893
FXUS61 KALY 050237
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
937 PM EST Wed Dec 4 2024

.SYNOPSIS...
A clipper system will bring widespread snowfall to the region
through Thursday, with locally heavy accumulations mainly in
higher elevations of the Adirondack and Green mountains. Breezy
winds, cold temperatures, and additional snow showers east of
Lake Ontario and upslope the higher terrain will follow behind
the clipper Thursday afternoon through Friday, with the coldest
temperatures of the season thus far expected into the weekend.

&&

.NEAR TERM /THROUGH THURSDAY/...
Key Messages:

- A clipper system will bring widespread snowfall through Thursday
  with windy conditions and lake effect and upslope snow showers
  developing behind the passage of an arctic cold front.

- Winter Storm Warnings and Winter Weather Advisories are in effect
  for portions of eastern New York and western New England from
  Wednesday afternoon into Thursday/Thursday night.

- Wind Advisories are in effect for areas along and south of
  Interstate 90 Thursday morning into Thursday night.

9:30 PM Update... Minor changes to wind gusts through the next
one to two hours as they have been observing 10 to 15 mph lower
than forecasted, but should continue to be between 15 and 30 mph
through tonight. Widespread snow continues tonight, see previous
discussion below for more details.

7:20 PM Update... Minor adjustment to decrease winds and wind
gusts through the next 1 to 2 hours before the front moves
through in the western Adirondacks as current surface
observations show winds have been between 2 and 6 mph. Otherwise
the rest of the forecast is doing well and on track for tonight,
see previous discussion below for more details.


Previous Discussion:

A deepening upper level trough/clipper currently in place over
northwest Ontario will move southeast over the next 12-24 hours, and
is progged to reach the coast of Maine and Nova Scotia by Thursday
morning. Ahead of the clipper, WAA and low-level isentropic lift
with increasing moisture from southwesterly flow will lead to
development of a widespread light to moderate snow for most of
eastern NY and western New England. Guidance remains consistent
with snow beginning mainly in the foothills of the southern ADKs
and western Mohawk Valley, with a gradually spread eastward
through the afternoon and evening as wetbulb processes overcome
dry air in place at the low-levels. Thanks to the cold air
already in place and the approach of an arctic front,
precipitation types should not be an issue as we remain all
snow.

As far as accumulations go, expected amounts have not changed
significantly with this forecast package. Deterministic guidance
remains in good agreement with placement, with the least confidence
in totals mainly around the Capital District due to effects from
downsloping from the Catskills. Highest totals remain favored in the
Adirondacks and Bennington County, VT where 6-12 inches of snow
is expected, with locally higher amounts possible. Elsewhere,
amounts of a coating to 6 inches are expected, with the lower
amounts within portions of the Hudson Valley from Albany and
points south and southern Litchfield County.

The more widespread snow will end from west to east by Thursday
morning with the passage of the arctic cold front. Additional snow
showers are expected along and behind the front with forcing from
the front and incoming arctic air. Snow squalls remain possible with
favorable low and mid-level lapse rates in place per fcst soundings,
which will mix low-level winds around 40-45 kts at times to the
surface.

Speaking of winds, it will be quite breezy behind the arctic front
with gusts around 30-50 MPH, especially during the late afternoon
and early evening. Areas most favored on the higher end of
gusts are the Mohawk Valley, Capital District, Berkshires and
eastern Catskills, where a Wind Advisory is now in effect
beginning Thursday morning. These winds will persist through the
daytime before gradually subsiding during the evening hours.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/...
Key Messages:

- Lake effect snows continue in the western ADKs and Mohawk Valley

- Coldest temperatures of the season thus far especially Friday AM

Discussion:

Northwesterly flow will remain locked in across the region through
the short term period, with 925-850 hPa temperatures plunging to
around -14 to -16 C Friday morning. This air will support a brief
period of well below normal temperatures, and the coldest
air of the season thus far. Despite persisting cloud cover,
lows Thursday and Friday night will range form the upper single
digits (terrain) to near 20 across the mid Hudson Valley. It
will remain breezy with gusts around 25-35 MPH, allowing wind
chills to drop into the single digits to lower teens. Some of
the higher elevations of the Adirondacks may see values below
zero Friday morning. Highs Friday will range from the upper
teens (terrain) to low 30s in the Mid Hudson Valley.

Snow showers will also continue mainly across the lake effect
belt of the Mohawk Valley and western Adirondacks and upslope
regions of the Berkshires and Greens. Additional light
accumulations are possible in these locations during this time
with little or no accumulation elsewhere.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Key Messages:

- High confidence for colder than normal temperatures through the
weekend.

- Increasing confidence for temperatures to trend milder than normal
for the first half of next week, along with multiple opportunities
for rain.

Upper level trough across the northeast will slowly shift eastward
this weekend, associated with below normal temperatures. Weak
disturbances and some lake enhanced moisture will keep some snow
showers around, mainly for areas north of I-90 and west of I-87
Saturday through Sunday morning.

The upper level flow flattens out later Sunday, then becomes
southwest for early next week. Disturbances riding northeastward
will bring some chances for rain, especially Monday-Monday night.
Depending on surface temps, can not completely rule out some mixed
precipitation at onset across portions of the southern
Adirondacks/southern VT and upper Hudson Valley, especially if
precipitation arrives late Sunday night.

Milder temperatures are expected Monday through Wednesday, with
highs reaching the 40s in many lower elevations, perhaps warmer
across the mid Hudson Valley, with lows in the teens Sunday morning,
20s to lower 30s Monday morning, and mainly 30s Tuesday-Wednesday
morning.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Through 00z Friday... Light snowfall continues to move from west
to east tonight with ceilings continuing to lower for all TAF
sites through the TAF period. Periods of MVFR/IFR conditions
can occur through tomorrow afternoon. Southeast winds continue
through tonight through tomorrow morning to be gusting between
20 and 35 knots.

Outlook...

Thursday Night: Moderate Operational Impact. Chance of SHSN.
Friday: Low Operational Impact. Slight Chance of SHSN.
Friday Night: Moderate Operational Impact. Chance of SHSN.
Saturday: Low Operational Impact. Slight Chance of SHSN.
Saturday Night: Low Operational Impact. Slight Chance of SHRA...SHSN.
Sunday: High Operational Impact. Likely RA.
Sunday Night: High Operational Impact. Likely RA.
Monday: Moderate Operational Impact. Chance of RA.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory until 1 PM EST Thursday for CTZ001-013.
     Wind Advisory from 7 AM to 10 PM EST Thursday for CTZ001-013.
NY...Wind Advisory from 7 AM to 10 PM EST Thursday for NYZ039-040-
     047>054-058>061-063>066.
     Winter Storm Warning until 4 AM EST Friday for NYZ032-033-038-
     082.
     Winter Weather Advisory until 1 AM EST Friday for NYZ039>043-
     047-050-054-058-063-083-084.
MA...Winter Weather Advisory until 1 PM EST Thursday for MAZ001-025.
     Wind Advisory from 7 AM to 10 PM EST Thursday for MAZ001-025.
VT...Winter Weather Advisory until 1 PM EST Thursday for VTZ015.
     Winter Storm Warning until 4 AM EST Friday for VTZ013-014.

&&

$$

SYNOPSIS...Speck
NEAR TERM...Rathbun/Speck/Webb
SHORT TERM...Speck
LONG TERM...KL
AVIATION...Webb