Area Forecast Discussion
Issued by NWS Burlington, VT

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FXUS61 KBTV 250812

Area Forecast Discussion
National Weather Service Burlington VT
412 AM EDT Tue Oct 25 2016

A trough of low pressure will continue to produce brisk winds and
chilly temperatures through midweek with scattered mainly mountains
snow showers. Temperatures will be in the 30s mountains to lower 40s
valleys today and Wednesday. A widespread precipitation event is
expected on Thursday into Friday with some snow accumulation likely
in the mountains and breezy southeast winds along the western


As of 347 AM EDT Tuesday...Water vapor shows deep cyclonic flow
associated with mid/upper level trof across the northeast
CONUS...with sharp moisture gradient from very dry air central NY
to some mid level moisture northern New England. The combination
of this moisture...with favorable upslope flow will produce mainly
mountain focus snow showers today. So far activity has been very
limited due to the very dry low levels and lack of upper level
support. Thinking as weak embedded vort in the flow aloft drops
across our northern cwa between 15z-20z today and interacts with
some instability from surface heating...scattered valley rain and
mountain snow showers will develop.

Hi resolution composite reflectivity progs show popcorn nature to
returns...with greatest concentration over the northern mountains.
Will continue to mention likely pops northern green mountains from
Mansfield to Jay Peak with a dusting to several inches possible.
Elsewhere...will mention slight to chance pops...with some
enhancement possible on the east side of Lake Champlain associated
with lake effect. Would not be surprised to see a few wet snow
flakes in the valley....given the chilly 925mb to 850mb thermal
profiles. Models in good agreement of values between -7c and -9c
today at 850mb and -1c to -3c at 925mb...these temps support highs
low/mid 30s mountain towns and upper 30s/lower 40s warmer valleys.
Still expecting breeze northwest winds at 10 to 20 knots with some
locally higher gusts especially midday.

Tonight...areal coverage of any leftover precip will dissipate by drier air at all levels develops across our region. Will
mention chance pops mainly in the mountains...and will still need to
watch the potential for some lake effect clouds and flurries on east
side of champlain overnight. Temps will cool into the lower/mid 20s
mountains to lower/mid 30s valleys.


As of 411 AM EDT Tuesday...Wednesday and Wednesday night will
likely be the quietest 24 hours of the next 7 days as a brief area
of high pressure both at the surface and aloft swing through the
North Country. The day will begin fairly cloudy across the higher
terrain with perhaps a few mountain snow showers lingering, while
in the deeper Saint Lawrence and Champlain Valleys some breaks in
the clouds will be developing. By the afternoon low/mid level
moisture will be decreasing with cyclonic flow aloft trending to
anti-cyclonic as an upper trough exits to our east and high
pressure builds in. Strong cold air advection remains in place on
brisk northerly flow so expect highs to continue to run well below
normal in the low 40s across the deeper valleys to upper 30s
elsewhere. Wednesday nights temps follow suit, running about 5-10
degrees below normal, mainly in the 20s to locally around 30 in
the Champlain Valley along Lake Champlain, to upper teens in the
coldest hollow of the Northeast Kingdom and northern Adirondacks.


As of 411 AM EDT Tuesday...Thursday onward through the weekend
the pattern becomes quite active again with mean troughiness
redeveloping aloft across the eastern CONUS and 2 clipper-like
systems bringing mixed precipitation to the North Country.

The first and more robust system comes Thursday mid-day through
Friday as low pressure develops out of the Great Lakes/Ohio River
Valley region and tracks northeast to the Maine coast by Friday
night. Precipitation along a warm frontal boundary works its way
into the area fairly quickly by mid-day on the nose of a strong
40- 50kt 925-850mb south-southeasterly jet with thermal profiles
initially supporting a mix of rain and snow in the valleys and
snow at the higher summits, but by the afternoon and overnight the
ptype forecast become a bit more tricky. Latest trends in NWP
guidance indicate a warm nose slightly above 0C at 925-850mb works
in after 00z and this coupled with marginally warm boundary layer
temps supports rain in the deeper valleys and a mixed bag of
rain/snow with possible brief periods of sleet and/or freezing
rain across the Adirondacks and eastern Vermont. As the low pushes
east on Friday, temps aloft support a transition back to snow for
the summits, but the boundary layer remains too warm at the
surface supporting showers/rain as precip becomes more orographic
in nature on developing northwest flow. Early thoughts on storm
totals through Friday show the highest elevations the big snow
winners with 6-8" along the Green Mountain spine, to 8-12" across
the high peaks of the Adirondacks. Below 1500 feet, a dusting to
perhaps 2" is possible outside of the Champlain and St. Lawrence

The strong jet mentioned above also presents the potential for
gusty downslope winds along the Green Mountain spine Thursday
night, but currently coincides with the bulk of precipitation
falling which limits mixing potential. While I think winds will be
gusty across the southeast downslope communities along the western
slopes, overall impacts should be minimal with gusts peaking only
in the 20- 30mph range.

Next system looks to swing through Saturday through Saturday
night, taking a more northern track than its predecessor, offering
even warmer thermal profiles, enough to produce mainly rain
showers with highs pushing into the mid/upper 40s. Behind it, high
pressure looks to return for Sunday night into Monday.


.AVIATION /08Z Tuesday THROUGH Saturday/...
Through 06z Wednesday...Mainly vfr conditions with occasional mvfr
possible at mpv/slk this morning associated with lowering cigs and
chances for mountain snow showers. The limited moisture both at
the surface and aloft will limit impacts on tafs with regards to
vis/cigs. Otherwise...still expecting breeze west to northwest
winds 10 to 20 knots with a few higher gusts through
today...before decreasing around sunset this evening at 4 to 8

Outlook 06z Wednesday through Saturday...
Active weather pattern continues with vfr trending toward mvfr/ifr
Thursday into Friday. Expecting a period of snow at most sites on
Thursday afternoon...with vis between 1-3sm...before changing to
rain in the valleys by evening. Also...gusty southeast winds are
possible...especially at rutland...creating areas of low level
wind shear and turbulence. As winds shift to the northwest on
Friday...ifr cigs are possible at BTV/RUT/SLK/MPV with areas of
scattered rain or snow showers. Next system arrives late Saturday
with additional precipitation and breezy southwest winds.
Occasional mvfr/ifr conditions are likely by late Saturday.




LONG TERM...Lahiff
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