-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KPHI 240928
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
428 AM EST SAT JAN 24 2015

.SYNOPSIS...
RAPIDLY INTENSIFYING LOW PRESSURE CROSSING EASTERN NORTH CAROLINA
EARLY TODAY WILL RACE PAST CAPE COD BY THIS EVENING. A WEAK RIDGE
OF HIGH PRESSURE BRIEFLY FOLLOWS SUNDAY. ATTENTION THEN TURNS TO LOW
PRESSURE IN KENTUCKY SUNDAY EVENING. IT MOVES TO THE NORTH CAROLINA
COAST MONDAY THEN INTENSIFIES ALONG ITS TRACK EAST OF NEW ENGLAND
ON TUESDAY. IN ITS WAKE...COLDER AIR FOR SEVERAL DAYS AS HIGH PRESSURE
HEADS FOR THE EAST COAST THURSDAY. A REINFORCING SURGE OF COLD AIR
ARRIVES AFTER A COLD FRONTAL PASSAGE FRIDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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WE HAVE UPGRADED OUR ADVISORIES NORTH AND WEST OF PHILLY TO WINTER
STORM WARNINGS...THEY GO THROUGH THIS MORNING.

THE WARM/ISENTROPIC LIFT FRONT END THUMP THIS MORNING WAS HANDLED
PRETTY WELL BY ALL THE GUIDANCE THE PAST COUPLE OF RUNS. THERMALLY
THE NAM SEEMED TO HAVE THE BETTER HANDLE ON THE MELTING LAYER
MOVEMENT, OR LACK THEREOF THIS MORNING. AS OF THIS WRITING IT SEEMS
THAT THE MELTING LAYER IS SITTING JUST TO THE SOUTH OF A LINE FROM
TTN WESTWARD TO PTW. DECENT SNOWRATES ARE STILL OCCURRING NORTH OF
THIS LINE AS A BIT MORE QPF WORKED ITS WAY INTO THE REGION LATE LAST
NIGHT. THE OMEGA RATES WITHIN THE DGZ WERE VERY IMPRESSIVE FOR
SEVERAL HOURS THIS MORNING ACROSS THE LEHIGH VALLEY AND NORTHWARD.
SEVERAL REPORTS OF CLOSE TO 5 INCHES WERE REPORTED DURING THE PEAK
INTENSITY OF THE MESO BANDS THAT SETUP IN SEPA AND NNJ. WE ALREADY
HAD A 4-6" SWATH RUNNING THROUGH THESE AREAS BUT FELT THAT AN
ADDITIONAL INCH OR TWO WOULD BE VERY POSSIBLE AND THEREFORE WE WENT
TO WARNINGS. WITH THE HEAVY WET SNOW, SCATTERED POWER OUTAGES ACROSS
THE WARNED AREA ARE QUITE POSSIBLE.

WE SHOULD BEGIN TO DRY FROM WEST TO EAST AS THE SURFACE LOW PRESSURE
TO OUR SOUTHEAST RAPIDLY MOVES NORTHEASTWARD AND CONTINUES TO
DEEPEN. THE COLUMN ALOFT DRIES OUT/WARMS UP TO THE POINT WE LOSE OUR
ICE CRYSTALS. MARGINAL SURFACE TEMPERATURES MAY MAKE FOR SOME
FREEZING DRIZZLE THOUGH IT SHOULD BE VERY ISOLATED. COLD AIR WILL
FILTER IN BEHIND THE DEPARTING LOW PRESSURE ALLOWING FOR ANY
REMAINING MOISTURE TO TURN BACK OVER TO SNOW. A FEW SNOW SHOWERS ARE
POSSIBLE THIS AFTERNOON/EVENING WITH MINIMAL ACCUMULATIONS AS
BOUNDARY LAYER TEMPERATURES WILL BE ABOVE FREEZING, MID-30S ACROSS
OUR EASTERN ZONES.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
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SNOW SHOWERS SHOULD COME TO AN END AS HIGH PRESSURE PRESSES IN FROM
THE WEST, ALBEIT BRIEFLY. SKIES WILL CLEAR WITH BRISK WESTERLY
WINDS. TEMPERATURES ARE EXPECTED TO DIP INTO THE MID TO
UPPER-20S...SLIGHTLY COLDER IN FRESH PACK AREAS.
-- End Changed Discussion --

