Area Forecast Discussion
Issued by NWS Burlington, VT

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000
FXUS61 KBTV 120227
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
927 PM EST THU FEB 11 2016

.SYNOPSIS...
A WEAK UPPER LEVEL TROUGH ACROSS THE ST. LAWRENCE VALLEY WILL
TRACK EASTWARD WITH JUST A FEW FLURRIES OR SNOW SHOWERS THROUGH
THE FIRST HALF OF TONIGHT. AS THIS FEATURE MOVES EAST...SKIES WILL
BECOMING PARTLY TO MOSTLY CLEAR AFTER MIDNIGHT WITH SURFACE HIGH
PRESSURE BUILDING IN FROM THE WEST. IT WILL BE COLD WITH OVERNIGHT
LOWS GENERALLY ZERO TO 5 ABOVE IN THE CHAMPLAIN AND CONNECTICUT
VALLEYS...AND GENERALLY ZERO TO 10 BELOW ELSEWHERE. ANOTHER UPPER
LEVEL LOW AND ARCTIC FRONTAL ZONE WILL APPROACH FROM THE GREAT
LAKES AND SOUTHEASTERN ONTARIO LATE IN THE DAY FRIDAY INTO FRIDAY
NIGHT. THIS FEATURE WILL BRING LOCALIZED LAKE EFFECT SNOWS TO
SOUTHERN ST. LAWRENCE COUNTY...AND THEN THE POTENTIAL FOR SNOW
SHOWERS OR SQUALLS ALONG THE ARCTIC FRONT AS IT MOVES THROUGH
DURING FRIDAY NIGHT. THIS WILL USHER IN THE COLDEST AIR MASS OF
THE WINTER FOR THE WEEKEND...WITH BITTERLY COLD TEMPERATURES. A
MODERATION IN TEMPERATURES WILL BEGIN MONDAY...WITH A STORM SYSTEM
BRINGING MIXED WINTRY PRECIPITATION POTENTIALLY FOR TUESDAY.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 927 PM EST THURSDAY...ADDITIONAL MINOR ADJUSTMENTS TO
SKY/T/TD/WINDS OVERNIGHT BASED OFF CURRENT OBSERVATIONAL TRENDS.
LINGERING LIGHT SHSN/FLURRIES TO GENERALLY END OVERNIGHT LEAVING
CLR/PTLY CLOUDY SKIES BY MORNING AS SHORTWAVE RIDGE PASSES
OVERHEAD. TEMPERATURES ARE RUNNING COLDER THAN EARLIER FCST BY
SEVERAL DEGREES, BUT ARE QUITE VARIABLE DEPENDING ON CLOUD COVER
AND WIND. THUS TOOK CURRENT 02Z READINGS AND LOWERED VALUES BY AN
ADDITIONAL 3-5 DEGREES OVERNIGHT PER LATEST GUIDANCE TRENDS. ALSO
OPTED TO RAISE SOUTHERLY WINDS AND WIND GUSTS CONSIDERABLY
TOMORROW AFTERNOON/EVENING AHEAD OF THE APPROACHING ARCTIC BOUDARY
WITH MODELS OFFERING A DEEPLY MIXED PBL AND A TIGHTENING P-GRAD.
GUSTS INTO THE 20-30 MPH RANGE LOOK REASONABLE, ESPECIALLY IN THE
BROADER VALLEYS. HAVE A GREAT NIGHT.

PRIOR DISCUSSION...
COMPACT MID-LEVEL VORT EVIDENT IN IR AND VIS IMAGERY ACROSS THE
ST. LAWRENCE VALLEY WILL SHIFT EWD ALONG THE INTL BORDER AND SHIFT
EAST OF VT BY 06Z. LOOKING AT JUST A FEW LIGHT SNOW SHOWERS WITH
THIS FEATURE THROUGH THIS EVENING...AIDED BY STEEP LOW-LEVEL LAPSE
RATES (IN LOW-LEVEL CAA REGIME) AND WLY 850MB FLOW OF 15-20KTS
PROVIDING SOME UPSLOPE INTO THE ADIRONDACKS AND NRN GREENS. ANY
ACCUMULATION EXPECTED TO BE AN INCH OR LESS...MAINLY CONFINED TO
AREAS OF OROGRAPHIC ASCENT. OTHERWISE...IT WILL BE A COLD NIGHT
WITH CLEARING SKIES AS NARROW SFC RIDGE BUILDS IN BRIEFLY FROM THE
WEST AFTER 06Z...CRESTING ACROSS VT AROUND 12Z FRIDAY. CORE OF
COLDEST 850MB TEMPS WILL BE IN PLACE THIS EVENING...GENERALLY -24C
TO -26C. SOME RADIATIONAL COOLING AND THIN LAYER OF SNOW COVER
WILL AID IN RADIATIVE COOLING...ESPECIALLY LATE WITH CLEARING AND
DIMINISHING WIND. LOOKING AT OVERNIGHT LOWS ZERO TO 5 ABOVE FOR
THE CHAMPLAIN VALLEY AND AROUND SPRINGFIELD VT...AND GENERALLY
ZERO TO -10F ELSEWHERE.

