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fxus61 kbtv 201806 
afdbtv

Area forecast discussion
National Weather Service Burlington Vermont
106 PM EST Mon Feb 20 2017

Synopsis...
north winds will provide the north country with cooler temperatures
and dry conditions today with increasing sunshine. Clear skies
and calm winds this evening will allow temperatures to quickly
fall before warming during the pre-dawn hours Tuesday. A weak
disturbance will spread a wintry mix of precipitation in the
mountains and mainly rain in the valleys on Tuesday night into
Wednesday...with only minor accumulations expected. The trend of
much above normal temperatures continue for most of the
week...with more rain arriving Friday into Saturday.

&&

Near term /through Tuesday/...
as of 936 am EST Monday...visible satellite trends indicate
continued clearing trend across the region with clouds eroding
last across E-central into nern Vermont. Have made slight adjustments
based on current observations, but forecast is generally on
track.

Previous discussion...increased hourly temps by 2 to 4 degrees
across the board due to slowly than expected cooling associated
with breezy northwest winds and low level cold air advection.
Thinking temps will fall another several degrees through
15z...before becoming steady and increasing during the afternoon
hours. Highs mainly teens mountains summits to mid 30s warmer
valleys...especially lower CT River Valley near vsf.
Otherwise...the combination of low level upslope flow and
leftover moisture continues to produce some clouds especially
from northern New York into the mountains of Vermont and parts of the cpv.
Expecting these clouds to dissipate by late morning with mostly
sunny skies this afternoon under building surface high pres.

Water vapor showing a very amplified and active pattern across
the Continental U.S. With trof over the northeast...ridge Central
Plains...and deep trof over the inter- mountain west. The
combination of dry air aloft/subsidence behind departing short
wave energy and building ridge will produce increasing amounts
of sunshine today...under breezy northwest winds. Our forecast
area continues under modest 925mb to 850mb cold air advection
through 15z today...with progged 850mb temps dropping between
-12c and -14c...before warming again. This makes for a tricky
high temp forecast...especially with warm temps to start...but
will trend toward the warmer side of guidance with highs ranging
from the upper teens mountain summits to l/M 30s warmer
valleys. A couple of mountain flurries are possible...especially
northern greens through 15z today...otherwise...soundings show
drying with mostly sunny skies by this afternoon.

Tonight..1031mb high pres is over northern New York at 00z and shifts into
eastern Vermont by 06z...before moving into central New England by
sunrise on Tuesday. This will provide ideal cooling conditions
through midnight...before winds shift and warming aloft occurs.
Expecting a strong low level inversion to develop with coldest
values in the deepest/protected valleys with lows ranging from 0f
slk/nek to mid/upper teens cpv and southern slv. I would expect
large ranges between the cold valleys and warmer midslope and Summit
regions overnight.

Tuesday...short wave ridge shifts across our region as mid/upper
level moisture and associated 500mb energy approach our western cwa
by 00z weds. Southerly 850mb winds of 25 to 35 knots will produce
moderate low level waa with progged 925mb to 850mb temps climbing
above 0c by 18z Tuesday. The developing fast southwest/west 500mb
winds of 45 to 55 knots will help to quickly push a ribbon of
enhanced 850 to 500mb rh from west to east across our region after
18z...with some light rain arriving by sunset over the Saint
Lawrence valley. Looks like some cooling occurs east of The Greens
with temps quickly dropping to near 0c by 00z weds...to support a
threat for pockets of freezing rain and sleet. Thinking some wet
bulb cooling will result in areas of sleet...especially Northeast
Kingdom of Vermont on Tuesday evening. Any qpf thru 00z weds will be
light and under tenth of an inch. Meanwhile...temps warm into the
upper 30s to mid 40s for highs.

&&

Short term /Tuesday night 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 Sunday/...
as of 339 am EST Monday...well above seasonal temperature trend
continues late week into the weekend with developing eastern
Continental U.S. 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 County Warning Area 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. European model (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 /18z 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 west-east 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.

&&

Btv watches/warnings/advisories...
Vermont...none.
New York...none.

&&

$$

Synopsis...Taber

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