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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBOX 091514
AFDBOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1014 AM EST MON DEC 9 2013

.SYNOPSIS...
LOW PRESSURE LIFTING NORTH FROM THE MID ATLANTIC WILL BRING MIXED
PRECIP TODAY. ANOTHER DISTURBANCE MAY BRING ACCUMULATING SNOW
TUESDAY...MAINLY SOUTH OF THE MASSACHUSETTS TURNPIKE. MAINLY
DRY...BUT UNSEASONABLY COLD AND BLUSTERY WEATHER IS EXPECTED FOR
THE REST OF THE WEEK.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

-- Changed Discussion --
1010 AM UPDATE...

WE ALLOWED THE WINTER WEATHER ADVISORY TO EXPIRE ACROSS RHODE ISLAND
AND SOUTHEAST MA...AS ONSHORE FLOW HAS ALLOWED TEMPS TO RISE ABOVE
FREEZING.

WINTER WEATHER ADVISORIES CONTINUE ELSEWHERE WITH TEMPS BELOW
FREEZING INTO THE AFTERNOON.  PTYPE HAS TRANSITIONED TO MAINLY
FREEZING RAIN WITH SOME SLEET STILL BEING REPORTED AS MID LEVELS
TEMPS TO WARM.  THERE STILL WAS A BIT OF SNOW LEFT IN SOUTHERN
NH...BUT THAT TO SHOULD BE TRANSITIONING TO SLEET/FREEZING RAIN BY
NOON.  MOST LOCATIONS HAVE SEEN A HALF TO 1 INCH OF SNOWFALL...BUT A
FEW ISOLATED SPOTS IN SOUTHERN NH MAY SEE 2 INCHES.

THE STEADIEST PRECIP WILL EXIT THE COAST BY EARLY AFTERNOON...AS THE
LIFT BECOMES EVEN SHALLOWER.  HOWEVER...AREAS OF LIGHT
SHOWERS/DRIZZLE WILL CONTINUE ACROSS MUCH OF THE REGION INTO AT
LEAST MID AFTERNOON WITH THE SHALLOW LIFT AND SATURATED LOW LEVELS.
THE PROBLEM IS ACROSS PORTIONS OF THE INTERIOR...WHERE SOME AREAS
WILL NOT BREAK FREEZING. THIS WILL RESULT IN THE CONTINUATION OF
LIGHT FREEZING RAIN/FREEZING DRIZZLE INTO THE AFTERNOON. MOS
GUIDANCE IS TOO WARM AS SHALLOW COLD AIR IS LOCKED IN PLACE.  ICE
ACCRETION SHOULD BE LIGHT SO NOT EXPECTING TREE DAMAGE/POWER
OUTAGES...BUT UNTREATED ROADS/WALKWAYS WILL BE ICY INTO THE
AFTERNOON.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
WAVE LIFTS TO THE NORTH THIS EVENING WITH DRIER WESTERLY FLOW
DEVELOPING. EXPECT MAINLY DRY CONDITIONS WITH LOW CLOUDS
ERODING...ALTHOUGH MID/HIGH CLOUDS WILL BE MOVING IN OVERNIGHT.
LOW TEMPS WILL BE MOSTLY IN THE 20S...EXCEPT LOWER 30S NEAR THE
COAST.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
HIGHLIGHTS...

* PERIOD OF SNOW POSSIBLE SOUTH OF MA PIKE ON TUE
* MAINLY DRY AND UNSEASONABLY COLD WED THROUGH FRI
* LOW CONFIDENCE FORECAST NEXT WEEKEND

OVERVIEW AND MODEL PREFERENCES...
09/00Z MODEL LONG RANGE GUIDANCE SHOWS GOOD AGREEMENT IN SYNOPTIC
PATTERN THROUGH MUCH OF THE LONG TERM UNTIL THE WEEKEND...AT WHICH
POINT DIFFERENCES IN PHASING OF BOTH THE SRN AND NRN STREAM
CONTINUE SHOW. THEREFORE...HAVE GENERALLY MODERATE TO HIGH
CONFIDENCE THROUGH MUCH OF THE WORK WEEK...AND IN THE ARCTIC
AIRMASS SETTLING OVER THE REGION. WITH THIS AGREEMENT WILL
CONTINUE TO BASELINE WITH A CONSENSUS BLEND OF DETERMINISTIC
GUIDANCE...WPC...AND PERSISTENCE.

