713  
FXUS61 KBTV 221756  
AFDBTV  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE BURLINGTON VT  
156 PM EDT FRI OCT 22 2021  
   
SYNOPSIS
 
 
A SHARP COLD FRONT IS PASSING THROUGH THE NORTH COUNTRY TODAY,  
USHERING IN SEASONABLY COOL AND DRY AIR. CYCLONIC FLOW AROUND AN  
UPPER LEVEL LOW WELL NORTH OF THE GREAT LAKES WILL PERIODICALLY  
SPREAD CLOUDS AND A FEW MOUNTAIN SHOWERS EASTWARD OVER THE  
WEEKEND, OTHERWISE WEATHER WILL BE QUIET WITH AREAS OF SUB  
FREEZING TEMPERATURES. A QUASI STATIONARY FRONTAL BOUNDARY WILL  
LIFT NORTHWARD EARLY NEXT WEEK SUPPORTING INCREASING CHANCES FOR  
A STEADY COLD RAIN, WITH ADDITIONAL WET WEATHER EXPECTED BY THE  
END OF THE WEEK.  
 

 
   
NEAR TERM /THROUGH SATURDAY/
 
 
AS OF 957 AM EDT FRIDAY...FORECAST REMAINS ON TRACK FOR THE REST  
OF TODAY WITH ONLY SLIGHT ADJUSTMENTS MADE TO SKY AND TEMPS  
BASED ON FRONTAL PASSAGE TIMING. OTHERWISE, NO CHANGES MADE.  
 
PREVIOUS DISCUSSION...  
A POTENT UPPER LEVEL SYSTEM IS CURRENTLY MOVING THROUGH THE  
NORTH COUNTRY BRINGING WIDESPREAD SHOWERS. GOES-16 NIGHTTIME  
MICROPHYSICS SATELLITE IMAGERY SHOWS DEEP CLOUDS OVER THE ENTIRE  
REGION WITH SHALLOWER CLOUDS JUST TO THE SOUTHWEST WHERE WATER  
VAPOR IMAGERY SHOWS MUCH DRIER AIR PUNCHING IN BEHIND THE UPPER  
LEVEL LOW. THEREFORE SHOWERS WILL NOT LAST MUCH LONGER AND  
LITTLE IF ANY PRECIPITATION WILL BE ALONG THE SURFACE FRONTAL  
PASSAGE AS IT MOVES THROUGH THIS MORNING. ADDITIONALLY, THE  
DRYING ALOFT IS ALREADY RESULTING IN LOWERING CLOUDS ACROSS THE  
ST. LAWRENCE VALLEY AND EXPECT GRAY SKIES TO PERSIST AREAWIDE  
FOR MUCH OF THE DAY GIVEN THE SHARPENING INVERSION AS COOLING  
LOW LEVEL AIR UNDERCUTS RELATIVELY WARM AIR ABOVE.  
 
THE COMBINATION OF MODEST COLD AIR ADVECTION ON NORTHWEST WIND,  
CLOUD COVER, AND DRIER AIR WILL HELP MAKE IT FEEL MUCH COLDER THAN  
YESTERDAY. TEMPERATURES WILL FALL BEHIND THE FRONT, RESULTING IN  
MIDDAY TEMPERATURES ONLY IN THE 40 TO 45 RANGE ACROSS NORTHERN NEW  
YORK. IN VERMONT, TEMPERATURES WILL TICK DOWNWARD DURING THE  
AFTERNOON HOURS AFTER BEING GENERALLY STEADY IN THE 50S THROUGH THE  
FIRST PART OF THE DAY. FORECAST SOUNDINGS FOR TONIGHT SHOW THE CLOUD  
LAYER MAY PERSIST ALONG WITH CONTINUOUS MIXING OF THE BOUNDARY LAYER  
BELOW THE INVERSION AS LOW LEVEL COLD AIR ADVECTION CONTINUES. AS A  
RESULT, WHILE TEMPERATURES WILL COOL INTO THE UPPER 20S TO MID 30S  
IN MOST LOCATIONS, FROST WILL LIKELY BE PATCHY AT MOST, BUT WILL  
NEED TO CONSIDER IT A POSSIBILITY NEVERTHELESS WITH THE LACK OF  
FREEZING TEMPERATURES SO FAR THIS SEASON.  
 
WHILE SURFACE HIGH PRESSURE AND DAYTIME HEATING WILL ERODE THE LOW  
CLOUDS, SHORTWAVE ENERGY LIFTING NORTHEASTWARD WILL SPREAD SOME  
HIGHER CLOUDS ACROSS THE REGION SATURDAY MORNING BEFORE A CLEARING  
TREND GETS UNDERWAY. THE CYCLONIC WEST-SOUTHWEST FLOW ALOFT WILL  
SUPPORT AT LEAST LOW CHANCES OF SPRINKLES OR EVEN FLURRIES ACROSS  
PARTS OF THE ADIRONDACKS, BUT IT WILL GENERALLY BE A DRY DAY WITH  
TEMPERATURES MAINLY IN THE MID AND UPPER 40S, OR ABOUT 5 DEGREES  
BELOW NORMAL, WITH LIGHT WINDS.  
 

