Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 241114

Area Forecast Discussion
National Weather Service Burlington VT
714 AM EDT Sat Mar 24 2018

A trough of low pressure aloft will prevail across the North
Country this weekend with below normal temperatures and a few
scattered snow shower expected. Given the lack of moisture any
snowfall will be light and under an inch. Temperatures will be
mainly in the 30s today, but warm into the 40s to lower 50s by
Tuesday with increasing amounts of sunshine. Our next weather
maker impacts our region with rain showers Wednesday into
Thursday with temperatures in the mid 40s to lower 50s.


As of 708 AM EDT Saturday...Updated to capture latest satl
trends and integrate into the sky grids...which shows a window
of clear skies over northern ny, before additional clouds
develop by 15z. Also, have sharpen elevation temp gradient as
Whiteface currently 12F...indicating the cold air advection
occurring around 850mb. Thinking with intervals of clouds/sun
and northerly winds...temps will only rise several degrees at
most today. All covered well in crnt forecast.

Water vapor shows mid/upper level trof across the ne conus with
our next short wave energy several hundred miles north of the
international border. Based on water vapor presentation, this
system has very limited moisture, but strong dynamics. The core
of the coldest 850mb to 500mb temps will pass to our west
overnight...while northerly winds prevail from the sfc thru
850mb. GFS/ECMWF and NAM 850mb to 500mb rh progs continue to
show deeper moisture advecting from ne to sw across our cwa btwn
03z-09z tonight...which combined with energy aloft will produce
some very light snow showers. Once again pws are <0.25" so any
qpf/snowfall will be light and generally under 1.0" The best
combination of lift/moisture will be northern Dacks/northern
Greens, including the NEK, where I will mention high chc pops

Temps will continue to be challenging, especially with periods
of clouds and general low level cold air advection today into
tonight. Progged 925mb to 850mb thermal profiles fall 1 to 3
degrees today under northerly flow...with values btwn -8c and
-15c by 18z. Expecting steady or slowly falling temps today with
mid 30s valleys with maybe a few readings near 40f lower CT
River Valley and upper teens summits. Lows tonight will be
highly driven by the areal coverage of clouds...which should
thin aft 09z, especially slv/western dacks. I have lows from 10f
to l/m 20s cpv/lower ct river valley. If more clearing
develops, these values will be way too warm, especially with
continued snow pack and low level thermal profiles.
Sunday...will feature increasing amounts of sunshine with brisk
north winds. Progged 850mb temps hover around -10c, with good
mixing support upper teens summits to mid/upper 30s warmest
valleys. Building ridge aloft and associated subsidence will
help in development of mostly sunny skies, except
central/eastern vt where some mid level moisture/clouds will


As of 403 AM EDT Saturday...Sunday night will be colder as a
ridge builds over the East Coast. At the surface, a
strengthening high over southern Quebec will usher in colder,
drier air from the northeast that will allow 850 mb temps to
once again drop below -10C over the forecast area. This will set
the stage for a night of fairly strong radiational cooling
under clear skies and light winds. Temperatures over valleys
will drop into the teens overnight and into the single digits in
the northern Adirondacks and Northeast Kingdom.

Monday will start off crisp and chilly.  During the day however,
expect temperatures to rebound and supply a fairly pleasant
March day. The surface high will shift eastward to the Canadian
Maritimes, putting the forecast area in the region of warmer,
southerly/southwesterly return flow behind the high by late
afternoon. The combination of warm air advection (850 mb temps
progged to warm 5+ degrees during the daytime hours), and the
strong March sun will allow daytime temperatures to climb to
back into the upper 30s/low 40s.

Monday night, warm air advection will continue under return
flow. Despite the warming air mass, clear skies overnight will
allow surface temperatures to drop to the teens/20s in the
valleys and once again into the single digits in the northern
Adirondacks and Northeast Kingdom. This should be the last night
of the week with below average lows however, as Tuesday during
the day we`ll see a pattern change with noticeably warmer
weather commencing.


As of 403 AM EDT Saturday...High clouds will start to move in
from southwest to northeast Tuesday morning as southwesterly
warm air advection/moisture advection kicks into full gear.
By this time, the aforementioned high pressure will have retreated
to the east coast of Canada, drawing behind it a long, fetch of
deep southwesterly flow extending from the Gulf Coast through
New England. Meanwhile, further west, a trough will dig over the
Rockies and into the central US, further reinforcing the
southwesterly fetch downstream. In terms of sensible weather,
this will bring us increasing coverage and thickening of clouds
starting Tuesday along with daytime high temperatures that will
top out near 50 Tuesday and only fall into the upper 20s/low 30s
Tuesday night. By Wednesday morning, increasing isentropic
ascent over the area as a warm front pushes northeastward will
support some precipitation. Model progged precipitable water
values of 0.75+ inch Wednesday indicate plenty of moisture
available, however deep southwesterly flow will lead to highly
variable coverage of precipitation controlled by terrain. The
Saint Lawrence Valley and the western Adirondacks will see some
measurable rain Wednesday out of this setup, however the
majority of areas further east will be mainly downsloped with
just some isolated showers sneaking in. This precipitation will
mainly be in the form of rain, however higher terrain could see
some snow or a rain/mix during the nighttime hours.

Wednesday night, the pattern will temporarily become more zonal.
This will act to cut off our better moisture feed from the
southwest, resulting in a brief dry spell in the weather. The
chance of precipitation then quickly returns Thursday night
however as both northern and southern stream shortwave energy
act to deepen the upstream trough over the central US. Daytime
highs both Wednesday and Thursday will once again top out around
50 in many locations, a good 5-10 degrees above normal for late

Looking further ahead into the early weekend, precipitation
chances continue as the upstream upper level trough continues to
send impulses through New England. As far as temperatures go,
Saturday looks to be the end of this week`s warmup thanks to
colder, northwesterly flow resuming after the trough axis
finally pushes through.


Through 12Z Sunday...VFR conditions prevail today with perhaps
some mvfr cigs at slk/mpv and btv overnight. The combination of
increasing moisture and short wave energy will help to lower
cigs by tonight...with a brief period of light snow possible at
slk/mpv. Have utilized tempo group to place 4sm -shsn at slk.
Otherwise...sfc analysis shows northerly gradient between high
pres over the northern Great Lakes and departing low pres over
northern Maine...supporting some localized gusts btwn 15 and 20
knots today. Any leftover snow shower activity and mvfr cigs
will quickly improve by Sunday across our taf sites.


Sunday: VFR. NO SIG WX.
Sunday Night: VFR. NO SIG WX.
Monday: VFR. NO SIG WX.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. NO SIG WX.
Tuesday Night: VFR. Slight chance SHSN.
Wednesday: Mainly VFR, with local MVFR possible. Chance SHRA,
Chance SHSN.




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