227
FXUS61 KALY 221959
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
259 PM EST Fri Nov 22 2024

.SYNOPSIS...
Wet snow in the higher elevations of the northern and eastern
Catskills winds down tonight but a rapidly deepening sfc low off
the New England coast will lead to light snow accumulations in
the southern Greens. Then, winds turn gusty tomorrow and any
higher terrain areas with wet snow on tree branches may
experience renewed power outages. Breezy winds linger Saturday
night into Sunday along with some lake effect rain showers. We
turn drier briefly early next week but we will monitor a few
additional storm systems heading into the Thanksgiving holiday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Winter Storm Warning in effect for western Greene and western
Ulster counties until 1 AM Saturday for elevations mainly above
1500 feet.

Winter Weather Advisory in effect for Schoharie County until 1
AM Saturday for elevations mainly above 1000 feet.

Our chilly and damp Friday continues as our mature/occluded
surface low meanders over the eastern Catskills and gradually
fills in/weakens. As the cold conveyor belt continues to wraps
into the east side of the surface low through this evening,
additional valley rain and wet snow showers for elevations at
and above 1000 feet in the northern/eastern Catskills will
continue. Wet snow accumulations will amount to an additional 1
to 4 inches for elevations above 1200 feet. Additional power
outages for these higher terrain areas are possible given the
wet snow that has already accumulated plus additional snow
through this evening. Otherwise, just plain rain showers in
below 500ft as temperatures in the upper-30 to low-40s this
afternoon cool into the mid-30s tonight. Areas above 1000 ft
drop into the upper 20s to around freezing so any wet and
untreated surface tonight can become slippery.

Based on latest NYS mesonet obs and ground truth data, highest
snowfall totals so far have occurred in the eastern Catskills
for elevators around and above 1500 feet where reports range
from 6 to 14 inches. Even western Albany County in elevations
above 1000 feet have received 2 to 5 inches of wet snow with wet
snow showers still evident on the NYS mesonet cameras.

Rain and higher elevation wet snow shower wind down this evening
before Midnight as the sfc low continues to weaken. However, a secondary
sfc low will rapidly develop off the New England Coast tonight as
a potent shortwave rotating around the parent cyclone becomes
negatively tilted and induces sfc cyclogenesis. There is good
agreement that an inverted/norlun trough develops on the west
side of the coastal low providing a focus for enhanced mid-
level FGEN resulting in a band of precipitation that extends
off the coastal low well inland. High res guidance suggests that
band including the HRRR reaches into southern VT around 03 - 06
UTC and continues through 12 UTC. While temperatures in valley
areas will likely be marginal enough to support plain rain, the
southern Greens, on the other hand, will be cool enough to
support wet snow accumulations, especially as diabatic cooling
processes cool the column down even further. Overall QPF amounts
look to range 0.10 - 0.30" and with marginal SLRs around 7-9:1,
total wet snow accumulations look to range 1 to 3 inches with
the highest amounts along the spine of the southern Greens. Some
light accumulations under 1 inch look to also accumulate in northern
Berkshire County mainly above 1500 ft.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...

Heading into Saturday, our secondary coastal low will continue
to rapidly deepen as it tracks into the Gulf of Maine and towards
Nova Scotia. In fact, expected pressure falls suggest it may
even become a "bomb cyclone" as it deepens to around 975 hPa by
Saturday afternoon. The pressure gradient over the Northeast
tightens as this occurs resulting in strong gusty north to
northwest winds. In fact, cold air advection on the backside of
the low will help deepen boundary layer mixing and promote
efficient momentum transfer of strong winds down to the sfc.
Probabilistic guidance shows greater than 30 - 60% chance for
wind gusts to exceed 30mph through much of the day tomorrow
mainly for areas down the Mohawk Valley into the Capital
District and Taconics as well as the eastern/northern Catskills
and nearly all of western New England. Areas that still have
heavy wet snow weighing on tree branches may see renewed power
outages as the winds become gusty tomorrow. Otherwise, as
northerly winds shift to the northwest, wrap around moisture
supports upslope showers in the Taconics and southern Greens.
Froude numbers remaining below 1 through the day indicate
blocked flow with upslope showers remaining on the west side of
the Taconics and southern Greens. Marginal temperatures in the
mid to upper 30s warming into the low-40s will support initial
rain and leftover wet snow showers in the southern Greens
transitioning to mainly plain rain p-type.

