Winter Storm and Winter Weather in Pennsylvania, February 11 to 12, 2006

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
140 PM EST SAT FEB 11 2006

.UPDATE (THIS AFTERNOON AND TONIGHT)...
ALL UPDATED DIGITAL GRAPHICS AND TEXT PRODUCTS ARE OUT. NEEDED TO DO
SOME TAFS BEFORE THE AFD. THANKS FOR YOUR PATIENCE.

MODEL EVOLUTION THE LAST 24 HOURS...

THE 12Z/10 MODELS SIGNALED A SHIFT WITH THE TRACK OF THE LOW. THE
SHIFT WAS FURTHER EAST AND OFFSHORE. THIS SHIFTED THE PRECIPITATION
EAST AS WELL WITH THE HEAVIEST SWATH OF SNOW SOUTH AND EAST OF THE
I-95 CORRIDOR AND ALMOST ALL THE WAY TO THE COAST. PROBABLY MORE
IMPORTANTLY, THERE WAS A SHIFT IN THE H5 LOW FROM A DEEPER CLOSED
FEATURE TO A MORE PROGRESSIVE, SLIGHTLY OPEN FEATURES (AT LEAST
THROUGH US). MODELS WERE STILL CLOSING OFF THE LOW, BUT WELL TO OUR
EAST. THIS WOULD SUGGEST A QUICKER EXIT OBVIOUSLY AFFECTING SNOWFALL
AMOUNTS. WITH THIS EASTWARD SHIFT CAME COLDER AIR AND LITTLE
SNOW/RAIN MIXING.

DURING THE OVERNIGHT...THE 00Z AND 06Z RUNS SLOWED THINGS DOWN SOME,
SHIFTED THE TRACK SLIGHTLY WEST AND BROUGHT MORE WARM AIR INTO THE
MIX. IT ALSO BROUGHT MORE INSTABILITY. THE 12Z NAM THIS MORNING
SHOWED AN EVEN SLOWER EXIT WITH THE PRECIP AS THE H5 LOW POSITION
CLOSED OFF AND DEEPENED FURTHER WEST. QPF VALUES INCREASED BECAUSE
OF THIS, BUT AT THE SAME TIME BROUGHT EVEN WARMER AIR INTO THE MIX.
THE 12Z GFS HELD ITS OWN AND ONLY SHIFTED THE LOW TO THE WEST BY
LESS THAN A DEGREE. WHATEVER PANS OUT AND WELL KNOW TOMORROW
AFTERNOON, THE GFS HAS BEEN EXTREMELY, EXTREMELY CONSISTENT WITH THE
LOW TRACK WITH HARDLY ANY SHIFT IN SPEED OR A WEST/EAST WOBBLE. IT
HAS SWAYED A BIT WITH QPF AMOUNTS, BUT HAS BEEN MORE CONSISTENT THAN
THE NAM. IN THE UPPER LEVELS, THE 12Z GFS ALSO SHIFTED THE LOW A TAD
TO THE WEST.

WITH THE SHIFT BACK TO THE WEST, WEVE UPGRADED THE ADVISORIES
ACROSS THE POCONOS TO WARNINGS. THIS IS EXACTLY WHY WE LEFT THE
WATCH UP OVER THE THIS AREA YESTERDAY EVEN THOUGH IT LOOKED LIKE A
SUB WARNING SNOWFALL AT THE TIME. ACROSS THE SOUTHERN ZONES, WEVED
UP THE WATCH TO WARNINGS. WITH THE H5 LOW WRAPPING UP CLOSER TO THE
COAST, THE QPF IS EXPECTED TO HOLD IN LONGER FURTHER SOUTH. SO EVEN
THOUGH THIS AREA WILL START OFF WITH A WINTRY MIX, ENOUGH SNOWFALL
WILL OCCUR OVER NIGHT TO REACH WARNING CRITERIA.

AS WITH MOST OF OUR NOREASTERS, ONE OF THE BIGGEST CHALLENGES IS THE
RAIN/SLEET/SNOW LINE. AS USUAL THIS WILL BE MOST PREVALENT ACROSS
THE SOUTHERN AND EASTERN ZONES. AS MENTIONED THE LOWER LEVELS WARMED
THE PAST 24 HOURS. THE FORECAST IS AS GOOD AS THE SOUNDINGS AND
PREDICTED SNOWFALL AMOUNTS ARE DEPENDENT ON THESE. FOR ANY
CHANGEOVER, THE PREDOMINANTLY EXCEPTED <1200 FT ELEVATION WAS USED
TO DELINEATE WHETHER THE PRECIP WOULD MAKE IT TO THE GROUND AS SNOW
OR CHANGEOVER TO RAIN. EVEN THOUGH THE SOUNDINGS CLEARLY SHOWED
EITHER RAIN OR SNOW, WE THREW IN SOME SLEET AS A TRANSITION USUALLY
OCCURS SOMEWHERE WITH THESE POWERHOUSE SYSTEMS.

