Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 122042 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 342 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 315 PM EST 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 /20Z FRIDAY THROUGH WEDNESDAY/... THROUGH 18Z SATURDAY...GENERALLY VFR THIS AFTERNOON WITH INCREASING MID-LEVEL CLOUDS. ONLY EXCEPTION IS AROUND KSLK...WHERE SWLY LOW-LEVEL FLOW FROM LAKE ONTARIO AND OROGRAPHIC ASCENT IS RESULTING IN IFR SNOW SHOWER ACTIVITY. IFR CONDITIONS WILL GENERALLY PERSIST AT KSLK UNTIL AFTER PASSAGE OF AN ARCTIC BNDRY TONIGHT (AROUND 06Z AT SLK). ELSEWHERE...WILL ALSO SEE DEVELOPMENT OF MVFR TO IFR SNOWFALL AT MSS AS ARCTIC BNDRY APPROACHES THE ST. LAWRENCE VALLEY FROM THE NW...AND AS MOISTURE FROM LAKE ONTARIO GETS ENTRAINED OUT AHEAD OF THE FRONTAL BNDRY. THE BNDRY WILL BRING A RELATIVELY BRIEF PERIOD OF IFR SNOW SHOWERS OR SNOW SQUALLS AS IT PASSES PBG (05-06Z), BTV (06-08Z) AND MPV (08-10Z) LATE TONIGHT. LOOKING FOR A QUICK DUSTING TO 2" OF DRY FLUFFY SNOW AT THE TAF SITES. WINDS GENERALLY S-SSW 10-15KT WITH GUSTS TO 22KTS THRU THIS EVENING...THEN RAPIDLY VEERING INTO THE NW WITH FRONTAL PASSAGE. SOME LINGERING MVFR IS LIKELY SATURDAY MORNING WITH SCATTERED FLURRIES. CONTINUED MODERATELY STRONG NW WINDS 10-20 KTS. OUTLOOK 18Z SATURDAY 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...BANACOS SHORT TERM...KGM LONG TERM...KGM AVIATION...BANACOS

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