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Area Forecast Discussion
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000
FXUS61 KBTV 180801
AFDBTV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BURLINGTON VT
401 AM EDT THU SEP 18 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 THIS MORNING/...
AS OF 108 AM EDT THURSDAY...GOING FORECAST REMAINS IN GOOD SHAPE.
NO REAL CHANGES NEEDED...ONLY MINOR ADJUSTMENTS MADE TO HOURLY
PARAMETERS TO REFLECT LATEST CONDITIONS AND TRENDS. FRONT NOW
SOUTH OF OTTAWA OF OTTAWA AND MONTREAL...AND CONTINUES TO PUSH
SOUTH TOWARDS FORECAST AREA. WIDELY SCATTERED LIGHT RAIN
SHOWERS/SPRINKLES POSSIBLE OVER NORTHERN AREAS OVERNIGHT. CURRENT
POPS OF 20-30 PERCENT LOOK REASONABLE. 

EARLIER DISCUSSION FROM 721 PM WEDNESDAY...
UPPER TROUGH AND SURFACE COLD FRONT CONTINUE TO APPROACH THE
REGION THIS EVENING WITH SOUTH/SOUTHWEST FLOW ACROSS THE AREA OUT
AHEAD OF THE FRONT...SHIFTING TO NORTH/NORTHWEST BEHIND FRONT IN
SOUTHERN CANADA. CLOUDS WILL INCREASE AREA-WIDE THIS EVENING WITH
A FEW SCATTERED RAIN SHOWERS POSSIBLE OVERNIGHT WITH FRONTAL
PASSAGE...AND THEN PERHAPS A FEW LINGERING INTO THURSDAY MORNING
WITH RESIDUAL MOISTURE AND NORTHWEST FLOW. FRONTAL PASSAGE TIMES
SHOULD BE AROUND 06Z IN THE SAINT LAWRENCE VALLEY...09Z CHAMPLAIN
VALLEY...AND THROUGH THE ENTIRE REGION BY 12Z. AREAS THAT START
CLEAR THIS EVENING WILL DROP RAPIDLY AT FIRST...BUT OVERALL
MINIMUM TEMPERATURES WON'T BE MET UNTIL LATE AFTER FRONT
PASSES...GENERALLY IN THE 40S FOR MOST.

&&

.SHORT TERM /7 AM THIS MORNING THROUGH SATURDAY/...
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 NIGHT THROUGH WEDNESDAY/...
AS OF 400 AM EDT THURSDAY...VERY LITTLE OVERALL CHANGE FROM
PREVIOUS FORECASTER THINKING AS MEDIUM RANGE GUIDANCE REMAINS IN
GOOD AGREEMENT IN REGARDS TO THE SYNOPTIC PATTERN DURING THE
EXTENDED PERIOD.

LONG TERM FORECAST STARTS OUT DRY FOR SATURDAY NIGHT WITH THE BTV
CWA ENTRENCHED IN THE WARM SECTOR OF A DEVELOPING SURFACE LOW
JUST NORTH OF THE GREAT LAKES. SHOULD BE A PRETTY MILD NIGHT
UNDER PARTLY CLOUDY SKIES AND A MODEST SOUTHERLY WIND WITH LOWS
RANGING THROUGH THE 50S AREA-WIDE TO LOW 60S IN THE CHAMPLAIN AND
ST. LAWRENCE VALLEYS. BY SUNDAY MORNING...LOW TRACKS NORTHEAST
THROUGH SOUTH-CENTRAL QUEBEC DRAGGING THE ATTENDING COLD FRONT
THROUGH THE NORTH COUNTRY. GFS AND ECMWF REMAIN IN GOOD AGREEMENT
FROM PREVIOUS RUNS IN REGARDS TO FROPA TIMING...AND FEEL
CONFIDENT WE'LL SEE A GOOD 6-HOUR PERIOD OF LIGHT RAIN AT ANY ONE
LOCATION AS THE FRONT TRAVERSES THE AREA. BETS GUESS AT TIMING
RIGHT NOW LOOKS LIKE 12-18Z ACROSS NORTHERN NEW YORK...CHAMPLAIN
VALLEY 18-00Z...AND EASTERN VERMONT 00-06Z SUNDAY NIGHT.