 
   
SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/
 
 
AS OF 409 AM EDT FRIDAY...MID/UPPER LVL TROF PREVAILS ACRS THE  
NORTHERN GREAT LAKES INTO THE NE CONUS DURING THIS TIME FRAME. THE  
CORE OF COLDEST AIR LOOKS TO REMAIN JUST NORTH OF OUR CWA, AS FAST  
CONFLUENT WESTERLY FLOW CONTINUES THRU SUNDAY EVENING. HAVE  
CONTINUED WITH SCHC/CHC POPS FOR LATE SATURDAY NIGHT INTO SUNDAY  
MORNING ASSOCIATED WITH SECONDARY VORT, POCKET OF 850 TO 500MB RH  
>70%, AND MODEST LAKE INSTABILITY. HOWEVER, CLOUD LAYER FLOW IS <30  
KNOTS AND FROM A WESTERLY DIRECTION, SO AREAL COVERAGE DOWNWIND OF  
LAKE ONTARIO WILL BE LIMITED. HIGHEST POPS WILL BE ACRS NORTHERN NY  
BTWN 06-12Z SUNDAY. TEMPS WL BE SEASONABLY COOL SAT NIGHT WITH LOWS  
UPPER 20S TO NEAR 40F, WARMEST NEAR LAKE CHAMPLAIN, WHILE HIGHS  
CLIMB BACK INTO THE UPPER 40S TO L/M 50S ON SUNDAY, WITH SUMMITS  
HOLDING IN THE 30S. SUNDAY NIGHT FAST CONFLUENT FLOW INCREASES AS  
MID/UPPER LVL TROF TRIES TO DIG SOUTH, WHILE RIDGE BUILDS ACRS THE  
SE CONUS. THIS PRODUCES STRONG 500MB WINDS OF 50 TO 80 KNOTS ACRS  
OUR FA, WHILE SHARPENING THE NORTH-SOUTH MOISTURE AND THERMAL  
FIELDS. LATEST 00Z TRENDS IN ALL THE GUIDANCE HAS BEEN FOR A SHIFT  
NORTHWARD IN THIS GRADIENT, PRODUCING STRONGER FORCING AND BETTER  
MOISTURE ACRS OUR CENTRAL/SOUTHERN CWA BY 12Z MONDAY. HAVE BUMPED  
POPS INTO THE SCHC NEAR INTERNATIONAL BORDER TO LIKELY FOR  
RUTLAND/WINDSOR COUNTIES, WITH SHARP NORTH-SOUTH GRADIENT  
ANTICIPATED. EXPECT ADDITIONAL SHIFTS IN THE POPS/QPF FIELDS AS WE  
HEAD INTO THE WEEKEND, ESPECIALLY IF NORTHERLY FLOW DEVELOPS FROM  
SFC HIGH PRES NEAR HUDSON BAY AND DRIER AIR ADVECTS SOUTHWARD. GIVEN  
THERMAL PROFILES SOME WET SNOW IS LIKELY ABOVE 4000 FEET LATE  
SUNDAY NIGHT, AS PROGGED 850MB TEMPS HOVER BTWN -1C AND 0C.  
COOLEST TEMPS WL BE NEK WITH LOWS MID/UPPER 20S TO LOWER 40S  
SOUTHERN SLV ON SUNDAY NIGHT.  
 

 
   
