Area Forecast Discussion
Issued by NWS Burlington, VT

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657
FXUS61 KBTV 122327
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
627 PM EST FRI FEB 12 2016

.SYNOPSIS...
LAKE EFFECT SNOW SHOWERS WILL CONTINUE ACROSS ST. LAWRENCE COUNTY
NEW YORK THROUGH THIS EVENING...IN ADVANCE OF AN APPROACHING
ARCTIC FRONT FROM SOUTHEASTERN ONTARIO. THE ARCTIC FRONT WILL
SWEEP ACROSS THE NORTH COUNTRY LATE TONIGHT...BRINGING WITH IT A
BRIEF PERIOD OF SNOW SHOWERS AND POSSIBLE SNOW SQUALLS. MODERATE
NORTHWEST WINDS BEHIND THE FRONT WILL USHER IN THE COLDEST AIR
MASS OF THE WINTER SEASON...WITH DANGEROUSLY LOW WIND CHILLS
SATURDAY...SATURDAY NIGHT...AND INTO SUNDAY. A MODERATION IN
TEMPERATURES WILL BEGIN MONDAY...WITH A STRONG AND MOISTURE LADEN
STORM SYSTEM BRINGING POTENTIAL MIXED WINTRY PRECIPITATION TO THE
NORTH COUNTRY FOR LATE MONDAY NIGHT THROUGH TUESDAY.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 627 PM EST FRIDAY...FORECAST REMAINS IN GOOD SHAPE AND ONLY
MINOR ADJUSTMENTS NEEDED TO MATCH CURRENT OBSERVATIONAL TRENDS AT
600 PM. DID OPT TO TREND SKY COVER LOWER TO PARTLY CLOUDY/MOSTLY
CLEAR ACROSS OUR VERMONT COUNTIES THIS EVENING AS A NICE CLEAR
SLOT HAS DEVELOPED AHEAD OF THE APPROACHING ARCTIC BOUNDARY.
OTHERWISE LITTLE ADJUSTMENTS NEEDED. AN INTENSE LAKE SNOW BAND HAS
DEVELOPED ACROSS THE SOUTHWESTERN PORTIONS OF ST LAWRENCE COUNTY
NY OVER THE PAST FEW HOURS. WHITEOUT CONDS LIKELY WITH IMPRESSIVE
SNOWFALL RATES UP TO 2 INCHES PER HOUR POSSIBLE FROM CANTON
SOUTHWEST TOWARD GOUVERNEUR/HAMMOND AREA THROUGH 900 PM MAKING FOR
DIFFICULT TO LOCALLY HAZARDOUS TRAVEL. IF TRAVELING ACROSS THESE
AREAS THIS EVENING PLEASE PLAN ACCORDINGLY. HAVE A GREAT EVENING.

PRIOR DISCUSSION FROM 315 PM FRIDAY...
MODERATE SOUTH TO SOUTHWEST WINDS ARE IN PLACE ACROSS THE NORTH
COUNTRY THIS AFTERNOON IN ADVANCE OF SHARP AND WELL-DEFINED ARCTIC
BNDRY MOVING SEWD ACROSS PORTIONS OF THE OTTAWA VALLEY AND
GEORGIAN BAY IN ONTARIO. THE SOUTHWESTERLY LOW- LEVEL FLOW AHEAD
OF THE FRONT HAS ALLOWED BANDS OF LAKE EFFECT SNOW EMANATING OFF
LAKE ONTARIO TO REACH THE ST. LAWRENCE VALLEY...AND WILL CONTINUE
TO SEE THESE BANDS LEADING TO MODERATE SNOW ACCUMULATIONS (3-7")
LOCALLY ACROSS ST. LAWRENCE COUNTY - ESPECIALLY SRN/WRN SECTIONS.
HAVE CONTINUED WINTER WEATHER ADVISORY THROUGH 06Z FOR POTENTIAL
SLOW TRAVEL CONDITIONS OWING TO SNOW COVERED ROADWAYS AND LOW
VSBY.

