510
FXUS61 KBUF 310844
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
344 AM EST Fri Jan 31 2025

.SYNOPSIS...
Low pressure will pass just south of the area today and this
evening. Rain will overspread the area south of Lake Ontario
through the first half of the day today. The rain will then mix
with, and change to wet snow in most areas by late this
afternoon and evening with minor, slushy accumulations expected.
A few light lake effect snow showers may linger later tonight
through early Saturday. It will turn much colder Saturday
through Saturday night, before a warming trend starts early next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Mid level low over the Central Plains will rotate into Illinois this
afternoon, before transitioning into an open wave over the Ohio
Valley tonight. There has been a consistent signal amongst the
models in showing a fairly robust axis of ascent shifting north
into the region today, along with a surge of plentiful moisture.
Light rain currently across northern Ohio and Pennsylvania will
gradually lift northward into the region this morning. Warm
advection has held temperatures overnight and early this morning
above freezing with 40s along the lowest elevations. A few
areas still at or below freezing across the Southern Tier and
along the south shore of Lake Ontario, could result in some
pockets of freezing rain at precipitation onset, but confidence
in this remains low.

The light rain should reach Lake Ontario on its way north by late
morning or early this afternoon. The strongest forcing looks to be
this afternoon and this evening, as the mid level low starts to
evolve into an open wave as it passes to our south. This will
result in a narrow axis of heavier precipitation, especially
south of Lake Ontario. Probabilistic guidance suggests this
being focused along and south of the NYS Thruway with 6 hour
(18z-00Z) precipitation amounts greater than a quarter inch
around 50 percent in this area and less than 25 percent north of
the Thruway.

The column will cool later this afternoon and this evening through
thermodynamic and weak advective processes. This will allow a
transition from rain to snow during the afternoon and evening as the
precipitation shield starts to drift off to the south with the
overall system movement. Due to the subtle nature of cooling of the
thermal profile, timing of change over to snow does carry some
uncertainty and therefore with forecast snowfall amounts. Ensemble
means generally giving amounts of 1-2" for areas south of Lake
Ontario, with some locally higher amounts possible across the higher
terrain (Wyoming and Bristol Hills).

Temperatures will fall quickly tonight and any wet surfaces will
freeze quickly creating black ice on untreated surfaces. Lows
will reach the teens across western New York to the single
digits east of Lake Ontario.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
An exiting mid-level trough axis into the East Coast Saturday will
support ridging to slide across the lower Great Lakes, which in turn
will result in Canadian high pressure and associated colder and
drier air to build across the region through Saturday night.
Lingering moisture from the previous exiting system combined with
northerly flow will support a few lake effect showers south of Lake
Ontario. However, as previously mentioned the dry air filtering in
across the area will act to end the lake effect showers throughout
the morning hours. Then dry weather will prevail the remainder of
Saturday and into Sunday morning. Now with regards to temperatures,
expect a chillier day than with highs ranging from the low teens
across the North Country to the mid to upper teens elsewhere due to
the cold Canadian airmass overhead. Low`s Saturday night will occur
early dropping into the single digits across WNY and a few degrees
below zero east of Lake Ontario. Warm air advection will begin work
in the area shortly after midnight supporting temperatures to warm.

After an initial dry start Sunday morning due to the departing
surface high into New England, the next mid-level trough will pass
across the Great Lakes, supporting a surface low to slide southeast
across the Upper Great Lakes draping a warm front to slide across
the region late Sunday/Sunday night. As a result, this will support
the next round of rain and snow showers across the area. Should note
that the best forcing and therefore best coverage of showers will
lie from Lake Ontario northward, though a few stray showers will be
possible across the Southern Tier. Initially, showers will be snow
before transitioning to rain as warm air works into the area from
southwest to northeast. With this forecast iteration, snowfall
amounts will range from a few flurries south of Lake Ontario to a
range of 2-4 inches east of Lake Ontario.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
A strengthening low pressure system moving east across Quebec will
send a cold front south-southeastward through the forecast area on
Monday. Warm air advection from overnight Sunday night will likely
lead to a rather mild feeling to start the day, however temperatures
will fall from the upper 30s and even 40s earlier in the day to the
low/mid 30s by day`s end, then tumble into the 20s Monday night.
Rain with some elevation snow associated with this departing system
may linger through the day especially east of Lake Ontario. PoPs
then decrease areawide through Monday night, though any leftover
precipitation will likely change over to all snow by Monday evening.

Looking at the synoptic setup moving later into the period, strong
zonal flow in the 250-500mb layer will be present over the Great
Lakes through the midweek timeframe, with the core of the northern
stream jet likely remaining in close proximity Monday night through
late Tuesday night. Several vorticity maxima to the north of this
jet will quickly shuffle eastward across Canada, before the core of
the northern jet lifts northeast as a potent southern stream system
emerges from the Mississippi Valley later in the week. With only
weak forcing for ascent until the overhead jet lifts north, chances
for precip look low Monday night through Tuesday. There is a fair
amount of uncertainty in how cold the overhead airmass gets behind
Monday`s cold front, with a possibility of it being supportive of a
weak lake response east/southeast of Lake Ontario during this
timeframe. Isentropic lift increasing ahead of the southern stream
system will lead to increasing chances for snow Tuesday night and
rain `likely` Wednesday night into Thursday, with a potential for a
wintry mix in between. Model spread is high in the track and timing
of this mid-week system so will need to iron out these details as
things come into focus.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
Wave of low pressure will pass just south of the area through this
evening. Axis of ascent and moisture will lift into the region with
light rain overspreading the area from the south. Conditions will
deteriorate from south to north today with CIGS going to IFR
across Western and Central New York through the first half of
the day, with widespread IFR VSBY also developing in the steady
rain, and then snow. CIGS/VSBY will remain low into this evening
before improving from north to south overnight.

Outlook...

Saturday...Mainly VFR with a chance of morning snow showers south of
Lake Ontario.
Sunday and Monday...VFR/MVFR with a chance of rain and snow showers.
Tuesday...Low chances for lake effect snow showers. Mainly VFR.

&&

.MARINE...
Variable winds under 10 knots today will becoming north and
northwest by tonight and increase to 15 to 20 knots on Lake Ontario
with marginal small craft conditions possibly developing late
tonight through early Saturday.

Winds lighten later Saturday and Saturday night before freshening
southerly winds develop Sunday and Sunday night. More significant
wave heights will be offshore into Canadian waters, but there
is a risk for small craft conditions developing on the east end
of Lake Ontario north of Mexico Bay.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...Hitchcock/HSK/TMA
NEAR TERM...TMA
SHORT TERM...EAJ
LONG TERM...EAJ/JJR
AVIATION...Hitchcock/TMA
MARINE...HSK/TMA