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000
FXUS61 KPHI 260248
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
948 PM EST SUN JAN 25 2015

.SYNOPSIS...
LOW PRESSURE IN THE OHIO VALLEY WILL TRACK EASTWARD AND MOVE OFF
THE MID ATLANTIC COAST ON MONDAY. THE LOW WILL THEN RAPIDLY
INTENSIFY IS IT MOVES NORTHEASTWARD, PASSING NEAR CAPE COD LATE ON
TUESDAY BEFORE REACHING NOVA SCOTIA ON WEDNESDAY. HIGH PRESSURE
FROM THE WEST IS FORECAST FOR WEDNESDAY. A WEAK LOW IS EXPECTED TO
FOLLOW AND PASS OVER OUR REGION ON EITHER THURSDAY NIGHT OR
FRIDAY. ANOTHER AREA OF HIGH PRESSURE IS THEN ANTICIPATED FOR NEXT
WEEKEND.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
AN ARCTIC FRONT CONTINUES TO OOZE ITS WAY SOUTHWARD ACROSS OUR AREA
AND IS ACROSS THE DELMARVA AT 02Z. THE COLDER AIR AND MORE NOTABLY
MUCH DRIER AIR IS EASING SOUTHWARD THIS EVENING. THIS BOUNDARY
CONNECTS INTO LOW PRESSURE OVER THE OHIO VALLEY, AND THIS WILL TRACK
OVER THE APPALACHIANS.

THE INCREASING LARGE SCALE LIFT AND ESPECIALLY ISENTROPIC LIFT UP
AND OVER THE COOLING LOW-LEVEL AIRMASS SOUTHWARD IS RESULTING IN
LIGHT RAIN/SNOW FROM ABOUT THE PHILADELPHIA METRO ON WESTWARD. THE
BULK OF THE LIFT FOR MUCH OF THE NIGHT APPEARS TO BE NEAR AND NORTH
OF THE MASON-DIXON LINE, AND THEREFORE THE POPS WERE LOWERED FOR
AWHILE ACROSS THE SOUTHERN AREAS. IT WILL BE A RACE BETWEEN THE
INCOMING PRECIPITATION SHIELD AND THE RATHER DRY LOW-LEVEL AIR
SEEPING SOUTHWARD. THE BOUNDARY LAYER ESPECIALLY IN THIS CORRIDOR
IS STILL JUST MILD ENOUGH EARLY ON THAT SOME LIGHT RAIN IS
OCCURRING, HOWEVER THIS SHOULD TRANSITION OVER TO A RAIN/SNOW MIX
THEN SNOW AS COOLING CONTINUES. AS OF NOW, SOME FREEZING RAIN IS NOT
ANTICIPATED TO BE A CONCERN.

IT APPEARS THAT UP TO 2 INCHES OF SNOW OVERALL OCCURS WITH THIS
MAINLY OVER THE WESTERN ZONES WHERE BETTER LIFT AND MOISTURE
DEVELOPS AND IS MAINTAINED. THEREFORE THE QPF AND SNOW AMOUNTS WERE
TWEAKED SOME. IT DOES APPEAR THAT SOME LOCALIZED HIGHER AMOUNTS ARE
POSSIBLE MAINLY TOWARD THE LOWER SUSQUEHANNA VALLEY, DUE TO
BETTER/LONGER LIFT AND MOISTURE.

THE HOURLY GRIDS WERE ADJUSTED TO SHOW INITIAL WARMER TEMPERATURES
AND HIGHER DEW POINTS ACROSS THE SOUTHERN HALF OF THE CWA, AND LOWER
DEW POINTS ACROSS THE NORTH. THE LAMP/LAV GUIDANCE WAS USED TO HELP
ASSIST WITH TRENDS. SOME TWEAKS WERE MADE TO THE LOW TEMPERATURES.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/...
THROUGH THE DAYTIME MONDAY, THE PREVIOUSLY MENTIONED LOW PRESSURE
WILL TRACK FROM AROUND THE CENTRAL APPALACHIANS EARLY MONDAY
MORNING TO OFF THE NORTH CAROLINA COAST. MEANWHILE, THE PREVIOUSLY
MENTIONED UPPER SHORTWAVE WILL DEEPEN AND BECOME A CLOSED UPPER
LOW. THESE FEATURES WILL THEN ULTIMATELY ALLOW FOR QUICK
INTENSIFICATION OF THIS SYSTEM AS IT TRACKS NORTHEAST FROM LATE-
DAY MONDAY THROUGH MONDAY NIGHT.

