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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBOX 100844
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
345 AM EST WED FEB 10 2010

.SYNOPSIS...
-- Changed Discussion --
A RAPIDLY INTENSIFYING COASTAL STORM WILL BRING SIGNIFICANT SNOW AND
STRONG WINDS TO PORTIONS OF SOUTHERN NEW ENGLAND TODAY AND THIS
EVENING...WITH AREAS ALONG AND SOUTH OF THE MASS TURNPIKE MOST AT
RISK FOR SUBSTANTIAL AMOUNTS. HIGH PRESSURE THEN BRINGS DRY AND
SEASONABLY COLD WEATHER THURSDAY INTO THIS WEEKEND. ANOTHER LOW
PRESSURE MAY SWIFTLY PASS US TO THE SOUTH SOMETIME MONDAY INTO
MONDAY NIGHT.
-- End Changed Discussion --

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
QUITE A BIT OF UNCERTAINTY STILL EXISTS WITH RESPECT TO POTENTIAL
SNOWFALL AMOUNTS FOR TODAY AND TONIGHT...BUT CONFIDENCE HAS INCREASED
IN A SIGNIFICANT SNOWSTORM FOR LOCATIONS ALONG AND SOUTH OF THE MASS
PIKE. BASED ON LATEST TRENDS...WE TEND TO FAVOR A BLEND OF THE
00Z GGEM/ECMWF/SREF/GFS. THIS AMOUNTS TO A SIMILAR FORECAST TO THE
PREVIOUS ONE...WITH LITTLE IN THE WAY OF CHANGES TO THE FORECAST
PACKAGE. MAX SNOW AMOUNTS ARE STILL EXPECTED CLOSER TO THE SOUTH
COAST OF RI/MASS AS WELL AS PORTIONS OF CT...AS THIS IS WHERE THE
MOST ORGANIZED SNOW BANDING IS EXPECTED TO TAKE SHAPE LATER THIS
MORNING INTO THE AFTERNOON HOURS.

AS OF 08Z EARLY THIS MORNING...LIGHT SNOW WAS GRADUALLY PROGRESSING
NORTHWARD ACROSS COASTAL CT. AS A POTENT SHORT WAVE TROUGH NEAR THE
OH VALLEY ROLLS EASTWARD TODAY...SFC LOW PRESSURE SOUTH OF LONG
ISLAND SHOULD RAPIDLY INTENSIFY. THIS WILL ALLOW FOR THE
PRECIPITATION FIELD TO BECOME MORE INTENSE AND ORGANIZED WHILE MOVING
INTO SOUTHERN NEW ENGLAND LATER THIS MORNING. WE THINK THE MORNING
RUSH HOUR WILL BE DRY FOR THE MOST PART...EXCEPT FOR SOME LIGHT SNOWS
POSSIBLY BREAKING OUT OVER SOUTHERN ZONES. THE HEAVIEST SNOWFALL IS
NOT EXPECTED TO ARRIVE UNTIL AFTER THE MORNING RUSH.

THE MAIN QUESTION IS /AND HAS BEEN/ HOW FAR NORTH DOES THE HEAVY
PRECIPITATION PROGRESS. THAT/S A HARD QUESTION TO ANSWER SINCE THIS
WILL RELY ON RATHER FICKLE MESOSCALE PROCESSES. BASED ON THE LATEST
DATA WE HAVE STUDIED OVERNIGHT...IT APPEARS AS THOUGH THE MASS PIKE
MAY BE A GOOD DEMARCATION LINE BETWEEN THE LIGHTER SNOWS AND THE REAL
HEAVY STUFF. HOWEVER...WOULD NOT BE SURPRISED IF IT ENDS UP NORTH OF
THERE FOR A TIME WHICH IS IN LINE WITH CLIMATOLOGY. WE TOOK THIS INTO
ACCOUNT IN OUR SNOWFALL GRIDS.

THE SNOWFALL GRADIENT NEAR THE NORTHERN END OF THE PRECIPITATION
SHIELD WILL PROBABLY BE SHARPER THAN FORECAST. FOR EXAMPLE...WE
WOULDN/T BE SURPRISED IF ONE LOCATION SEES A 12 TO 13 INCH
SNOWFALL...BUT A LOCATION 10 MILES TO THE NORTH SEES LESS THAN HALF
OF THAT. THIS COULD OCCUR AS FAR SOUTH AS THE SOUTH COAST...OR
FURTHER NORTH TOWARD THE MASS PIKE. THEREFORE...THERE REMAINS DECENT
BUST POTENTIAL DEPENDING ON LOCATION OF BANDING. NEXT SHIFT WILL BE
ABLE TO BETTER ASSESS THESE FACTORS AS THE STORM REALLY STARTS
GETTING IT/S ACT TOGETHER AND POTENTIALLY FINE TUNE THIS THINKING.
OUT LATEST SNOWFALL FORECAST MAP POSTED TO A WEB GIVES A GOOD GENERAL IDEA
OF WHAT TO EXPECT...ALTHOUGH SOME WILL SEE MORE AND SOME WILL SEE
LESS.

