Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 271748
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
1248 PM EST Fri Jan 27 2023

.SYNOPSIS...
A few snow showers will be possible across northern New York today
as a weak front slides up the St Lawrence Valley. Vermont will
remain dry though with partly to mostly cloudy skies. Better chances
for snow return on Saturday, mainly across the northern mountains.
Snow accumulations will be light both days. A stronger system will
then bring widespread snow to the region on Sunday, with a few
inches of accumulation possible. Temperatures will remain close to
seasonal normal.

&&

.NEAR TERM /THROUGH SATURDAY/...
As of 1226 PM EST Friday...Precipitation chances were increased
along the Saint Lawrence Valley where showers are evident as
they stream off of Lake Ontario. Impacts should be minimal since
showers aren`t particularly heavy and winds will be shifting
over the next couple of hours lowering chances that these
showers will continue. For locations close tor the Champlain
Valley and for much of Vermont, skies have broken out with ample
sunshine, a welcome change from the recent days of gray. The
forecast remains on track.

Previous Discussion...Minimal changes required, but did adjust
temperature curve which is running cooler than forecast,
especially across portions of northern New York . Otherwise, the
forecast is verifying well with scattered snow showers across
northern New York and the Adirondacks and partly cloudy skies
for the northern Champlain Valley.

Previous Discussion...No significant changes were
needed with this update. Cloud cover is highly variable across
the region, which has resulted in a wide range of temperatures
as well. Areas in northern NY that were able to see some
clearing have dropped into the single digits, while elsewhere
temperatures are in the mid teens to mid 20s. Clouds should
start to fill back in through the morning hours, especially over
northern NY. Light snow is already falling in portions of the
St Lawrence Valley, and this precipitation will spread north and
east today as a weak front lifts northward. The forecast
generally has this covered, so just made some tweaks to
temperatures and sky cover to match the latest trends.

Previous discussion...Much quieter weather is expected for the
end of the week, with just some localized chances for light snow
showers each day. Today, weak ridging will shift east across the
region, allowing a weak front to lift up into the St Lawrence Valley
on southwest flow. This boundary will interact with moisture off of
Lake Ontario, resulting in snow showers developing over the St
Lawrence Valley into the Adirondacks this morning into the early
afternoon hours. The snow will be fairly light given lack of robust
forcing, so expect just an inch or two at best, mainly over the
southern St Lawrence Valley; the remainder of northern NY will get
an inch or less. Areas from the Champlain Valley eastward will
remain dry under the aforementioned ridge, with partly to mostly
skies dominating. Highs will be near to perhaps a bit above seasonal
normals, generally in the mid 20s north to mid 30s south. Tonight`s
temperatures are bit trickier to forecast as it will depend how much
clearing can occur. Eastern Vermont has the best potential to see at
least some partial clearing, and temperatures there could drop into
the lower teens, perhaps even some single digits if clearing is more
widespread than currently anticipated. Elsewhere, lows will mainly
be in the upper teens to mid 20s.

For Saturday...low pressure will slide by well to our north,
dragging its attendant warm front across our region during the
morning hours, followed quickly by the cold front. Scattered snow
showers will develop once again early Saturday morning, with the
most persistent activity to remain in the northern mountains. With
the best forcing remaining well north of the international border,
expect the snow will be light, and amounts will be an inch or less
in most places, perhaps locally up to 2 inches in the higher
terrain. Highs will be warmer than Friday, generally in the mid to
upper 30s. However, winds will become gusty out of the west behind
the cold front, making for a brisk day.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/...
As of 301 AM EST Friday...Over Saturday night, a cold front will
attempt to make some southward progress, but will find it hard to so
with southwesterly flow largely continuing aloft. It appears the
front washes out over the area. This mainly makes the low
temperature forecast dependent on how far south this boundary sags
before it dissipates. Made a slight adjustment upwards for the
overnight lows, but guidance is split. For example MAV MOS forecasts
16 for BTV, while MET MOS is 29. The forecast blend lies just below
the 75th percentile of what`s available with teens north, and low to
mid 20s in the Champlain Valley and our southern borders.

