Area Forecast Discussion
Issued by NWS Burlington, VT-- Highlight Changed Discussion --
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FXUS61 KBTV 221938
Area Forecast Discussion
National Weather Service Burlington VT
238 PM EST Sun Jan 22 2017
A weak backdoor front will continue to produce clouds and slightly
cooler temperatures through Monday. A complex storm system will
spread a wintry mix of snow...sleet...and freezing rain across the
North Country on Monday Night into Tuesday. A plowable snow and
sleet accumulation is expected...with still some uncertainty on
exact amounts. Also...some ice accumulation is likely...especially
central and eastern Vermont.
.NEAR TERM /THROUGH MONDAY/...
As of 212 PM EST Sunday...Backdoor cold front is now south of our forecast
area with modest 925mb to 850mb cold air advection occurring.
The cold air advection will continue to strengthen overnight as
975mb to 850mb east/northeast winds develop at 15 to 25 knots.
Sounding profiles show this layer cooling between -2c and -5c by
12z Monday...along with better mixing to help lift some of the
low clouds and fog. Have continued to mention chc to low likely
pops across the high peaks into southern VT zones this
evening...associated with weak 5h vort in the flow aloft and
upslope flow on easterly winds. Any qpf/ice accumulation will
be very minor and mainly confined above 2000 feet. Spotty areas
of freezing drizzle/drizzle are possible given the lack of deep
moisture. An sps maybe issued later to highlight this potential
if temps cool fast enough with lingering moisture.
Temps will be tricky tonight as drier air moves into the
Northeast Kingdom...some clearing may occur allowing temps to
drop back into the mid 20s...elsewhere thinking mainly upper 20s
to lower 30s. Little change is anticipated on Monday with highs
mainly in the upper 20s to mid 30s most locations. Expect
northeast winds at 10 to 20 knots across the Saint Lawrence
Valley with some higher gusts possible near kmss. Models have
trended slower with precip arrival time associated with our next
complex system...so have chance pops central/southern cwa after
21z. Any precip will be light and under 0.05 through 00z
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
-- Changed Discussion --As of 212 PM EST Sunday...Short term period looking at a significant
sleet storm with light icing in eastern Vermont and mixing with
snow in northern New York. Low pressure moving off the mid
Atlantic states at the start of the short term period, with
ridge of high pressure over northern New England. Cool surface
flow around the high will bring surface temperatures in the 20s
Tuesday night. As the low moves northeast up the Atlantic coast,
easterly low level flow will bring a nose of +2 to +4C air
between 700 & 800 mb to the region. Forecasting predominantly
sleet with this weather event as the warm layer prevents snow
from reaching the ground in appreciable amounts.
As surface low moves northeast impressive 60 knot 850 mb jet noses
into southern Vermont at 06z and moves across eastern Vermont
through 12z. Expect 40-50 mph wind gusts mainly across the ridgetops
Tuesday night, with some downslope enhancement on the west side of
the southern Green Mountains. Will also see terrain enhancement
to precipitation with these winds, increasing precip amounts on
the eastern slopes of the Green and Adirondack mountains, with
some shadowing in the northern Connecticut and Champlain
Looking for precipitation to spread south to north across the
region, beginning 03-06z while surface low is centered off the
delmarva and overspread entire area by 12z. Usually a sharp cutoff
with precipitation as these move northeast somewhere over northern
NY. While far western part of our area in the St. Lawrence Valley
will be in the colder air, that is where there will be less QPF thus
lower snowfall amounts. Any snow will be heavy and dense with low
ratios. Even any areas that have primarily snow in northern New York
will have an 8:1 ratio at best. Winter Weather Advisory will be
issued with this afternoon package for the entire area, based more
on sleet and some light icing in Vermont, becoming more sleet and
snow in northern New York. Good confidence in the sleet forecast in
Vermont, but my confidence decreases with western extent.
Bulk of precipitation lifts north of the forecast area during the
day Tuesday, however as winds shift northwesterly with the passage
of the surface low will see some lingering upslope snowshowers. With
that in mind will have Winter Weather Advisory go through Tuesday
evening to encompass any lingering winter weather impacts.
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.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
-- Changed Discussion --As of 237 PM EST Sunday...While things will remain active, the extended
period looks to be mainly just an enhanced period of snow
shower activity as the region remains under the influence of
500mb through through the end of the period. Wednesday morning
starts with a quick break in showers before the next system
moves through Wednesday afternoon into Thursday bringing
snow/rain showers, though most of the stronger activity should
remain in the higher elevation`s with the valleys seeing
marginal activity at best. The week closes out with minimal
chances of snow showers, again mainly in the higher elevations
into the weekend as temps look to remain mild with highs in the
mid 30`s to 40`s and lows upper 20`s to lower 30`s until the
weekend when temps trend closer to Jan normals.
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.AVIATION /20Z Sunday THROUGH Friday/...
Through 18Z Monday...Aviation focus continues to be on low cigs
and associated ifr/lifr conditions at slk/rut/btv. Thinking mvfr
cigs will develop at btv by 20z...and 22z or so at rut...but
prevail most of the time at slk. Soundings at kmss show low
level moisture advecting back into the Saint Lawrence Valley
this evening so have lowered cigs back toward ifr conditions by
00z. Otherwise...used a persistent forecast overnight with cigs
ranging from vfr to ifr depending upon location. Not expecting
widespread fog...due to increasing 975mb to 925mb winds of 15 to
25 knots...especially after 06z.
Outlook 18Z Monday through Thursday...
Expecting a wintry mix of precip to develop on Monday evening
and continue into Tuesday with the potential for moderate icing
and major impacts to the aviation community. A mix of
snow...sleet...and freezing rain is expected...with the heaviest
precip occurring between 03z-15z Tuesday. Expect mvfr to ifr
cigs/vis with periods of lifr vis in the heavier bursts of
snow/sleet. Also...gusty southeast/east winds are likely at
Rutland during this time period...with areas of wind shear and
turbulence areawide associated with 925mb to 800mb winds of 50
to 60 knots. Improving conditions with lingering rain/snow
showers on Weds into Thursday.
VT...Winter Weather Advisory from 7 PM Monday to 10 PM EST Tuesday
NY...Winter Weather Advisory from 7 PM Monday to 10 PM EST Tuesday