BASED ON THE THINKING ABOVE...WE HAVE CONVERTED MUCH OF THE REMAINING
WINTER STORM WATCH OVER TO AN ADVISORY WHERE 4-6 INCHES OF SNOW WILL
PROBABLY FALL. HOWEVER...WE THINK A GOOD PORTION OF SOUTHERN NEW
HAMPSHIRE WILL FALL SHORT OF THEIR 4-INCH AVERAGE ADVISORY
CRITERIA...SO WE LEFT THEM OUT FOR NOW. WE INCLUDED MIDDLESEX COUNTY
IN THE WINTER STORM WARNING MAINLY DUE TO THE FACT THAT WE THINK THE
SOUTHERN HALF OF THE COUNTY NEAR THE MASS PIKE WILL SEE AT LEAST
MARGINAL WARNING CRITERIA. THERE WILL PROBABLY BE A SHARP SNOWFALL
GRADIENT ACROSS THE COUNTY WITH THE NORTHERNMOST PORTION GETTING
QUITE A BIT LESS THAN WHEN THEY GET IN FRAMINGHAM FOR INSTANCE.

THE SNOW MAY FALL AT A 1 TO 3 INCH PER HOUR CLIP FOR A TIME ACROSS
SOUTHERN ZONES THIS AFTERNOON...AND SOME OF THIS WILL BE HEAVY WET
SNOW. THEREFORE...POWER OUTAGES MAY BECOME AN INCREASING THREAT AS
ONE HEADS CLOSER TO THE COAST. DID NOT MENTION THUNDER IN THE
FORECAST...BUT ISOLD +TSSN CANNOT BE RULED OUT IN HEAVIER BANDING.

WINDS WILL BECOME AN ISSUE...ESPECIALLY THIS EVENING NEARER TO THE
COAST. THIS MAY CREATE NEAR-BLIZZARD CONDITIONS AT TIMES IN PORTIONS
OF RI AND SE MASS. DID NOT FEEL CONFIDENT IN ACTUAL BLIZZARD CRITERIA
BEING MET AT ANY ONE LOCATION...BUT THAT WOULD BE SOMETHING TO WATCH
OVER THE COURSE OF THE DAY.

NANTUCKET AND THE OUTER CAPE WILL PROBABLY SEE A DELAY IN WINTER STORM
CONDITIONS DUE TO RAIN OR A MIX. THEREFORE...WE PUSHED BACK THE
WARNING START TIME ON NANTUCKET UNTIL 20Z. THE HIGH WIND WARNING
REMAINS THE SAME.

THE EVENING RUSH HOUR WILL BE QUITE TREACHEROUS TO SAY THE
LEAST...ESPECIALLY ALONG AND SOUTH OF THE MASS PIKE.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
THE BULK OF THE NASTIEST WEATHER WILL OCCUR BETWEEN 00Z AND 05Z THIS
EVENING...THEN MOVE QUICKLY OUT TO SEA. THE HEAVIEST SNOWFALL DURING
THE EVENING HOURS WILL PROBABLY BE OVER SOUTHEASTERN MASS AND
PORTIONS OF MASS. DAMAGING WINDS WILL BE LIKELY ACROSS THE CAPE AND
ISLANDS AS THE NORTHEASTERLY LLJ REALLY RAMPS UP FOR A TIME. THIS MAY
COINCIDE WITH HEAVY SNOW...THEREFORE...A PORTION OF THE WINTER STORM
WARNING AREA MAY HAVE TO BE UPGRADED TO A BLIZZARD WARNING IF IT
LOOKS LIKE ALL THE CRITERIA WILL BE MET.

ALL PRECIP ENDS AFTER MIDNIGHT...ALLOWING FOR A DRY RUSH HOUR
THURSDAY MORNING.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --
WESTERN EDGE OF THE COMMA HEAD WILL BE MOVING EAST OF THE CAPE AND
ISLANDS BY 12Z THU SO MAINLY A DRY DAY EXPECTED.  THERE MAY BE A FEW
OCEAN EFFECT FLURRIES/SNOW SHOWERS LINGERING OVER THE CAPE...BUT
INSTABILITY IS MARGINAL AND INVERSION IS RATHER LOW SO PROBABLY
NOTHING MORE THAN A FEW FLURRIES.  RH TIME SECTIONS SUGGEST LOTS OF
SC WILL PERSIST...ESPECIALLY SE MA AND CAPE/ISLANDS WITH PARTIAL
SUNSHINE DEVELOPING IN THE INTERIOR IN THE AFTERNOON.