Where the front sets up will play a role in the afternoon
temperatures as well, as a weak surface low will quickly traverse
the thermal gradient. If the front makes little southward
progression, then as the surface low lifts towards the St. Lawrence
Valley, much of Vermont and parts of Essex County, NY will
transition to rain as surface temperatures warm into the mid 30s. If
the front makes it south of the forecast area, then the rain-snow
line will set up mainly across south-central Vermont. While
temperatures aloft are not too warm, the 40 to 50 knot 850hPa jet
could briefly allow 850hPa temperatures to warm just above freezing
while the low tracks across the region. It`s plausible there may be
a small area of sleet early Sunday morning. However, given the
larger than usual model discrepancies, have maintained a simple rain-
snow approach for the time being. Either way, fast flow aloft will
likely shadow much of Vermont from realizing appreciable
accumulation. Presently, mainly a dusting is expected south, with
about 1-2" across northern Vermont. Better low-level convergence in
northern New York and less warm intrusion should give areas west
towards the St. Lawrence River the higher snowfall totals with
values between 2-5".

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 301 AM EST Friday...While it will feel comparatively cold with
single digits to teens, these temperatures lie close to seasonal
norms. The day should begin dry as a narrow area of high pressure
quickly passes overhead. By afternoon, another weak surface trough
will zip by, and southwesterly flow should draw some moisture from
Lake Ontario into the area and produce scattered snow showers late
Monday afternoon into early Tuesday morning. Dry weather should
return again Tuesday as a larger area of high pressure sets up over
the eastern US. The potential weather outcomes diverges midweek,
with an upstream upper low across the Southern Plains and how
suppressed it remains beneath that large area of high pressure. Some
energy could break off and interact with another fast moving
northern stream trough, but given the time range and small size of
these features, leaned towards climatology for the most part. With
the expansive surface high though, did start trending PoPs a bit
downward for Wednesday at least, with any potential system more
likely focused further south. A very cold air mass should approach
towards the end of next week with below normal conditions likely to
start February.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
Through 18Z Saturday...A mix of VFR/MVFR will persist through
much of the TAF period, with KSLK/KMSS the most likley to see
ceilings below 3000 ft. Meanwhile, snow is now moving into the
St Lawrence Valley and western Adirondacks with a weak front.
Visibility will generally be 3-5sm at KMSS and KSLK in light
snow through 20z, though occasional IFR visibility will be
possible at KSLK. Otherwise, all other terminals to remain VFR
through the period. West/southwest winds around 5 kt will
continue through much of the day, gradually increasing to with
southerly gusts around 20kts by 12Z Saturday. LLWS has been
added to MSS/SLK/RUT/MPV where winds aloft increase 06-12Z out
of the southwest around 45kts. Light to moderate mechanical
turbulence should also be expected 12Z onward from 2000ft to at
least 6000ft with ridge level winds transverse to the terrain.

Outlook...

Saturday Night: Mainly VFR, with local MVFR possible. Chance SN.
Sunday: Mainly MVFR, with areas VFR possible. Chance SN, Likely
RA.
Sunday Night: Mainly MVFR, with areas VFR possible. Slight chance
SHSN.
Monday: VFR. Chance SHSN.
Monday Night: Mainly VFR, with local IFR possible. Slight chance
SHSN.
Tuesday: Mainly VFR, with local MVFR possible. NO SIG WX.
Tuesday Night: VFR. Slight chance SN.
Wednesday: Mainly VFR, with local MVFR possible. Slight chance
SN.

&&

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

&&

$$
SYNOPSIS...Hastings
NEAR TERM...Boyd/Hastings
SHORT TERM...Haynes
LONG TERM...Haynes
AVIATION...Boyd/Hastings


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