Winter Storm and Winter Weather in Pennsylvania, January 10 to 11, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
911 PM EST FRI JAN 9 2009

.SYNOPSIS...
LOW PRESSURE DEVELOPING OVER THE SOUTHERN PLAINS WILL MOVE
NORTHEAST TO THE OHIO VALLEY SATURDAY MORNING AND THEN OFF THE
EAST COAST SUNDAY MORNING. HIGH PRESSURE ON MONDAY WILL BE
FOLLOWED BY ANOTHER LOW PRESSURE AND FRONTAL SYSTEM ON TUESDAY.
YET ANOTHER LOW PRESSURE ON THURSDAY WILL USHER IN AN ARCTIC BLAST
FOR THE END OF THE WEEK.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
LATEST SATELLITE IMAGERY SHOWS A STRIP OF SC IN NERN PA AND NRN
NJ AND SOME SNOW SHOWERS OR FLURRIES FALLING FROM THOSE CLOUDS,
ESPECIALLY OVER THE POCONOS. EVERYWHERE ELSE WAS PRETTY MUCH
CLEAR. THEREFORE, WILL ADD SOME SLIGHT CHC POPS FOR THESE AREAS
FOR THE EARLY PORTION OF THE NIGHT. OTHERWISE, CLOUDS WILL BE ON
THE INCREASE AS THE NEXT SYS APPROACHES THE REGION. OVERALL, FCST
RATIONALE HAS NOT CHANGED, SO WILL JUST MAKE TWEAKS TO CLOUD COVER
AND EARLY POPS WHERE NEEDED.

HOWEVER...MID/HI CLOUDS ARE SPREADING RAPIDLY EASTWARD IN WARM
ADVECTION AHEAD OF THE NEXT SHRTWV TROF NOW MOVING INTO THE
GRTPLNS. SOME LIGHT SNOW IS ALSO BEING OBSERVED OVER OHIO AND FAR
WRN PA. CLOUDS AND LIGHT SNOW WILL CONT TO SPREAD EWD OVERNIGHT
BUT THE AMS OVER THE MID- ATLANTIC IS QUITE DRY ATTM AND SO OUR
FCST HAS JUST A MINIMAL CHANCE FOR LIGHT SNOW OVER ERN PA BY THE
END OF THE OVERNIGHT PERIOD. THIS WOULD MARK THE BEGINNING OF THE
APPROACHING STORM.

THE RAOBS VS THE MODELS 6 AND 12HR FCSTS VALID 00Z SATURDAY LOOK
BETTER THAN LAST NIGHT. THE ONE NOTED PROBLEM THEY ALL HAVE IS
THAT HEIGHTS AT DDC ARE 20M LOWER THAN ALL OF THE MODELS HAVE.
THIS MAY BE A SIGN THAT THE SHEARING PROCESS IS OCCURRING SLIGHTLY
AHEAD OF SCHEDULE, MAYBE NOT AS MUCH SHORT WAVE RIDGING PRECEDING
THE FOUR CORNERS TROF. WITH THE UPPER PLAINS TROF, THE NOD GOES TO
THE ECMWF, THAT FEATURE HAS A BIT MORE BITE TO IT THAN THE NAM AND
GFS SHOW. LASTLY THE 850MB TEMPS AROUND ARE CWA ARE ABOUT 1 TO 2C
COLDER THAN PROGGED. THIS LOOKS TO BE A BY PRODUCT OF THE MODELS
HAVING THE SUBSIDENCE INVERSION TOO LOW. FORECAST TEMPS ABOVE 850
MB LOOK OK. UNLIKE OTHER EVENTS THOUGH, THE WARM AIR IS FORECAST
TO COME IN BELOW 850MB SO WILL BE WORTH SEEING WHAT EFFECT THIS
WILL HAVE TO THE IMPENDING LOW LEVEL WARMING. LASTLY THE PCPN
PROGS VS ACTUAL AMOUNTS LOOK BETTER WITH THE GFS, THE EURO WAS TOO
WET AROUND THE GREAT LAKES AND THE WRF TOO STINGY. THE WRF LOOKS
LIKE ITS OFF TO A TOO DRY START BASED ON PRESENT ECHOES AND SOME
LIGHT SNOW REACHING THE GROUND ACROSS WESTERN PA.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
LIGHT SNOW IS EXPECTED TO SPREAD OVER THE AREA FROM WEST TO EAST
SATURDAY MORNING. HWVR BOTH NAM AND GFS ARE SUGG THAT SNOW MAY
HOLD OFF SRN NJ...DELMARVA AND PERHAPS THE PHILA AREA UNTIL
AFTERNOON. BY THAT TIME INCRG ELY LOW-LVL WINDS OFF THE ATLANTIC
SHOULD BRING IN SOME SLIGHTLY MILDER AIR ACROSS OUR DELMARVA
REGION AND SERN NJ. THESE AREAS SHOULD SEE MOSTLY RAIN. OVR FAR
NRN DELMARVA AND SOUTH-CNTRL NJ THE CHANGE-SHOULD BE SLOWER OR
THERE COULD BE A PERIOD OF MIXED PRECIP...ALLOWING FOR A COUPLE
INCHES OF SNOW/SLEET ACCUM. THIS AREA...ALONG WITH PARTS OF SERN
PA...HAS BEEN PLACED IN A WINTER WX ADVISORY...ALTHO THE PRECIP
COULD CHANGE TO ALL RAIN BY EVE. IN GENERAL... THE MIX OF PRECIP
TYPES WILL TEND TO HOLD ACCUMS DOWN IN THE ADVISORY AREA.

