218
FXUS61 KALY 080321
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
1021 PM EST Fri Feb 7 2025

.SYNOPSIS...
Lake effect snow showers north and west of the Capital Region
and gusty winds diminish tonight. Low pressure will approach
from the Midwest and Ohio Valley on Saturday with snow overspreading
the region Saturday night into Sunday morning, as its passes
south of Long Island. A widespread moderate to locally heavy
snowfall will occur before tapering to snow showers and flurries
during the afternoon, as some lake snow showers will persist
into Sunday night with below normal temperatures.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Key Messages:

 - Lake effect snow showers gradually diminish tonight for the
   southwest Adirondacks and Mohawk Valley.

Discussion:

As of 10 PM EST...Lake effect snow showers extending off Lake
Ontario are even more fragmented so we canceled the winter
weather advisory for southern Herkimer County in collaboration
with WFO BGM. Westerly wind gusts are still a bit gusty tonight
ranging 15 - 20kts and with cloud coverage still in place from
I-90 northward, temperatures have been slow to decline
overnight. Areas south of I-90 are clear with weaker winds so
still expecting a greater temperature drop off overnight.
Adjusted temperatures upwards a few degrees from the Capital
District northward where clouds/winds are expected resulting in
lows only in the mid to upper teens (cooler in the southern
Adirondacks in the low teens). Areas south will have more
efficient radiational cooling and therefore should also able to
fall into the low to mid-teens.

Previous discussion...Temps tonight were favored toward a blend
of the MAV/MET/NBM with lows in the teens with some single
digits over the western Dacks, eastern Catskills, and southern
Greens.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
Key Messages:

 - Moderate to high confidence for moderate/heavy snowfall
   Saturday night into Sunday morning, but low to moderate
   confidence on exact placement of the heaviest snow.

 - Uncertainty in potential warning level snow northward
   warranted a Winter Storm Watch for the Mohawk Valley,
   southwest Adirondacks, Lake George Saratoga Region and
   southern VT

 - Winter Storm Warning for 6-9" of snowfall from the Schoharie
   Valley, Greater Capital Region, Taconics and the Berkshires
   southward.

 Discussion:

Clouds quickly increase, thicken and lower on Saturday ahead of
a wave low pressure moving across the Midwest. High pressure
shifts offshore of New England. Inverted sfc trough and a mid
level short-wave may allow for some light snow to break out in
the late afternoon west and northwest of the Hudson River
Valley. The snow shield will increase into the early evening,
as the isentropic lift increases ahead of the wave moving from
the Ohio Valley along and north of the Mason Dixon line.

Some hints in the HREFs of 1"/hour snow rates in the 40-60%
range from the Capital Region, northern Catskills, Berkshires
and Mohawk Valley northward, as the low-level jet enhances
tapping gulf moisture. Left front quadrant of the mid and upper
level jet will also provide dynamical support. The NAM remains
the weakest and an on the low end of snow amounts and QPF. The
GEFS/GFS/ECMWF with 12-16:1 snow to liquid ratios support a
6-9" snowfall where we had the current watch. The dendritic
growth zone should be tapped into with the strong upward
vertical motion and the guidance showing the heaviest snow 00Z
to 12Z SUN. Some of the ensembles and the GFS show a surge of
moisture further north. WPC guidance supports 6-12" in the
northern most zones. We hoisted a watch before an advisory or
warning in these areas. WFO BTV and GYX were in collaboration
with the watch. The south/southwest flow off the higher terrain
with higher FGEN in the 700-500 hPa may support these higher
totals in the northern area. The 3rd period is a good set-up for
additional warnings or advisories.

This is a tricky forecast with a fast moving open wave. Some
mesoscale bandlets may set-up with 1"/hr bursts. Some of the
ingredients of laterally translating snowbands are there from
the CSTAR cool season research, but typically they are
associated with the right entrance region of the upper jet.
The latest NBM 4.2 24-hr > 7" snow probabilities were in the
55-80% range from the eastern Catskills, mid Hudson Valley
Taconics north and east through the Capital Region and across
western New England. All, said the latest super ensembles plume
give Albany an 8" mean amount for the event, and the GEFS Plume
is 7". 6-9" is forecast for the Greater Capital Region,
Schoharie Valley, Taconics, Berkshires southward into the mid
Hudson Valley, eastern Catskills, and NW CT. The watch is for
6-10" to the north.

Max temps Saturday will be in the 20s to lower 30s in the mid
Hudson Valley. Some teens over the Adirondack Park. Lows will
be in the teens to lower 20s and may rise or steady after
midnight.

