224
FXUS61 KALY 090532
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
1232 AM EST Tue Dec 9 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 THURSDAY 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".

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.

&&

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

- High confidence in below normal temperatures continuing,
  along with chances for light snow or snow showers.

Discussion:

Weak surface ridging looks to be over the area on Fri bringing
mainly dry conditions, although with a westerly flow aloft some
light lake effect snow showers may occur in parts of the W.
Adirondacks and W. Mohawk Valley. It will remain chilly. A
disturbance aloft brings additional chances for snow showers Fri
night into Sat, with the highest probs west of the Hudson
Valley due to lake effect/upslope enhancement. Any snowfall
looks to be light at this time.

As an upper level low and large scale trough digs across the
Great Lakes and SE Canada, the pattern becomes more amplified
which could result in a brief window for cyclogenesis along/near
the mid Atlantic coast Sat night into Sun. At this time
guidance is showing potential for development, but also for a
fairly weak/progressive system. This could spread some light
snow into at least parts of the area. Will continue to monitor
trends.

The upper trough settles into the Northeast Sun into Mon, with
another Arctic air mass building in. So temperatures should be
well below normal again during this time. 850 mb temperature
anomalies from the NAEFS are forecast to be -1 to -2 STDEV.
There will be some wind at least through Sun night with high
pressure to the west, so wind chills could be below zero across
much of the area. High pressure builds in on Mon with winds
diminishing, but temperatures remaining cold.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
Through 06z Wednesday...VFR conditions are expected to prevail
through the 24 hour TAF period, with the only exception a small
chance for brief -SHSN with MVFR vsby at KGFL/KPSF after 00z
Wed. Will mention PROB30 at these sites. Otherwise, SCT high
level clouds initially with increasing mid level clouds expected
later this afternoon well ahead of a clipper system approaching
from the Great Lakes. Winds will be calm into this morning,
becoming southerly around 5-10 kt later this morning into this
afternoon.

Outlook...

Wednesday Night: Moderate Operational Impact. Chance of RA.
Thursday: Low Operational Impact. Breezy. Slight Chance of SN.
Thursday Night: Low Operational Impact. Slight Chance of SN.
Friday: No Operational Impact. NO SIG WX.
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 tonight through Thursday morning
     for NYZ032-033-038-082.
MA...None.
VT...None.

&&

$$

SYNOPSIS...31
SHORT TERM...31
LONG TERM...07
AVIATION...07