Area Forecast Discussion
Issued by NWS Mt. Holly, NJ

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000
FXUS61 KPHI 221750
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1250 PM EST THU JAN 22 2015

.SYNOPSIS...
WEAK LOW PRESSURE IN NORTHEASTERN PENNSYLVANIA WILL MERGE WITH A
SEAWARD DEVELOPING LOW PRESSURE OFF THE MID ATLANTIC COAST. HIGH
PRESSURE IN THE CENTRAL PLAINS WILL SLIDE INTO OUR REGION THIS
AFTERNOON AND TONIGHT. THIS HIGH PRESSURE WILL MOVE THROUGH ON
FRIDAY BEFORE GIVING WAY TO A LOW PRESSURE SYSTEM TRACKING UP THE
COAST ON SATURDAY. ON SUNDAY A LOW PRESSURE SYSTEM WILL TRACK
ACROSS THE GREAT LAKES AND INTO OUR REGION ON MONDAY. THIS LOW
PRESSURE WILL DEPART THE REGION BY THE MIDDLE OF NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LOW LEVEL MOISTURE REMAINED IN PLACE OVER MUCH OF OUR FORECAST
AREA AT 1230 PM. A WESTERLY SURFACE WIND HAD DEVELOPED AND A SLOW
LIFTING AND BREAKING OF THE LOW CLOUD COVER WILL CONTINUE THROUGH
THE BALANCE OF THE AFTERNOON. BREAKS IN THE CLOUD COVER HAD
ALREADY WORKED THEIR WAY OVER NORTHERN NEW JERSEY AND OVER THE
UPPER DELMARVA.

RADAR CONTINUED TO SHOW SOME SNOW FLURRIES OVER BERKS COUNTY AND
CHESTER COUNTY. AS THE AIR GRADUALLY DRIES, FLURRIES SHOULD
DISSIPATE.

MAXIMUM TEMPERATURES SHOULD BE MAINLY IN THE 30S.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
TSECTIONS AND LAPSE RATES SUGGEST THAT CLEARING WILL BE FAIRLY
QUICK LATE THIS AFTERNOON/EVENING.

SO A MOSTLY CLEAR NIGHT IS EXPECTED. A LIGHT NW WIND.

PATCHY FOG IS NOT IN THE FCST TONIGHT BUT MAYBE IT WILL BE FROSTY
DUE TO STILL SOMEWHAT ELEVATED DEW POINTS.

TEMPS/DEWS/WINDS ARE A 50 50 BLEND OF THE 00Z/22 NAM/GFS MOS
GUIDANCE WITH SOME COOLING OF THOSE BLENDED TEMPS BY 2 DEGREES OR
SO IN THE PINE BARRENS OF SNJ AND ALSO IN THE COOLER RADIATORS OF
BUCKS AND MONTGOMERY COUNTIES IN PA WHERE A LITTLE SNOW
ACCUMULATED. ITS DEBATABLE HOW MUCH OF THAT SNOW WILL REMAIN BY
NIGHTFALL. THESE FORECAST LOWS ARE NEAR NORMAL FOR THE DATE.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
FRIDAY: HIGH PRESSURE WILL BUILD BACK INTO THE REGION RESULTING
IN A MOSTLY SUNNY DAY. DID NOT GO AS WARM AS THE NEW MAV AND MET
RUNS FOR TEMPERATURES BUT THIS COULD BE POSSIBLE GIVEN AMPLE
SUNSHINE.

FRIDAY NIGHT THROUGH SATURDAY NIGHT: LOW PRESSURE WILL TRACK UP
THE EAST COAST. THE SPREAD IN THE OPERATIONAL MODEL RUNS AND THE
VARIOUS ENSEMBLES HAVE DECREASED. THIS INCLUDES SOME OF THE
WESTERN ECMWF ENSEMBLES, THROUGH EXAMINATION OF THE MEAN. THE 18Z
GEFS ALSO APPEAR TO HAVE A TIGHTER SPREAD COMPARED TO PREVIOUS
RUNS. THE NAM AND GFS REMAIN FURTHER OFFSHORE AND LESS DEVELOPED
WITH THE ECMWF TRENDING IN THIS DIRECTION AS WELL. HOWEVER THE CMC
AND UKMET CONTINUE TO BE CLOSER TO THE COAST WITH HIGHER QPF. THE
OVERALL TREND OVERNIGHT WAS TO SHOW A MORE DISORGANIZED LOW
PRESSURE SYSTEM.