COLD FRONT SHIFTS EAST OF THE REGION MONDAY MORNING BUT THE
TRAILING UPPER TROUGH CONTINUES TO DIG INTO THE MID-ATLANTIC AND
NORTHEAST STATES WITH A SECONDARY SHORTWAVE DIVING SOUTHEASTWARD
MONDAY NIGHT INTO TUESDAY. BEST AVAILABLE LOW/MID LEVEL MOISTURE
IS EAST OF THE BTV CWA WITH THE FRONT BUT CAN'T RULE OUT A FEW
SHOWERS AS THE TROUGH PASSES AND FLOW TURNS TO THE NORTHWEST. WE
COULD EVEN SEE THE FIRST SNOWFLAKES OF THE SEASON ACROSS THE
HIGHER TERRAIN OF FAR NORTHERN VERMONT (JAY PEAK TO MANSFIELD) AS
PROGGED 850MB TEMPS OFF THE GFS FALL BELOW FREEZING AND 500-100MB
THICKNESS DIP BELOW 540DM. ECMWF IS SLIGHTLY WARMER SO WE'LL
SEE...BUT FALL WILL DEFINITELY BE IN THE AIR WITH THE TREND OF
BELOW NORMAL TEMPS CONTINUING.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
THROUGH 06Z FRIDAY...SURFACE COLD FRONT SHIFTING INTO THE REGION
EARLY THIS MORNING WITH SCT-OVC VFR CIGS AHEAD OF THE FRONT GRADUALLY
LOWERING TO MVFR FOR A BRIEF PERIOD BEHIND THE FRONT BEFORE RETURNING
TO VFR BY MID-DAY. CURRENT RADAR COVERAGE SHOWS WIDELY SCATTERED
SPRINKLES ALONG THE INTL BORDER WITH SURFACE OBS SHOWING NO
RESTRICTIONS TO VSBY. FEEL THIS WASN'T EVEN WORTH MENTIONING IN
THE TAF. HIGH PRESSURE BEGINS TO BUILD BACK INTO THE AREA THIS
AFTERNOON/EVENING WITH SKIES CLEARING OUT AFTER 00Z. LIGHT
SOUTH/SOUTHWEST FLOW SHIFTS TO NORTH/NORTHWEST (NORTHEAST FOR A
TIME AT PBG AND MSS) FOR THURSDAY FROM 5-10 KNOTS.

OUTLOOK 06Z FRIDAY THROUGH MONDAY...

06Z FRIDAY THROUGH 12Z SUNDAY...MAINLY VFR UNDER HIGH PRESSURE. IFR
IN EARLY MORNING FOG ALSO LIKELY EACH NIGHT...MAINLY FOR KSLK AND
KMPV.

12Z SUNDAY THROUGH 12Z MONDAY...VFR TRENDING TO MVFR IN SHOWERS
FROM WEST TO EAST AS A COLD FRONT TRACKS THROUGH THE REGION.

12Z MONDAY THROUGH 00Z TUESDAY...MORNING MVFR WITH LINGERING POST-
FRONTAL SHOWERS POSSIBLE...TRENDING TO VFR LATE IN THE DAY AS HIGH
PRESSURE RETURNS.

&&

.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 WARNING FROM 1 AM TO 8 AM EDT FRIDAY FOR VTZ003-004-
     006>008-010-016>018.
     FROST ADVISORY FROM 1 AM TO 8 AM EDT FRIDAY FOR VTZ002-005-009-
     011-012-019.
NY...FREEZE WARNING FROM 1 AM TO 8 AM EDT FRIDAY FOR NYZ026-027-
     029>031-034-087.
     FROST ADVISORY FROM 1 AM TO 8 AM EDT FRIDAY FOR NYZ028-035.

&&

$$
SYNOPSIS...BANACOS
NEAR TERM...RJS/MUCCILLI
SHORT TERM...BANACOS
LONG TERM...LAHIFF
AVIATION...LAHIFF
CLIMATE...NASH







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