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
500MB: A PAIR OF SHORT WAVES HEADING SOUTHEAST FROM CENTRAL NORTH
AMERICA SUNDAY WILL PROBABLY EVOLVE INTO A STRONG LONG WAVE TROUGH
OVER THE EASTERN SEABOARD STATES ON TUESDAY BEFORE RIDGING FOLLOWS
THURSDAY. A SHORT WAVE PASSAGE THROUGH SOUTHEAST CANADA FRIDAY SEEMS
TO WANT TO YANK THE POLAR VORTEX SOUTHWARD TO NEAR JAMES BAY BY THE
START OF NEXT WEEKEND.

TEMPERATURES: NEAR NORMAL SUNDAY THEN BELOW NORMAL MONDAY THROUGH
THURSDAY WITH POTENTIALLY WELL BELOW NORMAL TEMPS TUESDAY AND
WEDNESDAY.  A BRIEF RETURN TO NEAR NORMAL TEMPS EXPECTED FRIDAY.

FORECAST BASIS: UNLESS OTHERWISE NOTED WITHIN THE DAILIES. THIS
FORECAST IS A 50 50 BLEND OF THE 00Z/24 MAV/MET FOR SUNDAY-MONDAY.
THE 00Z/24 MEX MOS WAS APPLIED MONDAY NIGHT AND TUESDAY.NO CHANGES
WERE MADE TO THE FORECAST BEYOND TUESDAY.

THE DAILIES...

SUNDAY...A QUIET DAY WITH WEAK COLD AIR ADVECTION. INCREASING CLOUDS
AHEAD OF THE CLIPPER HEADING ESE FROM THE LOWER OHIO VALLEY.

SUNDAY NIGHT-MONDAY NIGHT...SNOW OVERSPREADS THE AREA SUNDAY EVENING.
PRECIP COULD BEGIN OVER NRN DELMARVA AS A MIX OF RAIN AND SNOW BUT
SHOULD CHANGE TO ALL SNOW OVERNIGHT AS THE PRECIP RATE INCREASES AND
SOME NOCTURNAL COOLING TAKES PLACE. PERIODS OF SNOW SHOULD CONTINUE
INTO MONDAY AS LOW PRESSURE MOVES BY TO OUR SOUTH AND THEN BEGINS TO
DEEPEN OFF THE MID-ATLANTIC COAST. THE MOST SIGNIFICANT SNOW COULD
OCCUR MONDAY MORNING...ALTO OVERALL AMOUNTS SHOULD BE LIGHT THOUGH
THERE IS OPPORTUNITY FOR THIS STORM TO DEEPEN CLOSER TO THE COAST
ON MONDAY. THIS CERTAINLY PORTENDS TO BECOME AT LEAST AN ADVISORY
SITUATION FOR THE DELMARVA AND COASTAL NEW JERSEY AND NEEDS TO BE
MONITORED FOR MORE SIGNIFICANT POWDERY AMOUNTS OF SNOW. SNOW WATER
RATIOS SHOULD BE MUCH DRIER THAN WHAT OCCURRED LAST NIGHT....IN
OTHER WORDS FLUFFIER.

A POTENTIAL HAZARDOUS MONDAY MORNING COMMUTE IS IN THE OFFING FOR
A PORTION OF OUR FORECAST AREA. GUSTY NORTHERLY WINDS TO 20 TO 25
MPH MAY CAUSE SOME DRIFTING OF THE SNOW ON THE DELMARVA...ESPECIALLY
THE DELAWARE COAST.

WIND CHILLS WILL BE NOTICED!

TIDAL SURGE: FAIRLY LARGE ON MONDAY AND TUESDAY DUE TO NORTHERLY
FLOW WITH SMALL POTENTIAL FOR MINOR COASTAL FLOODING ALONG THE
ATLANTIC SHORES.

