Area Forecast Discussion
Issued by NWS Burlington, VT-- Highlight Changed Discussion --
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FXUS61 KBTV 020440
Area Forecast Discussion
National Weather Service Burlington VT
1140 PM EST Thu Dec 1 2016
A closed upper low over southern Quebec will keep the north
country in cyclonic flow through Saturday, with cloudy skies and
chances for rain and snow showers from tonight through Saturday.
A ridge of high pressure will build into the region on Sunday,
with fair and dry weather expected from Sunday through Tuesday.
.NEAR TERM /UNTIL 6 PM FRIDAY EVENING/...
-- Changed Discussion --As of 1031 PM EST Thursday...No significant changes with the
late evening update. The closed, quasi-stationary mid-level low
over swrn Quebec will maintain a moist cyclonic flow regime
across the North Country overnight and during the day on Friday.
Prevailing surface to 800mb winds will continue from the WSW
overnight into Friday...which will be favorable for upslope
snow shower activity in the nrn Adirondacks and central/nrn
Green Mtns, but not offer much in the way of low-level CAA with
trajectories coming from the open waters of the ern Great Lakes.
Thus, temperatures will generally stay a bit too warm for snow
shower activity in the valley locations. Will continue to see
ISOLD/SCT light rain showers in the valleys, with more frequent
rain/snow shower activity across the higher elevations of the
nrn Adirondacks and central/nrn Green Mtns with more favorable
orographic ascent. At 0330Z, mosaic composite reflectivity and
surface observations indicate light snow shower activity at SLK,
and light rain MVL/MPV/EFK/CDA, with snow levels generally
around 1500-2000ft in the nrn Green Mtns. Should see snow
levels fall slightly to 1000-1500ft during the overnight hours,
with a coating to 2" possible above 1500ft or so overnight.
Also, it appears there is a shortwave trough across
southeastern Ontario, which will rotate across the region during
the pre-dawn hrs...so should see a bit of an increase in areal
coverage of shower activity after 06Z, and indicated some
increase in PoPs accordingly.
Temperatures not falling much from current readings thru the
remainder of the night. Other than some downslope clearing in
the CT river valley, mainly overcast skies and west-southwest
winds will help to keep temperatures above freezing overnight.
MOS guidance looks too cold for overnight min temperatures, so
have leaned toward the warmer GFS LAMP mos guidance for min
temperatures overnight. Winds will stay up overnight and this
combined with the cloud cover will keep temperatures several
degrees warmer than MOS guidance overnight.
On Friday, the North Country will continue to be under the
influence of the closed upper low over southern Quebec which
will keep in cloud cover, along with chances for rain and snow
showers. Snow showers will be mainly confined to the higher
elevations of the Adirondacks and Green Mountains where
additional accumulations of 1-3" are possible for the higher
summits of nrn NY and VT. Highs will be mainly in the low- mid
40s on Friday, except locally in the mid- upr 30s for the nrn
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.SHORT TERM /6 PM FRIDAY EVENING THROUGH SATURDAY NIGHT/...
As of 311 PM EST Thursday...500mb trough moves through the
region Friday night with snow showers expected about 1000ft and
above and rain/snow mix at lower elevations transitioning to
snow for the latter half of the night. Min temperatures will
randing from the mid 20s to low 30s.
As surface low pushes eastward toward the Canadian maritimes, a
ridge of high pressure builds across the lower Ohio valley,
putting the north country in NW flow. This will result in
precipitation becoming more orographic by Saturday morning.
FROUDE numbers of 0.5 to 1 indicate slow moving blocked flow on
Saturday, helping to focus snowfall on western slopes and in the
higher terrain. There`s a chance for brief disruption in flow
late in the day as 500mb vort swings across the North Country,
providing a slight chance to chance of mostly snow across the
forecast area. Max temperatures on Saturday will remain in the
Saturday night the surface ridge shifts eastward over the
eastern Great Lakes by Sunday morning. Moisture over the North
Country looks to diminish from top to bottom with lingering
clouds under inversion. Expect snow showers to end by daybreak.
Forecast snowfall totals throughout the short term are a dusting
to quarter inch in the broad valleys, with few tenths of an
inch to 3 inches in the higher elevations. Min temperatures
generally in the 20s.
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 311 PM EST Thursday...High pressure is the dominant
feature Sunday and Sunday night, resulting in a brief period of
dry weather. Remaining under light northerly flow, temperatures
remain cooler Sunday with maxes in the 20s to mid 30s. Min
temperatures will range from the mid teens to mid 20s Sunday
Another mid level trough arrives Monday morning, weakening as
it moves across the region and resulting in only chance POPs as
ridging returns Monday night. With max temperatures in the 30s,
generally expect light snow showers.
A more significant system takes form Tuesday, bringing in
precipitation from the south and west. Still much disagreement
among models, but as initial precip looks to be the result of
warm air advection/warm front, there`s a chance for mixed
precipitation Tuesday night into Wednesday. GFS shows southern
stream low develop into closed coastal low moving near the 70/40
benchmark as another surface low associated with very large
500mb trough approaches the region from the west. 12Z ECMWF not
available at time of forecast for comparison.
.AVIATION /06Z Friday THROUGH Tuesday/...
-- Changed Discussion --Through 06Z Saturday...Little overall change in aviation weather
conditions as a moist WSW flow remains in place south of closed
upper low over wrn Quebec. Expecting surface winds to continue
W-WSW at 5-10kts...increasing slightly during the late morning
through afternoon hours on Friday (10-12kts, with a few gusts
16-18kts). Ceilings start VFR (3-5kft) BTV/PBG/RUT and MVFR
(1-3kft) at KSLK/MPV/MSS with favorable moist flow from Lake
Ontario combined with upslope effects. It appears ceilings will
lower somewhat later Friday afternoon into Friday night as upper
trough rotates sewd across the area. That will bring prevailing
MVFR conditions. HIR TRRN will remain OBSCD throughout the
period. In terms of precipitation, not expecting anything
significant through 18Z, with passing valley sprinkles/showers,
and higher elevation snow showers at SLK with occasional 3-5SM
vsby. Mid-level trough brings better chance for widespread
shower activity later Friday into Friday night.
Outlook 06Z Saturday through Tuesday...
06Z Saturday through 18Z Sunday...Upper trough remains in
control with BKN-OVC skies, and general mix of MVFR/VFR
ceilings. Will see some additional chances for mainly light snow
showers, mainly with orographic effects at SLK/MPV. HIR TRRN
18Z Sunday through Tuesday...Mainly VFR with high pressure
building in from the west. Can`t rule out lingering MVFR
ceilings vcnty mtns, including SLK/MPV Taf locations.
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