WINDS WILL BE A PROBLEM IN THE MORNING WITH OUR MIXING TOOL SHOWING
POTENTIAL FOR 40-50 MPH GUSTS LINGERING OVER THE CAPE/ISLANDS...BUT
WINDS WILL BE DIMINISHING BY MIDDAY AS LLJ AXIS SHIFTS EAST...BUT
STILL BREEZY ACROSS ALL SNE WITH STRONG GRADIENT IN PLACE.  UNDERCUT
MAV GUIDANCE BY A FEW DEGREES BASED ON RAW 2M TEMPS AND EXPECTED
CLOUD COVER FOR AT LEAST THE MORNING.

THU NIGHT...NOT MUCH CHANGE WITH A FEW OCEAN EFFECT FLURRIES
POSSIBLE ON THE CAPE.  OTHERWISE MOCLDY SKIES GIVEN LOW LEVEL
MOISTURE IN PLACE.  WINDS DIMINISH BUT STILL BREEZY IN THE
EVENING.

WEATHER LOOKS FAIRLY TRANQUIL FRI THROUGH THE WEEKEND WITH PERIODS
OF CLOUDS AND MODEST NW FLOW BUT MAINLY DRY.  MEAN UPPER TROF
REMAINS ACROSS THE NE WITH SOME AMPLIFICATION SAT AS STRONG
SHORTWAVE ROTATES AROUND WELL TO THE SOUTH BUT ASSOCIATED COASTAL
STORM EXPECTED TO REMAIN WELL SOUTH OF NEW ENG.  TEMPS AT OR
SLIGHTLY BELOW NORMAL.

GFS AND EC SHOW ANOTHER POTENT MID LEVEL LOW MOVING TO THE MID ATLC
COAST MON WITH COASTAL DEVELOPMENT.  GFS FURTHER NORTH THAN EC/UKMET
BUT VORTEX OVER THE MARITIMES WOULD SEEM TO FAVOR A MORE SUPPRESSED
SOLUTION.  STILL LOTS OF UNCERTAINTY ON HOW THIS SCENARIO WILL PLAY
OUT AS STRENGTH/POSITION OF THE PV WILL LIKELY DETERMINE EVENTUAL
OUTCOME.  WE JUST HAVE LOW CHC POPS FOR MON.
-- End Changed Discussion --

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
EARLY MORNING...
VFR ACROSS SOUTHERN NEW ENGLAND AT 06Z BUT WITH A SHARP TRANSITION TO
IFR ON LONG ISLAND IN DEVELOPING SNOW. THIS WILL SHIFT NORTH AND
LIKELY REACH CONNECTICUT AND SOUTHERN RI BY 12Z. BAF AND BDL...BEING
ON THE EDGE...MAY JUST REACH MVFR BY THAT TIME.

TODAY...
HIGH CONFIDENCE ON IFR CONDITIONS ALL AREAS. MODERATE TO HIGH
CONFIDENCE IN LIFR CONDITIONS BOS-PVD-ORH-BDL IN HEAVY SNOW. UPSTREAM
CONDITIONS OVER NY/NJ SHOW CIGS AROUND 5O0 FEET AND VSBYS 1/2 MILE TO
1 MILE IN SNOW. THESE EXTRAPOLATE TO TAF SITES ROUGHLY 15Z-18Z.
NANTUCKET AND THE EASTERN CAPE MAY BE LIMITED BY A CHANGE TO RAIN SO
THAT VSBYS THERE WILL BE CLOSER TO 1 MILE THIS AFTERNOON. LOWEST
CONDITIONS SHOULD FOCUS IN THE 18Z-00Z TIME FRAME...THE LIFT ALOFT IS
FORECAST TO WEAKEN AFTER 00Z.

STRONG NORTHEAST WINDS ALOFT ARE ALSO FORECAST TO MOVE IN DURING THE
18Z-00Z TIME PERIOD. FORECAST VALUES AT 950 MB /ROUGHLY 2000 FEET/
SHOW 40 KNOTS ALOFT AT BOS AND PVD WITH 45-55 KNOTS OVER FMH-HYA-ACK.
HIGH CONFIDENCE OF LOW LEVEL WIND SHEAR OVER CAPE COD AND THE
ISLANDS...LOW TO MODERATE CONFIDENCE OVER BOS AND PVD.

