Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 171931 AFDBTV AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BURLINGTON VT 331 PM EDT WED SEP 17 2014 .SYNOPSIS... A COLD FRONT ACROSS ONTARIO AND SOUTHWESTERN QUEBEC WILL TRANSLATE SOUTHEASTWARD TONIGHT BRINGING A PERIOD OF CLOUDY CONDITIONS OVERNIGHT INTO EARLY THURSDAY MORNING...ALONG WITH A FEW LIGHT RAIN SHOWERS OR SPRINKLES...MAINLY OVER THE MOUNTAINS. WINDS TURN NORTHERLY BEHIND THE FRONT RESULTING IN FALL-LIKE AFTERNOON TEMPERATURES ON THURSDAY. STRONG HIGH PRESSURE BUILDS IN THURSDAY NIGHT AND FRIDAY...SETTING UP A WIDESPREAD FROST THURSDAY NIGHT WITH TEMPERATURES NEAR TO BELOW FREEZING IN MOST SECTIONS AWAY FROM LAKE CHAMPLAIN. FAIR AND SEASONABLY COOL CONDITIONS CONTINUE ON FRIDAY...FOLLOWED BY BREEZY AND WARMER WEATHER FOR SATURDAY. && .NEAR TERM /UNTIL 7 AM THURSDAY MORNING/... AS OF 320 PM EDT WEDNESDAY...SKIES ARE GENERALLY MOSTLY SUNNY ACROSS THE NORTH COUNTRY THIS AFTERNOON AS WEAK RIDGE OF HIGH PRESSURE PREVAILS FROM CENTRAL NEW YORK INTO WESTERN NEW ENGLAND. MEANWHILE...WEAK WAVE OF LOW PRESSURE IS DEVELOPING ALONG A FRONTAL ZONE IN THE OTTAWA VALLEY THIS AFTERNOON. THE LOW ITSELF WILL ZIP ENEWD ACROSS SRN QUEBEC TONIGHT...BUT THE TRAILING BOUNDARY WILL SHIFT SOUTHWARD AS A COLD FRONT REACHING THE ST. LAWRENCE VALLEY BY 04-06Z...AND ACROSS MOST OF THE CHAMPLAIN VALLEY OF 12Z. BASED ON UPSTREAM OBSERVATIONS...PLENTY OF LOW-MID LEVEL CLOUDS ALONG AND JUST BEHIND THE WIND SHIFT (ANAFRONTAL STRUCTURE)...SO ANTICIPATE A TREND TOWARD MOSTLY CLOUDY CONDITIONS LATER TONIGHT. MESOSCALE MODELS - INCLUDING THE BTV-4KM AND 12KM WRF RUNS - ARE NOT TOO BULLISH ON PRECIPITATION ASSOCIATED WITH THE FRONT...AS CONVERGENCE IS RELATIVELY SHALLOW AND LOW-LEVEL MOISTURE IS MARGINAL. WILL CONTINUE WITH JUST 20-30 POPS - HIGHEST ACROSS THE HIGHER TERRAIN OF THE NRN ADIRONDACKS AND NRN GREEN MTNS - FOR ANY LIGHT SHOWERS OR SPRINKLES WITH THE FRONTAL PASSAGE. RAINFALL AMTS GENERALLY A TRACE UP TO 0.05" ACROSS A FEW SPOTS. LOWS WILL GENERALLY BE WARMER THAN LAST NIGHT...IN THE LOW- MID 40S GIVEN INCREASE IN CLOUD COVER AND CONTINUED LIGHT S-SW WINDS SOUTH OF THE BOUNDARY THRU LATE THIS EVENING. && .SHORT TERM /7 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 320 PM EDT WEDNESDAY...LOOK FOR A NORTHERLY WIND SHIFT AS THE FRONT PASSES FROM NORTH TO SOUTH THROUGH THE REGION THURSDAY MORNING. SKIES WILL GRADUALLY CLEAR BY EARLY THURSDAY AFTERNOON BEHIND THE FRONT WITH INCREASING SUBSIDENCE. THE REINFORCING SURGE OF COOL CANADIAN AIR WILL ALSO DRIVE DEWPOINTS DOWN INTO THE UPR 30S THURSDAY AFTERNOON...SO IT WILL FEEL A BIT CRISP. HIGHS THURSDAY OF MID-UPR 50S NRN AREAS...AND LOCALLY IN THE LOW-MID 60S AROUND SPRINGFIELD VT WITH SOME DOWNSLOPE EFFECTS AND LATER ARRIVAL OF LOW-LEVEL COLD AIR ADVECTION EAST OF THE GREEN MOUNTAINS. CONDITIONS ARE IDEAL FOR A WIDESPREAD FROST/FREEZE EVENT THURSDAY NIGHT...AS STRONG HIGH PRESSURE SETTLES SOUTHEASTWARD ACROSS THE REGION FROM ONTARIO AND SWRN QUEBEC. 