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FXUS61 KBTV 241930
Area Forecast Discussion
National Weather Service Burlington VT
330 PM EDT Mon Oct 24 2016
The North Country will remain in cyclonic flow with variable
cloudiness and cooler than normal temperatures through most of
the week. A weak upper disturbance embedded in northwest flow
aloft will bring mostly cloudy skies tonight through Tuesday.
This feature will bring a chance of light rain showers in the
valleys. Snow showers are expected across the Northern
Adirondacks and north-central into northeastern Vermont tonight
through Tuesday. High pressure brings briefly drier conditions
Wednesday into Wednesday night. A more significant wave of low
pressure approaching from the Great Lakes and Ohio Valley will
bring periods of rain, generally late Thursday into the first half
of Friday. Precipitation may begin as a wintry mix across higher
terrain areas on Thursday before changing to rain.
.NEAR TERM /THROUGH TUESDAY/...
As of 253 PM EDT Monday...Little overall change in the large-scale
pattern during the next 24 hours across northern NY and VT. Deep
layer W-NW flow continues west of mean mid-level trough axis, but
within broad upper level trough across the nern CONUS and sern
Canada. This is contributing to below climo average temps this
afternoon, with readings generally in the mid-upr 40s, and only in
the upr 30s across the Northeast Kingdom.
Will see increase in cloud cover overnight as embedded shortwave
trough translates sewd out of srn Quebec across the area, with
cloud heights generally 3-5kft. Limited moisture (PW values
0.3-0.4"), however orographic ascent will bring light rain/snow
shower activity overnight into the day Tuesday, especially across
the nrn Adirondacks and nrn Green Mtns into far nern VT. Freezing
levels initially around 2500ft this aftn, will generally fall to
near 1000ft during the pre-dawn hours Tuesday. Thus, will see
falling snow levels overnight, and then rising a bit during the
day Tuesday. Not expecting any snow accumulation in the Champlain
Valley, but could see a dusting to 1" for towns in central/nrn VT
and across the nrn Adirondacks. The highest summits of nrn VT
could see 2-4" snowfall, including at Jay Peak and Mt. Mansfield
by Tuesday evening. Winds will generally continue from the NW.
Generally 10-20 mph gusting to 25 mph thru early evening,
diminishing to near 10 mph overnight, and increasing again to
10-20 mph for Tuesday. Low temps tonight generally low-mid 30s,
except 28-32F 1-2kft elevational band. Highs on Tuesday generally
low to mid 40s under cloudy skies.
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/...
As of 400 AM EDT Monday...A 1 to 2 STD below normal mid/upper
height field associated with a trof across the northeast CONUS
will continue to provide our region with below normal temps
through midweek. The combination of favorable 925mb to 850mb
upslope flow and ribbons of deeper layer moisture associated with
cyclonic circulation will continue to produce terrain focused
precipitation through Tuesday. The associated low level wind
fields are between 20 and 30 knots on Tuesday result in limited
low level forcing from upslope component...but weak embedded vort
at 500mb and some low level cold air advection will be enough to
produce light qpf across the mountains. Will mention likely pops
for Tuesday...with qpf generally 0.20 or less across the northern
dacks and western slopes...with only a trace to couple hundredths
in the valleys.
Thermal profiles show both 925mb and 850mb temps below 0c...with
850mb temps near -10c by 00z Weds...supporting mostly
snow...except the valleys and near the warmer Lake. Speaking of
Lake Champlain...some enhanced precipitation is possible on the
east side of the lake with moderate instability created between
the air/water temp difference...especially on Tuesday.
Also...noted with boundary layer heating and cold air
aloft...lapse rates steepen on Tuesday afternoon...supporting some
convective elements with potential graupel in the valley. Thinking
any snow accumulation below 1000 feet will be difficult during the
daytime...but some minor accumulation above 1000 feet between a
dusting to several inches is likely across the northern dacks and
mountains of central/northern VT. Its never too early to start
building the snow pack. Thermal profiles support about a 20 degree
difference between lower/mid 20s mountains summits to lower/mid
40s valleys on both Tuesday and Weds...with lows mainly upper
teens to lower 30s.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 400 AM EDT Monday...Active pattern continues for days 4
thru 7 with additional chances for rain and snow on Thursday into
Friday and another system next weekend. Overall...given the
progressive west to northwest flow aloft...temps will stay below
normal thru the period with additional chances to increase snow
pack across the mountains...especially Thursday Afternoon.
