Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 311918
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
318 PM EDT Sat Oct 31 2020

.SYNOPSIS...
As surface high pressure slides east of the region tonight,
winds will shift to the south and become breezy on Sunday with
warmer temperatures. A sharp cold front will produce showers
Sunday afternoon and evening, but as colder air develops, rain
will change to snow overnight. The snow showers linger into
Monday, which will be cold and blustery.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
As of 253 PM EDT Saturday...Clear skies and cooler than normal
temperatures are the main story for today and continuing
tonight. Winds picking up out of the south as high slides
eastward and pressure gradient increases ahead of approaching
warm front. Clouds will begin to increase during the second half
of the overnight into Sunday. A 45kt low-level jet will result
in temperatures holding steady or even rising a bit overnight,
especially in the St Lawrence and Champlain Valleys. Lows will
generally be in the mid 20s to lower 30s. Brisk conditions
continue during the day on Sunday as low pressure system
approaches from the west, as well as associated frontal systems.
Temperatures on Sunday will be about 10 degrees warmer than
today, reaching the upper 40s to around 50. Strong southerly
flow continues, with wind gusts to about 25 mph. Strongest winds
will be in the Champlain valley where gusts to 35 mph will be
possible. Showers preceding the frontal boundary will begin to
move into the St Lawrence Valley after 18z, then spread over the
remainder of the region by 00z. With warm temperatures, mainly
expecting snow for Sunday, except for the highest elevations
which could see an earlier change over to snow. Upper level
trough and colder air push into our area Sunday night, and
precipitation will change over to snow by early Monday morning.
Mix of rain and snow will hang on the longest in the Champlain
valley where temperatures struggle to drop below freezing.
Models continue to indicate secondary low pressure system
forming off the New England coast Sunday night, and best forcing
will be closer to this low center in southern New England.
Models are also still showing possibility of a pretty well
pronounced dry slot moving across the north country during the
second half of Sunday night.

&&

.SHORT TERM /MONDAY/...
As of 317 PM EDT Saturday...Looking at a very active period weather
with some welcomed early season snowfall across the higher terrain.
Too bad it won`t last. As the aforementioned surface low pressure
system shifts northeast into northern Maine early Monday morning, so
does the attending mid-level dry slot with the 700mb low becoming
juxtaposed just northeast of the CWA in a prime location for low
/mid-level moisture to wraparound back into the region on stiff
northwest flow. Precipitation will be highly terrain focused through
mid-day with modest 925-850mb flow around 40kts supporting
downsloping in the Champlain Valley and upslope across the
Adirondacks and northern Green Mountains. Very little directional
shear of these winds supports unblocked low-level flow so expect
little snow accumulation in the downslope valleys, and 1-2" across
central-northeast VT, while 2-4" from the summits peaks to the lee-
side of the Adirondacks and northern Greens is likely. Snowfall
wanes going into the afternoon as a weak ridge of high pressure
builds in with winds blustery through the day gusting 25-35 mph and
highs only in the 30s.

Brief high pressure drys us out early Monday night, but a re-
enforcing shot of shortwave energy and clipper-like surface low dive
southeastward from James Bay towards midnight with favorable upper
level jet dynamics supporting another quick shot of snow showers
overnight into Tuesday morning. An even stronger 850mb jet around
55kts and unidirectional shear will once again support a
downslope/upslope regime despite an open wave at 700mb, with similar
snowfall accumulations expected from Monday morning of 1-2" valleys,
and 2-4" mountains. Through the 48-hour period total snowfall will
range from a dusting to an inch below 1000 feet, 4-6" from 1000-2000
feet across the Adirondacks and central/northern VT and approaching
a foot at the highest peaks. Snow should wind down Tuesday mid-day
as broader and stronger high pressure begins to build into the
region with daytime temps remaining chilly in the 30s, and winds
blustery at 15-25 mph in the morning abating in the afternoon.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
As of 317 PM EDT Saturday...Much quieter and warmer weather is on tap
for the remainder of the week as broad high pressure takes residence
over the majority of the East Coast Tuesday night through the
remainder of the week. No precipitation and bountiful sunshine is
expected, along with a significant warming trend as west/southwest
flow becomes established east of the Mississippi River Valley
tapping into warmer southern air. As such, after a chilly start to
the week, highs will rebound to around normal Wednesday in the 40s,
then above normal from the mid 50s to low 60s for Thursday through
Saturday. All that glorious white gold that fell earlier in the week
will be gone. Hopefully the early season snow is a sign of good
things to come though.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
Through 12Z Sunday...VFR conditions are anticipated through the
entire TAF forecast period. Main forecast challenge is
increasing winds at the surface and aloft, and clouds moving in
during the daylight hours on Sunday. A 40kt low-level jet starts
to move over the region after 03z Sunday, so anticipate
widespread LLWS through the remainder of the period thereafter.
Showers will move into the area Sunday afternoon but mainly
after the 18z timeframe.

Outlook...

Sunday Night: Mainly VFR, with areas MVFR and IFR possible.
Likely SHRA, Likely SHSN.
Monday: Mainly VFR, with local MVFR possible. Windy with gusts to
30 kt. Chance SHSN.
Monday Night: Mainly VFR, with areas MVFR possible. Chance SHSN.
Tuesday: VFR. Slight chance SHSN.
Tuesday Night: VFR. NO SIG WX.
Wednesday: VFR. NO SIG WX.
Wednesday Night: VFR. NO SIG WX.
Thursday: VFR. NO SIG WX.

&&

.MARINE...
Lake wind advisory is in effect as winds pick up out of the
south this afternoon. Winds on Lake Champlain will be between
15-25 kts. Winds will remain gusty out of the South through
sometime Sunday night before becoming west northwesterly behind
departing cold front.

&&

.CLIMATE...
Record lows for Saturday morning (10/31)

Date  KBTV     KMPV   K1V4     KMSS   KPBG     KSLK
10-31 17|1925 16|2002 18|2002 16|2002 19|1972 4|1925

&&

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

&&

$$
SYNOPSIS...Neiles
NEAR TERM...Neiles
SHORT TERM...Lahiff
LONG TERM...Lahiff
AVIATION...Neiles
MARINE...Neiles
CLIMATE...WFO BTV


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