1000-500MB RH VALUES DROP BELOW 30 PERCENT...AND ANTICIPATE GENERALLY CLEAR SKIES WITH LIGHT WINDS. HAVE ISSUED A FREEZE WATCH FOR ALL ZONES EXCEPT GRAND ISLE COUNTY (CHAMPLAIN ISLANDS)...WHERE THE MODERATING INFLUENCE OF THE WARMER LAKE WATERS SHOULD LOCALLY PRECLUDE A FREEZE. TEMPS WILL RANGE FROM 31-35F FOR MOST OF THE CHAMPLAIN VALLEY (JUST A FROST IN SOME LOCATIONS NEAR THE LAKE)...AND GENERALLY MID 20S TO LOWER 30S ELSEWHERE ACROSS NRN NY AND VERMONT. THE FREEZE WILL BE CLIMATOLOGICALLY EARLY BY 1-2 WEEKS IN MANY AREAS OF CENTRAL/ERN VT AND THE ST. LAWRENCE VALLEY OF NY. WILL ALSO SEE SOME LOCALLY DENSE NOCTURNAL FOG IN THE FAVORED RIVER VALLEYS OF CENTRAL AND EASTERN VERMONT AFTER 04Z FRIDAY. IT MAY TAKE UNTIL 14-15Z FRIDAY FOR THE FOG TO DISSIPATE GIVEN EXPECTED STRENGTH OF THE NOCTURNAL INVERSION. AFTER A FROSTY START WITH SOME VALLEY FOG...FRIDAY SHOULD FEATURE RESPLENDENT BLUE SKIES AS SURFACE ANTICYCLONE REMAINS IN CONTROL...DRIFTING SEWD ACROSS NORTHERN NEW ENGLAND INTO THE GULF OF MAINE. WINDS WILL BECOME LIGHT SE-S DURING THE AFTERNOON HOURS. HIGH TEMPERATURES WILL CONTINUE BELOW NORMAL BY SEVERAL DEGREES...WITH HIGHS GENERALLY 55-60F IN MOST SECTIONS. SURFACE HIGH ELONGATES FROM SW-NE EAST OF NEW ENGLAND WITH INCREASING SOUTH TO SOUTHWEST WINDS DURING THE OVERNIGHT HOURS. WILL PROBABLY NEED A LAKE WIND ADVISORY OVER LAKE CHAMPLAIN AS WINDS REACH 20-25 KTS DURING THE PRE-DAWN HOURS. COMBINATION OF INCREASING GRADIENT FLOW AND MID-UPPER CLOUDS MOVING IN FROM THE WEST WILL KEEP TEMPERATURES ABOUT 10F WARMER THAN EXPECTED LOWS FOR FRIDAY MORNING. LOWS FRIDAY NIGHT GENERALLY LOW-MID 40S. MAY STILL SEE SOME PATCHY FOG IN THE DEEPER RIVER VALLEYS EAST OF THE GREENS MOUNTAINS. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 313 PM EDT WEDNESDAY...THERE APPEARS TO BE A LITTLE MORE AGREEMENT BETWEEN 12 UTC GLOBAL SOLUTIONS THAN PRIOR MODEL CYCLES. INITIAL PERIOD OF MILDER THAN NORMAL TEMPS SATURDAY/SATURDAY NIGHT BEFORE A STRONG COLD FRONT MOVES THROUGH LATE IN THE WEEKEND USHERING IN COOLER THAN NORMAL TEMPS. WARM FRONT ASSOCIATED WITH NORTHERN STREAM DISTURBANCE MOVING ACROSS SPREADS ACROSS THE NORTH COUNTRY EARLY SATURDAY WITH CLOUDS AND CHANCES FOR LIGHT SHOWERS. WARM-SECTOR AIRMASS ASSOCIATED WITH 850 MB TEMPS OF +13 TO +15C BECOMES BRIEFLY ENTRENCHED SATURDAY NIGHT/SUNDAY...LEADING TO DAYTIME HIGHS NEARING THE MID 70S AND LOWS IN THE 50S. PRIMARY FOCUS FOR POPS /LIKELY/ HOWEVER IS LATER SUNDAY INTO SUNDAY NIGHT WITH COLD FRONTAL PASSAGE. BELOW-NORMAL TEMPERATURES THEN EXPECTED FOR EARLY