IN TERMS OF WEATHER, SNOW OR THE CHANCES FOR MIXED PRECIPITATION
WILL BEGIN TO INCREASE FROM SOUTH TO NORTH FRIDAY NIGHT WITH
OVERRUNNING WAA. MODERATE PRECIPITATION WILL LIKELY OCCUR WITHIN
THIS PRECIPITATION SHIELD WITH THE BULK OF SNOWFALL ACCUMULATIONS.
THERMAL PROFILES SUGGEST THAT THE DELMARVA AND COASTAL NJ WILL
CHANGE TO RAIN BY SATURDAY MORNING, WITH SLEET MIXED AS WELL. THIS
IS DUE TO THE POTENTIAL OF MID-LEVEL WARMING IS GREATER THAN IN
THE AIR TEMPERATURE CLOSER TO THE SURFACE. LIGHTER PRECIPITATION
WILL BE NOTED NW OF PHL FURTHER FROM THE LOW. AFTER THIS PUSH OF
PRECIPITATION A DRY SLOT OR LINGERING LIGHT RAIN OR A RAIN/SNOW
MIX ( NW OF PHL) SHOULD CONTINUE INTO THE AFTERNOON, SURFACE
WARMING IS GREATER THAN MID-LEVEL WARMING AT THIS POINT. A CCB MAY
STILL FORM ON THE BACKEND OF THE LOW PRESSURE SYSTEM WITH A PERIOD
OF SNOW OR RAIN CHANGING TO SNOW. THE MORE DISORGANIZED TRENDS
HAVE DECREASED THE CHANCES OF THIS TO OCCUR. OUR QPF FORECAST TOOK
ELEMENTS OF THE WPC, SREF AND THE ECMWF. ALSO KEEPING IN MIND THE
MORE BULLISH QPF SOLUTIONS OF THE UKMET AND CMC. A ZONE FROM THE
LEHIGH VALLEY TO INTERSTATE 295 HAVE THE HIGHEST CHANCES OF SEEING
SNOW TOTALS FROM 3-4 INCHES, WITH LOWER AMOUNTS SURROUNDING THIS
ZONE. THIS IS DUE TO A QUICK CHANGEOVER SE AND LESS QPF NW. FOR
TEMPERATURES STAYED CLOSER TO THE MODELED TWO METER TEMPERATURES
WHICH RESPECTIVE MODELS HAD PRECIPITATION IN THE FORECAST.

SUNDAY: A TEMPORARY BREAK BETWEEN SYSTEMS WITH A MIX OF CLOUDS
AND SUN. TEMPERATURES COULD BE COOLER THAN ENSEMBLES/MEX GUIDANCE
DUE TO SNOW COVER.

SUNDAY NIGHT THROUGH MONDAY NIGHT: ANOTHER SYSTEM DIVES SOUTHEAST
FROM THE GREAT LAKES REACHING OUR REGION BY MONDAY MORNING. THIS
LOOKS TO BE ANOTHER CLIPPER TYPE SYSTEM WHICH THEN TRANSFERS IT`S
ENERGY TO A COASTAL LOW. THERE IS A HIGHER DEGREE OF SPREAD
COMPARED TO THE SATURDAY SYSTEM IN THE ENSEMBLES WITH THIS FEATURE
IN THE OVERALL TRACK AND HOW MUCH IT CAN STRENGTHEN ONCE IT
REACHES THE EAST COAST. FOR NOW CARRYING A CHANCE OF SNOW ACROSS
THE REGION WITH SOME MIX ACROSS THE COAST CHANGING TO SNOW FOR
SUNDAY NIGHT THROUGH MONDAY NIGHT. THOUGHT THE 00Z GFS WAS TO
STRONG WITH THIS FEATURE ALLOWING FOR EXCESSIVE WAA, OUR
PRECIPITATION TYPE FORECAST WAS CONSIDERABLY MORE WINTRY IN LINE
WITH THE ECMWF.