IN TERMS OF THE HEAVIEST SNOW, WE CONTINUE TO BE ABOUT 2 TO 2.5
DEGREES WEST OF THE PREDICTED SURFACE LOW TRACK. THIS ALSO
CORRELATES WELL WITH THE IDEA THAT THE HEAVIEST SNOW FALLS JUST TO
THE WEST OF THE MIX LINE.

WITH THE INCREASED INSTABILITY OVER THE REGION, WEVE MAINTAINED THE
THE MENTION OF THUNDER. MESOSCALE BANDING IS A THREAT AND COULD
PRODUCE LOCALIZED HIGHER AMOUNTS. ON THE FLIP SIDE, WHERE THE DRY
SLOT MIGRATES COULD ALSO HAMPER PREDICTED ACCUMULATIONS.

WEVE ONLY HAD SEVEN FEBRUARY SNOWSTORMS IN PHILLY(OFFICIALLY AT THE
AIRPORT SINCE THE LATE 1800S) WHERE 12 INCHES OR MORE HAVE FALLEN.
YA THINK THINGS HAVE TO FALL IN PLACE? THE LAST TIME WEVE HAD A
SNOWSTORM EXCEEDING A FOOT WAS IN 2003. STRANGELY ENOUGH, TODAY IS
THE ANNIVERSARY FOR THE 1983 BLIZZARD WHERE OVER 20 INCHES FELL AT
THE AIRPORT.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...HEAVY SNOW WARNING FOR PAZ054-055-060>062-067>069 FROM 4 PM
     SATURDAY TO 1 PM SUNDAY.
  ...WINTER STORM WARNING FOR PAZ070-071 FROM 4 PM SATURDAY TO 1 PM
     SUNDAY.
NJ...HEAVY SNOW WARNING FOR NJZ001-007>010 FROM 4 PM SATURDAY TO 1
     PM SUNDAY.
  ...WINTER STORM WARNING FOR NJZ012>027 FROM 4 PM SATURDAY TO 1 PM
     SUNDAY.
DE...WINTER STORM WARNING FOR DEZ001>004 FROM 4 PM SATURDAY TO 1 PM
     SUNDAY.
MD...WINTER STORM WARNING FOR MDZ008-012-015-019-020 FROM 4 PM
     SATURDAY TO 1 PM SUNDAY.
MARINE...GALE WARNING FOR ANZ430-431 FROM 7 AM SUNDAY TO 7 PM SUNDAY.
  ...SMALL CRAFT ADVISORY FOR ANZ430-431 FROM 7 PM SATURDAY TO 7 AM
     SUNDAY.
  ...GALE WARNING FOR ANZ450>455 FROM 7 PM SATURDAY TO 7 PM SUNDAY.

KRUZDLO

&&

.SHORT TERM (TODAY THROUGH SUNDAY)...
TRIED TO CONCENTRATE ON THE UPCOMING EVENT THIS PACKAGE.

INITIALLY, THE NAM AT H5 WAS A BIT STRONG WITH THE HEIGHTS NEAR
THE MID LEVEL IMPULSE DIVING INTO TEXAS AND THE LOWER MI RVR
VALLEY. AT THE SFC, IT WAS TOO WEAK WITH THE LAKE CHARLES LOW AND
OK WITH THE NEW ENGLAND HIGH. THE GFS WAS BETTER BOTH AT H5 WITH
THE HEIGHTS NEAR THE MID LEVEL IMPULSE AND ALSO AT THE SURFACE
WITH THE LAKE CHARLES LOW. IT ALSO WAS FINE WITH THE NEW ENGLAND
SFC HIGH. GFS STARTED SNOW IN WV BY 06Z, WHICH DID HAPPEN, WHILE
THE NAM DID NOT. WE ARE LEANING TOWARD THE GFS THIS PACKAGE.