The snow with the wave should advance quickly east of the
Hudson River Valley Sunday morning. If the dry slot gets into
the area, some patchy freezing drizzle will occur. We kept the
warning going until noon. As the previous discussion mentioned
and what happened last weekend, some Mohawk Hudson Convergence
could occur Sunday morning for the Greater Capital
Region/northern Taconics based on some of the deterministic
guidance. The CSTAR research with UAlbany on MHC supports a
couple more inches of snow in these areas. Also some lingering
mid and upper level deformation snow may occur. Some lake effect
may develop in the late afternoon off Lake Ontario for the
western Mohawk Valley, western Adirondacks and northern
Catskills with light snow accums of a half an inch to two
inches. Highs Sunday will be in the upper 20s to lower 30s in
the valleys and lower to mid 20s over the higher terrain.

Lake effect snow showers and flurries may persist Sunday night
west of the Hudson River Valley. Clearing skies with light to
calm winds with high pressure building in may allow temps to
drop quickly. The fresh snow cover may assist in radiative
cooling processes. We went cold with lows in the single numbers
to lower teens with below zero readings in the southern
Adirondacks.

&&

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

 - Active weather pattern throughout next week with daily chances
(50%) of snow after Tuesday night.

Discussion:

The long term starts with surface high pressure overhead for Monday
through Tuesday afternoon. Breezy and dry conditions are in the
forecast before our next weather system arrives Tuesday night.
Latest National Blend of Models (NBM) 4.2 data suggests
probabilities for greater than 1 inch of snow for the 24 hour period
from Tuesday night through Wednesday night is between 40 to 60% for
locations south of I-90. There is still a lot of disagreement with
the exact track of the low pressure system with ensemble forecast
model guidances for Tuesday night and Wednesday morning as some are
showing the track moving further south with less snow while others
are showing a track closer to the coast. This will continue to
fluctuate through the next forecast cycles.

Wednesday night through Thursday night is being monitored as well
for our next impactful chances of snow across eastern New York and
western New England. Ensemble forecast models vary on the track of
the low pressure system, so snowfall amounts and timing will shift
with future forecasts and probabilistic guidance (with widespread
probabilities of 80 percent of greater than 1 inch of snowfall) is
hinting at a more widespread snowfall event compared to the one
Tuesday night. Primary concern is going to be the Thursday morning
commute being slippery from snowfall overnight, but the track of the
low pressure system will shift with future forecast cycles and
snowfall amounts will fluctuate. Stay tuned for more details...

Temperatures remain cold through Thursday, with highs ranging in the
low 20s across the western Adirondacks to lower 30s across the Mid-
Hudson Valley. Low temperatures Monday night could be bitterly cold
as skies have thin high clouds and clearing with lows in the
negatives across the western Adirondacks to the southern Greens and
in the single digits elsewhere. range in the single digits to the
teens.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Through 00z Sunday...VFR conditions continue for all TAF sites
through 08/21z. Precipitation in the form of snow moves in between
21z and 09/00z, towards the end of this TAF period. Conditions will
quickly deteriorate once snowfall arrives to a mix of MVFR and IFR
in low visibility and low ceilings due to low level clouds. Kept
mention of onset snowfall in PROB30 groups as future forecasts can
narrow down the onset timing. Winds continue to gust at KPSF between
20 and 30 knots but trending to less than 20 knots through 08/06z.
Otherwise winds continue to decrease at all TAF sites through the
next few hours to light westerly winds. Winds switch out of the west
to the south tomorrow afternoon but still less than 15 knots through
the end of the TAF period.

Outlook...

Saturday Night: High Operational Impact. Definite SN.
Sunday: Moderate Operational Impact. Likely SHSN...SN.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: Low Operational Impact. Slight Chance of SHSN.
Tuesday Night: Moderate Operational Impact. Chance of SN.
Wednesday: Moderate Operational Impact. Chance of SN.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Winter Storm Warning from 7 PM Saturday to noon EST Sunday for
     CTZ001-013.
NY...Winter Storm Warning from 7 PM Saturday to noon EST Sunday for
     NYZ047>054-058>061-063>066.
     Winter Storm Watch from Saturday evening through Sunday
     morning for NYZ032-033-038>043-082>084.
MA...Winter Storm Warning from 7 PM Saturday to noon EST Sunday for
     MAZ001-025.
VT...Winter Storm Watch from Saturday evening through Sunday
     morning for VTZ013>015.

&&

$$

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