031
FXUS61 KALY 262341
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
641 PM EST Tue Nov 26 2024

.SYNOPSIS...
Behind a departing frontal boundary, colder air will
move into the region for tonight, allowing for a band of lake effect
snow to develop and impact the western Adirondacks.  After a dry and
seasonable day on Wednesday, rain and snow is expected across the
region on Thanksgiving, as a storm system slides by to the south.
Much colder and blustery conditions are expected for the rest of the
holiday weekend, with lake effect snow over the Adirondacks.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Key Message:

- Lake effect snow develops in western Adirondacks tonight into
  Wednesday. Light accumulation expected for areas north of Old
  Forge.

Discussion:

.Update as of 614 pm EST...The skies have cleared well in the
wake of the occluded front from the Hudson River Valley south
and east with some lingering clouds over the southern Greens.
More cloudiness northwest of the Capital Region. Diffuse lake
effect is organizing over the Tug Hill Plateau spilling into the
southern Adirondacks. We adjusted PoPs to higher chance 40% to
likely 60% for accumulations to start prior to midnight. Expect
a few inches of wet snow in the western and southern Dacks. Weak
cold advection will occur with temps falling into the 30s.
Clouds will increase north and west of the Capital Region prior
to midnight.

[PREV DISCUSSION 0341 pm EST]...

As of 341 PM EST...An occluded front has passed through the
forecast area and is now heading eastward across New England.
The steady precip has ended across the region, but radar imagery
continues to show a few showers, as cyclonic flow around the
shortwave trough over southern Canada is allowing for some
spotty precip. Otherwise, skies have been clearing out over the
last few hours, with partly sunny skies in valley areas and
partly to mostly cloudy skies for the high terrain.

For this evening into tonight, temps aloft will be cooling off
thanks to the ongoing cold advection. 850 hpa temps will be
falling to around -8 C by late tonight. With Lake Ontario temps
around 10 C, lake effect showers are expected to develop for
this evening into tonight. The westerly flow around the upper
level shortwave will allow for this precip to impact the western
Adirondacks. Initially it may be a rain/snow mix, but should go
over to all snow fairly quickly. A few inches of snow may
accumulate through the overnight hours, mainly for wilderness
areas north of Old Forge and Route 28 in northern Herkimer
County.

Elsewhere, skies will be partly to mostly cloudy through the
overnight hours. It will remain a little breezy through the
overnight thanks to decent pressure gradient in place and
ongoing cold advection. Some west-northwest gusts over 15 mph
will be possible through the overnight, mainly in the larger
valley areas. Temps look fairly seasonable with lows in the mid
20s to low 30s.

It will stay blustery and seasonable into the day on Wednesday
with surface high pressure south of the region near the mid
Atlantic coast. Skies will be fairly sunny through the day,
although some stratocu is expected across northern and western
areas from lake-effect activity. The lake effect snow showers
will gradually shift northward through the day towards the
northern Adirondacks, but will start to shut off towards the
afternoon hours.  Temps should reach into the 40s for valley
areas, with 30s for the high terrain.

&&

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

- Widespread precipitation expected Thanksgiving Day, with snow
  favored in high terrain and mainly rain at lower elevations.

- Precipitation type forecast remains sensitive to temperature
  and precipitation rates, with valley areas potentially seeing
  light accumulations of wet snow if forecast temperatures trend
  colder or expected precipitation rates increase.

Discussion:

A storm system will be impacting the region for the Thanksgiving
holiday. A fast moving progressive shortwave at 500 hpa will be
moving from the Ohio Valley towards the mid Atlantic and
Northeast for Wed night into Thursday. This feature looks rather
flat on most guidance, although the ECMWF has been more
persistent in showing a little stronger feature. The surface
storm looks to develop over the central Appalachians on Wed
night and shift towards the northern mid Atlantic coast on
Thursday before exiting across southern New England on Thursday
night. While the models are in better focus on the track, there
are still differences regarding the storm strength, which is
making the exact precip amounts and types difficult to predict.
If a stronger solution occurs, there could be a heavier
mesoscale band that moves across our area, especially during
Thursday afternoon.

The airmass in place won`t be overly cold, so p-type will
generally be rain for valley areas and rain/snow mix or snow for
the higher terrain. However, if heavier precip occurs, it`s
possible that the thermal profile could be isothermal, producing
wet snow down even into valley areas. For now, have leaned the
forecast towards the bulk of the forecast guidance, which is
mainly rain in valley areas (a little snow to start) and snow in
the higher terrain. A general 3 to 6 inches is possible in the
higher terrain, with some locally higher totals possible in the
Adirondacks and Greens, as the NBM probs show at 50% chance of
6"+ over the highest terrain in the central Adirondacks and
southern Greens. The trickiest forecast will be for valley
areas. NBM probabilities for just a coating is only about 10%,
although this could come up if a stronger system looks more
likely.

Based on the latest guidance, precip will spread across the
region from west to east on Wednesday night. Temps will have
fallen ahead of the precip down into the upper 20s to mid 30s.
Temps will then hold steady or slowly rise into the 30s on
Thanksgiving with cloudy skies. Precip should taper off from
west to east on Thursday night, with temps holding in the 30s.

&&

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

- Lake-effect snow showers continue into the weekend, with
  impactful accumulations possible in the Adirondacks.

- Below normal temperatures expected to begin December.

Behind this departing system, much colder air will be pouring
into the region for this weekend into early next week. A large
upper level trough will be in place over the Northeast through
the period, with a closed low located over Quebec. The cyclonic
flow around this upper level low, with plenty of colder air
around (850 hpa temps falling to -10 C), will make for periods
of lake effect snow off the eastern Great Lakes, beginning later
on Friday. These lake effect snow bands should impact the
western Adirondacks with a decent accumulation. The bands may
eventually shift towards the western Mohawk Valley towards early
next week as well. Outside of the heavier lake effect bands, it
will remain partly to mostly cloudy and blustery with some
passing snow showers or flurries possible through the weekend
and into early next week.

Temps will be turning below normal and chilly. Although Friday
may still see some valley areas reaching the lower to middle
40s, temps will only be reaching into the 30s for Sat/Sun and
into early next week. Overnight lows looks cold in the teens and
20s as well.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Through 00 UTC Thursday...VFR conditions begin the TAF cycle for
KGFL/KALB/KPOU/KPSF with subsidence in the wake of the occluded
front producing mostly clear skies. Clouds increase between
02Z-06Z/WED for KALB-KPSF-KGFL. Some MVFR cigs will develop in
the 2.5-3 kft AGL range for KGFL/KPSF. Expecting low VFR cigs at
KALB in the 3.5-5 kft AGL range. Further south KPOU with just
have high clouds. The post frontal and lake effect stratocumulus
will persist into the late morning /12Z-15Z/ before
dissipating. Sct-bkn stratocumulus and mid/high clouds in the
VFR range will continue in the late morning until the end of the
TAF cycle at the 4 TAF sites. Winds will be northwest to
southwest at less than 10 KT tonight. The winds will be west to
southwest 8-12 KT in the late morning into the early afternoon
with a few gusts approaching 15-20 KT at KALB/KPSF. The winds
will subside from the south to southwest at less than 10 KT in
the mid to late pm.


Outlook...

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

&&

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

&&

$$

SYNOPSIS...Frugis
NEAR TERM...Frugis/Wasula
SHORT TERM...Frugis
LONG TERM...Frugis
AVIATION...Wasula