THE MAIN CAVEAT IN THE MID TERM WILL BE A FAST MOVING WAVE ON TUE
INITIATING A WEAK SFC FRONTAL WAVE ON A STALLED FRONTAL BOUNDARY
TO THE S. THIS LOOKS TO INITIATE SOME SNOWFALL ACROSS THE SRN HALF
OF THE REGION PER LATEST SOUNDINGS. THE KEY WILL BE THE BEST MID
LVL F-GEN BAND AND HOW FAR N IT IS ABLE TO TRAVEL. LATEST NAM IS
MUCH FURTHER N...WHILE THE ECMWF CONTINUES TO BE THE FARTHEST
OFFSHORE. GFS SEEMS LIKE A GOOD MIDDLE GROUND AS IT IS LESS ROBUST
WITH PRECIP THAN THE NAM...BUT A BIT HIGHER THAN THE CURRENT ECMWF
/WHICH HAS COME FURTHER N THAN PREVIOUS RUNS/ THEREFORE...WILL
LEAN CLOSER TO THE GFS FOR TUE...THE ONLY BREAK FROM THE BLEND
PROPOSED ABOVE FOR THIS UPDATE.

DETAILS...

TUE...MODERATE CONFIDENCE.
WILL BE MONITORING FOR A PERIOD OF SNOW PARTICULARLY S OF THE
MASS PIKE FROM ABOUT MID MORNING INTO THE AFTERNOON HOURS AS A
WEAK SFC FRONTAL WAVE INITIATES SOME MODEST MID LVL F-GEN BANDING
TO ITS N. WHILE THE EXACT PLACEMENT OF THIS BAND IS A LITTLE
UNCERTAIN...HAVE AT LEAST ENOUGH CONFIDENCE TO ERR TOWARD HIGH
CHANCE-LOW LIKELY POPS FOR THIS POTENTIAL. INTERESTINGLY...THE
LIFT PROVIDED BY THE F-GEN BAND IS LOCATED ALMOST PERFECTLY IN THE
-10C TO -20C LAYER WHICH IS ICE-SATURATED...SOMETHING THIS
MORNING/S STORM WAS LACKING. GIVEN THAT THIS WAVE LOOKS TO HAVE
GULF ORIGINS...QPF VALUES WITHIN THE BAND RANGE FROM 0.1-0.4
INCHES DEPENDING ON ITS TRACK. RATIOS MAY BE A BIT HIGHER DUE TO
WEAKER WINDS AND BETTER SNOW GROWTH EFFICIENCY COULD YIELD NEAR
ADVISORY LEVEL SNOWFALL FOR SOME AREAS IN CT/RI/SE MA...BUT THERE
IS ALSO A FAIR AMOUNT OF NEAR SFC DRY AIR TO OVERCOME. NOT
CONFIDENT IN THE BAND SETUP TO PULL THE TRIGGER...BUT SOMETHING
WORTH WATCHING. FURTHER N...MAY BE A SHARP CUTOFF ACROSS NRN MA
AND SRN NH WHERE LITTLE TO NO SNOW MAY BE OBSERVED. TEMPS MAY ALSO
BE AN ISSUE AS SOME MAY JUST INCH ABOVE FREEZING AS SNOWS TAPER
OFF...SO HAVE TO WATCH OUT FOR DYNAMIC COOLING WHICH COULD PROMOTE
SNOW ACCUM DESPITE TEMPS WARMING TO THE MID 30S.

