Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 201507

Area Forecast Discussion
National Weather Service Burlington VT
1007 AM EST Mon Nov 20 2017

Snow showers will continue to linger across the mountains this
morning, especially in Northern New York. Any accumulations will
be light. Relatively dry weather is expected today, but
temperatures will be below normal. Southerly flow develops on
Tuesday. Sunshine, dry weather and high temperatures in the
upper 40s to lower 50s.


As of 1000 AM EST Monday...some modifications with the hourly
PoP/weather forecast for today based upon the latest
radar/satellite trends along with latest hi-res data from
BTV4km, BTV2km, NAM3km and HRRR. Latest obs and web cams from St
Lawrence County show light snow falling. GOES16 showing cooling
cloud tops across St Lawrence County stretching back into
Ontario. This is probably associated with a weak shortwave that
is located over central Quebec. All subtle features, but enough
to have the light snow develop. The hi-res models I mentioned
above do have indications of the light precip via their forecast
radar, and seem reasonable based upon latest radar data. I used
a blend of the "radar" output from those models to drive the
modifications I made.

Neat scenario unfolding. The current light snows across St
Lawrence Valley is actually a combo of lake effect streamers
from both Lake Superior and Lake Huron. GOES-16 visible imagery
shows the "bubbly" clouds well. With the westerly flow, this
moisture will advect eastward today, and spread into Vermont.
Just flurries in the Champlain Valley, but with orographic
influence, the northern Green Mountains should wring out some
light fluffy snow with perhaps upwards of 1" at higher
elevations. By late today and early evening, the overall flow
starts to turn southwest, so that the lake effect streamers off
Lakes Ontario will drift into the St Lawrence Valley as they
fade away. Hi-res models even suggest that the very last left
overs of Lake Erie effect clouds/flurries will get into the St
Lawrence Valley by midnight. A little bit of light snow from 4
Great Lakes within 24 hours, I think that`s kinda cool in a
geeky meterological way.

Dry and quiet weather will continue tonight with surface high
pressure slowly sliding away from the East coast. Minimum
temperatures will be just a bit colder than seasonal normals,
mainly in the 20s with some teens in the Northeast kingdom.

On Tuesday we will have a low pressure system approaching from
the Great Lakes region which will eventually pass well North of
our forecast area. May have some sunshine early in the day but
clouds will increase from the west through the day. Most notable
for the Tue timeframe will be temperatures reaching the 40s to
lower 50s, almost ten degrees above seasonal normals.


As of 239 AM EST Monday...Little change in the overall synoptic
pattern is expected in the short term period where once again
we`ll be dealing with another clipper low passing well north of
the region, dragging a cold front through the area Tuesday night
through Wednesday. Mild temperatures in the mid-30s to low-40s
ahead of the front will support mainly rain in the valleys and a
rain/snow mix at higher elevations as the boundary shifts into
northern New York around midnight Wednesday, the morning rush in
the Champlain Valley, and through eastern Vermont by mid-day.
Behind the front, temps will gradually fall through the day with
morning highs mainly in the mid/upper 30s, dropping to the
upper 20s to mid 30s by sunset. Little to no snow accumulation
is expected in the valleys, while elevations above 1000 feet may
see a dusting to perhaps 2".


As of 239 AM EST Monday...Extended period remains fairly active
with breaks of high pressure in between more clipper lows
passing north of the area through central Ontario and Quebec.
Quiet weather is expected under high pressure for Wednesday
night through Thanksgiving with seasonal to slightly below
normal temps in the 30s/40s for highs and teens/20s for lows.
First of 2 cold fronts to swing through the area arrives
Thursday night into Friday with little fanfare as the parent low
will track well north of the region, starving the boundary of
any real deep moisture. Thus, while the probability of
precipitation is high, the overall QPF is low with likely just
some scattered snow showers and little accumulation if any.

Brief high pressure builds back in for late Friday afternoon
into early Friday night before the next front approaches. While
several days out, this system looks similar to the one we just
had this past weekend with strong warm air advection, gusty
southwesterly winds and rain ahead of the cold front on
Saturday, sharply falling temperatures, rain changing to snow
showers and potential flash freeze Saturday night, followed by a
cold, brisk Sunday.


Through 12Z Tuesday...Gusty winds continued across our TAF
sites this morning. Ceilings will be improving shortly to VFR at
all sites. Currently some light snow showers at MPV and SLK,
should be short lived. Late in the day Monday afternoon and
evening SLK/MSS may become impacted by a lake effect snow band
that will be lifting towards the north. With potential for
varied intensity and timing, the forecast just mentions lowered
ceilings rather than specific detail about visibilities.


Tuesday: VFR. NO SIG WX.
Tuesday Night: Mainly VFR, with local MVFR possible. Chance SHRA,
Chance SHSN.
Wednesday: Mainly VFR, with areas MVFR possible. Chance SHRA,
Chance SHSN.
Wednesday Night: Mainly VFR, with local MVFR possible. NO SIG WX.
Thanksgiving Day: Mainly VFR, with local MVFR possible. NO SIG
Thursday Night: Mainly VFR, with areas MVFR possible. Chance
Friday: Mainly VFR, with areas MVFR possible. Slight chance SHSN.




NEAR TERM...Nash/Neiles
LONG TERM...Lahiff
AVIATION...Neiles is the U.S. government's official web portal to all federal, state and local government web resources and services.