FRIDAY INTO FRIDAY NIGHT: SECONDARY ARCTIC BOUNDARY AND ASSOCIATED
UPPER VORT DIGS ESEWD ACROSS THE NORTHERN GREAT LAKES. THIS ALLOWS
SFC-850MB FLOW TO BACK AHEAD OF THE TROUGH AXIS. LOW-LEVEL
TRAJECTORIES FROM LAKE ONTARIO BRING LAKE EFFECT SNOW BANDS INTO
ST. LAWRENCE COUNTY...LIKELY STARTING AROUND 14-15Z FRIDAY PER
BTV LOCAL WRF RUNS. PERIODS OF LAKE EFFECT SNOW WILL GENERALLY BE
CONFINED TO ST. LAWRENCE AND FRANKLIN COUNTIES DURING THE DAYLIGHT
HRS FRIDAY...WITH MAINLY DRY CONDITIONS ELSEWHERE WITH VARIABLY
CLOUDY CONDITIONS AND WEAK S-SW FLOW. LAKE EFFECT SNOW WILL BE
BRIEFLY AUGMENTED BY LOW-LEVEL FRONTOGENETIC FORCING AND
CONVERGENCE AS ARCTIC BNDRY SWEEPS INTO NRN NY BETWEEN
02-05Z...AND ACROSS VT AFTER MIDNIGHT. SHOULD SEE POTENTIAL SNOW
SQUALLS ALONG THE BNDRY AS IT MOVES ACROSS ENTIRE CWA DURING THE
OVERNIGHT HRS FRIDAY NIGHT. WILL SEE LAKE EFFECT SNOW END BEHIND
ARCTIC BNDRY AS MEAN FLOW VEERS RAPIDLY FROM SW-NW.

WILL BE REPLACING THE LAKE EFFECT SNOW WATCH WITH A LAKE EFFECT
SNOW ADVISORY THIS AFTN FOR SRN ST. LAWRENCE COUNTY 14Z FRIDAY
THROUGH 06Z SATURDAY TO COVER LAKE EFFECT SNOW AMOUNTS GENERALLY
3-6". WILL PROBABLY SEE A COUPLE OF COMMUNITIES IN EXCESS OF 6"
SNOWFALL AROUND FINE, NY...BUT ANTICIPATE THAT WILL BE ISOLD GIVEN
TRANSITIONAL NATURE OF THE LAKE EFFECT SNOW BAND AS LOW-LEVEL FLOW
BACKS AND THEN QUICKLY VEERS WITH FROPA. OTHERWISE...WILL SEE A
DUSTING TO 2" FRIDAY NIGHT WITH ARCTIC FRONTAL PASSAGE WITH SNOW
SHOWERS AND POSSIBLE SQUALL ACTIVITY. SNOW RATIOS GENERALLY 20:1
TO 25:1 GIVEN VERY COLD AIR MASS...AND NOT EXPECTING ANY
SIGNIFICANT IMPACTS (ALSO CONSIDERING PRE-DAWN HRS SATURDAY
MORNING WITH LIGHT TRAFFIC).