FOR THE COUNTIES JUST N OF PHILA AND NEWD INTO N-CNTRL NJ...THE
PRECIP SHOULD STAY MOSTLY SNOW DURG SAT AFTN AND WILL ACCUM
SEVERAL INCHES. THEN FOR THE EVE...WARMER AIR ALOFT IS EXPECTED TO
MOVE NWD OVER THIS AREA AS THE 850MB LOW MOVES E ACRS PA. THE SNOW
COULD MIX WITH SLEET OR FREEZING RAIN DURG THIS TIME WHICH AGAIN
WOULD CUT DOWN THE SNOW AMOUNTS...BUT STILL THE STORM TOTAL ACCUMS
OF SNOW AND SLEET ARE EXPECTED TO REACH OR EXCEED THE 6-INCH
CRITERION FOR WINTER STORM WARNINGS.

FOR THE LEHIGH VALLEY...SOUTHERN POCONOS AND NW NJ...FCST
SOUNDINGS APPEAR TO REMAIN COLD ENOUGH FOR AN ALL SNOW EVENT.
ALSO...THE NAM/GFS QPFS ARE HIGHEST ACROSS THIS AREA AS IS THE
FCST LOW-LVL FRONTO-GENESIS. SINCE THE TEMPS THERE ARE FAIRLY COLD
WE USED A SNOW-LIQUID RATIO OF 12:1 TO 15:1...OR SMWHT HIGHER
THAN CLIMO. STORM TOTAL SNOW AMOUNTS COULD REACH CLOSE TO 1O
INCHES OVER THE HIGHEST ELEVS...ALTHO MOST AREA WILL SEE SMWHT
LESS.

AS THE LOW PRESSURE MOVES OFF THE NJ COAST AFTER SAT MIDNIGHT...
WINDS WILL TURN MORE NLY AND COLDER AIR MAY BRIEFLY TURN THE PRECIP
BACK TO SNOW IN THE MIXED-PRECIP AREAS. THIS SHOULD BE FAIRLY
BRIEF HWVR AND ALL PRECIP SHOULD BE OVER BY SUN-UP SUNDAY. HIGH
PRESSURE BEHIND THE LOW IS RELATIVELY WEAK AND THE ASSOCD AIRMASS
IS NOT TERRIBLY COLD. HENCE SUNDAY SHOULD BE THE BETTER DAY OF THE
WEEKEND...AT LEAST AFTER ANY SNOW IS PLOWED.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
SEVERAL CLIPPER-TYPE SYSTEMS WILL AFFECT THE REGION DURING THE
EXTENDED PERIOD, BUT THE MAIN STORY WILL BE THE COLD AMS MOVING IN
AROUND MIDWEEK.

