Area Forecast Discussion
Issued by NWS Burlington, VT-- Highlight Changed Discussion --
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FXUS61 KBTV 021134
Area Forecast Discussion
National Weather Service Burlington VT
634 AM EST Fri Dec 2 2016
Deep low pressure moving slowly east through southern Quebec will
continue to influence the North Country`s weather through Saturday,
with abundant clouds and periods of higher terrain rain and snow
showers. Some sunshine is in the forecast for the later half of the
weekend as a ridge of high pressure builds into the region on
Sunday, with fair and dry weather continuing into the early part of
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --As of 634 AM EST Friday...Very little change from the previous
forecast thinking for the next 24 hours as deep low pressure
currently over southeast Quebec very slowly drifts eastward to
the Canadian maritimes by early Saturday morning. Saw a little
bit of a break in shower activity earlier this morning as deeper
moisture associated with the occlusion that passed through
yesterday shifted north and east of the area, with very very
slight mid-level ridging occurring in its wake. But now as we
move through the mid-morning hours, additional shortwave energy
currently shifting into the eastern Great Lakes will round the
base of the upper trough and redevelop rain and snow showers
again as more favorable west/northwest flow develops, focusing
precipitation along the higher terrain of the western slopes of
the Adirondacks and northern Green Mountains. As this energy
drops further into the region early this evening, we`re likely
to see some activity light up in the northern Champlain Valley
before the flow turns fully to the northwest and precipitation
once again becomes more orographic in nature through the
remainder of the night.
Freezing levels begin the period this morning generally around
mid- slope at 2500 feet, then gradually lower to around 1500
feet by 00z, and further almost right to the valley floor around
500 ft overnight. In general this supports snow as the dominant
ptype across the higher summits, while lower elevations will be
mainly rain during the day today, and a rain/snow mix tonight.
The resulting snow accumulations will be only a dusting to
perhaps an inch below 1500 feet, but upwards of 4-6" can be
expected above 2500 feet.
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.SHORT TERM /SATURDAY THROUGH SUNDAY/...
As of 300 AM EST Friday...Then more of the same for Saturday as
we remain in northwesterly flow and a final upper shortwave
swings through the region. Mainly cloudy skies with solid pops
in the 40-60 percent range will be maintained, mainly across
elevated terrain where orographic forcing will aid in boundary
layer ascent supportive of snow shower activity. Considerably
drier weather is expected in the valleys however with just a
passing light rain or snow shower here or there. High
temperatures continue seasonably cool in the 30s. By Saturday
night clouds will hang tough in the mountains despite thinning
moisture as weakening northwesterly flow persists with weak high
pressure approaching from the Great Lakes. Valley locales
should see some partial clearing after midnight however. Pops
will continue to wane leaving just some scattered light snow
showers or flurries across the highest of elevations by sunrise
Sunday. Low temperatures mainly in the 20s.
By Sunday high pressure will build across the region with sunny to
partly sunny skies and light winds. Little airmass change is
expected. In fact mean 925 mb thermal profiles actually cool
slightly so high temperatures generally ranging through the 30s
looks reasonable once again despite the added insolation. Winds
light. Pops nil.
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 300 AM EST Friday...Overall a fairly quiet period of
sensible weather is expected during the Monday/Tuesday time
frame with seasonably cool early December temperatures and only
low chances of light precipitation, mainly across our western
counties. Models remain generally consistent in tracking a
dampening shortwave trough through the area on Monday into
Monday evening with little fanfare. There will be a broad
increase in cloudiness, though with weakening dynamical upper
support and isentropic lift any precipitation should be light
and scattered at best, most focused across our northern New York
counties. By Tuesday high pressure returns to the region with
partial sunshine and light winds. Again, negligible airmass
change is expected with seasonal highs in the 30s both days and
overnight lows in the 20s to around 30.
Looking further out, this morning`s medium range guidance continues
to suggest the mean flow trends more amplified across the lower 48
from mid-week onward as the year`s first decent polar airmass dives
south into the Rockies and Northern Plains. This will eventually
drive cyclogenesis across the Southern Plains/northwestern Gulf
Coast which will track northeast toward the region. Still plenty of
uncertainty in regard to how quickly this system will consolidate
into a primary low pressure center with several solutions showing
some sort of lead energy and associated precipitation affecting the
area as soon as Tuesday night. At this point a blended solution
appears most reasonable given this uncertainty, and will concentrate
the bulk of higher precipitation chances during the Wednesday and
Thursday time frame. Still too early to confidently predict p-type,
though signals and synoptic pattern would suggest some sort of mix
and/or rain seems most probable at this point as warm advective
signatures increase solidly over time. Temperatures warm slightly
during this period as mean background flow trends southerly with
highs from the mid 30s to lower 40s or so, and lows in the mid 20s
to lower 30s.
.AVIATION /12Z Friday THROUGH Tuesday/...
-- Changed Discussion --Through 12Z Saturday...Generally VFR conditions out there this
morning outside of KSLK where IFR cigs persist. Trend through
the day though will be towards MVFR cigs, even at KSLK with some
light rain showers developing during the early/mid afternoon.
Brief reduction in vsby to MVFR is possible, but should mostly
remain VFR. After 00Z, showers become more terrain focused so
for almost all terminals should just be VCSH. Exception will be
KSLK where freezing levels will fall low enough to support a
transition to snow reducing vsby to IFR. Wind will be generally
out of the west-southwest at 5-10kts with few gusts up towards
20kts at KMSS/KSLK.
Outlook 12Z Saturday through Tuesday...
12Z Saturday through 12Z Sunday...Mix of VFR/MVFR with local
IFR possible at KSLK in scattered rain/snow showers.
12Z Sunday through Tuesday...Mainly VFR with high pressure
building in. Periods of MVFR ceilings possible, especially at
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