Winter Storm and Heavy Snow in Pennsylvania, December 9, 2005

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
540 AM EST FRI DEC 9 2005

.UPDATE...
ISSUED A QUICK UPDATE TO CANCEL THE WINTER WEATHER ADVISORY FOR
CAPE MAY COUNTY, NJ AND SUSSEX COUNTY, DE BASED ON THE LATEST
SURFACE OBS IN THE LOWER TO MID 40S. HAVE RECEIVED SEVERAL REPORTS
OF SLEET AND FREEZING RAIN IN PARTS OF SOUTH JERSEY WITH LESS SNOW
OCCURRING. WE ARE MONITORING THIS TREND, AND WILL MORE THAN LIKELY
ISSUE ANOTHER UPDATE TO LOWER SNOWFALL AMOUNTS EAST OF THE I-95
CORRIDOR (PROBABLY THROTTLED BACK FROM A WARNING TO AN ADVISORY).
EITHER WAY YOU CUT IT, A METEOROLOGICAL MESS GOING ON ACROSS THE CWA
EARLY THIS MORNING WITH SNOWFALL RATES OF AROUND 1-INCH PER HOUR
ACROSS THE NORTHWEST/WEST ZONES, AND A MIX OF EVERYTHING TO PLAIN
RAIN ACROSS THE SOUTHEAST.

&&

.PREVIOUS DISCUSSION...
ISSUED AT 350 AM.

.OVERVIEW...
AFTER STARTING ON THE WEAK SIDE WITH THE PRIMARY SURFACE LOW OVER
THE OHIO VALLEY, THE NAM CATCHES UP TO THE GFS BY FORECAST 12 HOURS.
HOWEVER, THE GFS TRENDS DEEPER THAN THE NAM WITH THE SYSTEM OFF THE
NEW ENGLAND COAST BY FORECAST 24 HOURS (LATE TODAY). AT THAT TIME
THE HIGH RESOLUTION CANADIAN GEM AND ECMWF FALL BETWEEN THE NAM AND
GFS, WHILE THE CANADIAN GLOBAL IS TOO WEAK WITH THE SURFACE LOW DUE
TO BEING WEAK/OPEN WITH THE FEATURE ALOFT. GIVEN THE VIGOROUS NATURE
OF THE MID LEVEL SYSTEM, THE CONSENSUS WAS TO LEAN MORE TOWARD THE
STRONGER GFS DEPICTION BY FORECAST 24 HOURS.

