Area Forecast Discussion
Issued by NWS Burlington, VT-- Remove Highlighting --
-- Discussion containing changed information from previous version are highlighted. --
FXUS61 KBTV 202039
Area Forecast Discussion
National Weather Service Burlington VT
339 PM EST Mon Feb 20 2017
-- Changed Discussion --High pressure will build eastward across the North Country
tonight bringing mostly clear skies, diminishing winds, and
chilly temperatures. Morning lows early Tuesday will be in the
single digits to mid teens across the region. A weak mid-level
disturbance approaching from the west will bring increasing
cloudiness and developing south winds on Tuesday, with light
precipitation Tuesday night. Precipitation will fall mainly as
light rain. However, pockets of light freezing rain are possible
east of the Green Mountains, and may result in a few icy spots.
Well above average temperatures are expected through the
remainder of the week, with a strong area of low pressure
passing to our west expected to bring widespread rainfall
Friday night through Saturday night.
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.NEAR TERM /THROUGH TUESDAY NIGHT/...
-- Changed Discussion --As of 936 AM EST Monday...Tranquil weather conditions this
evening and overnight as 1030mb surface high pressure drifts ewd
from sern Ontario with dry deep-layer RH profiles. Skies are
already clear across the North Country at 20Z, and anticipate
north winds (currently 10-15mph) diminishing as ridge axis moves
overhead and PBL stabilizes under clear skies. Expecting a
strong low level inversion to develop, with the coldest readings
tonight in the deeper valleys within the northern Adirondack
Region and Northeast Kingdom (near 0F). Lows elsewhere will be
in the upper single digits to mid teens, likely warmest near
For Tuesday, a shortwave ridge crests across the area with sfc
ridge shifting to our east into the Gulf of Maine by afternoon.
This will induce a southerly gradient flow with surface winds
increasing to 10-20 mph, with gusts to 25mph during the
afternoon hours (especially with channeled flow in the Champlain
Valley). The 12Z NAM RH profiles suggest increasing mid-upper
level clouds by 18Z from west to east ahead of next shortwave
trough across the Great Lakes. Despite increasing clouds, should
see warmer temps with highs in the upr 30s to lwr 40s.
Mid-level height falls and trough axis shift thru quickly during
Tuesday night. Low-levels remain relatively dry, and overall it
appears that approaching precipitation will undergo a
dissipating trend as the trough axis moves thru Tuesday night.
Maintained Likely PoPs during the overnight period, but QPF
values only 0.05-0.10" for most locations, and period of
precipitation will likely only span 2-3 hrs in most spots.
Vertical temperature profiles with continued south winds support
mainly rain with lows in the mid 30s. That said, should see
pockets of temps near freezing as the precipitation moves thru
in spots east of the Green Mtns, and have gone with a light ZR/R
for the ern half of VT. A few hundreths of an inch of freezing
rain is possible, and introduced mention in the Hazardous
Weather Outlook as a few icy spots are possibly for travelers
overnight Tuesday night. We will continue to monitor.
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.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 339 AM EST Monday...Fast moving warm frontal system with
westerly flow aloft along with narrow and weakening ribbon of
high and mid level moisture will produce a progressive narrow
axis of rain/snow/mix of light precipitation Tue night into
Wednesday. Thermal profiles still showing mostly rain in the
valleys but a mix of precipitation possible in the Adirondacks
and possible freezing rain east of the Green Mountains as colder
air lingers through Wednesday morning. QFP looks to be one to
two tenths in the Dacks and Greens with some downslope shadowing
likely here in the Champlain Valley associated with 850mb winds
of 30 to 45 knots.
Mild surface flow from the south and southwest will continue to
keep temps above seasonal norms with Wednesday highs in the 40`s
and pushing 50 in the Champlain Valley with overnight lows in
the mid to upper 30`s.
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 339 AM EST Monday...Well above seasonal temperature trend
continues late week into the weekend with developing eastern
CONUS mid/upper level ridging. The next storm system continues
to look like it will come Friday into Saturday with a low
pressure system tracking north and west of our region.
Thursday sees a weak short wave move to the north of the CWA with
some warm moist advection ahead of a weak cold front which
passes through late in the day or Thu eve. Highest chances for
precipitation will be in the north and mainly in the form of
light rain showers. High temperatures will range in the upper
40s to around lower 50`s with 925-mb temps of 3-8C north to
south but cooling below 0C late Thursday night.
Rising 500mb heights forecast along with primary low pressure
tracking north and west of our region through the Great Lakes
Friday through Saturday. Models have backed off potential
secondary low near the NE coast, keeping it much further to the
southeast, opening the door for even warmer conditions for
Saturday before precipitation moves in. ECMWF shows temperatures
in the Champlain Valley to reach nearly 60 degrees, so have
opted to trend closer towards the warmer temps with highs in the
mid 50`s. Things still look like we`ll be affected first by a
warm front Fri evening/Fri night and cold occluded front Sat
night before things quiet down on Sunday as the storm exits the
region. Looks like a mix of precip may fall with the warm front
on Friday followed by mainly windy and mild with rain showers on
Saturday, before changing back to snow showers Sat late night.
Sunday will see a return to closer to normal temps with highs in
the mid to lower 30`s.
.AVIATION /20Z MONDAY THROUGH SATURDAY/...
Through 18Z Tuesday...High pressure building ewd from sern
Ontario will bring mostly clear skies and VFR conditions to the
region through the TAF period. Will see increasing clouds above
15kft after 12Z Tuesday as high clouds advance from W-E ahead
of the next trough across the Great Lakes. Winds generally north
this afternoon at 10-12kts, becoming light and variable as
boundary layer stabilizes around sunset. As the high pressure
system shifts to the east, will see winds developing from the
south toward daybreak Tuesday, increasing to 10-12kts with
gusts to 20kts at BTV by 18z Tuesday.
Outlook 18Z Tuesday through Saturday...
A weak trough will bring periods of light rain, with pockets of
freezing rain east of the Green Mtns during Tuesday night. Brief
MVFR conditions are possible with this system, mainly during the
pre-dawn hours Wednesday. Generally returning VFR with high
pressure Wednesday afternoon through Friday morning. Warm front
approaches from the southwest Friday afternoon with increasing
chances for rain and periods of MVFR/IFR conditions. Will also
see possible sfc wind gusts locally in excess of 25kts with
low-level turbulence and wind shear late Friday through
Saturday as deep low pressure passes to our west across the
Great Lakes and Ontario.