MONDAY WILL START OFF DRY, AS THE AREA IS UNDER THE INFLUENCE OF WK
HIGH PRESSURE.  HOWEVER, A WK SFC LOW IS FCST TO MOVE FROM THE UPR
MS VLY TO ONTARIO MONDAY NIGHT DRAGGING A CDFNT AND PRECIP WITH IT
BY TUESDAY MORNING.  THE ECMWFS TIMING IS AT LEAST 6 HRS SLOWER
THAN THE GFS, EVEN THOUGH THE OVERALL SYNOPTIC FEATURES WITH THIS
SYS ARE SIMILAR.  DEPENDING ON THE TEMP PROFILE, WHICH IS DIFFICULT
TO FCST THIS FAR OUT, MOST PLACES WILL START AS SNOW, WITH SOME RAIN
MOVING INTO THE COASTAL PLAIN BY TUESDAY AFTN.  HOW FAR N AND W THIS
RAIN GETS, REMAINS TO BE SEEN.

TUESDAY NIGHT INTO WEDNESDAY LOOK DRY AGAIN AS WK HIGH PRESSURE
MOVES BACK OVER THE MID-ATLC, IN ADVANCE OF THE NEXT CLIPPER SYS.
THE GFS AND ECMWF ARE IN DECENT TIMING AGREEMENT WITH THIS CLIPPER.
THE LOW TRACKS FROM IL ACRS PA THEN OFF THE NEW ENG COAST.  THIS IS
A QUICK MOVER, BUT WITH COLD AIR IN PLACE, ALL THE PRECIP LOOKS TO
BE WINTRY ATTM.

BEHIND THIS DEPARTING LOW, A LARGE CANADIAN HIGH PRESSURE SYSTEM
MOVES INTO THE PLAINS.  THE GFS HAS THIS HIGH AT 1050 MB...WOW  THE
ECMWF IS SLIGHTLY WEAKER AT 1040+.  THIS HIGH THEN MOVES SWD INTO
THE SRN PLAINS AND BEGINS TO SLOWLY BUILD INTO OUR REGION BY THE END
OF THE WEEK.  AROUND MIDWEEK, THERE WILL LIKELY BE SOME GUSTY N TO
NW WINDS AS THE PRESSURE GRADIENT BETWEEN THE HUGE HIGH AND
DEPARTING CLIPPER WILL OBVIOUSLY BE LARGE.  AS THE HIGH BUILDS IN
THOUGH, THE WIND SHOULD DECREASE.  TEMPS WILL ALSO PLUMMET, WITH
HIGHS NOT LIKELY MAKING IT ABOVE 30 AT PHILLY ON WED AND POSSIBLY
NOT MUCH ABOVE 20 THU AND FRI.  CLEARLY, THIS WILL BE SOME OF THE
COLDEST AIR OF THE SEASON.

ALSO, WITH A HIGH THIS STRONG AND A TREMENDOUS AMOUNT OF SUBSIDENCE,
THERE SHOULD NOT BE MUCH IN THE WAY OF PRECIP.  INTERESTINGLY, THE
ECMWF HAS SOME PRECIP EXTENDING WAY TOO FAR INTO THE HEART OF THE
BIG HIGH.  THIS SEEMS OVERDONE AND IS LIKELY JUST SOME NOISE.  THE
GFS IS RELATIVELY PRECIP FREE DURING THE SAME TIME.  BY THE END OF
THE EXTENDED PD, BOTH THE ECMWF AND GFS WANT TO BRING YET ANOTHER
CLIPPER INTO SRN CANADA AND HAVE IT BEGIN TO APPROACH OUR REGION.
HOWEVER, IT IS VERY DIFFICULT FOR A WK CLIPPER TO DISLODGE SUCH A
LARGE HIGH PRESSURE SYSTEM, SO IT WOULD NOT BE SURPRISING IF THIS
LOW WERE SLOWER TO MOVE IN THAN CURRENTLY PROGGED.

TEMPS LOOK TO BE AT OR SLIGHTLY BLO NORMAL AT THE START OF THE
EXTENDED AND THEN WILL FALL OFF THE CLIFF AND BECOME AT LEAST 15 AND
POSSIBLY 20 DEGREES BLO NORMAL BY THE END OF THE FCST PD.

&&

.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG,
KMIV, KACY AND SURROUNDING AREAS.