&&

.NEAR TERM (TODAY)...
WATER VAPOR IMAGERY SHOWING A POTENT SHORT WAVE LIFTING INTO THE
EASTERN GREAT LAKES EARLY THIS MORNING. TREMENDOUS LIFT ASSOCIATED
WITH STRONG WAA ALOFT AND A 50-60 KNOT SOUTHERLY LOW LEVEL JET
MOVING EASTWARD. MSAS PRESSURE CHANGE ANALYSIS REVEALING THE GREATEST
FALLS OCCURRING ALONG THE VIRGINIA COAST WHERE NEW SURFACE TRYING TO
ORGANIZE, ALTHOUGH SEEMS TO NOT BE DOING SO IN A HURRY. ANOTHER AREA
OF LARGE PRESSURE FALLS CENTERED OVER NORTHWEST PENNSYLVANIA INTO
WESTERN NEW YORK AS THE POTENT SHORT WAVE MOVES INTO THAT REGION
EARLY THIS MORNING. REGIONAL RADAR SHOWING PLENTY OF MOISTURE MOVING
INTO THE REGION FROM SOUTHWEST TO NORTHEAST. INITIALLY SOME DRY AIR
TO OVERCOME, HOWEVER IT APPEARS THE DRY LAYER IS NOT ALL THAT DEEP
AS OBS TO OUR WEST AND SOUTHWEST SHOW FROM NEARLY NO SNOW TO
MODERATE TO HEAVY SNOWFALL, WITH EVEN SOME PELLETS MIXING IN AT
KBWI. THIS ACTION WILL TRANSLATE NORTHEASTWARD THIS MORNING,
THEREFORE STILL EXPECTING A QUICK HITTER WITH PERIODS OF HEAVIER
SNOW. HAVE BEEN GLUED TO THE OBS ACROSS THE DELMARVA ALL NIGHT AND
NOTING THE SOUTHEAST WIND INCREASING AT KOXB WITH THEIR TEMPERATURE
JUMPING INTO THE LOWER 40S. EVEN KGED IS UP TO 33F AS OF 8Z. THE
LATEST MODEL GUIDANCE PLOT OF THEIR SURFACE TEMPERATURE FIELDS
SHOWING A VERY TIGHT THERMAL GRADIENT ACROSS SOUTHEASTERN NEW JERSEY
INTO THE DELMARVA. LOOKING AT PLENTY OF FORECASTING SOUNDINGS, GOING
BACK AND FORTH WITH THE NAM AND GFS, AND STILL LOOKS LIKE A
CHANGEOVER ACROSS THE FAR SOUTHEASTERN ZONES WITH SOME MIXING
OCCURRING TOWARD THE I-95 CORRIDOR THIS MORNING. WARMER AIR SNEAKING
IN AROUND THE 925 MPH LEVEL UP TO PHL SHOULD ALLOW SOME MIXING OF
SLEET AND FREEZING RAIN TO OCCUR. SURFACE DEW POINTS STARTED OUT
VERY LOW, HOWEVER THEY HAVE BEEN GRADUALLY INCREASING EARLY THIS
MORNING.

BASED ON THE LATEST GUIDANCE, DID NOT MAKE MUCH IN THE WAY OF
CHANGES TO THE GOING FORECAST AS THE EVENT IS CONTINUING TO UNFOLD
ATTM. AM A LITTLE NERVOUS SINCE THE SNOW IS JUST GETTING UNDERWAY
AND WE HAD A COUPLE OF INCHES ACCUMULATING BY DAYBREAK. THINK THAT
MOST AREAS MAY ACTUALLY WIND UP ON THE LOWER END OF THE AMOUNTS,
ESPECIALLY CENTRAL AND SOUTHERN ZONES. HOWEVER, WE WILL MAINTAIN THE
CURRENT WARNINGS AND ADVISORIES (WITH SAME AMOUNTS) FOR NOW AND KEEP
AN EYE ON RADAR AND OB TRENDS. THE STORM WILL QUICKLY MOVE
NORTHEASTWARD AROUND MIDDAY WITH PRECIPITATION ENDING. AS THE STORM
DEEPENS OFF THE NEW ENGLAND COAST THIS AFTERNOON, THE PRESSURE
GRADIENT IS FORECAST TO REALLY TIGHTEN UP ACROSS OUR CWA AS HIGH
PRESSURE NOSES INTO THE OHIO VALLEY. IT LOOKS TO TURN WINDY THROUGH
THE DAY, AS WINDS OFF THE DECK INCREASE DRAMATICALLY. BUFKIT
PROFILES FROM THE NAM AND GFS HAVE 900 MB WINDS OF 40-50 KNOTS THIS
AFTERNOON. HOWEVER, THE PROFILE DOES NOT APPEAR TO SUPPORT FULL
MIXING DOWN TO THE SURFACE. THE TRANSFER MOMENTUM SCHEME OFF OF
BUFKIT IS NOT TO IMPRESSIVE WITH IT, THEREFORE WILL KEEP WINDS BELOW
ADVISORY CRITERIA AND GO WITH GUSTS AROUND 35 MPH. THIS WILL LIKELY
PRODUCE SOME BLOWING AND DRIFTING SNOW IN OPEN AREAS, ALONG WITH
COLD WIND CHILL VALUES.

TEMPERATURES TODAY ARE EXPECTED TO BE BELOW NORMAL.

