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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBTV 111756
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
1256 PM EST WED DEC 11 2013

.SYNOPSIS...
SNOW SHOWERS AND SNOW SQUALLS ARE EXPECTED THIS AFTERNOON AND
EVENING AHEAD OF AN ARCTIC COLD FRONT. FOLLOWING THE FRONTAL
PASSAGE...HIGHS ON THURSDAY WILL ONLY BE IN THE TEENS...AND IT
WILL ONLY BE SLIGHTLY MILDER ON FRIDAY. THERE WILL ALSO BE A FEW
SNOW SHOWERS EACH DAY. A STORM SYSTEM WILL AFFECT THE REGION LATE
SATURDAY INTO SUNDAY...BRINGING THE POSSIBILITY OF A WIDESPREAD
SNOW.

&&

.NEAR TERM /UNTIL 8 PM THIS EVENING/...
AS OF 914 AM EST WEDNESDAY...INTERESTING SETUP TODAY WITH INCREASING
LOW-LEVEL WSWLY FLOW FROM THE ERN GREAT LAKES IN ADVANCE OF ARCTIC
FRONT SAGGING SWD FROM THE OTTAWA VALLEY. THE ARCTIC FRONT WILL
INCREASINGLY INTERACT WITH THIS BETTER LOW-LEVEL MOISTURE AND
INSTABILITY (SURFACE-BASED CAPE 50-100 J/KG) TO YIELD HEAVIER
SNOW SHOWERS AND SNOW SQUALLS ALONG THE ARCTIC BNDRY THIS AFTN.
THIS WILL YIELD SLOW TRAVEL AROUND THE EVENING COMMUTE.

IN THE MEANTIME...THE INCREASING GREAT LAKES MOISTURE WILL BRING A
GRADUAL INCREASE IN SNOW SHOWER ACTIVITY ACROSS SRN ST. LAWRENCE
AND FRANKLIN INTO ESSEX NY COUNTIES. THE BACKGROUND FLOW IS STRONG
ENOUGH THAT THE UPSLOPE FLOW WILL BRING INCREASING SNOW SHOWER
ACTIVITY INTO THE CENTRAL GREEN MTNS INCLUDING ERN
ADDISON/WASHINGTON AND WRN ORANGE COUNTIES. INCREASED SNOW AMTS IN
THESE AREAS TO 3-4" TODAY...AND WOULDN`T BE SURPRISED TO SEE SOME
LOCALIZED HIGHER AMTS. ELSEWHERE...A CHANCE OF SNOW SHOWERS THRU
EARLY AFTN...THEN WE`LL SEE SNOW SQUALLS AS ARCTIC BNDRY MOVES
INTO THE NORTHERN ZONES. NAM SHOWS EXCELLENT 1-2KM UVV ALONG THE
FRONT INTERSECTING A SATURATED DENDRITE GROWTH LAYER (-12 TO 18C).
20-30 MINUTE PERIOD OF HEAVY SNOW POSSIBLE AT BTV BETWEEN 21-22Z
AND SURROUNDING AREAS OF NRN ZONES...AND THEN CLOSER TO 23-00Z
FURTHER SOUTH AS FRONTAL BOUNDARY HEADS SWD. COULD BE A SLOW
EVENING COMMUTE DUE TO THE SQUALLS AND QUICK 1-2" SNOW
ACCUMULATION IN THE CHAMPLAIN VALLEY...AND WE/LL HIGHLIGHT
ACCORDINGLY VIA SPS/SOCIAL MEDIA. BRISK SOUTHWEST TO WEST WINDS
GUSTING 20 TO 30 MPH WILL FURTHER REDUCE VISIBILITIES IN SNOW
SHOWERS OR SQUALLS. MAX TEMPERATURES TODAY WILL BE MOSTLY IN THE
MID-UPR 20S.

&&

.SHORT TERM /8 PM THIS EVENING THROUGH FRIDAY/...
AS OF 412 AM EST WEDNESDAY...THREAT OF SNOW SHOWERS WILL CONTINUE
THROUGH AROUND 06Z AS THE FRONT CONTINUES TO PUSH FURTHER SOUTH.
BEHIND THE FRONT...IT WILL BE NOTICEABLY COLDER WITH LOW
TEMPERATURES BY MORNING EXPECTED TO BE IN THE SINGLE NUMBERS
ACROSS MUCH OF THE REGION...WITH NORMALLY COLDER PORTIONS OF
ADIRONDACKS AND NORTHEAST KINGDOM DIPPING BELOW ZERO AS WINDS
ABATE AND WE SEE SOME PARTIAL CLEARING.