A GENERALLY LIGHT SNOW WILL BE ONGOING THROUGH MONDAY MORNING AS
THE INITIAL CLIPPER LOW IS PASSING BY TO OUR SOUTH ON ITS WAY TO
THE COAST, AND AS PREVIOUSLY MENTIONED ABOVE, A GENERAL ONE TO
THREE OR FOUR INCH SNOW ACCUMULATION CAN BE ANTICIPATED THROUGH
THE MIDDLE OF THE DAY MONDAY, WITH THE HIGHER AMOUNTS EXPECTED TO
EXTEND FROM PORTIONS OF EASTERN PENNSYLVANIA INTO CENTRAL AND
NORTHERN NEW JERSEY. MEANWHILE, AS TEMPERATURES BEGIN TO WARM
THROUGH THE DAYTIME MONDAY, SOME MIXING OR CHANGE-OVER TO RAIN IN
EXPECTED FOR SOUTHEASTERN PORTIONS OF NEW JERSEY AND DOWN INTO THE
DELMARVA, GENERALLY LIMITING ANY SUNDAY NIGHT TO MONDAY DAYTIME
ACCUMULATIONS TO AROUND AN INCH OR LESS.

NORTHEAST WINDS THROUGH THE DAYTIME MONDAY WILL BE INCREASING,
WITH GUSTS INTO THE 25 TO 30 MPH RANGE, ESPECIALLY BY THE END OF
THE DAY. MAXIMUM TEMPERATURES INCORPORATED SOME MET AND MAV
GUIDANCE WITH CONTINUITY, AND WE ANTICIPATE HIGHS TO RANGE FROM
THE LOWER AND MIDDLE 20S NORTH TO THE UPPER 30S AND PERHAPS SOME
40S INTO THE FAR SOUTHERN DELMARVA.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
***A MAJOR SNOWSTORM WILL AFFECT OUR REGION FOR MONDAY NIGHT INTO
TUESDAY***

930 PM UPDATE...WE ARE MAKING NO CHANGES TO THE WINTER WEATHER
HEADLINES ATTM. THE WATCH REMAINS ACROSS THE WESTERN/SOUTHWESTERN
ZONES AS UNCERTAINTY STILL EXISTS HERE ON HOW FAR WEST THE HEAVY
SNOW GETS. THERE LOOKS TO BE A SHARP CUTOFF WITH A WESTERN EXTENT,
AND THE OVERNIGHT SHIFT WILL EXAMINE ALL OF THE NEW GUIDANCE AND
THEN MAKE A DECISION EARLY MONDAY MORNING.

OTHERWISE, THE STORM FOR MONDAY NIGHT AND TUESDAY CONTINUES TO
COME TOGETHER. THE SURFACE LOW WILL INTENSIFY RAPIDLY OFF THE
MIDDLE ATLANTIC COAST ON MONDAY NIGHT BEFORE MOVING UP TOWARD THE
WATERS OFF EASTERN LONG ISLAND AND SOUTHEASTERN NEW ENGLAND FOR
TUESDAY. THE SYSTEM SHOULD THEN CONTINUE NORTHEASTWARD REACHING
NOVA SCOTIA ON WEDNESDAY.

ABUNDANT ATLANTIC MOISTURE WILL WRAP INTO THE STORM AND WE ARE
ANTICIPATING SIGNIFICANT SNOWFALL TOTALS. FROM NEW JERSEY
NORTHEASTWARD ONE TO TWO FOOT TOTALS ARE FORECAST TO BE COMMON.
AMOUNTS IN EXCESS OF TWO FEET ARE POSSIBLE IN OUR FORECAST ARE
TOWARD NORTHEASTERN NEW JERSEY AND THE NORTHERN PART OF THE NEW
JERSEY COAST, INCLUDING MONMOUTH COUNTY AND OCEAN COUNTY.

THE EASTERN EDGE OF PENNSYLVANIA MAY SEE AMOUNTS AROUND A FOOT.
AS ONE WORKS WESTWARD TOWARD THE SUSQUEHANNA RIVER VALLEY, AMOUNTS
MAY BEGIN TO LESSEN TOWARD THE 4 TO 6 INCH RANGE. THE SAME IS TRUE
FOR THE UPPER DELMARVA.

BASED ON HIGH CONFIDENCE, WE HAVE UPGRADED MOST OF OUR NEW JERSEY
COUNTIES, AS WELL AS MUCH OF SOUTHEASTERN PENNSYLVANIA TO A WINTER
STORM WARNING FOR MONDAY NIGHT AND TUESDAY. WE HAVE UPGRADED THE
BLIZZARD WATCH TO A BLIZZARD WARNING FOR THE COUNTIES OF
MIDDLESEX, MONMOUTH AND OCEAN.

FOR THE WESTERN AND SOUTHWESTERN PARTS OF OUR FORECAST AREA, WE
HAVE LEFT THE WINTER STORM WATCH IN PLACE UNTIL WE CAN GET A
BETTER HANDLE ON THE EXPECTED IMPACTS ON THE EDGE OF THE
PRECIPITATION SHIELD. THERE MAY VERY WELL BE A SHARP CUT OFF IN
SNOWFALL AMOUNTS AS ONE APPROACHES THE SUSQUEHANNA RIVER VALLEY
AND THE CHESAPEAKE BAY REGION.

