285
FXUS61 KALY 231552
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
1052 AM EST Mon Dec 23 2024

.SYNOPSIS...
After a chilly day, light snow overspreads the region tonight
into Tuesday morning leading to slippery travel conditions.
Snow ends by midday for most with dry weather returning for
Christmas Day through the rest of the week as high pressure
dominates.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

It will remain chilly today with temperatures slowly rising
into the upper teens and low 20s. Expect increasing clouds
through the day with southerly winds becoming a bit breezy this
afternoon as the sfc pressure gradient ahead of our incoming
clipper tightens a bit. Sustained winds reach 5-9 kts with
occasional gusts up to 15kts. With temperatures still cold in
the teens/low 20s, the winds will result in wind chills or "feel-
like" temperatures in the low to mid teens with single digits in
the southern/western Adirondacks. Snow holds off until after
dark.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
Key Message:

Light to moderate snowfall is expected throughout
eastern New York and western New England beginning this evening
through tomorrow morning. Confidence has increased in
accumulations likely reaching 3 to 5 inches in Herkimer County
where a Winter Weather Advisory is now in effect from 6 PM this
evening through 1 PM Tuesday.

By this evening, the core of the aforementioned surface high
will have shifted east, encompassing much of New England with
shortwave ridging aloft also exiting in close succession. As
this exodus takes place throughout the day, upstream a
positively- tilted shortwave trough associated with a clipper
surface low will dig south and east through the Upper Midwest
into the western Great Lakes and northwest Ohio Valley. The
primary surface low, deepening and separating from an elongated
area of low pressure along a weakening cold front, will settle
into northern Michigan, extending a warm front south and east
and a cold front south and west. Warm air advection ahead of
this system`s warm front, in tandem with a strengthening LLJ and
upward ascent ahead of the forward flank of the shortwave, will
allow an initial area of snow showers to develop and cross into
the Southwest Adirondacks and western Mohawk Valley by 6 to 8
PM this evening. This initial batch of snow showers will track
eastward, possibly leading to a couple of initial tenths of an
inch in the Upper-Hudson Valley as well before the stratiform,
steady snow approaches from the west and enters our CWA
boundaries by around midnight.

Steady snow will gradually overspread the region from northwest
to southeast throughout the overnight period tonight, leading to
light accumulations regionwide. Southerly flow throughout
eastern New York and western New England ahead of the incoming
warm front will contribute additional moisture to allow a couple
tenths to upwards of a half an inch even in areas displaced
from the better forcing in the Mid-Hudson Valley and Litchfield
Hills. Elsewhere, 1 to 3 inches will be common. However,
portions of the Southwest Adirondacks and western Mohawk Valley
will likely see moderate accumulations of 3 to 5 inches. With
southerly flow in place at onset gradually veering to the
southwest through Tuesday morning, upslope flow along south and
southwest-facing slopes will enhance vertical ascent, leading to
additional accumulations in the Southwest Adirondacks.
Additionally, latest CAMs also indicate an enhanced band of
snowfall entering the Mohawk Valley between 06 to 12z as
southerly flow channeling up the Hudson River Valley ushers
moisture into these areas where winds will briefly back to the
southeast. Enhanced convergence from southwest flow to the west
and upslope flow on southeast-facing slopes at the foot of the
Southwest Adirondacks will support the development of this band
whose snowfall rates could briefly reach 0.5" to 1"/hour per
the latest HREF where the probability of greater than 1"/hour
snowfall rates reach 50 to 70% in southern Herkimer County and
20 to 40% in southwest Fulton County. Therefore, a Winter
Weather Advisory has been issued for all of Herkimer County.
Additional zones may need to be added to the current advisory if
confidence increases in snowfall totals reaching or exceeding
4" (advisory criteria), but the current forecast does not
warrant this. Will monitor trends throughout the day and make
adjustments where necessary.

Most of the snow will fall between midnight tonight and 7 AM
tomorrow morning when steady snow begins to lessen in spatial
coverage becomes more showery in nature upon the passage of the
warm front by mid morning. Aloft, the axis of the associated
shortwave trough will also rotate through the region tomorrow
morning, allowing the axis of better forcing to shift eastward.
Be advised that early morning, Christmas Eve travel could be
slippery to difficult, especially on road surfaces within the
Advisory. Take extra caution when driving Tuesday morning.

Snow showers will persist through mid to late morning tomorrow
before dry conditions are reinforced across the region tomorrow
afternoon with the south and eastward build of a surface high
from southeast Canada and the approach of upper- level ridging
aloft. Low temperatures tonight will not be as cold as recent
nights with values only falling to the low to upper 10s and
isolated pockets of single digits in the Southwest Adirondacks.
Highs tomorrow then rise to the upper 20s to low 30s with
pockets of mid 20s in the Southwest Adirondacks and Southern
Greens and mid 30s in the Mid-Hudson Valley.

Tranquil weather will remain in place through the Christmas
Holiday with surface high pressure sprawled across much of the
Northeast and ridging in place aloft. Low temperatures Tuesday
night will be widely in the 10s. Highs Christmas Day, Wednesday,
will then rise widely to the upper 20s to low 30s before lows
drop to the low to mid 10s Wednesday night. Most places will
also have a classic white Christmas thanks to the snowfall
expected tonight into tomorrow and the previous snowfall from
Friday into Saturday which has stuck around courtesy of our
unseasonably cold temperatures of late. By definition, a "white
Christmas" occurs when there is at least an inch of snow on the
ground and according to the latest NOHRSC snowfall analysis,
over half of our CWA has at least one inch of snowfall on the
ground ahead of the snow expected tonight into tomorrow.

&&

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

 - Dry conditions with temperatures returning to near normal by late
week.
 - Increasing chances for precipitation (40-60%, mainly as rain) and
above normal temperatures next weekend.

High pressure should bring generally dry conditions and seasonable
temperatures for Thursday-Friday. Track of weak upper level
disturbance will need to be watched for some clouds and perhaps
light rain/snow showers passing just south of region during this
time frame.

Developing southwest flow aloft looks to bring increasing moisture
for next weekend as upper level disturbances approach within this
flow. Chances for rain increase, especially by late Saturday into
Sunday. Given time range, have included 40-60% PoPs at this time.
Temperatures will become milder, with highs reaching the mid 30s to
lower 40s by Sunday. These milder temperatures should favor mainly
rain, although will have to watch for some slightly colder air
trapped in sheltered northern areas, which could result in some
mixed precipitation including patchy freezing rain.

&&

.AVIATION /16Z MONDAY THROUGH FRIDAY/...
Mainly VFR conditions expected through 23Z/Mon, although a few
patches of freezing fog and brief MVFR/IFR Vsbys/Cigs can not be
completely ruled out at KGFL through 14Z/Mon. An approaching warm
front may (20-30% chance) bring a period of light snow to KGFL, KALB
and KPSF between roughly 00Z/Tue-03Z/Tue, with MVFR Vsbys. Better
chances (>60% chance) for steady snow and IFR conditions developing
between 06Z-10Z/Tue from northwest to southeast. Light/variable
winds through this morning become south to southwest at 5-10 KT this
afternoon into tonight.

Outlook...

Tuesday Night: No Operational Impact. NO SIG WX.
Christmas Day: No Operational Impact. NO SIG WX.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: No Operational Impact. NO SIG WX.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Winter Weather Advisory from 6 PM this evening to 1 PM EST
     Tuesday for NYZ032-038.
MA...None.
VT...None.

&&

$$

SYNOPSIS...Gant/Speciale
NEAR TERM...Gant/Speciale
SHORT TERM...Gant
LONG TERM...KL
AVIATION...KL