES.

MONMOUTH AND OCEAN COUNTIES OF NE NJ ARE SEPARATED AS WINTER STORM
WATCH, BUT READY TO TO CONVERT TO A BLIZZARD WARNING IF THREE
SUCCESSIVE RUNS OF THE ECMWF OPERATIONAL AND ENSEMBLE SOLUTIONS
ARE CORRECT.

MODEL DISAGREEMENT FOR THE 00Z/25 CYCLE WITH THE NAM THE MAIN OUTLIER
RIGHT NOW. THE UKMET IS LARGE BUT A FASTER DEPARTURE THAN THE ECMWF.

THE 00Z/06ZNAM WAS ACCEPTABLE THROUGH MIDDAY MONDAY AND THEREAFTER
DID NOT RELY ON THE NAM FOR ITS QPF...INSTEAD THIS FORECAST IS
BASED HEAVILY ON NCEP QPF/SNOWFALL AS WELL AS THE 00Z/25 ECMWF
AND GFS BLEND.

MONDAY: SEVERAL INCHES OF SNOW EXPECTED BUT AN ADVISORY NOT ISSUED
SINCE WE DID NOT WISH TO DRAW ATTENTION AWAY FROM THE POTENTIALLY
VERY HIGH IMPACT EVENT FOR MONDAY NIGHT. TOO WARM FOR MUCH ACCUMULATION
FAR SNJ AND MUCH OF THE DELMARVA. THE ARCTIC FRONT AND ITS SLOWLY
DEEPENING BOUNDARY LAYER COLD IS CRUCIAL FOR THE LIFT OF THE SELY
850MB FLOW AND A GENERAL SNOW IN EASTERN PA/MUCH OF NJ. COMMUTES
IMPACTED. HIGH CONFIDENCE.


MONDAY NIGHT INTO TUESDAY MORNING...UNCERTAINTY ON AMOUNTS ETC ALL
HINGING ON INTENSITY AND TRACK OF A COASTAL STORM. OVERALL, THIS
LOOKS LIKE A MAJOR STORM FOR US AND POTENTIAL FOR BLIZZARD CONDITIONS
IN NE NJ. OUR FORECAST AMOUNTS ARE PROBABLY CONSERVATIVE.

BANDING IN THE COMMA HEAD WITH A BENT BACK FRONT ALOFT LOOKS TO BE
A MAJOR PLAYER...GENERATING SNOWFALL RATES MONDAY NIGHT POSSIBLY
IN EXCESS OF AN INCH AN HOUR ACROSS NJ AND PORTIONS OF E PA. IF
THE 00Z/06Z NAM MASS FIELDS ALOFT ARE CORRECT THEN ALL THIS HEAVY SNOW
WOULD MISS TO THE EAST.

THOSE WITH TRAVEL PLANS IN E PA AND NJ ESPECIALLY FOR MONDAY NIGHT
AND TUESDAY SHOULD BE AWARE THAT THOSE PLANS MAY NEED MAJOR
ALTERATION/CANCELLATION. BE PREPARED WITH ALTERNATE PLANS. "IF"
CONFIDENCE IS VERY HIGH, WE MAY CONVERT TO WARNINGS LATE TODAY.

WATCHES DO NOT MEAN A DONE DEAL BUT DO PAY ATTENTION. A DRIER
MORE POWDERY SNOW WILL BE EASIER TO ACCUMULATE IN THE COLDER
AIRMASS THAN JUST WHAT OCCURRED EARLY SATURDAY. WIND WILL BECOME A
FACTOR IN BLOWING/DRIFTING, MAINLY IN NJ/DEL.


TUE NIGHT THRU WED NIGHT... HIGH PRESSURE WILL DOMINATE DURING THIS
PERIOD WITH FAIR BUT COLD WEATHER EXPECTED.

THU INTO FRI...THIS FORECAST WAS NOT UPDATED ON THIS MID SHIFT.
MODELS ARE SHOWING ANOTHER CLIPPER TYPE SYSTEM APPROACHING FROM
THE WEST AFTER THE MID WEEK PERIOD. TEMPERATURES WILL HAVE BEGUN
TO MODERATE BY THE TIME THE PRECIP ARRIVES...SO SOME RAIN/SNOW
LINE ISSUES WILL OCCUR. MOSTLY USED CHC POPS FOR NOW. TEMPS WILL
STILL BE BELOW NORMAL...BUT NOT AS COLD AS WED.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

TODAY...VFR CIGS AOA 4000 FT. STRATOCU DECK WILL REMAIN IN PLACE
MOST OF THE DAY UNDER WESTERLY WINDS WITH SOME GUSTS EXPECTED TO
NEAR 20 KT WITH THE CFP LATER THIS MORNING.

TONIGHT...MVFR/IFR IN AREAS OF SNOW. TIMING IS STILL A BIT SUSPECT
BUT LIGHT SNOW SHOULD OVERSPREAD FROM THE WEST-EAST BY LATE TONIGHT.
MINIMAL RAIN/SNOW MIXING EXPECTED VCNTY KMIV TOWARD 12Z MONDAY.
EXPECT SOME LIGHT ACCUMULATIONS THROUGH EARLY MONDAY MORNING...AROUND
1-2 INCHES PHL/ILG/TTN/PNE, MAYBE 2-3 INCHES RDG/ABE.

