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-- Discussion containing changed information from previous version are highlighted. --
752
FXUS61 KBTV 101446
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
946 AM EST Mon Dec 10 2018

.SYNOPSIS...
Mainly dry today with high pressure building across the region. A
couple of weak upper disturbances will bring colder than normal
temperatures and chances for light snow through mid week. A gradual
warming trend is expected towards the end of the week, but the
possibility of significant precipitation is looking less likely for
next weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 945 AM EST Monday...Overall, no major changes to the
forecast. Adjusted sky cover to account for good amount of
clearing across the area as surface high pressure continues to
build in. Just some pesky low level clouds trapped beneath the
inversion, especially along the northern Champlain
valley/International Border and mountain areas. Anticipate this
to gradually clear throughout the morning with many locations
seeing sunshine this afternoon. Only other thing of note is
there are still some very scattered light snow shower activity
in the vicinity of the Montpelier airport, however it looks very
localized as area webcams are showing clear skies and no
precipitation.

Previous Discussion...
Noted increasing reflectivity returns showing up on radar over
portions of the northwestern Champlain Valley, with light snow
being reported at KPBG and showing up on some webcams. This is
likely due to some light northeast upslope flow, as evidenced by
automated sites across the area. Also a bit of snow still being
picked up in a couple of Northeast Kingdom observations. Have
added some flurries into the forecast for the next few hours in
these locations, but don`t anticipate to last long or amount to
much as drier air will continue to move south out of Canada. Low
clouds have been persistent this morning as well as moisture
lingers under the subsidence inversion. Have increased cloud
cover through the morning hours accordingly, but still
anticipate some breaks later this afternoon. Otherwise the
forecast remains in good shape and no other changes were needed
this morning.


Previous discussion...A cold front will finish crossing the
region early this morning, bringing a reinforcing shot of cold air.
Any lingering snow showers or flurries will quickly come to an end
as this colder and drier airmass spreads southward. Anticipate
clouds to break up a bit as we head toward the afternoon; however,
mountain areas may stay a bit cloudier owing to cold air advection
and the possibility of moisture becoming trapped under the
subsidence inversion. Tonight will remain dry under increasing
clouds. Below normal temperatures prevail today and tonight; daytime
highs will be in the upper teens to mid 20s while overnight lows
will range from around 0 to around 10 above. Some spots may be
colder depending on how much clearing is able to occur tonight.

For Tuesday...yet another weak shortwave will slide southeast from
the northern Great Lakes/southern Ontario. As has been the trend
over the past several days, moisture with this system will be
relatively meager. However, some lake enhancement will be
possible through the day Tuesday as the flow turns more to the
southwest. Hence expect some snow showers to develop downstream
of Lake Ontario during the day, with the favored locations in
northern NY getting an inch or so of snow accumulation during
the day. Areas along and east of the Champlain Valley will
remain dry, with just increasing clouds. The southwest flow will
bring warmer, though still below normal, temperatures on
Tuesday as well; highs will be in the mid 20s to around 30.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/...
As of 259 AM EST Monday...A shortwave trough embedded in
northwesterly mid-level flow will traverse nrn NY and VT during
Tuesday night. Given limited moisture availability with this
system (precipitable water values only 0.2- 0.25 per 00Z GFS),
best chances for periods of light snow will be across St.
Lawrence and Franklin Counties, where WSW low-level flow from
Lake Ontario will result in some low-level moisture advection
and orographic ascent into the Adirondacks. Highest PoPs
(50-60%) are focused across St. Lawrence county and the nrn
Adirondacks, with generally 20-50% PoPs further east. Could see
a coating to 1" of snowfall across nrn NY with this system, but
with high snow-to- liquid ratios 18:1 to 22:1 should see limited
impact for travel. As the system and weak sfc reflection pass
to the east toward 12Z Wednesday, light northerly flow will
allow shallow layer of colder air to filter southward into our
region from Ontario and srn Quebec. Thus, should see lows mainly
in the teens for Tuesday night. Continued light north winds
expected at 5-10 mph on Wednesday, and potential for trapped
stratus layer, will keep temperatures below normal for mid-
December during the day Wednesday. High temperatures mainly in
the upper teens to lower 20s for Wed aftn.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 259 AM EST Monday...If clearing of low clouds can take
place, radiational cooling should be ideal for Wednesday night
as sfc 1032mb anticyclone crests over VT with light wind
conditions. At this point, anticipate mostly clear skies
yielding widespread low temperatures in the single digits, and
should see a few below zero readings across the nrn Adirondacks
and across Vermont`s Northeast Kingdom. As the sfc anticyclone
drifts east of New England on Thursday, should see a developing
southerly return flow across the region along with moderating
temperatures. Highs Thursday should reach the mid-upr 20s,
followed by highs 35-40F for Friday and into the low to mid 40s
potentially for Saturday. Synoptic evolution continues to be
complex with variability in the 00Z NWP modeling suite. Strong
southern stream wave is expected across the srn Plains into the
sern states Thu/Fri, but models are trending away from a phasing
of this system with the northern stream jet, thus decreasing
the chances for significant precipitation across the North
Country Friday and Saturday. This is especially true of the 00Z
ECMWF soln, which keeps any significant precipitation well south
of the area. A weaker northern stream trough would bring a
chance of rain/snow showers Friday night into Saturday per the
00Z ECMWF. The 00Z GFS operational run brings a leading northern
shortwave trough across NY and New England during Friday into
Friday night, but again, bulk of better forcing and moisture
remains south of the North Country. The 00Z FV3 remains with the
best chance of precipitation for the North Country, with 980mb
low over central NY at 18Z Saturday and potential for moderate
to heavy rainfall and possible windy conditions along the
western slopes of the Green Mtns.

At this point, forecast mainly reflects a blend of the GFS and
ECMWF, with potential for light rain/snow mainly Friday night into
early Saturday, and then trending drier for later in the weekend.
Have lowered PoPs accordingly, mainly 50-60% for Friday night, and
decreasing to 40-50% during the day Saturday. Given the wide range
of solns, will need to continue to monitor trends for Friday and the
weekend.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
Through 06Z Tuesday...Primarily VFR conditions through the next
24 hours, with local MVFR at some sites. Stratus remains
blanketed over much of the region, with ceilings generally AOA
3500 ft. However, sites such as KSLK and KPBG are reporting 1
1500-2500 ft deck, along with reduced visibility in light snow.
This may continue through 15z or so, but overall trends will be
for ceilings to lift and all sites to be VFR by late this
afternoon. Some clearing possible this evening, but clouds will
once again thicken and lower later tonight as low pressure
approaches from the northwest. North to northwest winds 5 to 10
kt will continue through the period.

Outlook...

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

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.

&&

$$
SYNOPSIS...Hastings
NEAR TERM...Hastings/LaRocca
SHORT TERM...Banacos
LONG TERM...Banacos
AVIATION...Hastings