TUE NIGHT INTO FRI...
PERIOD OF ANOMALOUS COLD AND MAINLY DRY WX PREVAILS AS 1040 HIGH
PRES SLIDES IN. ONLY FLY IN THE OINTMENT HERE IS A DRY PASSAGE OF
AN ARCTIC COLD FRONT ON WED NIGHT-THU INTRODUCING THE COLDER
TEMPS. THIS MAY LEAD TO A PERIOD OF OCEAN EFFECT SNOWS POSSIBLE
FOR THE CAPE/NANTUCKET AS V-COMPONENT TO THE WIND SHIFTS MORE
NORTHERLY BEHIND THE FRONT. AM NOTING H85 TEMPS DIPPING AS LOW AS
-18C TO -20C...SO SUSPECT HIGHS PARTICULARLY THU AND FRI MAY
STRUGGLE TO BREAK INTO THE 30S WHILE LOWS DIP BACK INTO THE SINGLE
DIGITS ACROSS MANY LOCATIONS. IN ESSENCE AVG TEMPS ABOUT 10-15
DEGREES BELOW NORMAL.

THIS COMING WEEKEND-EARLY NEXT WEEK...
AS MENTIONED ABOVE...GUIDANCE CONTINUES TO SHOW SIGNIFICANT
STRUGGLES REGARDING THE PHASING OF A NORTHERN AND SOUTHERN STREAM
SHORTWAVES WHICH ARE YET TO BE SAMPLED. LATEST DETERMINISTIC RUNS
ARE MORE SIMILAR TO PREVIOUS 00Z ITERATIONS...WITH THE ECMWF
PHASING THE TWO AND THE GFS NOT. ENSEMBLES SUPPORT BOTH NEARLY
EQUALLY AT THIS POINT. THE ECMWF/S PHASING SUPPORTS A COASTAL
STORM WHILE THE GFS IS AN INSIDE RUNNER BECAUSE IT TRANSITIONS THE
NRN WAVE INTO QUEBEC. WILL CONTINUE TO HIGHLIGHT SOME POPS FOR
MORE UNSETTLED WX FOR SUN...BUT BLEND THE WARM/COLD SOLUTIONS FOR
THE TIME BEING UNTIL THE WAVES ARE BETTER SAMPLED AND CONFIDENCE
BECOMES HIGHER IN ANY ATTENDANT LOW TRACK.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

NEAR-TERM /THROUGH TONIGHT/...

GENERALLY HIGH CONFIDENCE IN TRENDS TODAY...BUT LOWER CONFIDENCE
OF TIMING OF PRECIP TYPE CHANGES AND THE PRECIP/FOG ENDING THIS
EVENING-OVERNIGHT.

MAINLY IFR/MVFR TODAY. WIDESPREAD LIGHT MIXED PRECIP IS EXPECTED
TO CONTINUE THROUGH THE MORNING. THIS WILL INCLUDE A PERIOD OF
LIGHT SNOW AND FREEZING RAIN WITH LIGHT SNOW/ICE ACCUMULATIONS. IT
MAY ACTUALLY BE THAT FREEZING RAIN IS MORE OF A FREEZING DRIZZLE
MUCH OF THE DAY. THERE WILL BE A SLOW CHANGE FROM S TO N TO ALL
RAIN OVER THE NEXT SEVERAL HOURS BUT TIMING IN TAFS MAY BE OFF BY
A COUPLE OF HOURS. EXPECT THROUGH THE LATE AFTERNOON AND EVENING
FOR THE PRECIP TO GRADUALLY END AND FOG TO LIFT THROUGH THE
EVENING HOURS...LEADING TO VFR CONDITIONS OVERNIGHT.

KBOS TAF...HIGH CONFIDENCE IN MVFR/IFR CONTINUING. WITH WINDS OUT
OF THE E...MAINLY RAIN EXPECTED THROUGH THE MORNING VERY SOON.

KBDL TAF...HIGH CONFIDENCE IN MVFR/IFR CONTINUING. LOW CONFIDENCE
IN TIMING OF PTYPE TRANSITIONS. FREEZING PRECIP LIKELY LINGERS FOR
AT LEAST A FEW MORE HOURS YET.