&&

.SHORT TERM (TONIGHT THROUGH SATURDAY)...
HIGH PRESSURE BUILDS TO OUR SOUTH OVERNIGHT TONIGHT WITH THE
PRESSURE GRADIENT GRADUALLY RELAXING. IT WILL BE RATHER COLD TONIGHT
WITH MANY AREAS OUTSIDE OF THE LARGER CITIES GETTING INTO THE TEENS.
WENT A LITTLE COLDER THAN THE MOS TONIGHT GIVEN THAT A DECENT AMOUNT
OF SNOW SHOULD BE ON THE GROUND FOR MANY LOCATIONS. THERE SHOULD BE
A FAIR AMOUNT OF SUNSHINE ACROSS THE REGION SATURDAY WITH HIGH
TEMPERATURES BELOW NORMAL.

&&

.LONG TERM (SUNDAY THROUGH THURSDAY)...
MAIN FOCUS IS WITH THE NEAR AND SHORT TERM, THEREFORE NOT MUCH
CHANGE TO THE LONG TERM EXCEPT FOR SOME ADJUSTMENTS MAINLY TO
TEMPERATURES BASED ON THE 00Z MEX GUIDANCE. THE MAJORITY OF THE
DISCUSSION FROM THE DAY CREW WITH SOME TWEAKS FOLLOWS: THE 00Z/9 GFS
SHOWS A SURFACE FRONT AND AN UPPER LEVEL TROUGH SWINGING THROUGH
SUNDAY NIGHT INTO MONDAY. SOME FLURRIES CANNOT BE RULED OUT MAINLY
ACROSS THE NORTHWESTERN PORTION OF THE CWA, HOWEVER WILL NOT INCLUDE
ATTM. OVERALL IT APPEARS THERE ARE NO SIGNIFICANT WEATHER SYSTEMS
EVIDENT IN THE MODELS UNTIL ABOUT MIDWEEK, AND WE HAVE INCLUDED ONLY
SLIGHT CHANCES AT THIS POINT FOR MIXED PRECIPITATION TYPES (SNOW
SHOWERS WEDNESDAY NIGHT, MIXED DURING THE DAYTIME PERIODS WEDNESDAY
AND THURSDAY). THERE MAY BE AT LEAST SOME WEAK SHORT WAVE ENERGY
EMBEDDED IN THE FAST FLOW ALOFT, WHICH COULD IMPACT THE AREA.
HOWEVER, THE MODELS MAY NOT PICK UP ON THEM SUBSTANTIALLY UNTIL ANY
POSSIBLE EVENT NEARS CLOSER IN TIME.

TEMPERATURES LOOK LIKE THEY WILL BE COLDER THAN NORMAL FOR THIS TIME
OF YEAR.

&&

.AVIATION...
PRECIP IS ONGOING IN THE WEST (ALL SNOW) AND SHOULD BE BREAKING OUT
ACROSS THE EASTERN TAFS DURING THE NEXT FEW HOURS.  PRECIP TYPE IS
EASY FOR KABE AND KRDG, AS THERE WILL BE ALL SNOW.  FOR THE OTHER
LOCATIONS, THERE IS THE POSSIBILITY OF MIXING, WITH THE BEST CHANCES
FOR KACY AND KMIV.  CIGS AND VSBYS WILL RAPIDLY DECREASE WITH THE
ONSET OF SNOW.  THERE IS THE POTENTIAL FOR SOME MODERATE TO HVY
BANDS AS WELL.  PRECIP SHOULD END BY LATE MORNING ACROSS THE TAF
SITES, AND CIGS AND VSBYS WILL BECOME VFR ONCE AGAIN. WINDS WILL
INCREASE BEHIND THE LOW AND WILL GUST CLOSE TO 30 KTS THIS
AFTERNOON, WHICH WILL CAUSE SOME BLOWING AND DRIFTING OF SNOW IN
THOSE LOCATIONS THAT RECIEVE PREDOMINANTLY SNOW.

