Potential Historic Three Day New Years' Snowstorm Update 2

000
FXUS61 KCAR 312044
AFDCAR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CARIBOU ME
344 PM EST THU DEC 31 2009

.SYNOPSIS...
-- Changed Discussion --A COMPLEX LOW PRESSURE SYSTEM WILL AFFECT THE REGION THROUGH THE
UPCOMING HOLIDAY WEEKEND. THE FIRST OF TWO AREAS OF LOW PRESSURE
WILL MOVE NORTHEAST FROM THE MID ATLANTIC STATES EARLY THIS EVENING
TO A POSITION SOUTH OF WESTERN NOVA SCOTIA BY LATE FRIDAY BEFORE
DISSIPATING. A SECOND...STRONGER AREA OF LOW PRESSURE WILL DEVELOP
WELL SOUTH OF NOVA SCOTIA LATER FRIDAY NIGHT. THIS SYSTEM WILL THEN
INTENSIFY AS IT MOVES BACK NORTHWEST TOWARDS MAINE ON SATURDAY AND
IS EXPECTED TO REACH A POSITION NEAR THE COAST OF MAINE BY LATER
SATURDAY NIGHT. THIS SYSTEM WILL THEN DRIFT SOUTH ACROSS THE GULF OF
MAINE ON SUNDAY AND EVENTUALLY WEAKEN AND DRIFT NORTHEASTWARD INTO
THE CANADIAN MARITIMES THROUGH EARLY NEXT WEEK.-- End Changed Discussion --
&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
-- Changed Discussion --MODELS FINALLY COMING INTO SOME KIND OF AGREEMENT CONCERNING TRENDS
FOR THE NEXT FEW DAYS W/ OUR AREA TO BE AFFECTED BY TWO DISTINCT
SYSTEMS... THE FIRST INVOLVES A WAVE OF LOW PRES WHICH IS CURRENTLY
DEVELOPING FROM THE SRN NEW ENGLAND COAST SW TO JUST OFF THE MID
ATLC COAST. THIS LOW IS FCST TO TRACK NE TO A POSN JUST S OF WRN NS
BY LATE FRI BEFORE DISSIPATING. THIS SYSTEM ALREADY SPREADING SOME
LGT SNOW ACROSS FAR SWRN MAINE ATTM W/ LGT TO OCNLY MDT SNOW NOW
BEING RPTD. THIS AREA WILL LIFT NEWRD NXT 12-24 HRS...REACHING OUR
SWRN ZNS LATER THIS AFTN AND FAR NERN ZNS LATE TNGT/ERLY FRI.
GENERALLY XPCTG A LGT SNOW THIS EVENT W/ SOME MDT SNOW PSBL FAR SRN
AND SWRN AREAS. ACCUMS XPCTD TO RANGE FROM A FEW INCHES FAR NE TO
AS MUCH AS 7-8 INCHES FAR SW. HOWEVER...THESE SNOW ACCUMS SPREAD
OUT OVR 36 HRS SHOULD CREATE ONLY MINOR TRAVEL DIFFICULTIES AND
HEADACHES SPCLY SINCE STRONG WNDS AND SIGNIFICANT BLOWING/DRIFTING
NOT ANTICIPATED ATTM. THUS...HAVE DECIDED TO DROP THE WNTR STORM
WATCH FOR THIS FIRST WAVE AND WILL GO W/ A WNTR WX ADV FOR SRN AND
CNTRL SECTIONS TNGT THRU SAT AM AND FRO THE N AND NE FRI AM THRU SAT
AM.