OUTLOOK...MONDAY NIGHT THROUGH FRIDAY...

TUE...MODERATE CONFIDENCE.
A PERIOD OF SNOWFALL MAY LEAD TO IFR/MVFR CIGS/VSBYS AT TERMINALS
ESPECIALLY S OF THE MASS PIKE. SOME TERMINALS N MAY REMAIN VFR
MOST OF THE DAY /ESPECIALLY IN SRN NH/ CONDITIONS IMPROVE
EVERYWHERE DURING THE EVENING HOURS.

TUE NIGHT INTO FRI...HIGH CONFIDENCE.
MAINLY VFR THRUT. ONLY CAVEAT WILL BE THE POSSIBILITY OF
LOCALIZED MVFR CONDITIONS IN SOME OCEAN EFFECTS -SHSN/SHRA FOR
CAPE/ISLAND TERMINALS WITH THE BEST CHANCES WED NIGHT AND THU.
STRONG NW WIND GUSTS ALSO POSSIBLE LATE TUE NIGHT INTO WED NIGHT.
-- End Changed Discussion --

&&

.MARINE...
FORECASTER CONFIDENCE LEVELS...

LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.

NEAR-TERM /THROUGH TONIGHT/...HIGH CONFIDENCE.

A PERIOD OF EASTERLY WIND GUSTS TO 25-30 KT EXPECTED OVER THE
OPEN WATERS THROUGH THE MORNING...ESPECIALLY SOUTH OF THE COAST.
WINDS DIMINISH AND VEER TO THE S AND SE LATER TODAY.

ANOTHER PULSE OF G25 KT POSSIBLE THIS EVENING OVER THE OUTER
WATERS AS WINDS SHIFT TO THE WEST.

SMALL CRAFT ADVISORIES CONTINUE. AREAS OF RAIN/DRIZZLE AND FOG
WILL LIMIT VSBYS AT TIMES TODAY.

OUTLOOK...TUESDAY THROUGH FRIDAY...HIGH CONFIDENCE.

TUE...MODERATE CONFIDENCE.
SEAS GRADUALLY SLACKEN THROUGH THE DAY BUT MAY REMAIN ABOVE 5 FT
ON THE ERN OCEAN WATERS. WINDS GENERALLY BELOW 20 KT SAVE FOR A
FEW STRONGER GUSTS ON NRN WATERS. SOME SMALL CRAFT ADVISORIES MAY
REMAIN FOR SEAS ALONE.

TUE NIGHT INTO FRI...HIGH CONFIDENCE IN TRENDS BUT LOWER
CONFIDENCE IN EXACT TIMING OF ANY HEADLINES.
A PROLONGED PERIOD OF AT LEAST SMALL CRAFT ADVISORY CONDITIONS
LOOKS LIKELY THROUGH THIS PERIOD AS W-NW WINDS WILL OFTEN REMAIN
25 KT OR HIGHER THROUGH THE PERIOD WITH SEAS 5-8FT ON THE OUTER
WATERS. THERE IS ALSO THE LOW PROBABILITY THAT OCCASIONAL GALE
FORCE WIND GUSTS OCCUR LATE TUE NIGHT AND AGAIN THU NIGHT.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR CTZ002.
     WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
     CTZ003-004.
MA...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR
     MAZ002>004-008>011-026.
     WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
     MAZ005-006-012>014.
NH...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NHZ011-
     012-015.
RI...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR
     RIZ001.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
     ANZ231>234.
     SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR ANZ230.
     SMALL CRAFT ADVISORY UNTIL 7 AM EST TUESDAY FOR ANZ235-237-250-
     254>256.
     SMALL CRAFT ADVISORY UNTIL 1 AM EST TUESDAY FOR ANZ251.
-- End Changed Discussion --

&&

$$
SYNOPSIS...KJC/DOODY
NEAR TERM...FRANK
SHORT TERM...KJC
LONG TERM...DOODY
AVIATION...KJC/DOODY
MARINE...KJC/DOODY