DAY STARTS WITH I290 TO I295 ISENT LIFT PCPN MOVING UP FROM THE
SOUTH. THEN, GFS SHOWS OUR REGION IN THE LEFT FRONT QUAD OF AN UPPER
JET DURING THE SECOND PERIOD (AS DOES NAM). THE H5 PATTERNS STARTS
THE SECOND PERIOD AS DIFLUENT AHEAD OF THE MID LEVEL LOW AND
EVENTUALLY WE ARE JUST NORTH OF A LOW CENTER ITSELF. THE GFS IS A
LTL SLOWER TO DEVELOP THAT CENTER OVER THE DELMARVA, BUT NOT MUCH,
THAN THE NAM. THERE ARE DEFINITE INDICATIONS OF SLANTWISE CONVECTION
SECOND PERIOD BOTH THE GFS AND THE NAM OVER MOST OF THE SERN HALF TO
TWO THIRDS OF THE FA WITH THE H7 TROWAL, H8 TO H6 FRONTOGENESIS, H6
EPV, MID LEVEL DRY SLOT AND I290 TO I295 ISENT STREAMLINES ALL
SUPPORTING IT. THE GFS SURFACE PATTERN TAKES LOW PRES OFF THE COAST
BETWEEN HAT AND ORF BETWEEN 00Z AND 06Z, WHILE THE NAM SURFACE
PATTERN HAS THE LOW MOVING OFF THE COAST BETWEEN HAT AND ORF AROUND
06Z. BOTH SHOW A SFC HIGH OVER EXTREME NORTHEASTERN U.S.THAT
ONR COULD HOPE WAS STRONGER, BUT IT NONETHELESS IS THERE. FLOW AT
THE SFC IS NORTHEAST AND DOES NOT LOOK ONSHORE, ALTHOUGH STRONG H8
FLOW IS EASTERLY AND PERHAPS COULD CAUSE SOME WARMING THAT MIGHT
LEAD TO A PERIOD OF SLEET OR RAIN OVER PORTIONS OF THE COASTAL PLAIN
WHERE NAM SOUNDINGS SHOW PLAIN SNOW BUT GFS SOUNDINGS A BIT WARMER.
SOUNDINGS AND PRECIPITATION VALUES SHOW RATIOS COULD EXCEED 20 TO 1
IN THE FAR NWRN ZONES. AS ALLUDED TO ABOVE, GFS SOUNDINGS HAVE A
PERIOD OF RAIN OR MIXED PRECIP IN THE SERN ZONES.

BUFKIT SHOWS THERE IS NO COMING TOGETHER OF OMEGA, SNOW GROWTH AND
EQVIV POT TEMP INSTAB FOR THE FAR NWRN ZONES, BUT THERE LOOKS TO BE
SOME FOR ABE AND THERE CERTAINLY IS FOR TTN AND POINTS SOUTH. THIS
HAPPENS DURING THE SECOND PERIOD, WHEN ABOVE ELEMENTS COME
TOGETHER. WE HAVE THEREFORE GONE WITH THE HEAVIEST PRECIP DURING
THE OVERNIGHT PERIOD, MENTIONED THE POSSIBILITY OF SOME THUNDER
AND INCREASED SNOWFALL AMOUNTS SOME.

WENT TO A SNOW ADVISORY FOR THE SRN POCONOS, A HEAVY SNOW OR
WINTER STORM WARNING FOR THE REST OF EASTERN PA, FAR NERN MD, NRN
DE AND THE REST OF THE NRN THREE QUARTERS OF NJ, AND KEPT THE
WATCH GOING OVER FAR SRN NJ, CENT AND SRN DE AND THE ADJACENT MD
ERN SHORE. THE WATCH IN THE SOUTH STAYS A WATCH BECAUSE RAIN IS
EXPECTED LATER TODAY INTO THIS EVENING PER THE GFS SOUNDINGS. PCPN
IN THE SOUTH MAY BEGIN AS SNOW DUE TO THE DECENT INITIAL
TEMP/DWPT SPREAD THANKS TO THE SFC HIGH TO THE NORTH.

&&

.LONG TERM (SUNDAY NIGHT THROUGH FRIDAY)...
WE ACCEPTED HPCS EXTENDED.