TUESDAY AND WEDNESDAY: INDICATIONS CONTINUE TO A FAIRLY POTENT
ARCTIC AIR MASS COMING IN BEHIND THE DEPARTING SYSTEM. SEVERAL GEFS
MEMBERS ARE QUITE POTENT DELIVERING AN AIR MASS WITH 850 MB TEMPS
AROUND -20C AND MOST OPERATIONAL MODELS ARE AT LEAST -10C.
UNDERCUT ENSEMBLE GUIDANCE. A FRESH SNOW COVER COULD ALSO MAKE THIS
PERIOD RATHER CHILLY. SKIES WILL BE MOSTLY CLEAR WITH A NORTHWEST
FLOW.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

THE LOW CONDITIONS WILL CONTINUE TO LIFT AND BREAK SLOWLY DURING
THE AFTERNOON HOURS. IT APPEARS AS THOUGH OUR TAF SITES SHOULD
ALL IMPROVE INTO THE VFR CATEGORY BY ABOUT 2000Z TO 2100Z WITH
CEILINGS LIFTING INTO THE 3500 TO 4000 FOOT RANGE. THE CLOUD COVER
IS EXPECTED TO DISSIPATE FOR TONIGHT WITH A MAINLY CLEAR SKY
ANTICIPATED ALONG WITH NO VISIBILITY RESTRICTIONS.

A WEST TO NORTHWEST WIND AT 6 TO 12 KNOTS IS FORECAST THROUGH
THIS AFTERNOON. WIND SPEEDS ARE EXPECTED TO DIMINISH TO 4 TO 8
KNOTS FOR TONIGHT.

OUTLOOK...
FRIDAY: VFR, INCREASING CLOUDS

FRIDAY NIGHT THROUGH SATURDAY NIGHT: IFR/LIFR CEILINGS AND
VISIBILITIES IN SNOW AND RAIN. LOWEST CEILINGS FROM 08-14Z
SATURDAY, ACCUMULATING SNOW AT PHL EXPECTED. MORE RAIN SOUTHEAST
OF PHL AND SNOW NORTHWEST OF PHL. NORTHWEST GUSTS UP TO 20 KNOTS
SATURDAY AFTERNOON AND NIGHT.

SUNDAY: VFR.

SUNDAY NIGHT AND MONDAY: INCREASING CLOUDS, POTENTIAL LOWER
CEILINGS DUE TO SNOW LATE SUNDAY NIGHT AND MONDAY.

&&

.MARINE...
LIGHT W-NW WIND INCREASING THIS AFTERNOON AND TONIGHT WITH NW
GUSTS TO 20 KT. SMALL CHANCE OF BRIEF GUSTS 25 KT THIS EVENING
VCNTY DELAWARE BAY. NO SCA ATTM...THROUGH DAYBREAK FRIDAY.

WAVE HEIGHTS ON OUR OCEAN WATERS SHOULD BE 2 TO 4 FEET THROUGH
DAYBREAK FRIDAY.

OUTLOOK...
FRIDAY AND FRIDAY NIGHT: SUB SCA SEAS AND WINDS INCREASING FRIDAY
NIGHT.

SATURDAY AND SATURDAY NIGHT: SCA SEAS AND GUSTS BY AFTERNOON.
WINDS FROM THE EAST SHIFTING TO NORTHWEST BY SATURDAY NIGHT. SOME
GALE FORCE GUSTS POSSIBLE SATURDAY NIGHT.

SUNDAY AND SUNDAY NIGHT: SEAS AND WIND GUSTS DECREASING BELOW SCA
CRITERIA BY SUNDAY AFTERNOON.

MONDAY: AN SCA MAY BE NEEDED AS AN ALBERTA CLIPPER REDEVELOPS OFF
THE MID ATLANTIC COAST.

&&

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

&&

$$

SYNOPSIS...DRAG/GAINES
NEAR TERM...IOVINO
SHORT TERM...DRAG
LONG TERM...GAINES
AVIATION...GAINES/IOVINO
MARINE...DRAG/GAINES






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