THE MORE SUBSTANTIAL SNOW AND WND EVENT NOW APPEARS ON TAP FOR LATER
SAT INTO SUN AS STRONGER LOW PRES BACKS IN FROM THE SE AND MORE
DETAILS ON THIS EVENT FOLLOW IN THE SHORT TERM SECTION.-- End Changed Discussion --
&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
-- Changed Discussion --PRESSURE IS EXPECTED TO INTENSIFY TO THE SOUTHEAST OF THE GULF OF
MAINE AT THE BEGINNING OF THIS FORECAST PERIOD. AT THE SAME TIME
UPPER LEVEL LOW PRESSURE WILL BE LOCATED OVER CENTRAL PENNSYLVANIA
AN RAPIDLY MOVING TO THE EAST. THIS SYSTEM WILL EVENTUALLY MOVE
OVER THE GULF OF MAINE SATURDAY NIGHT AND CAPTURE THE SURFACE LOW
PRESSURE SYSTEM. ONCE CAPTURED BY THE UPPER LOW...THE SURFACE LOW
WILL DRIFT WEST THEN SOUTHWEST WARD LATE SATURDAY INTO SUNDAY.
THIS WILL RESULT IN A FLOW OF MOISTURE OFF THE ATLANTIC INTO THE
FORECAST AREA AND DEVELOP A THERMAL GRADIENT EXTENDING FROM NEW
BRUNSWICK INTO MAINE AS WARMER MARITIME AIR MOVE WESTWARD TO THE
NORTH OF THE SURFACE LOW WITH HEAVIEST PRECIPITATION DEVELOPING IN
THIS FRONTAL AREA. HAVE USED A BLEND OF THE NAM12 AND GFS40 TO
INITIALIZE QPF AMOUNTS. HAVE MADE SOME MANUAL ADJUSTMENT ON
QPF...THEN DEVELOPED SNOW AMOUNTS FROM QPF USING A 10:1 RATIO.
WILL KEEP WINTER STORM WATCH IN PLACE FOR THIS TIME FRAME. FOR
WIND HAVE INITIALIZED GRIDS WITH NAM12 AND HAVE MADE SOME MANUAL
CHANGES TO LOWER SOME OF THE HIGHER NUMBERS. FOR TEMPERATURE AND
DEW POINT HAVE USED GMOS BUT WILL LOWER SOME HIGHER TEMPERATURES
ALONG COAST SUNDAY.-- End Changed Discussion --
&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
-- Changed Discussion --SUNDAY NIGHT THE STORM SHOULD STILL BE IN THE AREA. EXPECT SNOW TO
CONTINUE WITH WINDY CONDITIONS...GUSTS ON SUNDAY NIGHT COULD STILL
REACH UP TO 30 MPH. MONDAY MORNING THE STORM SYSTEM STILL HANGS
AROUND IN THE CANADIAN MAIRTIMES AND WITH THE FLOW AROUND THE SYSTEM
WILL CONTINUE TO CARRY CHANCE POPS FOR SNOW ACROSS MOST OF THE CWA.
EXPECT CLOUDY SKIES ESPECIALLY IN THE NORTHERN PARTS OF THE CWA TO
HANG AROUND THE ENTIRE FORECAST PERIOD. MONDAY NIGHT INTO TUESDAY
THINGS BEGIN TO CALM DOWN A LITTLE BIT. THE REMNANTS OF THE STORM
STILL CONTINUE TO SPIN WELL NORTH OF THE CWA THE FLOW AROUND TAHT
COULD STILL TRIGGER A FEW SNOW SHOWERS IN THE NORTHERN PARTS OF THE
CWA. WEDNESDAY AND THURSDAY EXPECT CLOUDY SKIES TO PREVAIL IN THE
NORTH AND LOOKS FOR SOME CLEARING DOWNEAST. STILL CANNOT RULE OUT A
CHANCE OF A STRAY SNOW SHOWER IN THE NORTHWESTERN PARTS OF THE CWA.
USED GMOS FOR TEMPERATURES THROUGHOUT THE FORECAST PERIOD AND
ADJUSTED AS NEEDED.-- End Changed Discussion --
&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
-- Changed Discussion --NEAR TERM: GENERALLY MVFR CONDS ACROSS OUR TAF SITES ATTM... XPCT
CONDS TO GRADUALLY LOWER TO IFR AT ALL TAF SITES LATER THIS AFTN
DOWN SOUTH AND ACROSS THE N LATER TNGT OR FRI. PERIODS OF MAINLY
LGT SNOW TO AFFECT THE REGION THRU FRI NGT W/ CONDS VARYING FROM
IFR TO LOW MVFR... MORE SUBSTANTIAL SNOW/WND DEVELOPS ACROSS THE
REGION ON SAT W/ WDSPRD IFR XPCTD ALL TAF SITES SAT THRU SUN.

SHORT TERM: EXPECT IFR CONDITIONS SATURDAY THROUGH SUNDAY.
CONDITIONS IMPROVING TO MVFR/VFR MONDAY AND TUESDAY.-- End Changed Discussion --
&&

.MARINE...
-- Changed Discussion --NEAR TERM: BENIGN WNDS/SEAS AT THIS TIME W/ INCRSG WNDS/SEAS XPCTD
LATER TNGT THRU FRI - CONTG THRU FRI NGT. GLW CONDS XPCT BY SAT
AFTN SO HAVE DROPPED THE GLW WTCH IN FAVOR OF A GLW WRNG AND W/
THE GLW WRNG IN PLACE...WILL NOT CARRY ANY SCA HEADLINES IN THE
NEAR TERM.

SHORT TERM: FOR WINDS HAVE USED A 50/50 BLEND OF THE NAM12 AND
GFS40. WILL INCREASE THE WIND SPEED SEVERAL KNOTS AS LOW PRESSURE
INTENSIFIES OFF SHORE AND DRIFTS TO THE WEST. FOR WAVE: HAVE
INITIALIZED GRIDS WITH WNA/4. SPECTRAL DATA INDICATES VERY LITTLE
LONG PERIOD WAVE DEVELOPING AHEAD OF THIS SYSTEM. WAVE MODEL WIND
SPEED MAY HOWEVER BE UNDER ESTIMATED RESULTING IN WAVE FIELD
UNDERESTIMATE. HAVE ADJUSTED WAVE HEIGHTS CLOSER TO NAM SWAM WAVE
HEIGHTS. WILL ISSUE GALE WARNING FOR SATURDAY.-- End Changed Discussion --
&&

.TIDES/COASTAL FLOODING...
-- Changed Discussion --CONCERN DUE TO EXTREMELY HIGH ASTRONOMICAL TIDE LATE SATURDAY MORNING.
AS LOW PRESSURE BACKS IN TO COAST SATURDAY WIND SPEEDS SUFFICIENT
FOR 1 TO 2 FOOT STORM SURGE. THIS COMBINED WITH VERY HIGH
ASTRONOMICAL TIDE COULD BRING STORM SURGE ABOVE 14 FEET AT BAR
HARBOR TIDE STATION. WILL ALSO MONITOR BANGOR TIDES.-- End Changed Discussion --
&&

.CAR WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --ME...WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SUNDAY
EVENING FOR MEZ001>006-010-011-015>017-029>032.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 7 AM EST
SATURDAY FOR MEZ003>006-010-011-015>017-029>032.
COASTAL FLOOD WATCH FROM SATURDAY MORNING THROUGH SATURDAY
AFTERNOON FOR MEZ029-030.
MARINE...GALE WARNING FROM 1 PM TO 10 PM EST SATURDAY FOR ANZ050>052.-- End Changed Discussion --

&&