240
FXUS61 KBTV 220246
AFDBTV
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
946 PM EST SAT DEC 21 2024
SYNOPSIS
A DEPARTING UPPER LEVEL TROUGH WILL RESULT IN GRADUAL CLEARING
TONIGHT AND A LESSENING OF SNOW SHOWERS AND FLURRIES ACROSS
NORTHERN NEW YORK AND VERMONT. SOME LIGHT ADDITIONAL SNOW
ACCUMULATION IS POSSIBLE EAST AND SOUTHEAST OF LAKE CHAMPLAIN
ASSOCIATED WITH LOCALIZED LAKE EFFECT SNOW. A COLD HIGH PRESSURE
SYSTEM BUILDING EASTWARD FROM THE GREAT LAKES WILL RESULT IN
COLD TEMPERATURES THROUGH MONDAY. AN AREA OF LOW PRESSURE
APPROACHING FROM THE WEST BRINGS WIDESPREAD LIGHT SNOW TO THE
NORTH COUNTRY ON MONDAY NIGHT, WITH MOUNTAIN SNOW SHOWERS AND
FLURRIES CONTINUING INTO CHRISTMAS EVE DAY. SEASONABLY COLD AND
QUIET CONDITIONS RETURN CHRISTMAS DAY WITH HIGH PRESSURE IN
PLACE ACROSS THE NORTHEASTERN UNITED STATES.
NEAR TERM /THROUGH MONDAY/
AS OF 941 PM EST SATURDAY...A VERY CHILLY NIGHT WITH BITTERLY
COLD WIND CHILL VALUES ARE EXPECTED. CRNTLY TEMPERATURES ARE
HOVERING EITHER SIDE OF ZERO ACRS NORTHERN NY WITH WHITEFACE MTN
DOWN TO -15F, WHILE VALUES NEAR LAKE CHAMPLAIN ARE NEAR 10F.
BRISK NORTH TO NORTHWEST WINDS CONTINUE TO ADVECT COLDER AIR
INTO THE REGION AND ARE PRODUCING WIND CHILL VALUES BETWEEN 5F
AND -20F CURRENTLY. THE CORE OF THE COLDEST 925MB AND 850MB
TEMPS ARE DIRECTLY OVERHEAD AT 12Z SUNDAY, WHILE A LITTLE
GRADIENT PREVAILS AS SFC HIGH PRES IS CENTERED OVER THE GREAT
LAKES. LOWS GENERALLY 5F TO -10F, EXCEPT 15 TO 20 BELOW ZERO
ACRS THE HIGHER ELEVATION SUMMITS. ANOTHER COLD BUT SUNNIER DAY
IS ANTICIPATED ON SUNDAY WITH BUILDING HIGH PRES. NO SIGNIFICANT
CHANGES NEEDED TO CRNT FCST.
PREVIOUS DISCUSSION BELOW:
A STRONG AND COLD SURFACE HIGH PRESSURE SYSTEM (1038MB)
CENTERED NORTH OF LAKE SUPERIOR THIS AFTERNOON WILL REMAIN OUR
CONTROLLING WEATHER SYSTEM THROUGH SUNDAY NIGHT. THE PREVAILING
COLD NORTH-NORTHWESTERLY LOW-LEVEL FLOW BROUGHT LOCALIZED LAKE
EFFECT SNOW OFF LAKE CHAMPLAIN EARLIER TODAY, WITH UP TO 6" SNOW
ACCUMULATION IN THE SOUTH BURLINGTON AND SHELBURNE AREAS.