TEMPERATURES WILL BE MOSTLY IN THE 20 TO 30 DEGREE RANGE DURING
THE SNOW EVENT WITH THE BRISK NORTHEAST WIND BACKING TOWARD THE
NORTHWEST. FREQUENT GUSTS IN EXCESS OF 35 MPH ARE ANTICIPATED IN
OUR NORTHERN COASTAL COUNTIES AND THAT IS THE REASON FOR THE THREE
COUNTIES BEING INCLUDED IN THE BLIZZARD WARNING.

THE SNOW SHOULD END GRADUALLY FROM SOUTHWEST TO NORTHEAST IN OUR
FORECAST AREA FROM TUESDAY AFTERNOON THROUGH EARLY TUESDAY NIGHT.

IT SHOULD BE DRY AND COLD FOR WEDNESDAY AND WEDNESDAY NIGHT.

A CLIPPER SYSTEM FROM THE NORTHWEST AND WEST MAY BRING A SHOT OF
LIGHT SNOW FROM LATE THURSDAY INTO FRIDAY.

ANOTHER SHOT OF COLD DRY AIR IS ANTICIPATED FOR NEXT WEEKEND.

&&

.AVIATION /03Z MONDAY THROUGH FRIDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

**HIGH IMPACT EVENT EXPECTED MONDAY AND TUESDAY**

REST OF TONIGHT...VFR CEILINGS LOWERING TO MVFR TOWARD MIDNIGHT THEN
TO IFR BY DAYBREAK. SOME RAIN/SNOW THEN SNOW IS ANTICIPATED TO
OVERSPREAD MOST OF THE AREA FROM THE WEST TO EAST THROUGH 06Z, WITH
MOST OF THIS FROM THE KPHL METRO AREA ON NORTH AND WEST. SNOW
ACCUMULATIONS ARE ANTICIPATED TO BE UP TO 2 INCHES MAINLY WEST OF
KPHL. NORTHEASTERLY WINDS INCREASING TO 10 TO 15 KNOTS. SOME
GUSTINESS SHOULD DEVELOP LATE ESPECIALLY CLOSER TO THE COAST.

MONDAY...GENERALLY IFR TO POSSIBLE LOW-END MVFR CONDITIONS ARE
ANTICIPATED TO CONTINUE WITH LIGHT SNOW. SOME RAIN/SNOW MIX IS
EXPECTED BY LATE MORNING THROUGH THE AFTERNOON FOR KMIV/KACY.
GUSTY NORTHEAST WINDS ARE ANTICIPATED, WITH GUSTS REACHING BETWEEN
25 TO 30 KNOTS. ADDITIONAL DAYTIME ACCUMULATIONS TO AROUND AN
INCH, WITH HEAVIER SNOW DEVELOPING THEN INTO MONDAY NIGHT.

OUTLOOK...
MONDAY NIGHT AND TUESDAY...SIGNIFICANT SNOWFALL WILL LIKELY BRING
AIR TRAFFIC TO A STANDSTILL ON MONDAY NIGHT AND TUESDAY.
CONDITIONS ARE FORECAST TO BE LIFR AND SNOW ACCUMULATIONS IN
EXCESS OF ONE FOOT ARE ANTICIPATED AT KPHL WITH GREATER AMOUNTS TO
THE NORTHEAST AND SLIGHTLY LOWER AMOUNTS TO THE SOUTHWEST.

TUESDAY NIGHT...CLEARING IS ANTICIPATED WITH A GUSTY NORTHWEST
WIND.

WEDNESDAY THROUGH THURSDAY MORNING...MAINLY VFR.

THURSDAY AFTERNOON THROUGH FRIDAY...A CHANCE OF SNOW. CONDITIONS
MAY LOWER INTO THE MVFR OR IFR RANGE FOR A TIME.