HIGH TEMPERATURES ON FRIDAY GENERALLY GENERALLY TEENS TO LOWER
20S. STRONG CAA LATE FRIDAY NIGHT WILL BRING TEMPS DOWN TO 5 TO 10
BELOW ACROSS THE ADIRONDACKS AND ST. LAWRENCE VALLEY BY DAYBREAK
SATURDAY...INCLUDING WIND CHILLS 25 TO 30 BELOW (SEE FORTHCOMING
SHORT-TERM FORECAST SECTION FOR MORE DETAILS ON DANGEROUSLY LOW
WIND CHILLS FOR THE WEEKEND). LOWS ACROSS VERMONT AND THE NY SIDE
OF THE CHAMPLAIN VALLEY FRIDAY NIGHT MAINLY ZERO TO +7F.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
AS OF 347 PM EST THURSDAY...WIND CHILL WATCH IN EFFECT EARLY
SATURDAY MORNING THROUGH SUNDAY.

COLD ARCTIC AIR WILL CONTINUE TO FILTER INTO THE NORTH COUNTRY IN
THE WAKE OF STRONG COLD FRONT SATURDAY. TEMPERATURES WILL FALL
THROUGHOUT THE DAY...WITH MAXES OCCURRING IN THE MORNING IN THE
NEGATIVE SINGLE DIGITS ACROSS MOST OF NORTHERN NY...AND THE
POSITIVE SINGLE DIGITS ACROSS THE CHAMPLAIN VALLEY EASTWARD.
MOUNTAIN TOPS WILL REMAIN BELOW ZERO. PRESSURE GRADIENT INCREASES
AS DEPARTING SURFACE LOW MOVES NEWD AND RIDGING BUILDS OVER THE
MID-WEST. THIS WILL RESULT IN BREEZY CONDITIONS AT THE SURFACE
WITH GUSTS 15-25KTS POSSIBLE. COLD TEMPERATURES COMBINED WITH
WINDS WILL RESULT IN WIND CHILLS OF 20 TO 40 DEGREES BELOW ZERO
THROUGHOUT THE WEEKEND AS 850MB TEMPERATURES FALL INTO -30C TO
-25C EARLY SUNDAY. THIS COLD FRIGID AIR IS EXPECTED TO PERSIST
UNTIL SUNDAY NIGHT WHEN THE RIDGE OF HIGH PRESSURE MOVES OVERHEAD
AND WINDS SUBSIDE WHILE TEMPERATURES BEGIN TO INCREASE ALOFT. AIR
TEMPERATURES SATURDAY NIGHT WILL BE BELOW ZERO...RANGING FROM
NEGATIVE TEENS TO NEGATIVE 20S. SUNDAY WILL SEE MAX TEMPERATURES
IN THE SINGLE DIGITS ABOVE AND BELOW ZERO.

PRECIPITATION-WISE...SOME RESIDUAL MOISTURE IN THE NORTHWESTERLY
WINDS WITH FROUDE NUMBERS SHOWING SLOW MOVING/BLOCKED UPSLOPE FLOW
WILL KEEP SNOW SHOWERS ACROSS THE NORTHEAST KINGDOM AND WESTERN
SLOPES OF THE GREENS AND NORTHERN ADIRONDACKS FOR SATURDAY WITH A
DRYING TREND THEREAFTER. WITH LAKE CHAMPLAIN WATER TEMPERATURES
STILL IN THE MID 30S, CANNOT RULE OUT SOME STEAM CLOUDS DEVELOPING
IN COLDER AIR AND POSSIBLE TEA KETTLE TYPE SNOW SHOWERS IN THE
CHAMPLAIN VALLEY SATURDAY AND SUNDAY.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 347 PM EST THURSDAY...SURFACE HIGH PRESSURE WILL SLOWLY
SHIFT EASTWARD SUNDAY NIGHT INTO MONDAY WITH SLIGHT RIDGING ALOFT.
ON THE WESTERN SIDE OF THE RIDGE AXIS, SOUTHERLY FLOW WILL HELP
MODERATE TEMPERATURES MONDAY...WITH MAXES REACHING THE 20S.

