509  
FXUS61 KBTV 111821  
AFDBTV  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BURLINGTON VT  
121 PM EST WED DEC 11 2019  
   
SYNOPSIS
 
 
DRY CONDITIONS LINGER THROUGH THIS MORNING, THEN EXPECT SNOW SHOWERS  
TO INCREASE ACROSS NORTHERN NY AND NORTHERN VT THIS AFTERNOON AND  
EVENING AS A COLD FRONT CROSSES THE REGION. SOME OF THIS ACTIVITY  
MAY BE BRIEFLY HEAVY LATE IN THE DAY, ESPECIALLY IN THE ST LAWRENCE  
VALLEY AND NORTHERN ADIRONDACKS, WHERE A COUPLE INCHES OF SNOW WILL  
BE POSSIBLE. DRIER BUT COLDER WEATHER ARRIVES ON THURSDAY. THE NEXT  
CHANCE FOR WIDESPREAD PRECIPITATION WILL OCCUR SATURDAY, WITH  
MODERATE RAIN GENERALLY EXPECTED ACROSS THE NORTH COUNTRY.  
 

 
   
NEAR TERM /THROUGH THURSDAY/
 
 
AS OF 120 PM EST WEDNESDAY...NO SIGNIFICANT CHANGES MADE WITH  
THIS UPDATE. THE MAIN CONCERN FOR THE DAY IS THE ONGOING LAKE  
EFFECT SNOWS ACROSS OUR WESTERN NY ZONES. THE FOCUS THEN SHIFTS  
TO THE POTENTIAL FOR BRIEF, MODERATE/HEAVY SNOW SHOWERS ALONG A  
COLD FRONT BETWEEN 21-03Z. LAKE EFFECT SNOW HAS BEGUN TO  
OVERSPREAD THE ST LAWRENCE RIVER VALLEY WITH WEBCAMS IN THE AREA  
(HAMMOND) SHOWING WHITEOUT CONDITIONS AND VISIBILITIES 1/4 MI  
OR LESS WITH SNOW BEGINNING TO ACCUMULATE. ADDITIONALLY,  
PARAMETERS ARE STILL FAVORABLE FOR A BAND OF CONVECTIVELY DRIVEN  
SNOW TO MOVE ACROSS OUR NORTHERN ZONES THIS EVENING ALONG A  
FRONTAL BOUNDARY.  
 