PLEASE SEE OUR RECENTLY ISSUED PUBLIC INFORMATION STATEMENT FOR
SNOWFALL REPORTS DURING THE PAST 24 HOURS. LAKE EFFECT SNOW OFF
LAKE CHAMPLAIN HAS LARGELY DIMINISHED AS DEWPOINTS BELOW 10F
HAVE ADVECTED IN FROM SOUTHERN QUEBEC, YIELDING STRONG PBL
DRYING AND LESSENING RADAR REFLECTIVITY NEAR KCXX. MAY STILL SEE
SOME LAKE-INDUCED FLURRIES AND LOW STRATUS OVERNIGHT WITH NW
FETCH ACROSS LAKE CHAMPLAIN CONTINUING OVERNIGHT. SNOWFLAKES
HAVE BECOME VERY FINE GIVEN THE LIMITED MOISTURE, WITH JUST A
DUSTING TO 1" ADDITIONAL ACCUMULATION POSSIBLE FOR COMMUNITIES
ALONG THE E AND SE SHORES OF LAKE CHAMPLAIN. MAY ALSO SEE SOME
LIGHT SNOW SHOWERS OR FLURRIES IN THE NORTHERN MOUNTAINS
ASSOCIATED WITH NW OROGRAPHIC FLOW, BUT TREND OVERNIGHT WILL BE
FOR THAT ACTIVITY TO DIMINISH AS WELL WITH GRADUAL CLEARING
TAKING PLACE. ANY ADDITIONAL SNOW ACCUMULATIONS ARE EXPECTED TO
BE LIGHT.
MAIN STORY TONIGHT AND SUNDAY WILL BE THE ARCTIC AIR MASS IN
PLACE. A COLD WEATHER ADVISORY REMAINS IN EFFECT STARTING AT
MIDNIGHT TONIGHT AND CONTINUING THROUGH 9 AM SUNDAY MORNING FOR
THE COMMUNITIES OF THE ADIRONDACKS. DANGEROUS WIND CHILL
TEMPERATURES BETWEEN 15 AND 25 BELOW ARE EXPECTED IN THIS
REGION, AND GENERALLY 10 TO 20 BELOW ELSEWHERE ACROSS OUR
FORECAST AREA. NW WINDS WILL CONTINUE 10-15 MPH WITH GUSTS UP TO
25 MPH AT TIMES. AFTER MIDNIGHT, THE P-GRADIENT DOES BEGIN TO
SLACKEN A BIT, SO WIND SPEEDS SHOULD SLOWLY DIMINISH TOWARD
DAYBREAK SUNDAY.
ARCTIC HIGH PRESSURE WILL EASTWARD BUILD ACROSS OUR REGION
SUNDAY AND SUNDAY NIGHT WITH ABUNDANT, ALBEIT INEFFECTIVE,
SUNSHINE. LOOKING FOR DAYTIME HIGHS ON SUNDAY IN THE LOW TEENS
ACROSS THE CHAMPLAIN, CONNECTICUT, AND ST. LAWRENCE VALLEYS, AND
GENERALLY IN THE SINGLE DIGITS ELSEWHERE ACROSS THE NORTH
COUNTRY. SUNDAY NIGHT WILL BE CHARACTERIZED BY EXCELLENT
RADIATIONAL COOLING WITH ARCTIC HIGH PRESSURE OVERHEAD. WITH
FRESH SNOWPACK, CAN BTV DIP TO ZERO DEGREES OR BELOW FOR THE
FIRST TIME SINCE 2/26/2023 (A RECORD 664 CALENDAR DAYS)? THERE'S
A LOW CHANCE (15%) OF THAT HAPPENING PER 13Z NBM, BUT CURRENT
OFFICIAL FCST IS FOR A LOW OF 4F AT KBTV. MANY AREAS AWAY FROM
THE CHAMPLAIN VALLEY WILL DROP BELOW ZERO. READINGS OF -5F TO
-15F ARE EXPECTED ACROSS VERMONT'S NORTHEAST KINGDOM AND WITHIN
THE NORTHERN ADIRONDACKS OF NEW YORK. WINDS SUNDAY NIGHT WILL BE
LIGHT AND VARIABLE AND CONTROLLED BY LOCAL OROGRAPHIC
INFLUENCES.
SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/
AS OF 304 PM EST SATURDAY...AFTER A COLD START TO THE DAY MONDAY,
THE CENTER OF THE SURFACE ANTICYCLONE WILL SHIFT TO OUR EAST,
TAKING THE CORE OF THE ARCTIC AIR WITH IT. RETURN SOUTHERLY FLOW
WILL DEVELOP IN THE WAKE AND 850 MB TEMPS WILL RISE FROM AROUND
-13C EARLY MONDAY MORNING TO -7C BY MONDAY AFTERNOON. SURFACE
TEMPS WILL ACCORDINGLY TOP OUT IN THE UPPER TEENS TO MID 20S.
MONDAY WILL BE DRY WITH JUST SOME HIGH CLOUDS SPREADING OVERHEAD
AHEAD OF AN APPROACHING SYSTEM.
MONDAY NIGHT, A WEAK LOW PRESSURE SYSTEM AND SHORTWAVE ALOFT WILL
TRACK EASTWARD INTO OUR FORECAST AREA, SPREADING SOME SNOW OVER THE
NORTH COUNTRY. SNOW WILL START AS EARLY AS MONDAY EVENING IN
NORTHERN NEW YORK, BUT THE STEADIEST SNOW CAN BE EXPECTED OVERNIGHT
MONDAY NIGHT/TUESDAY MORNING. ONCE THE LOW MOVES TO OUR EAST BY
MIDDAY TUESDAY, WIDESPREAD SNOW WILL DIMINISH INTO MORE LOCALIZED
SHOWERS THAT WILL MAINLY BE TIED TO HIGHER TERRAIN. TOTAL QPF
ASSOCIATED WITH THE SYSTEM WILL BE IN THE 0.1 TO 0.4 INCH RANGE.
SNOW RATIOS AROUND 15:1 WILL EQUATE TO A WIDESPREAD 2-4 INCHES OF
SNOW OUT OF THE EVENT, WITH SOME HIGHER AMOUNTS POSSIBLE OVER THE
MOUNTAIN SUMMITS. THE GOOD NEWS IS THAT TEMPERATURES REMAIN COLD
ENOUGH DURING THE EVENT TO KEEP PRECIPITATION TYPE AS ALL SNOW,
WHICH WILL PROVIDE A NICE BACKDROP FOR A WHITE CHRISTMAS AND
OVERALL LIMIT THE IMPACTS OF THE SYSTEM.
LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/
AS OF 304 PM EST SATURDAY...SURFACE HIGH PRESSURE WILL QUICKLY BUILD
IN BY LATE TUESDAY, WHICH WILL BRING IN DRIER AIR AND ALLOW FOR
AN END TO LINGERING SNOW SHOWERS. WEDNESDAY THROUGH SATURDAY
WILL SEE VERY QUIET WEATHER AS AN OMEGA BLOCK SETS UP, WITH
STRONG RIDGING REMAINING OVER THE NORTH COUNTRY. TEMPERATURES
WILL START OFF NEAR TO SLIGHTLY BELOW NORMAL FOR CHRISTMAS DAY,
THEN GRADUALLY WARM TO ABOVE NORMAL BY THE WEEKEND. THE MAIN
WEATHER STORY IN THE PERIOD FOLLOWING CHRISTMAS WILL BE THE
WARMTH. WHILE IT'S TOO FAR OUT TO GET TOO SPECIFIC WITH
TEMPERATURES, THE CLIMATE PREDICTION CENTER TEMPERATURE
OUTLOOKS FOR 6-10 DAYS AND 8-14 DAYS SHOW HIGH PROBABILITIES OF
ABOVE NORMAL TEMPERATURES FOR MUCH OF THE NORTHERN US,
INCLUDING OUR CWA.