NEXT WEEK WITH FRONTAL PASSAGE AS 850 MB TEMPS CRASH BACK TO THE +5 TO +7C RANGE MONDAY NIGHT INTO TUESDAY UNDER NORTHWEST FLOW. BOTH GFS AND ECMWF SHOW A SECONDARY SHORTWAVE DIVING SOUTHEASTWARD MONDAY INTO TUESDAY...BUT COLD FRONT AND ASSOCIATED THERMAL GRADIENT SHIFTS FAR ENOUGH EAST TO KEEP ANY SFC LOW DEVELOPMENT ALONG THE BOUNDARY OFFSHORE. EARLIER 00Z ECMWF HAD SHOWN MORE DEVELOPMENT ALONG THE SAGGING BAROCLINIC ZONE AND WAS MORE UNSETTLED THAN THE GFS. STRONG RIDGE OF HIGH PRESSURE THEN BUILDS IN FOR TUESDAY/TUESDAY NIGHT WITH THERMAL TROUGHING STILL IN PLACE ALOFT. PRIMARILY HAVE STUCK WITH SUPERBLEND GUIDANCE THROUGH MIDWEEK. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... THROUGH 18Z THURSDAY...VFR AREA WIDE WITH SCT-BKN CLOUD DECKS BETWEEN 4000-7000FT. WHAT YOU SEE IS PRETTY MUCH WHAT YOU GET FOR THE REST OF THE AFTERNOON. OVERNIGHT A COLD FRONT WILL START MOVING ACROSS THE AREA. WON`T BE MUCH, IF ANY, PRECIPITATION. DID PUT IN A "VCSH" MENTION FOR SLK AND MSS SINCE IF THERE ARE ANY SHOWERS THE CHANCES THERE ARE A BIT HIGHER (~30%). WITH THE FRONTAL PASSAGE, WINDS WILL SHIFT TO THE NORTHWEST. EXPECT CEILINGS TO BRIEFLY DROP TO MVFR AT SLK AND MSS. MVFR CEILINGS COULD HAPPEN FOR A BRIEF PERIOD AT BTV THURSDAY MORNING AS WELL, BUT AT THIS POINT LEFT THAT OUT. WITH THE CLOUDS, THERE SHOULD NOT BE MUCH FOG. COULD BE BRIEF MVFR AT MPV SINCE THEY`LL HAVE LONGER TIME BEFORE THE COLD FRONT RELATED CLOUDS COME IN. IF WE HAD TAFS DOWN IN SPRINGFIELD VT (VSF), I`D BET THAT THEY STILL END UP AT LIFR CONDITIONS DUE TO LONGER PERIOD OF CLEAR SKIES. ANYWAY, CLOUDS BREAK UP AS WE GET CLOSER TO 18Z THURSDAY, LEAVING VFR CONDITIONS FOR EVERYONE. OUTLOOK 18Z THURSDAY THROUGH MONDAY... 18Z THURSDAY THROUGH 12Z SUNDAY...MAINLY VFR UNDER HIGH PRESSURE. IFR IN EARLY MORNING FOG ALSO LIKELY EACH NIGHT, MAINLY FOR KSLK AND KMPV. 12Z SUNDAY ONWARD...TRENDING MVFR AS SHOWERS DEVELOP LATER SUNDAY AND LASTING INTO MONDAY. && .CLIMATE... AS OF 150 PM EDT WEDNESDAY... FOLLOWING ARE THE RECORD LOWS FOR FRIDAY MORNING SEPT 19TH. GIVEN THE EXPECTED BLAST OF CHILLY AIR, WE MAY BE APPROACHING RECORDS AT SOME LOCATIONS. LOCATION...............RECORD...YEAR MT MANSFIELD (MMNV1)...24F 1979 RUTLAND (RUTV1)........27F 1990 MONTPELIER (MPV).......29F 1959 ST JOHNSBURY (SJBV1)...29F 1943 MASSENA (MSS)..........30F 2008 BURLINGTON (BTV).......32F 1959 && .BTV WATCHES/WARNINGS/ADVISORIES... VT...FREEZE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING FOR VTZ002>012-016>019. NY...FREEZE WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY MORNING FOR NYZ026>031-034-035-087. && $$ SYNOPSIS...BANACOS NEAR TERM...BANACOS SHORT TERM...BANACOS LONG TERM...LOCONTO AVIATION...NASH CLIMATE...NASH

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