&&

.AVIATION...
SHIELD OF AS/CS ACROSS THE AREA EARLY THIS MORNING. CIGS WILL LOWER
AND CONDITIONS WILL DETERIORATE THIS AFTERNOON FROM SOUTH TO NORTH
TODAY. I TOOK CONDITIONS RIGHT TO LIFR IN THE AREAS WHERE THE
HEAVIEST SNOWS ARE EXPECTED AND LEFT THEM IFR FURTHER NORTH. VSBYS
WILL NO DOUBT REMAIN LOW WITH SN AND BLSN RIGHT THROUGH THE NIGHT
AND INTO THE FIRST PART OF SUNDAY. THE POSSIBILITY OF SOME THUNDER
WITH THE SNOW EXISTS TONIGHT OVER THE SOUTHERN TAF SITES, BUT I AM
NOT COMFORTABLE PUTTING THIS IN THE TAFS ATTM.

&&

.MARINE...
GALE WARNINGS ALREADY UP FOR THE WATERS, AND I SEE NO REASON TO
CHANGE ANYTHING FOR NOW. THE GFS AND NAM ARE SIMILAR WITH THE TRACK
OF THE LOW. IT MOVES FROM NEAR SOUTH CAROLINA AT 18Z TODAY (1007 MB)
TO NEAR 40N 70W BY 18Z SUNDAY. THE GFS IS SLIGHTLY STRONGER WITH THE
LOW AT 18Z SUN OFFERING 978 MB (COMPARED TO 980 MB WITH THE NAM).
THE GFS SFC WIND GUIDANCE SHOWS AN AREA OF 45KT TO 50KT WINDS
WRAPPING AROUND TO THE WEST OF THE LOW (BUT JUST EAST OF THE
FORECAST WATERS) EARLY SUNDAY. OFFSHORE FORECASTS HAVE STORM FORCE
WINDS IN THE FCST FOR SUNDAY AND OUR ADJACENT OFFICE TO THE NORTH
HAS INDICATED THAT THEY WILL BE GOING WITH STORMS IN THEIR CWF SINCE
THEY WILL BE CLOSER TO THE CENTER OF THE LOW. ANY CHANGE IN TRACK OR
INTENSITY OF LOW MAY REQUIRE STORMS FOR OUR WATERS.

&&

.TIDAL FLOODING...
SSE AND ECS GUIDANCE VALUES INCREASE TO BETWEEN 1.5 AND 2.5 ABOVE
PREDICTED TIDAL VALUES IN THE 00Z TO 12Z TIME FRAME ON TONIGHT AND
SUNDAY. THE HIGHEST VALUES OCCUR AROUND 12Z SUNDAY WHICH IS WITHIN A
FEW HOURS OF THE HIGHER DAILY HIGH TIDES. SUNDAY THE 12TH IS ALSO
THE DAY OF THE FULL MOON WHICH MEANS THE TIDAL RANGE WILL BE
GREATEST ON THIS DAY. ALL ADDED UP...MINOR TIDAL FLOODING WILL OCCUR
ALONG THE NJ COAST SUNDAY MORNING WITH THIS EVENT. WE DONT HAVE A
STRONG ENOUGH SIGNAL YET TO RAISE A CFW SINCE WIDESPREAD MODERATE
READINGS ARE NOT EXPECTED. SINCE THE VALUES DO GET CLOSE...WE WILL
ADVISE THE DAY SHIFT TO LOOK THINGS OVER. -- STAY TUNED

SHORT TERM...DELISI
LONG TERM...HPC
AVIATION/MARINE/TIDES...OHARA

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
506 AM EST SAT FEB 11 2006

ANZ430-431-450>455-DEZ001>004-MDZ008-012-015-019-020-NJZ001-
007>010-012>027-PAZ054-055-060>062-067>071-121100-
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-
NEW CASTLE-KENT DE-INLAND SUSSEX-DELAWARE BEACHES-CECIL-KENT MD-
QUEEN ANNES-TALBOT-CAROLINE-SUSSEX-WARREN-MORRIS-HUNTERDON-
SOMERSET-MIDDLESEHT. A GALE WARNING
IS IN EFFECT FOR THE COASTAL AREAS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THE AFOREMENTIONED STORM WILL BE MOVING AWAY SUNDAY, BUT IT WILL
STILL PRODUCE SOME ACCUMULATING SNOW DURING THE MORNING HOURS. THE
STRONG WINDS BEHIND THE STORM AND THE HIGH ASTRONOMICAL TIDES WILL
PRODUCE SOME MINOR TIDAL FLOODING DURING THE MORNING ALONG THE NEW
JERSEY SHORE AREAS. HIGH TIDE TIMES ARE BETWEEN 630 AM AND 830 AM.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO CALL WITH SNOWFALL TOTALS OR ANY OTHER
SIGNIFICANT WEATHER OBSERVATIONS TONIGHT AND SUNDAY.

OHARA