Area Forecast Discussion
Issued by NWS Burlington, VT

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000 FXUS61 KBTV 160850 AFDBTV Area Forecast Discussion National Weather Service Burlington VT 350 AM EST Thu Nov 16 2017 .SYNOPSIS... Low pressure will move northwest of the region today while a secondary low develops on the New England coast then moves into the Gulf of Maine tonight. Precipitation may start as light snow mainly in the mountains and eastern Vermont, but will be mostly rain across northern New York and the Champlain Valley. A wintry mix will persist across central and eastern Vermont until about noon, producing light accumulations and slowing down the morning commute. Rain showers will change to snow showers tonight, with some accumulation primarily for the higher terrain and along the west slopes of the mountains of northern Vermont and New York. Dry weather returns for Friday as a weak area of high pressure moves in before the next low pressure system brings another round of rain and snow along with gusty winds for Saturday night and Sunday. && .NEAR TERM /UNTIL 2 PM THIS AFTERNOON/... As of 112 AM EST Thursday...Surface temperatures have risen into the 30s and 40s, a bit faster than forecast, mainly west of the Green mountains so have continued that trend while holding onto temps below freezing east of the Greens. So this will limit much in the way of any mixed precip west except in the high peaks region of NY. East of the greens keeping the mixed precip going and have used the RAP profiles to drive derived ptype from the top down. Still looking at perhaps an inch or less of wet snow/sleet from the Green eastward this morning. Southerly winds will be gusting 25-35 mph, especially in the Champlain Valley as a low level jet continues this morning. Eventually warmer air aloft will win out as boundary layer temperatures warm enough that everywhere will turn to light rain showers by late morning. Temperatures will push well into the 40s from the Champlain Valley westward. Some guidance suggests even 50F in a few spots. Southerly winds will remain gusty at times during the mornings. Highs will be a bit cooler across eastern Vermont, but still above freezing. Thursday night a cold front sweeps eastward through during the evening hours with winds switching to the west/northwest. An interesting setup appears to be coming together. An upper level shortwave also drops down from the northwest just after the front. This feature will also bring a brief increase in deeper moisture. All the hi-res models show a roughly 6 hour period of time Thursday night with a strong orographic signal across the `Dacks and northern Green Mountains. Thus expecting an uptick in snow shower activity across the higher terrain. Interesting to note that we`ll have a strongly blocked flow situation (per forecast Froude Numbers around 0.6) as well, so expecting the highest chances of snow showers to be along and just west of the spine of the Green Mountains, and likely backing the moisture up enough that even Burlington gets in on some snow shower activity and perhaps the first measurable snow of the season here at the airport. Looks like 1-3" of snow will fall at elevations above 1000ft in the northern Greens and into the northeast Kingdom Thursday night. The northwest winds will also be a bit gusty at times, probably in the 20-25mph range. && .SHORT TERM /2 PM THIS AFTERNOON THROUGH SATURDAY/...
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As of 350 AM EST Thursday...The changeable weather pattern then continues for the short term. We start the period with a narrow high pressure axis traversing the area Friday night with partly cloudy skies and light winds. Low temperatures generally in the 20s to locally around 30 in the Chanplain Valley. By Saturday a larger storm system will evolve across the eastern portions of the midwest and begin to deepen rapidly as it tracks toward southwest Ontario in the Detroit/Toronto/Buffalo region by early evening. Models continue to slow the arrival of precipitation associated with this feature, not unreasonable given the increased amplification of the synoptic background flow and as such have held back bringing steadier rainfall into northern NY by late morning/early afternoon, and into VT from mid to late afternoon. Boundary layer thermal profiles support a brief mix with wet snow at time of precipitation onset across the Adirondacks and northern Greens, but this should be short lived as increasingly gusty southerly flow will boost temperatures into the upper 30s to mid 40s for most locales as the day progresses.
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&& .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
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As of 350 AM EST Thursday...Deepening surface low then takes a typical climo track into the St. Lawrence Valley Saturday night into Sunday with widespread light rains/snows along with breezy to windy conditions. Have discounted the 00Z NAM/GEM solutions showing an atypical track toward the Adirondacks. Given broad consensus among this morning`s ECMWF/GFS/UKMET in showing a potential sub-980 mb surface center a backside southwesterly jet in excess of 50 kts at 925 mb may evolve across the St. Lawrence Valley east along the northern slopes of the Adirondacks into extreme northwest VT by Sunday morning. A quick look at GFS sounding profiles during this period suggest these areas may approach or exceed wind advisory criteria. Time will tell. As colder air pushes into the region behind the system`s cold front later Saturday night into Sunday rainfall will change to wet snows or snow showers across the much of the area with some minor accumulations possible in higher elevations. Low temperatures mainly in the upper 20s to lower 30s with corresponding highs on Sunday in the upper 30s to lower 40s - typical November-type stuff. Mountain snow showers then continue Sunday night before waning on Monday as high pressure builds into the region. Looking further out, a general progressive flow pattern will continue across the northern tier of states through the remainder of next week along with a fairly seasonal temperature pattern. After dry weather Monday night into Tuesday, additonal rain/snow shower activity enters the forecast again by Wednesday into Thursday as northern stream energy tracks east from the Great Lakes.
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&& .AVIATION /09Z THURSDAY THROUGH MONDAY/... Through 06Z Friday...Becoming mainly MVFR toward the morning push as ceilings will lower from west to east between 8 and 12Z as warm conveyor moves through. Mainly light rain will also develop from the Champlain Valley west across northern NY, although it may start as a very brief period of mixed rain snow sleet, especially at higher elevations especially MPV where there may be several hours between roughly 11z-14z before changing to rain. Looking for a break in the precip during midday but MVFR ceilings will persist area during the rest of the day. There is some chance of precipitation lingering longer into the afternoon at MPV with a coastal low forming near KBOS. Winds will southerly and gust to around 20-35 knots at KPBG/KBTV through midday with LLWS possible at KSLK early as a low level southerly jet of 40+kt moves through with the precipitation. Conditions will be slow to improve later in the day Friday. Aft 00z winds will shift to NW as a cold front moves through and will increase with some gusts over 20 kt by the end of the TAF period. Will be some showers around 00-06z with the front and falling temps will lead to a change to snow in the higher terrain (mainly SLK and in the mountains) with some IFR visibilities and icy runways. Outlook... Friday: Becoming VFR. NO SIG WX. Friday Night: VFR. Slight chance FZRA. Saturday: Mainly VFR, with local MVFR possible. Likely RA, Chance SN. Saturday Night: Mainly MVFR, with local IFR possible. Definite RA, Likely SHSN, Likely SHRA. Sunday: Mainly MVFR, with areas VFR possible. Chance SHRA, Chance SHSN. Sunday Night: Mainly VFR, with areas MVFR possible. Slight chance SHSN. Monday: VFR. Slight chance SHSN. && .MARINE... As of 250 PM Wednesday...A Lake Wind Advisory will be in effect overnight into Thursday morning. southerly winds are expected to strengthen during the evening hours and continue into Thursday morning. Winds will top out near 30 knots, especially across the open broad lake. Southerly winds will diminish on Thursday. However Thursday evening a cold front will move across the region. Behind the front, winds will switch to the west/northwest and increase again to 25-30 knots, requiring another Lake Wind Advisory being raised at that time. Anyone out boating will need to be aware of the rough conditions that will result from the strong winds. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Sisson NEAR TERM...Sisson SHORT TERM...JMG LONG TERM...JMG AVIATION...Sisson MARINE...Nash

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