THE ARCTIC FRONT ITSELF IS ASSOCIATED WITH A NARROW BAND OF SNOW
SHOWERS AND SQUALLS, PER OTTAWA RADAR. THE MESOSCALE
MODELS...INCLUDING BTV- 4KM AND 12KM WRF...AND BTV SNOW SQUALL
PARAMETER...SUGGEST THIS BAND OF ACTIVITY WILL MANAGE TO SHIFT
ESEWD ACROSS NRN NY BETWEEN 3-06Z...AND THROUGH THE BTV AREA
06-08Z. MAY SEE SOME DECREASE EAST OF THE GREENS...BUT MAINTAINED
CHC -SW EASTERN SECTIONS LATE. A QUICK DUSTING TO 2" OF VERY DRY
SNOW ARE POSSIBLE...BUT GIVEN TIME OF DAY/WEEK...LIGHT TRAFFIC
VOLUME AND TEMPS ALREADY WELL BELOW FREEZING SHOULD LIMIT OVERALL
IMPACT FROM ANY SNOW SQUALL ACTIVITY.

LOW-LEVEL COLD AIR ADVECTION WILL BE VERY STRONG BEHIND THE
BNDRY...CURRENTLY SEEING MID-DAY READINGS -20F NORTH OF LAKE
HURON...AND 850MB TEMPS ARE -25C TO -32C. THE LOW-LEVEL CAA
ARRIVES FIRST IN NRN NY...DRIVING DAYBREAK TEMPS DOWN TO -10 TO
-15F FOR THE ADIRONDACKS AND ST. LAWRENCE VALLEY. WON/T BE QUITE
AS COLD ACROSS VT (+2F AT BTV 12Z AND 5-10F EAST OF THE
GREENS)...BUT NW WINDS OF 10-15 MPH AND GUSTS TO 25 MPH WILL
RESULT IN VERY LOW WIND CHILLS.

WIND CHILLS BECOME MORE SEVERE DURING THE DAY SATURDAY -
ESPECIALLY ACROSS VT - WITH NEAR STEADY TO FALLING TEMPS NEAR
ZERO. WILL REMAIN BELOW ZERO ALL DAY SATURDAY ACROSS NRN NY...WITH
HIGHS -5F TO -10F IN THE ST. LAWRENCE VALLEY AND NRN SLOPES OF THE
ADIRONDACKS. WIND CHILLS 25 TO 35 BELOW...ESPECIALLY ACROSS NRN
NY. HAVE MAINTAINED WIND CHILL WARNINGS...WHICH TAKE EFFECT EARLY
SATURDAY MORNING. A FEW STRAY FLURRIES ARE POSSIBLE ON
SATURDAY...BUT GENERALLY DRY AND BECOMING MOSTLY CLEAR. MAY SEE A
FEW STRATOCU DUE TO COLD AIR ACROSS THE OPEN WATERS OF LAKE
CHAMPLAIN...BUT NW RATHER THAN N WINDS SHOULD LIMIT OVERALL
FETCH/EXTENT OF ANY LAKE-INDUCED CLOUD COVER.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
AS OF 315 PM EST FRIDAY...WIND CHILL WARNING IN EFFECT EARLY
SATURDAY MORNING THROUGH SUNDAY.

COLDEST AIR OF THE SEASON TO AFFECT THE NORTH COUNTRY OVER THE
WEEKEND. 850MB TEMPERATURES WILL PLUMMET TO AROUND -30C SATURDAY
NIGHT INTO SUNDAY MORNING. WITH NORTHWEST FLOW SITTING OVER THE
REGION, DEPARTING MOISTURE AND DECREASING CLOUDS EXPECT AIR
TEMPERATURES TO FALL TO 15 TO 35 DEGREES BELOW ZERO. WIND SPEEDS OF
8-15KTS WILL RESULT IN WIND CHILL VALUES -30 TO -40 DEGREES WITH
COLDER WIND CHILLS IN THE MOUNTAINS.