PREVIOUS DISCUSSION...A FAIRLY QUIET START TO THE DAY TODAY  
WITH THE COLD FRONT POSITIONED OFFSHORE AND WELL TO OUR SOUTH. MUCH  
DRIER AIR HAS SPREAD ACROSS THE NORTH COUNTRY BEHIND THE FRONT,  
SHUNTING THE STEADIER PRECIPITATION INTO SOUTHERN AND EASTERN NEW  
ENGLAND. CONDITIONS WILL CHANGE THIS AFTERNOON, HOWEVER, AS LOW  
PRESSURE CURRENTLY OVER LAKE SUPERIOR WILL SCOOT EASTWARD, MOVING  
NORTH OF OUR REGION LATER TODAY AND TONIGHT. WINDS WILL TURN TO THE  
SOUTHWEST AS THE LOW APPROACHES THIS AFTERNOON, ALLOWING ENHANCED  
MOISTURE TO STREAM OFF OF LAKE ONTARIO AND INTO NORTHERN NY.  
MEANWHILE, THE LOW'S ATTENDANT COLD FRONT WILL PUSH EASTWARD,  
ENTERING THE ST LAWRENCE VALLEY MID-LATE AFTERNOON, AND INTO THE  
ADIRONDACKS EARLY THIS EVENING. THIS FRONT WILL SERVE TO FOCUS THE  
LAKE-ENHANCED MOISTURE. LOW-LEVEL LAPSE RATES WILL STEEPEN UNDER  
COLD AIR ADVECTION; NOTE THAT MODEL GUIDANCE CONTINUES TO SHOW  
SBCAPE VALUES POSSIBLY EXCEEDING 100 J/KG. HENCE EXPECT THERE WILL  
BE A SHARP LINE OF BRIEFLY HEAVY SNOW THAT WILL MOVE THROUGH THE ST  
LAWRENCE VALLEY INTO THE NORTHERN ADIRONDACKS LATE THIS AFTERNOON  
INTO EARLY EVENING. HI-RES CAMS AGREE WITH THIS SCENARIO, WITH THE  
BAND BREAKING UP AS IT MOVES EASTWARD THROUGH THE ADIRONDACKS AND  
INTO NORTHERN VT. ONE POSSIBLE SNAG IS THE LACK OF SUBSTANTIAL  
MOISTURE FOR THOSE AREAS WELL AWAY FROM LAKE ONTARIO. STILL, WOULD  
EXPECT A QUICK INCH OR TWO OF ACCUMULATION WITH THIS BAND ALONG AND  
WEST OF THE WESTERN SLOPES OF THE ADIRONDACKS, WITH LESSER AMOUNTS  
TO THE SOUTH AND EAST. THE AFOREMENTIONED STEEPENING LAPSE RATES  
WILL ALSO SERVE TO ALLOW AMPLE MIXING OF WINDS ALOFT DOWN TO THE  
SURFACE. THE LATEST NAM SOUNDING FOR MSS INDICATES MIXING TO 10 KFT  
POST-FRONT, AND WITH 30-40 KT AT THE TOP OF THE MIXED LAYER, SO  
EXPECT WINDS WILL BE GUSTY WITH AND AFTER THE FRONT. THE REINFORCING  
SHOT OF COLD AND DRY AIR BEHIND THE FRONT WILL BRING SNOW TO AN END  
BY MIDNIGHT OR SHORTLY THEREAFTER, LINGERING LONGEST IN THE NORTHERN  
GREEN MOUNTAINS. TEMPERATURES WILL BE COLD UNDER CLEARING SKIES,  
THOUGH WINDS WILL REMAIN GUSTY MUCH OF THE NIGHT DUE TO THE  
AFOREMENTIONED COLD AIR ADVECTION/MIXING. LOWS WILL RANGE FROM THE  
SINGLE DIGITS IN THE ADIRONDACKS AND NORTHEAST KINGDOM TO THE MID  
TEENS IN THE WIDER VALLEYS.  
 
THURSDAY WILL BE CHILLY BUT DRY AS HIGH PRESSURE SLOWLY BUILDS OVER  
THE NORTHEAST CONUS. WE'LL START OUT WITH PLENTY OF SUNSHINE, BUT  
HIGH CLOUDS WILL SPREAD FROM WEST TO EAST DURING THE AFTERNOON AHEAD  
OF WEAK LOW PRESSURE PUSHING INTO THE GREAT LAKES. WINDS WILL TURN  
TO THE SOUTH/SOUTHWEST LATE IN THE DAY AS THE RIDGE AXIS MOVES EAST,  
BUT TEMPERATURES WILL REMAIN WELL BELOW NORMAL FOR MID DECEMBER.  
HIGHS WILL RANGE THE UPPER TEENS IN THE NORTHEAST KINGDOM TO THE MID  
AND UPPER 20S IN THE MORE SOUTHERN VALLEY LOCATIONS.  
 

 
   
SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/
 
 
AS OF 331 AM EST WEDNESDAY...THURSDAY NIGHT INTO THE PRE-DAWN HOURS,  
QUIET CONDITIONS ARE EXPECTED, THOUGH INCREASINGLY GUSTY WILL ADD  
SOME DISRUPT THE QUIET. AS HIGH PRESSURE SHIFTS OFFSHORE, STRONG  
PRESSURE GRADIENTS WILL RESULT IN INCREASING SOUTHERLY FLOW THAT  
WILL CHANNEL THROUGH THE CHAMPLAIN VALLEY, IN PARTICULAR. A WEAK  
UPPER SHORTWAVE WILL PASS TO OUR NORTH WITH THE MAIN IMPACTS BEING  
CLOUD COVER. WITH THAT AND THE INCREASING WINDS, OVERNIGHT LOWS ARE  
EXPECTED TO REMAIN IN THE TEENS TO MID 20S.  
 