TONIGHT...
INITIAL IFR CONDITIONS IN SNOW...BUT WITH A TREND TO IMPROVEMENT.
CONDITIONS IMPROVE TO MVFR 02Z-04Z IN THE WEST AND 05Z-08Z IN THE
EAST.

CONTINUED STRONG WINDS ALOFT WITH GUSTS 50-55 KNOTS POSSIBLE CAPE AND
ISLANDS AND 40 KNOTS BOS AND PVD...LESSER GUSTS FARTHER WEST.

OUTLOOK...THURSDAY THROUGH SUNDAY...

THURSDAY...CONDITIONS IMPROVING TO VFR...BUT AREAS OF MVFR CIGS MAY
PERSIST AT HYA/ACK.  GUSTS TO 35-40 KT MAY LINGER THROUGH MID
MORNING HYA-ACK BEFORE DIMINISHING.

FRIDAY INTO SUNDAY...HIGH CONFIDENCE VFR.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
TODAY AND TONIGHT...AS LOW PRES RAPIDLY DEVELOPS S OF NEW ENGLAND
AND PUSHES NEAR 40N LATITUDE...EXPECT E-NE WINDS TO QUICKLY INCREASE
TO GALE FORCE WED AFTERNOON...THEN SOME STORM FORCE GUSTS ON THE
OUTER WATERS MAINLY NEAR AND S OF CAPE COD AND THE S COAST WHERE THE
STRONG LOW LEVEL JET PASSES. HAVE CONTINUED A STORM WARNING FOR
THOSE AREAS AND GALES ELSEWHERE...MAINLY FOR THIS EVENING. SEAS WILL
BE ROUGH.

OUTLOOK...THURSDAY THROUGH SUNDAY...
N/NW GALES WILL DIMINISH TO SCA FROM WEST TO EAST DURING THU MORNING
POSSIBLY LINGERING UNTIL TIL EARLY AFTERNOON WATERS EAST OF CAPE COD
AND ACK.  THEN PERIODS OF SCA NW FLOW WILL LIKELY CONTINUE THROUGH
THE WEEKEND WITH SCA SEAS ALSO PERSISTING OVER OUTER WATERS.
-- End Changed Discussion --

&&

.TIDES/COASTAL FLOODING...
-- Changed Discussion --
TIDES WILL PEAK AT 2-2.5 FT ABOVE NORMAL ACROSS THE EASTERN MA COAST
TONIGHT INTO THU MORNING WITH 20 FT SEAS DEVELOPING OFFSHORE BY LATE
WED NIGHT.  FORTUNATELY...ASTRO TIDES ARE RELATIVELY LOW DURING THIS
PERIOD WHICH WILL LIMIT THE FLOOD POTENTIAL.  THE WORST CASE
SCENARIO IS FOR SPLASHOVER OR MINOR COASTAL FLOODING FOR THIS
EVENING AND THU MORNING HIGH TIDE CYCLES ACROSS EAST COASTAL MA.
THE THURSDAY MORNING HIGH TIDE MAY BE MORE VULNERABLE AS IT IS THE
HIGHER OF THE 2 TIDE CYCLES.
-- End Changed Discussion --

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...WINTER STORM WARNING FROM 8 AM THIS MORNING TO 1 AM EST
     THURSDAY FOR CTZ002>004.
MA...WINTER STORM WARNING FROM 8 AM THIS MORNING TO 1 AM EST
     THURSDAY FOR MAZ005-008>023.
     HIGH WIND WARNING FROM 6 PM THIS EVENING TO 5 AM EST THURSDAY
     FOR MAZ022>024.
     WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO 1 AM EST
     THURSDAY FOR MAZ024.
     WINTER WEATHER ADVISORY FROM 10 AM THIS MORNING TO 1 AM EST
     THURSDAY FOR MAZ002>004-006-007-026.
NH...NONE.
RI...WINTER STORM WARNING FROM 8 AM THIS MORNING TO 1 AM EST
     THURSDAY FOR RIZ001>008.
MARINE...STORM WARNING FROM 6 PM THIS EVENING TO 5 AM EST THURSDAY FOR
     ANZ231-232-250-254>256.
     GALE WARNING FROM 1 PM THIS AFTERNOON TO 7 AM EST THURSDAY FOR
     ANZ230-233>237-251.

&&

$$
SYNOPSIS...EKSTER
NEAR TERM...EKSTER
SHORT TERM...EKSTER
LONG TERM...KJC
AVIATION...WTB/KJC
MARINE...KJC/EKSTER
TIDES/COASTAL FLOODING...