SURFACE HIGH PRESSURE WILL BUILD INTO THE REGION SUNDAY WITH
GRADUALLY MODERATING TEMPERATURES. 850MB TEMPERATURES INCREASE TO
AROUND -20C ON SUNDAY AND A COUPLE DEGREES WARMER SUNDAY NIGHT AS
RIDGING OCCURS ALOFT AND THE SURFACE RIDGE STARTS TO SLIDE EAST,
PUTTING THE NORTH COUNTRY INTO MODERATING LIGHT SOUTHERLY FLOW.

CLEARING SKIES SUNDAY, COLD AIR TEMPERATURES AND WARM WATERS OF LAKE
CHAMPLAIN MAY RESULT IN TEA KETTLING STEAM CLOUDS AND LIGHT SNOW
SHOWERS OFF THE LAKE IN THE CHAMPLAIN VALLEY. BUFKIT MODEL SOUNDINGS
SHOW STEEP LOW LEVEL LAPSE RATES SUPPORTING BOUTS OF LIGHT SNOW
SHOWERS AT BTV DURING THE MORNING HOURS. ELSEWHERE COLD BY BENIGN
WEATHER EXPECTED WITH MAX TEMPERATURES RANGING FROM THE NEGATIVE
SINGLE DIGITS TO POSITIVE SINGLE DIGITS WITH DECREASING WINDS.
SUNDAY NIGHT TEMPERATURES WILL ABOUT 10 DEGREES WARMER THAN SATURDAY
NIGHT...REMAINING BELOW ZERO.

MONDAY CONTINUES TO SEE MODERATING TEMPERATURES AS THE RIDGE SLIDE
INTO THE ATLANTIC. TEMPERATURES NEARING NORMAL IN THE MID TEENS TO
MID 20S.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
AS OF 315 PM EST FRIDAY...
MODELS CONTINUE TO TRACK DIGGING TROUGH AND ASSOCIATED SURFACE LOW
THAT FORMS LATE MONDAY...TRACKING NORTHEASTWARD WITH PLENTIFUL
MOISTURE. THERE CONTINUE TO BE DIFFERENCES IN SURFACE LOW TRACK AND
RESULTING PTYPE AND AMOUNTS OVER THE NORTH COUNTRY. 12Z GFS TRACKS
SURFACE LOW JUST TO OUR EAST...CROSSING NH ON TUESDAY/TUESDAY NIGHT.
GFS ENSEMBLES MEAN SIMILAR WITH THE LOW TRACKING OVER VT/EASTERN VT.
12Z ECWMF SIMILAR TO PREVIOUS RUN, KEEPING A MORE WESTERLY TRACK
WITH THE LOW MOVING IN THE WESTERN ST LAWRENCE VALLEY TUESDAY NIGHT.

MODEL SIMILARITIES...PRECIP MOVES INTO THE NORTH COUNTRY FROM THE
SOUTH AND WEST MONDAY NIGHT IN STRONG SOUTHERLY FLOW. PWAT ANOMALIES
IN EXCESS OF 3 STANDARD DEVIATIONS ABOVE NORMAL RESULT IN STORM
TOTAL QPF GREATER THAN 2 INCHES. ANY WARM AIR ASSOCIATED WITH THIS
SYSTEM HOLDS OFF TO THE SOUTH THROUGH AROUND 12Z TUESDAY...MEANING
PRECIP WILL START AS SNOW.

MODEL DIFFERENCES WILL AFFECT PTYPE. GFS WITH THE MORE EASTERLY
TRACK KEEPS COLD AIR ACROSS NORTHERN NY AND WARMER AIR IN THE
CHAMPLAIN VALLEY AND AREAS EAST. WHILE 850MB AND 925MB ZERO DEGREE
LINES ARE IN CLOSE PROXIMITY TO EACH OTHER THROUGHOUT THE EVENT ON
THE GFS...SOME WINTRY MIX/ICING IS POSSIBLE, ESPECIALLY AS ARCTIC
TEMPERATURES PRIOR TO THIS EVENT WILL LEAD TO FROZEN GROUND. ECWMF
ON THE OTHER HAND MOVES THE WARM AIR WEST OF THE ST LAWRENCE
VALLEY...BUT PERSISTENT NE FLOW DOWN INTO THE VALLEY WILL KEEP LOW
LEVEL/NEAR SURFACE TEMPERATURES AOB FREEZING. THIS COULD BE THE SET
UP FOR A SIGNIFICANT ICING EVENT.