OUTLOOK...
MON AND MON NIGHT...IFR/LIFR SOUTH AND MVFR OR INTERMITTENT IFR
NORTH IN SNOW OR PERIODS OF SNOW. N-NE WINDS GUSTING 20-30 KT AT
TIMES WITH 35 KT GUSTS POSSIBLE VCNTY KACY. VERY HIGH CONFIDENCE.
PLOWABLE AMOUNTS AND POTENTIAL FOR AIRPORT CLOSURES AT NIGHT INTO
EARLY TUESDAY DEPENDENT ON SNOW AMOUNTS AND RATE OF FALL AS WELL
AS DRIFTING.

TUE...IFR PROBABLE EARLY IN COMMA HEAD BENT BACK BANDING OF THE BIG
NOREASTER THEN PROBABLY BECOMING VFR BY LATE IN THE DAY. NORTHWEST
WINDS GUSTING 20-30KT, EXCEPT POSSIBLY STRONGER VCNTY KACY.
AVERAGE CONFIDENCE.

TUESDAY NIGHT-WED: MOSTLY VFR. N-NW WINDS. HIGH CONFIDENCE:

THURSDAY: CONDITIONS MAY DEGRADE IN A PERIOD OF PCPN DURING THE
AFTERNOON OR NIGHT.

&&

.MARINE...
TODAY...WE REMOVED THE SCA ON THE BAY AS WINDS AND SEAS ARE BELOW
THRESHOLDS. THE OCEAN FRONT CONTINUES TO GO THROUGH 18Z TODAY THOUGH
IT IS POSSIBLE THAT OUR SOUTHERN WATERS MAY BE PULLED SOONER AS SEAS
CONTINUE TO SUBSIDE THROUGHOUT THE MORNING.

TONIGHT...SUB-SCA EXPECTED. LOW PRESSURE WILL MOVE BY TO OUR SOUTH
LATE AS WINDS VEER TOWARDS THE NORTH-NORTHEAST. SEAS BEGIN TO BUILD
ACROSS THE SOUTHERN WATERS LATE AS DO THE WINDS. GALE WARNINGS/STORM
WATCHES IN PLACE STARTING MONDAY AFTERNOON.


OUTLOOK...
MONDAY INTO TUESDAY...MOSTLY GALE CONDITIONS ON THE WATERS BUT POCKETS
OF STORM FORCE GUSTS. HAVE FORECAST WHERE THE STORM FORCE 50 KT GUSTS
OVER THE NJ WATER WHERE THEY ARE MOST LIKELY TO OCCUR, BUT WITH THE
UNDERSTANDING THAT ISOLATED STORM FORCE GUSTS MAY OCCUR IN THE
DELAWARE WATERS AS WELL. THE HEADLINES ARE THE MOST LIKELY WORST
CASE SCENARIO.

TUESDAY AFTERNOON THROUGH THURSDAY...MAINLY SCA CONDITIONS WITH
AREAS OF FREEZING SPRAY EXPECTED.

&&

.TIDES/COASTAL FLOODING...
ANOTHER NORTHEASTER IS EXPECTED TO AFFECT THE COASTAL WATERS OF
DELAWARE AND NEW JERSEY FROM MONDAY NIGHT INTO TUESDAY. MINOR TO
POSSIBLY MODERATE TIDAL FLOODING SHOULD OCCUR AROUND THE TIMES OF
HIGH TIDE, MAINLY THE MIDNIGHT TUESDAY MORNING HIGH TIDE CYCLE.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY
     MORNING FOR PAZ054-055-060>062-070-071-101>106.
NJ...WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY
     MORNING FOR NJZ001-007>010-012>020-026-027.
     WINTER STORM WATCH FROM MONDAY EVENING THROUGH TUESDAY MORNING
     FOR NJZ021>025.
DE...WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY
     MORNING FOR DEZ001.
     WINTER STORM WATCH FROM MONDAY EVENING THROUGH TUESDAY MORNING
     FOR DEZ002>004.
MD...WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY
     MORNING FOR MDZ008.
     WINTER STORM WATCH FROM MONDAY EVENING THROUGH TUESDAY MORNING
     FOR MDZ012-015-019-020.
MARINE...STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY MORNING FOR
     ANZ450>453.
     SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
     ANZ450>455.
     GALE WARNING FROM 11 AM MONDAY TO 11 AM EST TUESDAY FOR ANZ431-
     454-455.
     GALE WARNING FROM 5 PM MONDAY TO 11 AM EST TUESDAY FOR ANZ430.

&&

$$
SYNOPSIS...DRAG
NEAR TERM...HEAVENER
SHORT TERM...HEAVENER
LONG TERM...DRAG 654
AVIATION...DRAG/HEAVENER 654
MARINE...DRAG/HEAVENER 654
TIDES/COASTAL FLOODING...






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