THE NEXT SIGNIFICANT SYSTEM WILL EVOLVE FROM DIGGING 500MB TROUGH
THAT APPROACHES FROM THE WEST MONDAY NIGHT INTO TUESDAY. WHILE
MODELS STILL DIFFER ON TRACK OF ASSOCIATED SURFACE THAT DEVELOPS,
EXPECT LOW TO BEGIN BRINGING PRECIPITATION IN FROM THE SOUTH ON
TUESDAY. BOTH GFS AND ECMWF CURRENTLY BRING SIGNIFICANT WARMING TO
THE NORTH COUNTRY AND RESULT IN ABOVE FREEZING TEMPERATURES ON
TUESDAY. TEMPERATURES MAY BE WARM ENOUGH FOR PRECIP TO TRANSITION
TO RAIN LATE TUESDAY. BUT AS THE LOW LIFTS NORTH AND EAST, COLD
AIR RETURNS TO THE REGION ON THE BACKSIDE OF THE SYSTEM WITH SNOW
SHOWERS EXPECTED. MULTIPLE VORTICES IN 500MB TROUGH MAY KEEP
CHANCE FOR PRECIPITATION INTO WEDNESDAY AS THE MAIN SURFACE LOW
CONTINUES TRACKING NORTHWARD INTO COASTAL CANADA.

&&

.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
THROUGH 00Z SATURDAY...TREND TOWARD VFR OVERNIGHT AS UPPER LEVEL
RIDGE MOVES OVER THE AREA AND NW FLOW RELAXES GENERALLY AFTER 06Z.

AT BTV...NW FLOW ACROSS THE 37 DEGREE WATERS OF LAKE CHAMPLAIN
MAY BRING FLURRIES OR EVEN A SNOW SHOWER FOR A WHILE TONIGHT. FOR
NOW JUST MENTIONING AS VCTY SNOW SHOWERS BUT ITS ENTIRELY POSSIBLETHAT
CIGS GO MVFR AND VSBY IFR FOR A BRIEF PERIOD BEFORE 04Z. NOT
EXPECTING MUCH ACCUMULATION ON RUNWAYS.

OTHERWISE MVFR CIGS (2-3 KFT) GENERALLY LIMITED TO SLK OTHERWISE
THE TREND TO VFR LATE TONIGHT INTO FRIDAY MORNING.

WILL BEGIN TO SEE MVFR CEILINGS AND LOCALLY IFR VSBY AT SLK/MSS
WITH -SHSN POSSIBLE AFTER 17Z ASSOCIATED WITH INCREASING SWLY FLOW
FROM LAKE ONTARIO AND FRINGE IMPACT FROM LAKE EFFECT SNOW BANDS.

NW WINDS BRIEFLY GUSTY 15 TO 20KTS THRU EARLY EVENING...THEN
GENERALLY LESS THAN 10KTS TONIGHT AND FRIDAY MORNING THEN SHIFTING
TO THE S AND SW AROUND 10KTS THROUGH FRIDAY MORNING.

S WINDS MAYBE A PROBLEM AT KBTV GROUND OPERATIONS FRIDAY
AFTERNOON INTO THE NIGHT WITH DRIFTING OR BLOWING SNOW BY 00Z SAT AND
MAY BE GUSTING OVER 30KTS UNTIL THE ARCTIC FRONT PASSES EARLY SAT
A.M.

OUTLOOK 00Z SATURDAY THROUGH MONDAY...LCL VLIFR IN SNOW SQUALLS
BRIEFLY POSSIBLE FRIDAY NIGHT 02-05Z ACROSS NRN NY AND 05-09Z
ACROSS VT AS ARCTIC FRONT MOVES THRU...WITH VSBY BRIEFLY LESS THAN
1/2 MILE AND A WIND SHIFT TO NW WITH GUSTS 20 TO 30 KTS. MODEST
IMPACT TO AIRPORT GROUND OPERATIONS WITH DUSTING TO 2" SNOWFALL
PSBL. GENERALLY VFR AFTER 12Z SATURDAY WITH FLURRIES POSSIBLE. NW
WIND GUSTS TO 25KT POSSIBLE SATURDAY AFTN AND EVE.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WIND CHILL WATCH FROM LATE FRIDAY NIGHT THROUGH SUNDAY EVENING
     FOR VTZ001>012-016>019.
NY...WIND CHILL WATCH FROM LATE FRIDAY NIGHT THROUGH SUNDAY EVENING
     FOR NYZ026>031-034-035-087.
     LAKE EFFECT SNOW ADVISORY FROM 9 AM FRIDAY TO 1 AM EST
     SATURDAY FOR NYZ029-087.

&&

$$
SYNOPSIS...BANACOS
NEAR TERM...BANACOS/JMG
SHORT TERM...KGM
LONG TERM...KGM
AVIATION...BANACOS/SISSON


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