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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBTV 181446
AFDBTV

Area Forecast Discussion
National Weather Service Burlington VT
946 AM EST Sat Jan 18 2020

.SYNOPSIS...
After one last very cold morning, temperatures will begin to
warm today as a low pressure system approaches from the
southwest. The system will send a warm front through later
today, resulting in widespread snowfall over the region. The
heaviest snow will fall late this evening into the first part of
tonight, before tapering off through the day Sunday. Snowfall
amounts will be between 3-7 inches with locally higher amounts
across high terrain. Quieter weather with below normal
temperatures is expected for the first half of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 940 AM EST Saturday...Winter Weather Advisories remain in
effect for the entire forecast area, valid from 1 PM this
afternoon to 4 PM Sunday.

No significant changes were needed with this update. Chilly
conditions continue this morning, with most locations still in
the positive/negative single digits. Cloud cover will only
continue to thicken, so don`t anticipate much sunshine today,
which will temper any warming. Radar is showing light returns
spreading over northern NY, but surface observations indicate
the precipitation is still well to our west, in the Buffalo
area. Therefore, still anticipate snow will hold off until mid-
late afternoon for much of our region. The forecast has this all
pretty much covered, so just made some very slight tweaks to
PoPs and temps to match the latest radar/observation trends.
Overall the forecast remains on track.

Previous discussion...Cold start to the weekend this morning
with temperatures starting out near or below zero for much of
the area. Morning satellite imagery shows high clouds streaming
into the area ahead of a developing low over the central US.
High temperatures today will be slow to warm under the
thickening blanket of clouds, despite developing southerly flow
over the region as the low approaches from the west. Have
knocked down forecast highs for the day today, with readings now
expected to top out in the mid to upper teens across most of
the area.

The approaching low will track to the Great Lakes Region this
afternoon, pushing a warm front northeastward through our
forecast area as the center of the low tracks to our north and
west. Warm air advection driven snow will start as the boundary
moves through, with snow start times ranging from 2-4 PM this
afternoon in northern NY to 4-6 PM this afternoon in VT. Progged
925 to 950 mb fgen (mainly over northern NY) as the initial
warm front moves through does support the potential for a
heavier band (or bands) of snow, especially this evening/early
overnight when upper-level support will line up with best lower-
level circulation. Any bands that do form could contain some
heavier snow and low visibilities. BUFkit soundings show that
best omega and RH is not necessarily lined up within DGZ, so not
expecting snowfall rates to be overly impressive at this time.
After the initial warm front pushes through, forcing for ascent
decreases and snowfall rates will lessen for the remainder of
Sunday night. The center of the low will ride up the Saint
Lawrence Valley early Sunday morning, allowing strong southerly
flow to veer to the west. At this point, expecting snow to
become more tied to terrain, with downsloping hole emerging the
Champlain Valley and continued upslope snow over the
northwestern Adirondacks and the northern Greens. This pattern
will continue through the day Sunday, with little additional
accumulations expected in valley locations but another few
inches over higher terrain during the day.

All said and done, total snow accumulations will range from 3-7
inches, locally higher in higher terrain.  The Champlain Valley will
see the lowest accumulations, while the northern Adirondacks
and northern Greens will see the highest.

In addition to snow, the low will bring some gusty winds to the
area. A 50+ kt southerly low-level jet will move overhead this
evening.  Given the strong inversion resulting from the warm air
advection just off the surface, mixing will be minimal and the vast
majority of the momentum aloft will not be transferred to the
surface.  However, there will be some briefly gusty (15 to 25 mph)
winds this evening, especially over higher terrain and channeled
up the Champlain Valley.

&&

.SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/...
As of 303 AM EST Saturday...Evening snow showers then wane and
end overnight Sunday as eastward extension of polar high
pressure across the Northern Plains settles across the region.
Still some lingering clouds, but a trend toward partly cloudy
conditions by sunrise Monday still appears reasonable at this
point. Low temperatures near seasonable mid-winter norms in the
single digits.

Then partly cloudy and quiet on Monday as aforementioned high
pressure continues to build slowly east. High temperatures
seasonably cold in the teens to locally near 20 in broader southern
valleys.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 303 AM EST Saturday...A welcome break in active weather
then looks to continue for most of the work week as high
pressure becomes anchored across the Mid-Atlantic/Northeast. A
glancing blow by another polar front Monday night may spark a
few northern mountain flurries, otherwise partly cloudy skies
and dry weather are expected over the 5 day period with a
gradual warming trend. Highs on Tuesday similar to Monday in the
teens, then 20s for Tuesday and 30s from Wednesday onward as
modified air of Pacific origin bridges across the CONUS. Some
suggestion that another system may affect the region toward next
weekend but confidence is low at this point with a broad lack
of consensus among medium range guidance so just lower end
chance pops will be offered by next Saturday.

&&

.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
Through 12Z Sunday...High and mid clouds will continue to
spread over the forecast area, thickening and lowering through
the TAF period. Expect all TAF sites to remain VFR through 18Z.
Snow will spread northeastward from NY through VT after 18Z,
accompanied by reduced visibilities and ceilings to the MVFR/IFR
range. Some localized LIFR conditions are possible after 00Z,
especially at KSLK and KRUT where bands of snow will form and
snowfall will be heaviest. Light and variable winds this
morning will become south/southeast this afternoon at 6-12 kts.
Have included mention of LLWS at most TAF sites this evening as
southwesterly jet moves in aloft. In addition to LLWS, areas of
turbulence can be expected.

Outlook...

Sunday: Mainly MVFR, with areas VFR possible. Chance SHSN, Areas
BS.
Sunday Night: Mainly VFR, with areas MVFR possible. Chance SHSN.
Martin Luther King Jr Day: VFR. NO SIG WX.
Monday Night: VFR. NO SIG WX.
Tuesday: VFR. NO SIG WX.
Tuesday Night: Mainly MVFR, with areas VFR possible. NO SIG WX.
Wednesday: Mainly VFR, with areas MVFR possible. NO SIG WX.

&&

.BTV WATCHES/WARNINGS/ADVISORIES...
VT...Winter Weather Advisory from 1 PM this afternoon to 4 PM EST
     Sunday for VTZ001>012-016>019.
NY...Winter Weather Advisory from 1 PM this afternoon to 4 PM EST
     Sunday for NYZ026>031-034-035-087.

&&

$$
SYNOPSIS...Duell
NEAR TERM...Duell/Hastings
SHORT TERM...JMG
LONG TERM...JMG
AVIATION...Duell