Area Forecast Discussion
Issued by NWS Burlington, VT-- Remove Highlighting --
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FXUS61 KBTV 271901
Area Forecast Discussion
National Weather Service Burlington VT
301 PM EDT Thu Oct 27 2016
Precipitation will continue to overspread the region this
afternoon with light rain or light snow at the lower elevations
and light snow in the mountains. Eventually the lower elevations
will change to rain tonight with snow continuing in the mountains.
Watch for gusty southeast winds along the western slopes of the
Green Mountains and the higher terrain this evening through the
overnight hours. Rain will taper off by Friday afternoon before
our next system arrives on Saturday for more precipitation.
.NEAR TERM /THROUGH FRIDAY/...
As of 142 PM EDT Thursday...Forecast playing out with
temperatures in the mid 30s to lower 40s right now...but still
some larger temperature dew point spreads over the area. As light
precipitation continues to move in from southwest to northeast
this afternoon...cooling will take place and allow for a mix of
rain and snow at the lower elevations due to wet-bulbing...but
snow continuing at the higher elevations with no warm layer aloft
moving in. Could get a little slippery east of the Green Mountains
later this afternoon and evening with light snow followed by rain
and colder pavement temperatures on secondary roads. Special
weather statement issued earlier has this scenario handled well.
Otherwise...going forecast in good shape.
For tonight...initial band of warm air advect lift is located
near the international border by 06z...with additional forcing
arriving with potent short wave energy and strong upper level
divergence signature. This combined with a deepening and closing
off 5h/7h circulation moving from the Eastern Great Lakes into
southern New England will produce additional precip across our
region overnight into Friday. Models show good 1000 to 500mb
relative humidity with favorable 850 to 500mb q-vector forcing
parameters from 06z to 18z Friday. Will continue to mention pops
near 100% overnight...before tapering off from west to east on
Friday. Given the track of surface low pressure into the Gulf of
Maine and closed 5h/7h circulation...thinking additional moisture
with area of rain and summit snow continues for most of VT on
Friday...including the Champlain Valley...as strongly blocked flow
Total precipitation will range between 0.50 Saint Lawrence to
1.50 southern Greens and eastern Dacks. Given developing 925mb to
850mb low level jet of 40 to 50 knots from the southeast...expecting
some impacts of terrain on precipitation fields. Highest amounts
will be along the southeast upslope regions from Ludlow/Killington
to Stowe to Jay Peak...with some shadowing in the Champlain
Valley/Northeast Kingdom initially. However...as wind shift to the
northwest on Friday...the northeast kingdom and western
slopes/champlain valley will see some additional precipitation.
Snow levels become very tricky overnight into Friday as soundings
show warm layer developing between 5000 and 7000 feet associated
with southwest winds with cold pocket from 2500 to 3500 feet
associated with upslope cooling on southeast winds. By 15Z
Friday...cooling aloft occurs as winds change to the east then north
by early afternoon and progged 850mb temps drop below 0c. Current
thinking snow continues near the summits through early this
evening...then changes to a wintry mix with pockets of freezing rain
in the midslopes...before changing back to all snow by midday friday
at the summits and cold rain below 2000 feet. Once again snow
accumulations will be very elevation dependent with summits above
4000 feet seeing around 6 inches with several inches possible
around 2000 feet and some minor ice accumulation in between. This
should have very limited impacts...given elevation.
Still anticipating breezy to gusty southeast winds along the western
slopes from near Rutland to East Middlebury to Nashville tonight.
The strongest winds will occur between 7 PM and 2 AM associated with
925mb to 850mb jet of 40 to 50 knots. Thinking localized surface
wind gusts to 35 knots is possible with a few isolated power outages
Temperatures mainly in the mid 30s to mid 40s today...fall back only
into the lower 30s to lower 40s overnight...with similar profiles
expected on Friday. Hourly temps will drop several degrees when
precip starts today and during higher precip rates...have tried
to show this detail in grids.
.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 316 AM EDT Thursday...Brief ridging at the surface and
aloft builds in over the North Country for the first half of
Friday night before heights begin to fall again ahead of weak low
pressure which will pass north of the Canadian border on Saturday.
Overnight temp forecast will be tricky as winds slacken in the
wake of an exiting system to our east, but pick up again markedly
after midnight from the southwest. Not expecting a whole lot of
clearing, so think mins will be mild and slightly above freezing.
Timing of lows I think will fall early across the St. Lawrence and
Champlain Valleys before warming slowly through the night with
increasing winds, but elsewhere likely follow the normal diurnal
Weak low passes north of the border on Saturday and while low/mid
level moisture is abundant with this system, overall forcing is
rather weak so even though we continue to highlight likely PoPs
for showers, QPF will be light with temps pushing well above
seasonal normals into the upper 40s east to mid 50s west. By
nightfall, the deepest low level moisture begins to shift east as
the low tracks off into the Canadian maritimes and thus
precipitation will gradually taper to nil by Sunday morning as
high pressure building eastward into the Great Lakes approaches.
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 316 AM EDT Thursday...The extended period looks to be
fairly dry with a fast zonal flow aloft Sunday trending towards
ridging for Monday and Monday night. A strong low developing out
of the northern plains Monday afternoon tracks north of Lake
Superior Monday night to the tip of James Bay by Tuesday night
pushing a dry warm front through the area. We remain mainly dry
all the way through Wednesday with temps warming well into the 50s
for Tuesday and Wednesday in increasing south/southwesterly flow.
.AVIATION /19Z Thursday THROUGH Tuesday/...
Through 18z Friday...Current VFR conditions will quickly lower to
MVFR by 20z as light precipitation moves into the region.
Precipitation should be a mix of rain and snow at the lower
elevations before becoming all rain after 00z...with snow in the
mountains. Winds will be from the east and southeast with gusts in
the 15 to 25 knot range through about 12z...then shift around to
the northwest after 12z. At this point...ceilings and visibilities
will lower into the IFR and MVFR categories for the remainder of
Outlook 18z Friday through Tuesday...Conditions will gradually
improve back to MVFR and VFR after 18z Friday as precipitation
comes to an end. A warm front feature lifting across our taf sites
on Saturday morning will shift the winds to the southwest with
some scattered showers possible...especially mss/slk. Expecting
mainly vfr conditions with intervals of mvfr cigs possible across
northern NY taf sites on Saturday. Gusty southwest up to 35 knots
are possible at MSS with 30 knots expected at SLK/BTV on Saturday.
Another wind shift to the west/northwest will occur Sat Night into
Sunday with additional scattered showers. Drier conditions with
vfr flight conditions for Sunday afternoon into Monday.
-- Changed Discussion --As of 255 PM Thursday...Several bouts of strong winds and rough
conditions are expected on the lake the next few days. South/southeast
winds of 15 to 25 knots are expected through late evening, before
diminishing after midnight. During the day Friday, winds will
switch to the northwest and strengthen, with winds approaching 25
knots for the afternoon and early evening. Winds will diminish
Friday night, but then switch to southerly on Saturday morning.
Winds will quickly increase again to around 25 knots during the
mid-day hours. These strong and gusty winds will result in choppy
conditions out on the lake.
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