&&

.MARINE...
GALE WRNG WILL BE CONTINUED WITH INTENSIFICATION OF LOW PRESSURE,
EXPECTED TO FORM NR THE DELMARVA COAST.  NO CHANGE TO ENDING TIME
FOR GALES AS THE SFC LOW DOES MOVE ALONG RAPIDLY. A WEAK CFP IS
EXPECTED TO MOVE THRU ON SUN OR SUN NIGHT AND WINDS MIGHT REACH SCA
CRITERIA BEHIND THIS FRONT SUN NGT OR MON IN THE CAA.

&&

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...HEAVY SNOW WARNING FOR PAZ054-055-060>062 UNTIL NOON FRIDAY.
  ...WINTER STORM WARNING FOR PAZ067>071 UNTIL NOON FRIDAY.
NJ...HEAVY SNOW WARNING FOR NJZ001-007-008 UNTIL NOON FRIDAY.
  ...WINTER STORM WARNING FOR NJZ009-010-012-015>019 UNTIL NOON
     FRIDAY.
  ...WINTER WEATHER ADVISORY FOR NJZ013-014-020>022-026-027 UNTIL
     NOON FRIDAY.
DE...WINTER STORM WARNING FOR DEZ001 UNTIL NOON FRIDAY.
  ...WINTER WEATHER ADVISORY FOR DEZ002 UNTIL NOON FRIDAY.
MD...WINTER STORM WARNING FOR MDZ008-012 UNTIL NOON FRIDAY.
  ...WINTER WEATHER ADVISORY FOR MDZ015-019-020 UNTIL NOON FRIDAY.
MARINE...GALE WARNING FOR ANZ430 FROM NOON FRIDAY TO 10 PM FRIDAY.
  ...GALE WARNING FOR ANZ431-450>455 FROM 7 AM FRIDAY TO 10 PM
     FRIDAY.
&&

UPDATE...GORSE
OVERVIEW/NEAR TERM/SHORT TERM...GORSE
LONG TERM...GORSE/GIZOT
AVIATION/MARINE...NIERENBERG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
443 AM EST FRI DEC 9 2005

ANZ430-431-450>455-DEZ001>004-MDZ008-012-015-019-020-NJZ001-
007>010-012>027-PAZ054-055-060>062-067>071-101000-
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-MIDDLESEX-WESTERN MONMOUTH-EASTERN MONMOUTH-MERCER-SALEM-
GLOUCESTER-CAMDEN-NORTHWESTERN BURLINGTON-OCEAN-CUMBERLAND-
ATLANTIC-CAPE MAY-ATLANTIC COASTAL CAPE MAY-COASTAL ATLANTIC-
COASTAL OCEAN-SOUTHEASTERN BURLINGTON-CARBON-MONROE-BERKS-LEHIGH-
NORTHAMPTON-CHESTER-MONTGOMERY-BUCKS-DELAWARE-PHILADELPHIA-
443 AM EST FRI DEC 9 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EASTERN
PENNSYLVANIA, DELAWARE, THE NORTHERN MARYLAND EASTERN SHORE AND
NEW JERSEY, EXCLUDING THE FIVE NORTHEAST COUNTIES.

.DAY ONE...TODAY AND TONIGHT

WINTER WEATHER WARNINGS AND ADVISORIES ARE IN EFFECT UNTIL NOON
TODAY FOR MOST OF THE FORECAST AREA. PLEASE SEE THE LATEST
STATEMENTS FOR ADDITIONAL DETAILS. ALSO, A GALE WARNING IS IN
EFFECT FOR THE MARINE AREAS FROM 7 AM THIS MORNING THROUGH THIS
EVENING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO REPORT THEIR SNOWFALL AMOUNTS TODAY,
AND ANY HEAVY SNOWFALL RATES IF POSSIBLE.

GORSE