TUESDAY-WEDNESDAY...HIGH PRES AND DRIER AIR WILL GRADUALLY MOVE IN
FOR MID WEEK ON CONTINUED NORTHERLY FLOW WITH GUSTS TO 20 MPH
DURING THE DAYLIGHT HOURS.  .

THURSDAY...WAA CLOUDS AND POSSIBLE SNOW SHOWERS LATE THURSDAY AHEAD
OF THE NEXT SHORT WAVE...THIS ONE IN CANADA WITH A STRONG COLD FRONT
TO FOLLOW FRIDAY.

FRIDAY...CAA DEVELOPS BEHIND THE CFP.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

TODAY...IFR/LIFR, POSSIBLE VLIFR, IN AREAS OF MODERATE TO
HEAVY WET SNOW. TTN-ABE-RDG SHOULD REMAIN MOSTLY SNOW THROUGH THE
MORNING BEFORE POSSIBLY DRYING OUT SOME AS WE NEAR MID-DAY.
ELSEWHERE MOSTLY RAIN IS EXPECTED TO CONTINUE THROUGH THE DAY WITH
SOME DRYING TOWARDS THE AFTERNOON HOURS.

TONIGHT...VFR. BRISK WNW WINDS.

OUTLOOK...
SUN...VFR. ABOVE AVERAGE CONFIDENCE.

SUN NIGHT...CONDITIONS DIMINISHING WITH IFR POSSIBLE AND SNOW BY
EARLY MONDAY MORNING....ESPECIALLY KTTN SOUTHWARD.  CONFIDENCE:
ABOVE AVERAGE

MON...MVFR/IFR WITH LOWER CIGS/VSBYS IN SNOW...ESPECIALLY KILG AND
KMIV.  CONFIDENCE: ABOVE AVERAGE.

MON NIGHT - CONDITIONS SLOWLY IMPROVING TO MVFR...POSSIBLY VFR LATE.
CONFIDENCE: AVERAGE SINCE THE DEVELOPING STORM MAY FORCE SNOW TO
LINGER ALONG THE COAST.

TUE - WED...MOSTLY VFR.  CONFIDENCE: ABOVE AVERAGE.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
TODAY - TONIGHT...CONTINUED SCA CONDITIONS EVERYWHERE AS COASTAL
LOW PRESSURE RAPIDLY DEEPENS TODAY AND RACES OFF TOWARDS THE
NORTHEAST. NORTHEAST WINDS SHIFT TOWARDS THE WEST-NORTHWEST LATER
TODAY BEHIND THE DEPARTING LOW PRESSURE.

OUTLOOK...
STRONG SMALL CRAFT ADVISORY CONDS ARE EXPECTED TO DEVELOP EARLY
MONDAY MORNING AND MAY CONTINUE THROUGH WEDNESDAY. POTENTIAL GALES
MONDAY AND MONDAY NIGHT DELAWARE COAST. SEAS COULD EASILY BUILD TO
12 FEET EAST OF CAPE MAY TO EAST OF DELAWARE IN PERSISTENT NNE FLOW.
LIGHT TO POSSIBLY MODERATE FREEZING SPRAY POTENTIAL MONDAY NIGHT AND
WEDNESDAY NIGHT.
-- End Changed Discussion --

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING UNTIL 11 AM EST THIS MORNING FOR PAZ054-
     055-060>062-103-105.
     WINTER WEATHER ADVISORY UNTIL 8 AM EST THIS MORNING FOR PAZ070-
     071-101-102-104-106.
NJ...WINTER STORM WARNING UNTIL 11 AM EST THIS MORNING FOR NJZ001-
     007>010.
     WINTER WEATHER ADVISORY UNTIL 8 AM EST THIS MORNING FOR NJZ012-
     013-015.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST SUNDAY FOR ANZ450>455.
     SMALL CRAFT ADVISORY UNTIL 6 AM EST SUNDAY FOR ANZ430-431.

&&

$$
SYNOPSIS...DRAG
NEAR TERM...HEAVENER
SHORT TERM...HEAVENER
LONG TERM...DRAG/HEAVENER
AVIATION...DRAG/HEAVENER
MARINE...DRAG/HEAVENER