THURSDAY IS STILL SHAPING UP TO THE COLDEST DAY OF THE WEEK. WITH
850 MB TEMPS ONLY AROUND -20C DURING THE AFTERNOON...WE CAN EXPECT
HIGHS ONLY IN THE TEENS. CHANCE OF SNOW SHOWERS THURSDAY WILL BE
HIGHEST OVER THE SOUTHERN SAINT LAWRENCE VALLEY AND THE
ADIRONDACKS AS FLOW BECOMES WESTERLY ONCE AGAIN...ALLOWING FOR
SOME LAKE EFFECT MOISTURE TO RETURN.

CHANCES FOR SNOW SHOWERS INCREASE THURSDAY NIGHT INTO FRIDAY
MORNING ONCE AGAIN AS YET ANOTHER COLD FRONT DROPS SOUTH ACROSS
THE AREA. WEST-SOUTHWEST FLOW IN ADVANCE OF THE FRONT SHOULD ALLOW
FOR SUFFICIENT MOISTURE FROM THE GREAT LAKES FOR SCATTERED TO
NUMEROUS SNOW SHOWERS...WHICH WILL BE MOST PREVALENT OVER THE
ADIRONDACKS AND HIGHER TERRAIN OF NORTHERN VERMONT WHERE A FEW
INCHES OF ACCUMULATION ARE POSSIBLE. LOWER POPS AND LESS
ACCUMULATION IN THE CHAMPLAIN VALLEY AND ACROSS SOUTHERN VERMONT.
MIN TEMPS THURSDAY NIGHT RANGING FROM 5 TO 15F ACROSS MOST OF THE
AREA. MORNING HIGHS ON FRIDAY WILL BE IN THE UPPER TEENS TO MID
20S...WITH FALLING TEMPS IN THE AFTERNOON BEHIND THE FRONT.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 301 AM EST WEDNESDAY...LITTLE OVERALL CHANGE FROM PREVIOUS
FORECAST THINKING FOR THIS VERSION OF THE EXTENDED FORECAST FROM
FRIDAY NIGHT ONWARD WITH INCREASING CONFIDENCE THAT WE`LL SEE
SOME SNOWFALL THIS WEEKEND.

FAIRLY BENIGN WEATHER STARTS THE PERIOD FOR FRIDAY NIGHT AND
SATURDAY WITH SURFACE HIGH PRESSURE IN PLACE BUT A FAST WESTERLY
FLOW ALOFT. THE RESULT WILL BE GENERALLY CLOUDY SKIES AND A FEW
FLURRIES OR LIGHT SNOW SHOWERS POSSIBLE ALONG WITH CONTINUED BELOW
NORMAL TEMPERATURES WITH LOWS IN THE SINGLE DIGITS AND HIGHS IN THE
TEENS.

WEATHER BECOMES MORE ACTIVE GOING INTO SATURDAY NIGHT AND SUNDAY AS
WE CONTINUE TO MONITOR THE POSSIBILITY OF A COASTAL STORM BRINGING
ACCUMULATING SNOWFALL TO THE NORTH COUNTRY. THERE REMAINS DECENT
CONSISTENCY BETWEEN THE ECMWF AND GFS IN REGARDS TO THE OVERALL
SYNOPTIC FEATURES AND STORM TRACK...BUT SOME DIFFERENCES IN THE
FINER DETAILS SUCH AS QPF. THE MAIN IDEA IS THAT LOW PRESSURE
DEVELOPS OVER THE DELMARVA PENINSULA SATURDAY NIGHT AND TRAVELS
NORTHEAST RIGHT OVER OR JUST INSIDE THE BENCHMARK SUNDAY MORNING.
WHILE THIS IS USUALLY A FAVORABLE STORM TRACK FOR SIGNIFICANT SNOW
ACROSS PORTIONS OF THE BTV CWA...THE UPPER FLOW IS PROBLEMATIC AS
THE 500MB AND 700MB LOWS ARE OFF TO OUR WEST/NORTHWEST WITH A
BROAD MID/UPPER LEVEL FLOW OUT OF THE SOUTHWEST. NOT EXACTLY THE
IDEAL SETUP IF YOU WANT BIG SNOW...AND FEEL THE MODEL FORECAST QPF
MAY ACTUALLY BE A LITTLE OVERDONE OVER OUR AREA. NEVERTHELESS...WE
WILL GET SOME SNOW...THOUGH LOOKING MORE LIKE AN ADVISORY LEVEL
EVENT AT THIS TIME.