CLOUDS SHOULD BRIEFLY CLEAR AS MOISTURE CONTINUES TO LIFT NORTH AND  
EAST. WE SHOULD ALSO SEE GUSTY WINDS PEAK LATE MORNING/EARLY  
AFTERNOON ONCE WARM AIR ADVECTION ALOFT REDUCES OUR MIXING  
POTENTIAL. WE SHOULD SEE HIGHS CREEP ABOVE FREEZING ACROSS MUCH OF  
THE REGION, EXCEPT AT SOME OF OUR COLDER HOLLOWS.  
 
TOWARDS THE EVENING HOURS, SOME DRIZZLE OR FLURRIES COULD BEGIN TO  
WORK ITS WAY NORTHWARD INTO SOUTH-CENTRAL VERMONT INTO THE  
ADIRONDACKS AS WARM, MOIST ADVECTION CONTINUES TO INCREASE. FORECAST  
SOUNDINGS ARE FAIRLY COMPLEX WITH LITTLE CLOUD ICE SUGGESTING MORE  
DRIZZLE/FLURRY AT ONSET. DEEP LAYER MOISTURE WILL CONTINUE TO  
INCREASE. AS THE PREVIOUS FORECASTER NOTED, SOME OF OUR COLD HOLLOWS  
COULD HOVER AROUND THE FREEZING MARK AND REMAIN NEAR THAT POINT FROM  
WET-BULBING. THERE IS A VERY QUICK WINDOW WHERE A BRIEF SNOW AND  
FREEZING RAIN MIX TAKES PLACE AS THE WARM NOSE STRENGTHENS AND WHILE  
THE WET-BULB EFFECT MAINTAINS THE COLDER AIR ACROSS THOSE COLDER  
HOLLOWS.  
 

 
   
LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/
 
 
AS OF 331 AM EST WEDNESDAY...ANY MIXED PRECIP TYPES SHOULD TRANSITION  
TO RAIN DURING THE PRE-DAWN HOURS ON SATURDAY. THE HIGHER SUMMITS  
WILL BE THE EXCEPTION AND WILL BE THE LAST TO TRANSITION TO RAIN.  
FORECAST GUIDANCE REMAINS CONSISTENT IN STRONG WARMING WITH SURFACE  
TEMPERATURES WARMING INTO THE 40S.  
 
NEGATIVELY TILTED TROUGH WILL MOVE IN DURING THE DAY ON SATURDAY  
WITH A COASTAL LOW LIKELY TRACKING INTO INTERIOR NEW ENGLAND. NOT  
MUCH HAS CHANGED IN THE OVERALL DETAILS WITH NEAR RECORD PWATS STILL  
FORECAST ALONG WITH THE POTENTIAL FOR DOWNSLOPE WINDS ON THE WESTERN  
SLOPES FROM A 40-45KT EAST-SOUTHEASTERLY LOW-LEVEL JET TO THE NORTH  
OF THE LOW. WITH THE MOSTLY STABLE AIR, NOT ANTICIPATING TOO MUCH  
GUSTINESS, BUT PORTIONS OF THE SOUTHERN GREENS SEEMS THE MOST LIKELY  
TO SEE GUSTY WINDS CHANNELING THROUGH ANY GAPS IN THE MOUNTAIN  
RANGE. AS FOR PRECIPITATION AMOUNTS, EARLY INDICATIONS ARE STILL FOR  
ABOUT A 0.50"-1.00" WITH A LOCALLY UP TO 1.5", PARTICULARLY EAST OF  
THE GREENS.  
 
