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251
FXUS61 KALY 021432
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
932 AM EST Mon Dec 2 2024

.SYNOPSIS...
Mainly dry and cold weather will continue early this week with
some lake effect snow showers and flurries mainly across the
Catskills. A clipper low will bring widespread light to locally
moderate snow Wednesday into Thursday with lake effect and
upslope snow showers and blustery conditions developing in its
wake lingering into Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Key Message:

- Mainly dry and cold weather will continue outside of a few
  lake effect snow showers and flurries mainly across the
  western Mohawk and Schoharie valleys and eastern Catskills.

9:30 AM EST Update... Minor changes this morning to increase winds
and wind gusts across southern Vermont for the next 2 to 3 hours,
especially along VT-9 as current surface observations have
shown wind gusts have been between 10 and 15 mph. The rest of
the forecast is doing well and on track for today. See previous
discussions below for more details.

.UPDATE...As of 655 AM EST, lake-effect snow band off Lake
Ontario has briefly weakened and is outside of our CWA at this
time, resulting a mainly dry start to the day. Latest CAMs
suggest this band may mostly stay to the south and west of our
area through the day, but still kept slight chance PoPs in, but
trended them slightly downward. Otherwise, the going forecast
remains in good shape with little additional changes.

Previous Discussion:
Longwave upper level troughing remains in place through tonight
with northwesterly flow resulting in lake effect snow showers
and flurries oriented toward the western Mohawk Valley,
Schoharie Valley and eastern Catskills. The overall weakness of
the band should limit accumulations to less than one inch in
these areas through tonight. Otherwise, another cold day is in
store with a few isolated flurries not completely ruled out.
Highs will top out in the 30s in the valleys and 20s in the
higher elevations. Lows tonight fall back into the teens to
around 20.
-- End Changed Discussion --

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
Key Message:

- A clipper system will bring widespread light to moderate snow
  later Wednesday through Thursday.

An upper-level trough will remain overhead on Tuesday with
northwesterly flow continuing. Light lake effect snow showers
and flurries will continue with slightly more coverage compared
to Monday due in part to a couple of passing embedded
shortwaves. The lake effect band may also extend farther inland
to bring a snow shower or flurry to portions of the mid-Hudson
Valley into southern Berkshire County and northern Litchfield
County. Still, minimal accumulations are expected with up to a
coating to an inch or so mainly across the eastern Catskills.

Weak upper level ridging builds in Tuesday night into Wednesday
as flow turns southerly. This will disrupt/weaken the lake
effect band and drift it northward. So, some additional light
snow showers of flurries are possible across the western Mohawk
Valley and Adirondacks. Otherwise, dry and cold weather will
remain.

A widespread light to moderate snowfall is expected later
Wednesday through Thursday as a potent upper-level trough and
clipper system tracks across the region. A northward lifting
warm front/isentropic lift will bring periods of snow to the
area beginning Wednesday afternoon and continue through
Wednesday night before the systems cold front crosses the
region on Thursday. South to southwesterly low-level flow is
expected to result in orographic enhancement across portions of
the southern Adirondacks resulting in the higher snowfall totals
in these areas (potentially 3 to 7 inches). Elsewhere, a
general coating to 3 inches appears likely at this time. With
strong southwesterly flow in place, some precipitation
shadowing/downsloping could occur, resulting in local minimums
in accumulation, but confidence on where this could occur
remains low at this time. There remain some slight differences
in the timing of the cold front on Thursday as well. Should the
front wait until the later morning or afternoon hours on
Thursday, steep low-level lapse rates as seen on forecast
soundings could support some localized heavier snow showers or
squalls. Blustery conditions will develop behind the cold front,
especially Thursday afternoon, with some gusts over 30 mph
expected. The arrival of colder air aloft will also begin to
develop lake-effect and upslope snow showers which will continue
into the long term period.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
Key Message:

- Confidence remains high (60 - 80%) for temperatures to range
  10 to 15 degrees below normal through next weekend.

In the wake of our arctic cold front on Thursday, strong cold
air advection and gusty winds continue into Thursday night.
Initial westerly flow will maintain lake effect snow showers
into the western Adirondacks; however, as low and mid-level flow
veers to the northwest in response to a ~1030-1035 hPa high
from the Ohio Valley building eastward, the lake effect response
will likely weaken overnight and snow shower activity trends
downwards. Winds look to remain gusty as cold air advection and
strong pressure rises behind the departing shortwave trough
maintain deep mixing. In fact, probabilistic guidance suggests
25 - 50% chance for wind gusts to exceed 30mph Thurs night. With
overnight temperatures feeling more like early January than
December, the combination of gusty winds and chilly temperatures
will support wind chills in the single digits by early Friday.
Breezy and chilly Friday morning with any lingering lake effect
snow showers ending as subsidence from our incoming 1035hPa high
builds into the Northeast. Winds gradually weaken through the
afternoon as the sfc pressure gradient relaxes with
probabilities for wind gusts to exceed 30mph dropping under 20%.

Heading into the weekend, uncertainty increases as the medium
range guidance indicates a split flow regime. There are
opportunities for both northern and southern stream shortwaves
to produce light precipitation events but given large
discrepancies in timing, placement, and available moisture,
limited POPs 15 to 30% Saturday and 0 to 30% Sunday. While
precipitation is uncertain for the weekend, confidence remains
high (60 - 80%) for below normal temperatures with the NAEFS
showing temperatures ranging 2 to 3 standard deviations below
normal.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
As of 12 UTC/02, MVFR ceilings developed at PSF overnight due to
lake effect moisture and upslope flow and ceilings will remain
MVFR through 00 UTC/03. Included TEMPO group for ALB for MVFR
ceilings 12-15 UTC given incoming lake moisture and occasional
MVFR cigs. Elsewhere, VFR conditions continue to prevail with
clouds becoming FEW if not briefly clearing through 15 UTC
before sites reach their respective convective temperature and
ceilings redevelop by 16- 17 UTC. This should result in BKN cigs
around 4-5kft at POU, ALB, and GFL through the end of the TAF
period. Skies then likely clear this evening by 00 - 02 UTC/03.
Otherwise, light and variable winds become west northwest by
16-18 UTC and become sustained 5-8kts with gusts 12-15kts.

Outlook...

Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: Low Operational Impact. Slight Chance of SN.
Wednesday Night: High Operational Impact. Definite SN.
Thursday: High Operational Impact. Windy With Gusts To 32 kts. Likely SHSN...SN.
Thursday Night: Moderate Operational Impact. Breezy. Chance of SHSN.
Friday: Low Operational Impact. Breezy. NO SIG WX.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: Low Operational Impact. Slight Chance of SHSN.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.

&&

$$

SYNOPSIS...Rathbun
NEAR TERM...Rathbun/Webb
SHORT TERM...Rathbun
LONG TERM...Speciale
AVIATION...Speciale