822
FXUS61 KALY 082018
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
318 PM EST Mon Dec 8 2025

.SYNOPSIS...
Cold temperatures continue through tonight ahead of a weak
clipper for tomorrow evening that will bring light snow to areas
mainly near and north of I-90. Then, a stronger disturbance on
Wednesday ushers in a period of widespread snow in the morning
before it mixes with rain in valley areas followed by upslope
and lake effect snow showers Wednesday night into Thursday. The
highest accumulations and most impacts are expected in the
southern Adirondacks.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Key Messages:

- Winter Storm Watch issued for the southern Adirondacks from 4AM
  Wednesday through 7AM Thursday where there is a 50 to 80%
  chance of greater than 6 inches of snow. The highest
  accumulations will likely remain north of the New York
  Thruway.

- Winter Weather Advisories will likely be needed in the
  southern Greens and Upper Hudson Valley on Wednesday where is
  there a 40 to 80% chance for greater than 4 inches of snow.

Discussion:

Chilly temperatures will continue through tonight across eastern
NY and western New England as a broad area of Canadian high
pressure centered in the Great Lakes builds eastward. West to
northwest winds continue to advect a continental polar (Cp) air
mass into the Northeast as latest visible satellite imagery
shows widespread snow covering stretching across Central and
Eastern Canada into the Great Lakes. With ideal radiational
cooling conditions expected tonight including clear skies and
light winds under a deep snow pack, very cold overnight lows are
likely. In fact, probabilistic guidance from the NBM shows 50
to 75% chances widespread throughout the region for tomorrow morning
lows in the single digits with even 40 to 50% chances for below
zero readings in the southern Adirondacks and southern Greens.
After a very chilly start to our Tuesday, clear skies fade
behind increasing clouds Tuesday afternoon ahead of our next
weak clipper. However, the associated shortwave incoming from
the Great Lakes flattens out and becomes sheared out as it
tracks up the Saint Lawrence River Valley tomorrow evening.
While overall forcing and moisture look weak, a period of
isentropic lift arrives 21 UTC Tues - 00 UTC Wed and spreads
from southwest to northeast Tuesday night with guidance
suggesting some snow showers break out, especially in the
southern Adirondack and southern Greens where upslope looks to
enhance precipitation potential. However, even this will have to
overcome a dry air mass as PWATs likely remain under 0.50" so
only expecting coating up to 2 inches of snow mainly near/north
of I-90. The highest amounts likely in the south/southwest
facing slopes of the southern Adirondacks and southern Greens.

While we should see a brief break from the snow Tuesday night
but the respite will last a few hours as the next system arrives
right on its tail. A compact shortwave with Pacific origins will
dive into the Upper Midwest before a closed low positioned in
the Hudson Valley steers it northward up the Saint Lawrence
River Valley tomorrow. As the two begin to phase Wed morning,
the shortwave intensifies resulting in increasing forcing for
ascent. This includes a strong push of isentropic lift as
southerly winds in the 925-850hPa layer increases to 45-50kts
which will help direct a plume of moisture from the Gulf
northward. Thus, there is increasing confidence that as snow
arrives from southwest to northeast Wednesday morning, it will
fall moderately to heavily with the HREF showing a 20 to 30%
chance for greater than 1 inch per hour snowfall rates in the
southern Adirondacks due to upsloping enhancement. Latest
guidance shows the snow beginning initially west of the Hudson
River 12 - 15 UTC or during the A.M commute before snow quickly
spreads eastward. Despite strong southerly winds in the low and
mid-levels, expecting a steady period of all snow throughout
the region Wednesday morning as wet-bulbing cooling processes
likely supports cold enough thermal profiles before enough
warming occurs in valley areas by 18 - 21 UTC that snow turns
wetter and struggles to accumulate. In addition, isentropic lift
by Wed P.M turns weaker as winds shift to the west and a dry
slot punches northward leading to lighter precipitation. This
also means travel conditions should improve by the Wed P.M
commute outside the higher terrain areas. Overall, expecting
coating up to 2 inches in the Hudson Valley from the Greater
Capital Region southward into the mid-Hudson Valley and NW CT
while there is 30 to 70% chance for greater than 7" in the
southern Adirondacks (especially along south facing slopes) with
only a 30 to 40% chance of 7"+ in the southern Greens. Winter
Storm Watches have been issued for all of Herkimer, Hamilton and
northern Fulton where probabilities for greater than 7" of snow
are highest (mainly north of the NY Thruway). Winter Weather
Advisories will likely be need in the southern Greens and in
parts of the Upper Hudson Valley but there is low confidence in
exceeding 7".

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Key Message:

- Below normal temperatures remain in place along with continued
  chances of snow showers.

Discussion:

While the strongest moisture transport/forcing exit to our east
by 21 - 00 UTC Wed, the main cold front pushes through the
region overnight Wednesday. Once the winds shift to the west in
the wake of the boundary, winds turn gusty and ensuing cold air
advection will support additional snow showers through Thursday
morning, mainly in the higher terrain areas. Thursday remains
blustery and chilly as the parent closed low swings through
Quebec. This will support westerly winds in the low and mid-
levels across the Northeast, leading to lake effect snow bands and
even a multi-lake connection by Thursday afternoon as a
favorable fetch and cold air advection develop over the Great
Lakes. We increased POPs to chance Thursday afternoon to help
message returning snow showers and additional light snow
accumulations, especially in the Mohawk Valley. We remain chilly
heading in Thursday night as westerly winds maintain cold air
advection.

West to northwesterly flow aloft will continue Friday through next
weekend. This will bring continued below normal temperatures to the
region. There are some timing differences amongst the members on any
additional passing shortwaves, though at least one additional
clipper system could bring another round of snow sometime over the
weekend. Surface high pressure and rising heights should then bring
drier weather by the start of next week.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
Through 18z/Tue...High pressure over the region will bring
continued VFR conditions through the upcoming TAF period with
just some passing high clouds. North to northwesterly winds
between 5-10 kt this afternoon will become light to calm
tonight, then southerly at 5-10 kt on Tuesday. A few gusts to 20
kt will continue at KPOU for a few more hours before easing by
the early evening hours.

Outlook...

Tuesday Night: Low Operational Impact. Slight Chance of SN.
Wednesday: High Operational Impact. Definite SN.
Wednesday Night: High Operational Impact. Likely SHSN.
Thursday: Moderate Operational Impact. Breezy. Chance of SHSN.
Thursday Night: Low Operational Impact. Slight Chance of SHSN.
Friday: Low Operational Impact. Slight Chance of SHSN.
Friday Night: Moderate Operational Impact. Chance of SN.
Saturday: Moderate Operational Impact. Chance of SN.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Winter Storm Watch from late Tuesday night through Thursday
     morning for NYZ032-033-038-082.
MA...None.
VT...None.

&&

$$

SYNOPSIS...31
SHORT TERM...31
LONG TERM...31/33
AVIATION...33