AVIATION /03Z SUNDAY THROUGH THURSDAY/
THROUGH 00Z MONDAY...SNOW SHOWERS PERSIST AT SLK, MPV, AND EFK
THIS EVENING, AND HAVE GENERALLY ENDED ELSEWHERE. THERE'S STILL
THE POTENTIAL FOR SOME LIGHT SHOWERS TO RETURN TO THE CHAMPLAIN
VALLEY, IMPACTING BTV, BUT IT IS A LOWER POTENTIAL. AT THE
AFFECTED SITES, VISIBILITIES HAVE FALLEN BELOW 3 MILES, THOUGH
SOME FLUCTUATION IN VIS IS APPARENT IN LATEST 5 MINUTE
OBSERVATIONS. LOW CONFIDENCE ON EXACTLY HOW LONG THIS LOWER VIS
WILL CONTINUE, SO WENT WITH TEMPO GROUPS FOR THE NEXT 2 HOURS IN
THESE SPOTS. ELSEWHERE, CEILINGS 2700-4500 LINGER ACROSS
PORTIONS OF THE FORECAST AREA, THOUGH CLEARER AREAS ARE
DEVELOPING RAPIDLY. ALL SITES SHOULD MAKE THE RETURN TO VFR
CONDITIONS BY ABOUT 12Z-18Z, THOUGH IT WOULD NOT BE ENTIRELY
SURPRISING IF THIS HAPPENED SLIGHTLY SOONER THAN EXPECTED AS
SATELLITE IMAGES CONFLICT WITH MUCH OF THE AVAILABLE MODEL
GUIDANCE IN THIS REGARD. WINDS GUSTING NORTHWESTERLY 20-30 KNOTS
WILL DECREASE THROUGHOUT THE NIGHT TONIGHT, BUT SHOULD RETAIN
WESTERLY TO NORTHWESTERLY DIRECTION AND SUSTAINED WINDS 5-10
KNOTS.
OUTLOOK...
SUNDAY NIGHT: VFR. NO SIG WX.
MONDAY: VFR. NO SIG WX.
MONDAY NIGHT: MAINLY VFR, WITH AREAS MVFR AND IFR POSSIBLE.
DEFINITE SN.
TUESDAY: MAINLY VFR, WITH AREAS MVFR POSSIBLE. CHANCE SHSN.
TUESDAY NIGHT: VFR. NO SIG WX.
CHRISTMAS DAY: VFR. NO SIG WX.
WEDNESDAY NIGHT: VFR. NO SIG WX.
THURSDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. NO SIG WX.
MARINE
A LAKE WIND ADVISORY IS IN EFFECT FOR LAKE CHAMPLAIN. COLD N-NW
WINDS WILL CONTINUE AT 15-25KTS THROUGH TONIGHT ACROSS LAKE
CHAMPLAIN COURTESY OF A MODERATELY STRONG PRESSURE GRADIENT EAST
OF THE ARCTIC HIGH PRESSURE SYSTEM OVER THE NORTHERN GREAT
LAKES. WAVE HEIGHTS WILL RANGE FROM 2-4 FT THIS EVENING,
OVERNIGHT, AND DURING SUNDAY MORNING. WAVE HEIGHTS WILL LIKELY
BE HIGHEST ACROSS THE EASTERN PORTION OF THE BROAD LAKE AND IN
THE VICINITY OF SHELBURNE BAY. SOME FREEZING SPRAY IS POSSIBLE
WITH TEMPERATURES FALLING INTO THE LOW TEENS AND SINGLE DIGITS
ABOVE ZERO OVERNIGHT.
BTV WATCHES/WARNINGS/ADVISORIES
VT...NONE.
NY...COLD WEATHER ADVISORY UNTIL 9 AM EST SUNDAY FOR NYZ029>031-034.
SYNOPSIS...BANACOS
NEAR TERM...BANACOS/TABER
SHORT TERM...DUELL
LONG TERM...DUELL
AVIATION...STORM
MARINE...BANACOS
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