A VFR FORECAST IS MAINTAINED THROUGH THE EVENING. THERE ARE STILL
ONE OR TWO LAKE EFFECT VFR SC BANDS MOVING THROUGH THE NORTHERN
TERMINAL AREA. THE FLOW IS BACKING AWAY FROM THE LAKES AND THESE
BANDS SHOULD DISSIPATE. CONVERSELY MID AND HIGH LEVEL CLOUDS
ASSOCIATED WITH THE NEXT LOW PRESSURE SYSTEM ARE ALREADY IN
WESTERN AND CENTRAL PENNSYLVANIA.

AFTER MIDNIGHT, WE ARE FOLLOWING A BAND OF SNOW THAT IS CURRENTLY
OVER SOUTHWESTERN PENNSYLVANIA. THIS BAND WILL MOVE INTO THE
TERMINAL REGION TOWARD MORNING. FORECAST GUIDANCE SUGGESTS ALL THE
TERMINALS SHOULD BE AFFECTED BY THIS BAND, WITH KACY AND KMIV
AFFECTED THE LEAST. BECAUSE IT IS SO EASY FOR IFR VSBYS TO OCCUR
WITH SNOW, WE INCLUDED SOME IFR VSBYS IN THE TERMINALS NW OF KPHL
AND KPNE. IT WOULD NOT BE A SURPRISE IF IFR VSBYS OCCUR FOR PART OF
THE MORNING EVEN AROUND THE KPHL TERMINALS. THIS BAND IS FORECAST TO
LIFT NORTHEAST AND THERE SHOULD BE A PRECIP LULL FROM THE KPHL
TERMINALS SOUTHWARD AND SOUTHEASTWARD. KABE HAS THE BEST CHANCE TO
REMAIN IN STEADY SNOW. AS THE NEXT LARGER AREA OF PRECIPITATION
ARRIVES DURING SATURDAY AFTERNOON, WARMER AIR ALOFT WILL BRING THE
POSSIBILITY OF MIXED PRECIPITATION AROUND THE KPHL TERMINALS. AT
KACY AND KMIV IT SHOULD BE TOO WARM ALOFT FOR ANY SNOW AT THAT POINT
AND KRDG AND KABE SHOULD REMAIN SNOW WITH IFR CIGS AND VSBYS
PREVAILING. THIS TRANSITION AWAY FROM SNOW AS A PTYPE WAS CONTINUED
IN THE KPHL 30HR TERMINAL FORECAST SATURDAY EVENING.

OUTLOOK...IMPROVING CONDITIONS WILL OCCUR ONCE THE PRECIP ENDS LATER
SAT NIGHT OR BEFORE DAWN SUN. IFR CIGS AND VSBYS ARE LIKELY
ESPECIALLY AT KRDG AND KABE. GUSTY NW WINDS AND IMPROVING CIGS WILL
BE ACROSS THE AREA SUN AND SUN NIGHT. NEXT WEATHER TO CAUSE IMPACTS
TO OUR AREA WILL BE ON TUE.

&&

.MARINE...
THE SMALL CRAFT ADVISORY HAS BEEN ALLOWED TO EXPIRE. WINDS WILL
NOT BE VERY STRONG AS THE NEXT LOW APPROACHES SATURDAY, SO NO
FLAGS ARE ANTICIPATED. ONCE THE LOW PASSES BY SCA FLAGS WILL
PROBABLY BE NEEDED AGAIN FOR SAT NIGHT INTO SUNDAY.

&&

.TIDES/COASTAL FLOODING...
THE OFFSHORE FLOW IS CONTINUING, BUT IS EXPECTED TO RELAX TONIGHT.
BLOWOUT TIDE VALUES WERE NOT REACHED ALONG THE SHORE WITH THE
PREVIOUS LOW TIDE, ALTHOUGH IT WAS CLOSE. THE LOW WATER ADVISORY HAS
EXPIRED AND WILL NOT BE RE-ISSUED.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING FROM 7 AM SATURDAY TO 7 AM EST SUNDAY FOR
     PAZ054-055-060>062-068-069.
     WINTER WEATHER ADVISORY FROM 7 AM SATURDAY TO MIDNIGHT EST
     SATURDAY NIGHT FOR PAZ067-070-071.
NJ...WINTER STORM WARNING FROM 7 AM SATURDAY TO 7 AM EST SUNDAY FOR
     NJZ001-007>010-012-015.
     WINTER WEATHER ADVISORY FROM 7 AM SATURDAY TO MIDNIGHT EST
     SATURDAY NIGHT FOR NJZ013-014-016>020.
DE...WINTER WEATHER ADVISORY FROM 7 AM SATURDAY TO MIDNIGHT EST
     SATURDAY NIGHT FOR DEZ001.
MD...WINTER WEATHER ADVISORY FROM 7 AM SATURDAY TO MIDNIGHT EST
     SATURDAY NIGHT FOR MDZ008.
MARINE...NONE.