&&

.MARINE...
SUB-ADVISORY CONDITIONS ARE EXPECTED FOR THE COASTAL WATERS AND
DELAWARE BAY FOR MOST OF TONIGHT. TOWARD THE EARLY MORNING OF
MONDAY, CONDITIONS WILL BE RAMPING UP TO SCA LEVELS AS NORTHEAST
WINDS WILL BE GUSTING UP TO AROUND 30 KNOTS BY THE 12Z TO 15Z
MONDAY TIMEFRAME. FOR THE REST OF MONDAY THEN, CONTINUED
DETERIORATING CONDITIONS ARE EXPECTED THROUGH MONDAY AFTERNOON,
WITH GALE FORCE WIND GUSTS EXPECTED FOR DELAWARE BAY AND THE
COASTAL WATERS. BY MONDAY NIGHT, STORM FORCE GUSTS ARE ANTICIPATED
FOR THE COASTAL WATERS. SEAS WILL BE BUILDING TO BETWEEN 3 AND 6
FEET FOR DELAWARE BAY DURING MONDAY AND INTO MONDAY NIGHT, WITH
SEAS EVENTUALLY BUILDING TO BETWEEN 10 AND 16 FEET FOR THE COASTAL
WATERS LATER MONDAY NIGHT. MARINE HEADLINES INCLUDE A GALE WARNING
FOR DELAWARE BAY AND FOR THE COASTAL WATERS FROM CAPE MAY TO
FENWICK ISLAND, FROM MONDAY AFTERNOON THROUGH THE DAYTIME TUESDAY,
WITH STORM WARNINGS ISSUED FOR THE COASTAL WATERS FROM SANDY HOOK
TO CAPE MAY, NJ THROUGH THE DAYTIME TUESDAY.

OUTLOOK...
MONDAY NIGHT AND TUESDAY...A MARINE STORM WARNING IS IN EFFECT
FOR OUR OCEAN WATERS OFF NEW JERSEY. A GALE WARNING IS IN EFFECT
FOR THE WATERS OFF DELAWARE AND FOR DELAWARE BAY.

TUESDAY NIGHT...GALE FORCE WIND GUSTS ARE LIKELY. FREEZING SPRAY
WILL BE AN ISSUE, AS WELL.

WEDNESDAY...SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED WITH
ADDITIONAL FREEZING SPRAY ISSUES.

WEDNESDAY NIGHT THROUGH FRIDAY...NO MARINE HEADLINES ARE
ANTICIPATED.

&&

.TIDES/COASTAL FLOODING...
WE HAVE ISSUED A COASTAL FLOOD WATCH FOR MONDAY NIGHT`S HIGH TIDE
ALONG THE COASTS OF NEW JERSEY AND DELAWARE AND ON DELAWARE BAY.
WITH THE STRENGTHENING STORM OFF THE MIDDLE ATLANTIC COAST AND THE
STRONG NORTHEAST TO NORTH WIND, MODERATE TIDAL FLOODING APPEARS
LIKELY.

WE ARE THINKING THAT THERE COULD BE SOME MINOR TIDAL FLOODING ON
THE TIDAL DELAWARE RIVER AND PERHAPS ON THE UPPER EASTERN SHORE OF
CHESAPEAKE BAY. HOWEVER, WE HAVE TIME TO ADDRESS THAT WITH AN
ADVISORY, IF NECESSARY.

ALSO, WE WILL KEEP AN EYE ON THE DAYTIME HIGH TIDE ON TUESDAY. IF
THE WIND IS SLOW TO BACK TO THE NORTHWEST, WE MAY EXPERIENCE
ANOTHER CYCLE WITH MINOR TO MODERATE TIDAL FLOODING.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING FROM NOON MONDAY TO 6 PM EST TUESDAY FOR
     PAZ070-071-103>106.
     WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY
     MORNING FOR PAZ054-055-060>062-101-102.
NJ...WINTER STORM WARNING FROM NOON MONDAY TO 6 PM EST TUESDAY FOR
     NJZ001-007>010-015>019-021>025-027.
     COASTAL FLOOD WATCH FROM MONDAY EVENING THROUGH LATE MONDAY
     NIGHT FOR NJZ012>014-016-020>027.
     BLIZZARD WARNING FROM NOON MONDAY TO 6 PM EST TUESDAY FOR
     NJZ012>014-020-026.
DE...COASTAL FLOOD WATCH FROM MONDAY EVENING THROUGH LATE MONDAY
     NIGHT FOR DEZ001>004.
     WINTER STORM WATCH FROM MONDAY EVENING THROUGH TUESDAY MORNING
     FOR DEZ002>004.
     WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY
     MORNING FOR DEZ001.
MD...WINTER STORM WATCH FROM MONDAY EVENING THROUGH TUESDAY MORNING
     FOR MDZ012-015-019-020.
     WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY
     MORNING FOR MDZ008.
MARINE...STORM WARNING FROM NOON MONDAY TO 6 PM EST TUESDAY FOR
     ANZ450>453.
     GALE WARNING FROM NOON MONDAY TO 6 PM EST TUESDAY FOR ANZ430-
     431-454-455.

&&

$$
SYNOPSIS...GORSE/IOVINO
NEAR TERM...GORSE
SHORT TERM...KLINE
LONG TERM...GORSE/IOVINO
AVIATION...GORSE/IOVINO/KLINE
MARINE...IOVINO/HEAVENER/KLINE
TIDES/COASTAL FLOODING...IOVINO