AFTER THIS SYSTEM EXITS THE REGION SUNDAY NIGHT...IT`S REPLACED BY HIGH
PRESSURE BOTH AT THE SURFACE AND ALOFT. STRONG COLD AIR ADVECTION
UNDER CLEARING SKIES AND LIGHT WINDS WILL LEAD TO A CHILLY MONDAY
NIGHT WHERE TEMPS AREA-WIDE COULD BE IN THE SINGLE DIGITS ABOVE AND
BELOW ZERO. VERY LITTLE QPF WILL BE SEEN FOR THE REMAINDER OF THE
FORECAST PERIOD THOUGH TUESDAY NIGHT WITH THE HIGH OVERHEAD...AND
TEMPERATURES WILL REMAIN BELOW NORMAL.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
-- Changed Discussion --
THROUGH 18Z THURSDAY...AVIATION CHALLENGE THRU THIS AFTN/EVENING
WL BE TIMING OF ARCTIC BOUNDARY AND ASSOCIATED SNOW SHOWERS/SNOW
SQUALLS WITH BRIEF PERIOD OF IFR/LIFR CONDITIONS. CRNT SFC
ANALYSIS PLACES BOUNDARY APPROACHING THE SLV WITH KMSS DOWN TO 1
1/4SM IN -SN/BR. THIS BOUNDARY WL IMPACT SLK BTWN 20-21Z...CPV
(PBG/BTV) BY 22Z...AND THRU MPV/RUT BY 23Z THIS EVENING. EXPECT A
15 TO 30 MINUTE WINDOW OF IFR/LIFR IN SNOW SQUALLS WITH A WIND
SHIFT TO THE NORTHWEST AT 10 TO 15 KNOTS WITH GUSTS TO 20 KNOTS.
THE COMBINATION OF SOUTHWEST FLW AHEAD OF SYSTEM AND VERY DRY SFC
DWPTS AT PBG/BTV MAY LIMIT IFR POTENTIAL...THEREFORE HAVE KEPT VIS
ASSOCIATED WITH SNOW SHOWERS AT 3SM. AT MPV/SLK...UPSLOPE FLW AND
LLVL CAA MAY HELP TO SQUEEZE OUT REMAINING LLVL MOISTURE AND
CONTINUE TO PRODUCE LIGHT SNOW SHOWER ACTIVITY WITH IFR CONDITIONS
THRU 02Z. OTHERWISE...HIGH PRES WL RESULT IN VFR CONDITIONS AFT
06Z WITH CLRING SKIES AND LIGHT WINDS. SOME PATCHY FZFG COULD BE
POSSIBLE GIVEN VERY COLD AIRMASS BTWN 09-12Z AT SLK ON THUR
MORNING...BUT CONFIDENCE IS LOW ATTM.

OUTLOOK 18Z THURSDAY THROUGH SUNDAY...
SFC HIGH PRES WITH VFR CONDITIONS PREVAIL THRU 00Z FRIDAY...BEFORE
THE COMBINATION ANOTHER SFC BOUNDARY AND LAKE EFFECT MOISTURE
IMPACTS OUR TAF SITES THURS NIGHT INTO FRIDAY. THIS WL PRODUCE
ADDITIONAL SNOW SHOWERS WITH POTENTIAL IFR CONDITIONS AT SLK/MPV
WITH MVFR ELSEWHERE. SFC LOW PRES WL PRODUCE WIDESPREAD LIGHT SNOW
LATE SATURDAY INTO SUNDAY WITH A PERIOD OF IFR/LIFR CONDITIONS
LIKELY.
-- End Changed Discussion --

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...NONE.
NY...NONE.

&&

$$
SYNOPSIS...RJS
NEAR TERM...BANACOS/RJS
SHORT TERM...RJS
LONG TERM...LAHIFF
AVIATION...TABER