&&

SYNOPSIS...AMC
NEAR TERM...AMC/NIERENBERG/GIGI
SHORT TERM...AMC
LONG TERM...NIERENBERG
AVIATION...DELISI/GIGI
MARINE...GIGI/OHARA
TIDES/COASTAL FLOODING...OHARA

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
849 PM EST FRI JAN 9 2009

NJZ001-007>010-012-015-PAZ054-055-060>062-068-069-110200-
SUSSEX-WARREN-MORRIS-HUNTERDON-SOMERSET-MIDDLESEX-MERCER-CARBON-
MONROE-BERKS-LEHIGH-NORTHAMPTON-MONTGOMERY-BUCKS-
849 PM EST FRI JAN 9 2009

...WINTER STORM WARNING IN EFFECT FROM 7 AM SATURDAY TO 7 AM EST
SUNDAY...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL NEW JERSEY...NORTHERN
NEW JERSEY...NORTHWEST NEW JERSEY...EAST CENTRAL
PENNSYLVANIA...NORTHEAST PENNSYLVANIA AND SOUTHEAST PENNSYLVANIA.

.DAY ONE...TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER STORM WARNING.

WINTER STORM WARNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

DEZ001-MDZ008-NJZ013-014-016>020-PAZ067-070-071-110200-
NEW CASTLE-CECIL-WESTERN MONMOUTH-EASTERN MONMOUTH-SALEM-GLOUCESTER-
CAMDEN-NORTHWESTERN BURLINGTON-OCEAN-CHESTER-DELAWARE-PHILADELPHIA-
849 PM EST FRI JAN 9 2009

...WINTER WEATHER ADVISORY IN EFFECT FROM 7 AM SATURDAY TO MIDNIGHT
EST SATURDAY NIGHT...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHERN DELAWARE...NORTHEAST
MARYLAND...CENTRAL NEW JERSEY...SOUTHERN NEW JERSEY AND SOUTHEAST
PENNSYLVANIA.

.DAY ONE...TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   WINTER WEATHER ADVISORY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

DEZ002>004-MDZ012-015-019-020-NJZ021>027-110200-
KENT-INLAND SUSSEX-DELAWARE BEACHES-KENT MD-QUEEN ANNES-TALBOT-
CAROLINE-CUMBERLAND-ATLANTIC-CAPE MAY-ATLANTIC COASTAL CAPE MAY-
COASTAL ATLANTIC-COASTAL OCEAN-SOUTHEASTERN BURLINGTON-
849 PM EST FRI JAN 9 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL DELAWARE...SOUTHERN
DELAWARE...NORTHEAST MARYLAND AND SOUTHERN NEW JERSEY.

.DAY ONE...TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

ANZ430-431-450>455-110200-
DELAWARE BAY WATERS NORTH OF EAST POINT NJ TO SLAUGHTER BEACH DE-
DELAWARE BAY WATERS SOUTH OF EAST POINT NJ TO SLAUGHTER BEACH DE-
COASTAL WATERS FROM SANDY HOOK TO MANASQUAN INLET NJ OUT 20 NM-
COASTAL WATERS FROM MANASQUAN INLET TO LITTLE EGG INLET NJ OUT 20 NM-
COASTAL WATERS FROM LITTLE EGG INLET TO GREAT EGG INLET NJ OUT 20 NM-
COASTAL WATERS FROM GREAT EGG INLET TO CAPE MAY NJ OUT 20 NM-
COASTAL WATERS FROM CAPE MAY NJ TO CAPE HENLOPEN DE OUT 20 NM-
COASTAL WATERS FROM CAPE HENLOPEN TO FENWICK ISLAND DE OUT 20 NM-
849 PM EST FRI JAN 9 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS AND
DELAWARE BAY WATERS.

.DAY ONE...TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

TFG