ACTIVE WEATHER CONTINUES INTO SUNDAY AS THE MID-LEVEL LOW TRACKS  
ACROSS THE REGION. PLENTY OF SYNOPTIC SCALE FORCING FOR ASCENT  
REMAINS AS THE COLD FRONT MOVES ACROSS DURING THE MORNING HOURS.  
UNFORTUNATELY, COLDER AIR WILL BE SLOW TO MOVE IN AS THE MID-LEVEL  
LOW TRACKS NORTH OF US, KEEPING MORE WEST-SOUTHWESTERLY FLOW IN  
PLACE. BY THE TIME COLD AIR DOES ARRIVE, THE BACKSIDE OF THE TROUGH  
BEGINS TO LIFT OUT OF THE REGION WITH MOISTURE QUICKLY THINNING  
SUNDAY NIGHT INTO MONDAY. MAINLY MOUNTAIN SNOW SHOWERS WILL BE  
POSSIBLE SUNDAY EVENING/MONDAY. OTHERWISE, MOSTLY DRY CONDITIONS  
MONDAY INTO EARLY TUESDAY. THE NEXT SYSTEM WILL ALREADY BE AT OUR  
DOORSTEP ON TUESDAY.  
 

 
   
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
 
 
THROUGH 18Z THURSDAY...LAKE EFFECT SNOW WILL CONTINUE ACROSS  
THE ST LAWRENCE VALLEY THROUGH EARLY EVENING WITH MVFR CEILINGS  
AND IFR VISIBILITIES, WITH LOCALLY LOWER LIFR VISBILITIES (DOWN  
TO 1/4 MI) IN THE HEAVIEST SNOWS. A COLD FRONT WILL MOVE ACROSS  
THE REGION FROM WEST TO EAST THIS EVENING AND ALONG WITH IT  
PROVIDE FOCUS FOR A BAND OF MODERATE TO BRIEFLY HEAVY SNOW. THIS  
FRONT IS EXPECTED TO IMPACT KMSS AND KSLK BETWEEN 22-23Z, KPBG  
AND KBTV 23-00Z AND KMPV AROUND 00-01Z. VISIBILITIES MAY BRIEFLY  
DROP DOWN TO IFR. AFTER 02Z, ALL SITES WILL BECOME VFR EXPECT  
KSLK WHICH COULD SEE SOME MVFR SNOW SHOWERS LINGER THROUGH 04Z.  
SOUTHWESTERLY WINDS BETWEEN 10-15 KNOTS WILL PREVAIL THROUGH THE  
REMAINDER OF THE AFTERNOON/EVENING, WITH GUSTS AROUND20 KNOTS  
POSSIBLE. AFTER THE FRONT MOVES THROUGH WINDS WILL TURN OUT OF  
THE WEST WITH GUSTS UP TO 25-30 KNOTS AT TIMES.  
 
OUTLOOK...  
 
THURSDAY NIGHT: VFR. NO SIG WX.  
FRIDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. NO SIG WX.  
FRIDAY NIGHT: MVFR/IFR CONDITIONS POSSIBLE. DEFINITE RA, CHANCE  
FZRA, SLIGHT CHANCE SN.  
SATURDAY: MAINLY IFR, WITH AREAS MVFR POSSIBLE. DEFINITE RA.  
SATURDAY NIGHT: IFR. LIKELY RA, LIKELY SN.  
SUNDAY: MAINLY MVFR, WITH AREAS IFR POSSIBLE. LIKELY SN, CHANCE  
RA.  
SUNDAY NIGHT: MAINLY VFR, WITH AREAS MVFR POSSIBLE. CHANCE SN,  
SLIGHT CHANCE FZRA.  
MONDAY: VFR. NO SIG WX.  
 

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

 
 

 
SYNOPSIS...HASTINGS  
NEAR TERM...HASTINGS/LAROCCA  
SHORT TERM...HAYNES  
LONG TERM...HAYNES  
AVIATION...LAROCCA  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab VT Page
The Nexlab NY Page Main Text Page