GFS/GEM and ECMWF in good agreement with potent 5h energy in the
northern jet stream crossing the Great Lakes and NE CONUS on
Thursday into Friday. Meanwhile...initial surface low pres tracks
across the central Great Lakes with weak secondary development
over southern New England by 12z Friday. The combination of 1036mb
high pres over eastern Canada and developing secondary low
pres...suggests warmer air will have difficulties advecting into
our region...supporting potential for additional snow
accumulations in the mountains. Sea level pres fields show a cold
air damming signature. Latest ECMWF only briefly increases the
850mb temps to 0c around 06z Friday...before winds shift to the
northwest and colder air follows. Current thinking a band of
rain/mixed with wet snow flakes develops from southwest to
northeast on Thursday...associated with moderate to strong warm
air advection. The combination of evaporational cooling and
progged 925mb to 850mb profiles below 0c initially supports even
some wet flakes in the valley with no accumulation...before
quickly turning over to rain. Meanwhile...cold air remains locked
east of the greens and across the northeast kingdom with a longer
duration of snow...with several inches of wet snow accumulation
possible Thursday afternoon/evening...before changing over to
rain. Mountain thermal profiles are tricky as progged 850mb temps
stay near 0c...but warm nose around 5000 feet associated with
southerly jet...supports some freezing rain possible near the
summits of the dacks and greens on Thursday Night. It shall be
interesting to see what the picnic table on Mansfield receives.
Otherwise...the potential for gusty downslope southeast winds
will have to be watched...as latest GFS shows 850mb winds of 40 to
50 knots. The strongest winds are collocated when precip will be
falling and difficult to determine how much mixing will
occur...but something to watch along the western slopes on
Next system arrives late Saturday into Sunday with additional
chances for precipitation and once again thermal profiles support
mainly rain valleys and a mix in the mountains...as 850mb 0c line
bisects the area. Temps during the period mainly in the 30s
mountains and 40s valleys with lows in the 20s to mid/upper 30s.
.AVIATION /19Z Monday THROUGH Saturday/...
Through 18z Tuesday...Persistent W-NW flow will bring variably
cloudy conditions, but mainly VFR (ceilings 3.5-5kft) at the TAF
locations. Sole exception should be at SLK, which will
occasionally see ceilings 2-3 KFT. Visibility generally
unrestricted with gusty/well-mixed low-level conditions. Will see
a few orographic showers/snow showers develop as we head into
tonight thru Tuesday morning. This may bring some VSBY
restrictions vcnty of the HIR TRRN. Also, may see brief MVFR at
SLK in snow showers toward daybreak. W-NW winds will remain
moderately strong...12-15kt with gusts to 25kt thru sunset. Winds
will diminish somewhat overnight (8-10kt), then increase to
similar speeds (12-15ktG25kt) from the NW during the daylight
Outlook 18z Tuesday through Saturday...
18Z Tuesday through 12Z Wednesday: Isold/sct rain and snow
showers will persist vcnty of the nrn Adirondacks/nrn Greens
Tuesday aftn into first half of Tuesday night. Could see intervals
of MVFR conditions at SLK, and possibly also at MPV. At the
remaining TAF sites, BKN-OVC conditions but with VFR ceilings
expected. Winds NW 8-15kts.
12Z Wednesday Through 12Z Thursday: Surface high pressure across
the region will bring generally VFR conditions and lighter winds.
12Z Thursday Through Saturday: Low pressure system approaching
from the Great Lakes/Ohio Valley brings developing rain Thursday
afternoon into Thursday night, with MVFR and intervals of IFR
conditions possible. After a brief break on Friday, another wave
of low pressure brings additional showers and possible MVFR
conditions on Saturday.
AS OF 308 PM EDT MONDAY...Lake Wind Advisory continues through
this evening with northwest winds 15-25kts and waves 2-4kt.
Highest waves along eastern shores exposed to a greater fetch on
northwest winds; specifically those locations adjacent to the open
waters north of the Charlotte Ferry and south of Valcour Island.
Expect these strong winds and waves to gradually diminish
overnight as wind speeds decrease slightly to 10-20kts.