Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 060451

Area Forecast Discussion
National Weather Service Burlington VT
1151 PM EST Mon Dec 5 2016

Clouds and a few light snow showers are expected for the
overnight hours across the North Country. Tuesday will feature
plenty of clouds in the morning with some late day clearing
possible...before our next system arrives on early Wednesday
Morning. This system looks to bring another round of light
accumulating snow during the early morning commute.


As of 1151 PM EST Monday...Just some minor cloud tweaks based
on trends...which indicate some clearing taking place. But still
plenty of clouds upstream for more clouds to move in overnight.
Threat for snow showers keeps lowering and have sped up the
timing regarding the end of the snow showers...which should be
after 09z.

Previous discussion...An overachieving warm front this morning
produced a widespread 2 to 6 inch snowfall across our
region...causing a difficult morning commute...but outstanding
early season ski conditions at local resorts per pictures
received this afternoon.

For tonight...weak surface boundary near the international border
will drop south this evening and winds will shift to the northwest.
Soundings show 10 to 20 knots through 850mb this evening...which
combined with some leftover 1000 to 700mb moisture through
03z...will support occasional snow showers. An additional an inch or
so is possible...before limited moisture in the favorable snow
growth decreases toward midnight...resulting in mainly flurries and
areas of light freezing drizzle. Always difficult to determine areal
coverage of freezing drizzle associated with light flow and abundant
low level moisture. Not expecting any ice accumulation...but could
impact snow surfaces for the slopes on Tuesday. Expecting limited
diurnal change in temps overnight with plenty of clouds and areas of
light precip...mainly 20s mountains to near 30f champlain/saint
lawrence valleys.

Tuesday...the big question becomes do we see any
sunshine...especially eastern side of the champlain
valley...mountains of ny/vt...and northeast kingdom. Latest nam12km
and 4km soundings show plenty of low level moisture between surface
and 925mb...with much drier air aloft through 18z. Thinking low
level inversion combined with very weak wind profiles will result in
plenty of clouds through 18z...before some clearing occurs toward
sunset. Better chances of seeing sun will occur across the lower ct
river valley....western cpv...and parts of the saint lawrence valley
on Tuesday. Temps hold mainly in the 20s mountains to mid 30s warmer
valleys with more clouds and less sun.


As of 220 PM EST Monday...By Tuesday night into Wednesday
another weak warm thermal advection episode is progged to
advance northeast into the region while weakening over time as
primary energy bundle exits the mid-Atlantic seaboard. The idea
of a thickening and lowering overcast with light snows arriving
southwest to northeast after midnight Tuesday still appears
reasonable at this point, though some minor timing details do
exist among this morning`s deterministic guidance. Light snows
will then slowly taper to scattered rain and snow shower
activity through the day on Wednesday as lower boundary layer
warms above freezing in most valley locales. Similar to this
morning`s event, minor snow accumulations of 1 to 3 inches will
be possible with the highest totals generally in elevated
terrain. Temperatures will remain fairly uniform during this
period with overnight lows steady in the upper 20s/lower 30s,
and corresponding highs on Wednesday from 35 to 42.

By Wednesday night the mean background flow remains deep
southwesterly with plenty of mid-level moisture keeping skies mostly
cloudy as a whole. Some minor lake effect response and associated
snow showers may tend to form to the northeast of Lake Ontario over
time, but boundary layer thermal progs quite marginal for anything
heavy. Elsewhere just some scattered flurries here and there, mainly
across the north. Low temperatures in the 20s to around 30 look


As of 220 PM EST Monday...looking at this morning`s medium
range guidance the models remain on board showing a gradual
cooldown from Thursday into Saturday of next weekend as our
first true modified continental polar airmass pushes into the
area. Some important caveats lie beneath the bed so to speak,
not the least of which is the fact that the mean flow aloft will
be predominantly west to southwest through much of the period
and quite moist. Thus no true push of arctic air will occur and
given the abundant clouds overnight lows won`t be all that
chilly by December standards despite the fact the readings as a
whole will trend colder. This flow also proves a tad problematic
with precipitation chances with transition to the colder
airmass coming in several discrete frontal/trough passages.
Overall theme will be for lake effect snow to generally blossom
across the Lake Ontario snowbelts on Thursday/Thursday night
with activity becoming more pronounced across the northern
portions of VT as well over time as moisture feed deepens and
aforementioned troughing swings into the area. Some light
accumulating snows still appear reasonable in this period with
slightly fluffier/higher totals possible in the snowbelts.

Clouds continue to hang tough on Friday as we gradually enter the
colder airmass and shsn/flurries wane over time, though at least
some partial clearing is expected by Friday night into Saturday with
high pressure at the surface building across the eastern seaboard.
Temperatures will be on the cool side, but not excessively so with
highs by next Saturday in the upper teens to mid 20s and overnight
lows generally from 5 to 15 above.

By next Sunday into Monday our next system is progged to swing into
the region as low pressure across the northern Great Lakes drives
additional warm advective precipitation into our area. These latter
periods are of lower confidence with distinct differences in timing
and thermal profiles. For now have leaned toward a blended output
suggesting additional chances for light snows, though if some of the
deterministic guidance like the ECMWF are correct, boundary layer
temperatures may warm enough by next Monday for mixed rain/snow
shower activity or all rain.


.AVIATION /06Z Tuesday THROUGH Saturday/...
Through 06Z Tuesday...Generally looking at VFR and MVFR
conditions through 15z with just some scattered light snow
showers. There may be some brief periods of IFR conditions. After
15z...VFR conditions are expected as areal coverage of the
clouds decreases. The clouds will begin to return to the area
from southwest to northeast. However...ceilings will generally
be above 10000 feet. Winds will generally be under 10 knots
through the period.

Outlook 06z Tuesday through Saturday... Vfr with some lingering
mvfr cigs at slk/mpv on Tuesday...before another warm front
produces another round of widespread light snow across our
region on Weds. Similar to Monday`s event thinking a period of
ifr/lifr likely between 12z-18z Weds across our taf sites with
vis below 2sm and cigs between 500 feet and 2000 feet. An arctic
boundary will produce more scattered snow showers and potential
snow squalls on Thursday into Friday with brief periods of ifr
conditions possible. Improving conditions with mvfr valleys and
ifr/mvfr in scattered snow showers persist on Saturday.




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