411
FXUS61 KALY 250845
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
345 AM EST Mon Nov 25 2024

.SYNOPSIS...
High pressure building in from the west today will bring dry
conditions and seasonable temperatures. A low pressure system
approaching from the Great Lakes will move across the area late
tonight into Tuesday, bringing widespread rain and pockets of
freezing rain to some mountain areas north of Albany. In wake of
this system, lake effect snow will develop in the western
Adirondacks late Tuesday into Wednesday with dry and breezy
conditions elsewhere.

&&

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

- Winter Weather Advisory issued for light freezing rain across
  Hamilton and northern Warren Counties in New York, and
  Windham County in southern Vermont from 1 AM tonight to 1 PM
  Tuesday.

- Widespread light to moderate rain late tonight into Tuesday.

Satellite imagery showing some lingering lake enhanced clouds
for areas south/west of Albany early this morning. Otherwise
mainly clear skies to start the day with temperatures in the 20s
to mid 30s. Mostly sunny and tranquil conditions expected
today, with a small area of high pressure moving in. High
temperatures should be slightly above normal with upper
30s/lower 40s in the mountains to mid/upper 40s in the valleys.
High/mid level clouds will start to increase later in the day
ahead of a storm system approaching from the Great Lakes.

This night starts out dry during the evening, but rain showers
will approach and move into the area from west to east overnight
as a surface cyclone and associated upper level trough track
into the lower Great Lakes region. Prior to precip onset
temperatures will cool into the upper 20s to mid 30s with the
coldest readings in the Adirondacks and S. Green Mountains. This
will allow for potential for a brief period of freezing rain at
the onset for a few hours in these areas. Light icing may occur
with surface temperatures at or just below 32F. There is high
enough confidence to issue a Winter Weather Advisory for small
area including Hamilton and N. Warren Counties in NY and Windham
County in VT. Outside of these higher terrain areas, a cold
rain will occur.

Most of the area will see another widespread rainfall from this
system with forecast QPF ranging form around 0.25-0.50" through
Tue morning. As the primary surface cyclone tracks near the
Georgian Bay and Lake Ontario area Tue morning, a secondary
cyclone is forecast to develop over southern New England as the
progressive upper level trough becomes negatively tilted. So
even the southern part of the area should receive beneficial
rainfall from this system. A drying trend is expected Tue
afternoon as the main synoptic features and forcing shift east
into New England. Westerly winds will increase late in the day
behind the system, with mixing up to ~850 mb from forecast
sounding. So high temperatures should reach into the 40s to
lower 50s in the well mixed environment.

&&

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

- Lake effect snow develops in western Adirondacks Tuesday night
  and lasts into Wednesday. Light to moderate accumulation
  possible.

Well-aligned westerly flow will quickly develop by Tue evening
within a cold advection regime. Temperatures aloft do not look
very cold for this time of year (-7C to -8C at 850 mb), but cold
enough to initiate a lake response with the Lake Ontario
surface temperature around +10C resulting in conditional lake
induced instability. So lake effect snow will become likely with
forecast soundings indicating a moist mixed layer with fairly
high inversion heights ~750 mb. Lake effect snow should weaken
Wed with lowering inversion heights. Light to moderate
accumulations of 3-6" are expected at this time. A Winter
Weather Advisory will likely be issued at some point for N.
Herkimer/Hamilton Counties for areas mainly along and north of
Route 28. South/east of the lake effect it will be dry and
breezy Tue night into Wed. Both lows Tue night and highs Wed
look to be near to slightly above normal for late November.

&&

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

- Widespread precipitation expected Thanksgiving Day, with snow
  favored in high terrain and rain at lower elevations. Lake-
  effect snow showers continue into the weekend.

- Temperatures trend from near-normal on Thanksgiving to below
  normal for early December this weekend.

Discussion:

Lingering lake-effect rain and snow showers in the southwestern
Adirondacks and western Mohawk Valley Wednesday night will give
way to more widespread precipitation chances across the region
through Thanksgiving Day. A progressive positively-tilted upper
trough will amplify as it slides eastward toward the Mid-
Atlantic while a surface low develops along the Southeast coast
before tracking offshore toward the Canadian Maritimes or Cape
Cod. Confidence remains high in precipitation occurring during
the day Thursday across the region, with multi-model ensembles
supporting an 80% or greater chances of measurable (>0.01")
precipitation and a 65-85% chance of 0.1" or more, with higher
values south of Albany and nearer to the storm track. At this
lead time, precipitation type remains less certain, with snow
favored above 1500 ft and rain at lower elevations, however the
distribution of p-types will remain sensitive to the forecast
low track and resultant temperature profiles. At higher
elevations, there is a 30-50% likelihood of advisory-level (>4")
snow accumulations through Friday morning. Rain and snow
chances will linger through Friday, before a more robust lake
response develops late Friday into the weekend, with snow
showers likely in the southwestern Adirondacks.

Temperatures near normal on Thanksgiving will trend downward
through the period as colder air from central Canada is advected
about the southwestern flank of persistent low pressure near
James Bay. High temperatures on Thursday in the upper 20s to
upper 30s in high terrain and upper 30s to mid 40s at lower
elevations on Thanksgiving will cool a few degrees each day,
only reaching the 20s in high terrain and 30s at lower
elevations by Sunday. Overnight lows look to similarly trend
colder, from mid 30s to mid 30s on Wednesday night to 10s to low
20s across the region by Sunday night.

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
Through 06Z Tuesday...VFR conditions expected throughout the
period at all terminals. An area of lake-effect clouds extending
downwind of Lake Ontario will continue to bring few low clouds
at 3-5 kft to ALB/POU/PSF into tonight, with skies trending
clearer by 12Z Mon. Otherwise, high clouds at 20+ kft increase
after 18Z Mon, before bkn cigs at 5-10 kft arrive by 00Z Tue
ahead of rain showers expected later Tuesday morning.

West to northwest winds at 5-10 kt will persist through 15-18Z
Mon at all terminals, with gusts to 15 kt possible at PSF. Wind
shear may approach 25-30 kt out of the northwest in the lowest 2
kft at PSF through 12Z Mon, however speeds are expected to
remain below TAF inclusion criteria (30 kt). Winds diminish to 5
kt or less after 18Z Mon, before becoming calm across the
region after 00Z Tue.

Outlook...

Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: Low Operational Impact. Breezy. NO SIG WX.
Wednesday Night: Moderate Operational Impact. Chance of SHRA.
Thanksgiving Day: High Operational Impact. Likely RA.
Thursday Night: Moderate Operational Impact. Chance of RA.
Friday: Moderate Operational Impact. Chance of SHRA...SHSN.
Friday Night: Moderate Operational Impact. Chance of SHSN.
Saturday: Low Operational Impact. Breezy. Slight Chance of SHSN.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Winter Weather Advisory from 1 AM to 1 PM EST Tuesday for
     NYZ033-042.
MA...None.
VT...Winter Weather Advisory from 1 AM to 1 PM EST Tuesday for
     VTZ014-015.

&&

$$

SYNOPSIS...JPV
NEAR TERM...JPV
SHORT TERM...JPV
LONG TERM...Picard
AVIATION...Picard