As we lose daytime, winds shift to become more west-northwest
and will support enhanced cold air advection and as well as an
increased fetch off Lake Ontario. With Lake Ontario waters still
around 10-11C, the incoming air mass over the lake will surpass
the 13C difference criteria and likely will generate lake
effect showers that extend into the Mohawk Valley and northern
Catskills Saturday night. However, temperatures in the boundary
layer remain too marginal to support much in the way of snow,
especially in valley areas. In fact, a lack of moisture in the
mid-levels suggests cloud temperatures may be too mild to even
support ice nuclei. With sfc temperatures also only dropping
into the mid-30s, expecting mainly rain showers from lake effect
Saturday night. Otherwise, gusty northwest winds Saturday
evening gradually weakens overnight but winds remains breezy.

&&

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

- Active long term with several chances of precipitation

Discussion:

High pressure will build across the region Sunday night into the
daytime Monday, and should give us a brief break in precipitation
chances before the arrival of our next weather maker Monday night.
Morning lows in the 20s to near 30 will quickly rise into the upper
40s to low 50s with a warm front lifting in from the south.
Increased lift along the front with a trailing shortwave will
increase precipitation chances, especially north of the Mid Hudson
Valley. Rain is favored, though some wet snow may mix in at higher
elevations late Tuesday as flow switches back to the west/northwest
with a cold front. Much cooler air will follow with lows back into
the 20s to low 30s Tuesday night, and highs ranging from the upper
20s/low 30s (terrain) to mid 40s (valleys) Wednesday.

Most will see dry weather for the middle of next week, though some
lake effect/upslope rain and snow showers will be possible across
the Mohawk Valley and western ADKs Wednesday. Will need to keep an
eye on the Thanksgiving holiday as some guidance continues to
suggest potential for another system to track over or just near the
region. With confidence on the system track and timing still low
this far out, will continue to advertise low chance (20-40%) POPs at
this time. Temperatures look to average below normal for the end of
November.

&&

.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
Through 18z Saturday... Periods of IFR and MVFR conditions
continue through the TAF period for all TAF sites due to low
ceilings or low visibilities. Our weather system continues to
bring scattered rain showers to all KPSF, KGFL, and KALB
through the TAF period and KPOU will continue to see a mix of
snow or rain showers through the TAF period. Wind gusts
decrease tonight from 15 to 25 knots to between 5 and 10 knots
that continues through the end of the TAF period. For KPOU,
periods of mist can occur through tonight into tomorrow morning
due to the recent rain/snowfall.

Outlook...

Saturday Night: Moderate Operational Impact. Windy With Gusts To 30 kts. Chance of SHRA.
Sunday: Moderate Operational Impact. Windy With Gusts To 31 kts. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.
Monday Night: High Operational Impact. Likely SHRA.
Tuesday: High Operational Impact. Breezy. Likely SHRA.
Tuesday Night: Low Operational Impact. Breezy. Slight Chance of SHRA.
Wednesday: Low Operational Impact. Breezy. NO SIG WX.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Winter Weather Advisory until 1 AM EST Saturday for NYZ047.
     Winter Storm Warning until 1 AM EST Saturday for NYZ058-063.
MA...None.
VT...None.

&&

$$

SYNOPSIS...Speciale
NEAR TERM...Speciale
SHORT TERM...Main
LONG TERM...Speck
AVIATION...Webb