LONG TERM /MONDAY THROUGH THURSDAY/
 
 
AS OF 409 AM EDT FRIDAY...FCST CHALLENGE REMAINS POPS/QPF FOR EARLY  
WEEK, ASSOCIATED WITH SHARP BOUNDARY DRAPED ACRS THE MID ATLANTIC/NE  
CONUS. 00Z TRENDS IN ALL THE GUIDANCE HAS BEEN TO PLACE HIGHER 850  
TO 500MB RH FIELDS FURTHER NORTH, ALONG WITH BETTER FGEN FORCING  
ASSOCIATED WITH TIGHTENING THERMAL GRADIENT ACRS OUR FA FOR MONDAY  
INTO TUES. HAVE NOTED GFS/GEM AND UKMET IN GOOD AGREEMENT, WHILE  
ECMWF IS STILL THE SLOWEST WITH BUILDING PRECIP FIELDS NORTHWARD  
INTO OUR CWA. GIVEN THE TRENDS AND POSITION OF SFC HIGH PRES NEAR  
HUDSON BAY INSTEAD OF BUILDING SOUTHWARD INTO OUR CWA, I HAVE  
INCLUDED POPS INTO THE LIKELY RANGE FROM CENTRAL/SOUTHERN CWA WITH  
CHC FOR NORTHERN AREAS ON MONDAY. THESE POPS ARE TAPERED BACK TO CHC  
FOR MONDAY NIGHT INTO TUESDAY, BUT IF TRENDS PREVAIL WL NEED TO  
INCREASE SOME MORE, ESPECIALLY IF 00Z GUIDANCE IS CORRECT. A COLD,  
RAW AND DAMP DAY IS LIKELY ACRS OUR CWA MONDAY, WITH PROGGED 925MB  
TO 850MB TEMPS HOVERING BTWN -2C TO +2C FROM NORTH TO SOUTH ACRS OUR  
FA. THESE VALUES SUPPORT THE IDEA OF SNOW LEVELS NEAR 4000 FT ON  
MONDAY FROM THE NORTHERN DACKS INTO THE HIGHER SUMMITS OF VT, WITH  
SEVERAL INCHES POSSIBLE. HAVE TRIMMED BACK TEMPS AND TRENDED TOWARD  
THE NBM 25% VALUES FOR MONDAY/TUES BASED ON NORTHERLY WINDS, CLOUDS  
AND PRECIP, WHICH SUPPORT UPPER 30S/LOWER 40S TO MID/UPPER 40S,  
WHILE SUMMITS HOLD IN THE 30S. STILL SOME UNCERTAINTY ON HOW FAST  
MID/UPPER LVL SYSTEM AND ASSOCIATED SFC LOW PRES EJECT EASTWARD INTO  
THE NORTHERN ATLANTIC FOR TUES/WEDS, WITH ECMWF/GEM MUCH SLOWER,  
WHILE GFS IS THE FASTEST. THE ECMWF/GEM SHOW DEEPENING AND CLOSING  
OFF 7H/5H CIRCULATION OVER SNE, WITH 996MB LOW PRES OVER CAPE COD BY  
12Z WEDS, WHILE GFS HAS SAME IDEA, BUT WELL EAST OF THE 40/70  
BENCHMARK. THE OVERALL PATTERN HAS A LOW PREDICTABILITY ESPECIALLY  
WHEN GUIDANCE IS TRYING TO TRANSITION FROM A FAST CONFLUENT FLOW  
ALOFT TO MORE OF A BLOCKING/AMPLIFYING MID/UPPER LVL PATTERN. BASED  
ON THIS HAVE CONTINUED WITH CHC POPS FOR TUES/WEDS WITH TEMPS ON THE  
COOLER SIDE OF GUIDANCE, ESPECIALLY FOR DAILY HIGHS. NEXT LARGE  
SCALE SYNOPTIC SYSTEM LOOKS TO APPROACH FA LATE THURS INTO FRIDAY  
WITH ADDITIONAL PRECIP CHCS, ALONG WITH SOME WIND THREAT. OVERALL  
SYSTEM EVOLUTION AND STRENGTH WL BE BETTER MODELED IN THE DAYS  
AHEAD, SO STAY TUNED.  
 

 
   
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
 
 
THROUGH 18Z SATURDAY...DIFFICULT AVIATION FORECAST FOR THE NEXT  
12 HOURS AS HIGH PRESSURE BUILDS IN BEHIND A SURFACE COLD FRONT,  
BUT A DEVELOPING LOW LEVEL INVERSION WILL KEEP MOISTURE TRAPPED  
NEAR THE SURFACE FOR MANY LOCATIONS. FEEL KBTV/KPBG/KMSS WILL  
LARGELY REMAIN VFR, WITH MVFR PREVAILING AT KMPV/KEFK, IFR AT  
KSLK AND A MIX OF MVFR/VFR AT KRUT. ANY GUSTY WINDS THIS  
AFTERNOON ABATE THIS EVENING GOING LIGHT AND VARIABLE OVERNIGHT.  
AFTER 12Z SATURDAY, SUBSIDENCE ALOFT SHOULD BEGIN TO EAT AWAY AT  
LOW CLOUDS, SCATTERING OUT THROUGH THE MORNING WITH ADDITIONAL  
HIGH CLOUDS STREAMING IN DURING THE AFTERNOON.  
 
OUTLOOK...  
 
SATURDAY NIGHT: VFR. SLIGHT CHANCE SHRA.  
SUNDAY: VFR. SLIGHT CHANCE SHRA.  
SUNDAY NIGHT: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. CHANCE RA.  
MONDAY: MAINLY VFR, WITH LOCAL MVFR POSSIBLE. CHANCE RA.  
MONDAY NIGHT: MAINLY MVFR, WITH LOCAL IFR POSSIBLE. CHANCE RA,  
CHANCE SN.  
TUESDAY: MAINLY IFR, WITH AREAS MVFR POSSIBLE. CHANCE RA.  
TUESDAY NIGHT: MAINLY IFR, WITH LOCAL MVFR POSSIBLE. CHANCE RA.  
WEDNESDAY: MAINLY IFR, WITH AREAS MVFR POSSIBLE. SLIGHT CHANCE  
SHRA.  
 

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

 
 

 
SYNOPSIS...KUTIKOFF  
NEAR TERM...KUTIKOFF/LAHIFF  
SHORT TERM...TABER  
LONG TERM...TABER  
AVIATION...LAHIFF  
 
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