SO WITH ALL OF THESE FACTORS YET TO BE RESOLVED BY THE MODELS WHAT
WE CAN EXPECT IS A VERY MOIST STRONG LOW PRESSURE SYSTEM WITH
CENTRAL LOW PRESSURE FALLING INTO THE 970-980MB RANGE AS IT PASSES
ACROSS THE REGION LATE TUESDAY/TUESDAY NIGHT. PRECIP FROM THIS
SYSTEM WILL START AS SNOW WITH PORTIONS OF THE AREA SEEING WINTRY
MIX DURING THE DAY TUESDAY INTO TUESDAY NIGHT. STRONG WINDS MAY ALSO
BE AN ISSUE AS SOUTHERLY JET AT 850MB WITH SPEEDS GREATER THAN 50KTS
ENTERS THE REGION EARLY TUESDAY STRENGTHENS DURING THE DAY. ON THE
BACKSIDE OF THIS STORM, STRONG NW WINDS TAKE OVER AT 30-45KTS.

WEDNESDAY THE LOW WILL BE DEPARTING NORTH AND EAST WITH SOME
LINGERING SNOW SHOWERS CONTINUING AS UPPER TROUGH CONTINUES TO
AFFECT THE REGION INTO WEDNESDAY NIGHT.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
THROUGH 00Z SUNDAY...ONGOING LAKE EFFECT SNOW PRODUCING
LIFR/VLIFR CONDITIONS AT MSS, WITH VFR ELSEWHERE. AN EVENTUAL
DETERIORATION ANTICIPATED ACROSS THE TAFS AS ARCTIC COLD FRONT AND
ASSOCIATED SNOW SQUALLS PUSH EASTWARD. EXPECT A SHORT-DURATION (AN
HOUR OR LESS) VISIBILITY DROP TO LIFR/VLIFR IN SNOW SQUALLS WITH A
GUSTY WIND SHIFT FROM SOUTH TO NORTHWEST. SEE TAFS FOR SPECIFIC
TIMING, BUT IS GENERALLY IN THE 02-06Z WINDOW. GREATEST IMPACT TO
BTV TERMINAL AND AVIATION GROUND OPERATIONS AROUND 05Z. MORE RAPID
CLEARING TOWARD VFR FROM WEST TO EAST AFTER 07Z, THOUGH GUSTY
NORTHWEST WINDS WILL CONTINUE INTO SATURDAY AFTERNOON, AS HIGH AS
25 KNOTS.

OUTLOOK 00Z SUNDAY THROUGH TUESDAY...GENERALLY VFR AFTER 18Z
SATURDAY WITH FLURRIES POSSIBLE. NW WIND GUSTS TO 25KT POSSIBLE
SATURDAY AFTERNOON AND EVE. MONDAY NIGHT INTO TUESDAY A COASTAL
STORM WILL SPREAD HEAVY MIXED WINTRY PRECIPITATION NWD INTO THE
REGION WITH WIDESPREAD IFR AVIATION WX CONDITIONS LIKELY FOR
TUESDAY AND TUESDAY NIGHT.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...WIND CHILL WARNING FROM 3 AM SATURDAY TO 7 PM EST SUNDAY FOR
     VTZ001>012-016>019.
NY...WIND CHILL WARNING FROM 3 AM SATURDAY TO 7 PM EST SUNDAY FOR
     NYZ026>031-034-035-087.
     LAKE EFFECT SNOW ADVISORY UNTIL 1 AM EST SATURDAY FOR NYZ029-
     087.

&&

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



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