853
FXUS61 KBUF 270634
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
234 AM EDT Thu Mar 27 2025

.SYNOPSIS...
High pressure will build across the area through Thursday
morning...before drifting east across eastern New York and New
England Thursday afternoon and night. This will provide us with
mainly dry weather through most of Thursday...with a passing weak
cold front then bringing a brief round of rain and snow showers to
areas east of Lake Ontario Thursday evening. Elongated low pressure
will then extend eastward across our area later Friday through the
weekend...bringing more widespread unsettled weather that will
feature periods of rain for most areas...and possibly some mixed
precipitation across the North Country.

&&

.NEAR TERM /THROUGH FRIDAY/...
Regional radars show the last remains of some spotty light snow
showers in the process of dying out across Lewis county. These
should pretty much fade out altogether by 3 am...leaving behind
largely clear skies for the balance of the night. Coupled with our
still-chilly airmass...this will allow overnight lows to range from
the upper teens across interior portions of the western Southern
Tier to the lower and mid 20s elsewhere.

On Thursday...surface-based ridging initially draped across our
region during the morning will slowly drift east across eastern New
York and New England Thursday afternoon and night. Meanwhile...
another northern stream shortwave and its attendant weak/relatively
moisture-starved cold front will quickly dive southeastward across
Ontario and Quebec...with this next surface boundary crossing our
region Thursday evening. The approach of this system may help to
trigger a few widely scattered rain showers across the western
Southern Tier late this afternoon into early this evening...with the
North Country likely seeing a brief round of scattered to numerous
rain and snow showers Thursday evening owing to its closer proximity
to the base of the supporting shortwave/some what better moisture
and some modest upsloping. Across the higher terrain of the Tug Hill
and western Adirondack foothills...this could lead to some fresh
snow accumulations of under an inch.

Prior to the arrival of this system...expect dry conditions with
warm air advection helping Thursday`s high temps to rebound into the
upper 30s to mid 40s east of Lake Ontario and to the mid 40s to
lower 50s elsewhere...with a brief period of breezy conditions
(featuring wind gusts up to 30-35 mph) likely across far western New
York later Thursday afternoon into early Thursday evening right out
ahead of the surface cold front. Conditions will then dry out again
later Thursday night as a narrow wedge of high pressure builds in
behind the departing front...with overnight lows in the upper 20s to
lower 30s expected south of Lake Ontario...and in the mid to upper
20s across the North Country.

On Friday the narrow wedge of high pressure will drift eastward into
New England...while broad low pressure over the Plains states
elongates and extends northeastward across the Upper Mississippi
Valley. As this occurs...the surface warm front attendant to the low
will also extend eastward across the southern Great Lakes...with
this boundary reaching western New York during Friday afternoon. A
corresponding increase in moisture and isentropic upglide will bring
thickening clouds to our area...along with increasing chances of
rain showers to areas south of Lake Ontario during Friday afternoon.
This will particularly be the case across far western New York...
where showers should become likely (60 percent chance) by late
afternoon. Otherwise we can expect a decent north-south gradient in
temperatures...with highs ranging from around 40 across the North
Country to the lower 50s across the southern Tier and interior
Finger Lakes.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
Large-scale flow across the CONUS becomes more zonal this
period. At the same time, an initial southern-stream shortwave
trough will make its way eastward through this developing zonal
flow regime, leading to the development of a broad surface low
across the Plains States Friday and Saturday. Well out ahead of
this low...a surface warm front/tightening baroclinic zone will
gradually extend eastward across the southern Great Lakes Friday
and across our region Friday night. Difference from previous
package is that overall trend in guidance is to continue a
slight shift northward with the surface front/baroclinic zone,
placing the boundary across Lake Ontario and northern NYS for
later Friday night and Saturday.

Between later Friday afternoon and Saturday, this boundary will
serve as the conduit for what appears to be at least a couple weak
eastward-propagating waves of low pressure and associated surges of
warm air advection, which will result in fairly widespread
precipitation along and to its north. With the latest boundary
placement in mind, expect steadier area-wide precipitation first
half of Friday night, to then transition to areas mainly from the
Thruway corridor northward for later Friday night and Saturday.
Otherwise, expect more in the way of showery precipitation to the
south of the boundary.

The key to the forecast during this timeframe continues to be the
position of the surface front, as this will have a huge impact on
both temperatures and precipitation potential/type at any given
location. This said, pinning down the exact location of this feature
remains rather problematic at this vantage point, as our region will
lie either directly within or very close to the battleground between
warmer air trying to advect in from the Ohio Valley...and Canadian
high pressure and much colder air firmly anchored near James Bay.
That stated, subtle differences in the exact positioning of the
boundary persist amongst the various guidance packages.

All of this translates into a significant forecast bust potential,
particularly Friday night through the first half of Saturday, before
warmer air works far enough northward for an all rain p-type across
the bulk of western and northcentral NY by Saturday afternoon. The
exception may linger across the Saint Lawrence valley, where cold
northeasterly drainage flow may continue a threat for some mixed
precipitation toward far northern Jefferson County. Digging a bit
more into the weeds...the front will be the demarcation line between
temps in the 30s/40s to its north and temps in the 50s/60s to its
south. For now the forecast continues to exhibit a marked north-
south dichotomy in temperatures during this timeframe and will
likely need continued refinement over the next couple of days as
forecast details become more clear. Putting it all
together...precipitation across western NY currently appears more
likely to be in the form of just plain rain, while a period of
snow/mixed precipitation appears more likely east of Lake Ontario
(especially the North Country, which should remain on the north (and
colder) side of the surface boundary until at least Saturday
afternoon. Will continue to call the latter just a plain rain/snow
mix for now given the uncertainty, however some freezing rain and/or
sleet certainly appears to be a possibility, mainly across the North
Country.

Saturday night, the aforementioned surface front will try to take a
slight shift back southward as the weak aforementioned waves pull
east of the area. At the same time, another wave will be approaching
from the southwest. This will likely halt any southward progress of
the surface boundary, while also bringing in the next slug of
moisture across our area, with mainly rain expected, although still
can`t rule out the chance for some mixed precipitation toward far
northern Jefferson County.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
A potent shortwave trough will slide northeast across the Plains
towards the Great Lakes Sunday and Monday supporting a surface low
to lift northeast  across the region. While medium range guidance
continues to exhibit differences with the track of this system
(greatly impacting precipitation type), the general pattern will
result in active weather for the end of the weekend and the start of
the new work week. Overall expect widespread precipitation to last
through Sunday and Monday (likely in the form of just rain), before
pulling east Monday night, changing rain over to snow as cold air
wraps in behind the exiting low. Additionally, there will be some
weak instability ahead of the system Sunday and Sunday night
supporting the slight chance for some rumbles of thunder.

In the wake of the passing system, surface high pressure will slide
east across the region Monday night into Wednesday. The next surface
low will then enter the Great Lakes region late Wednesday increasing
the chances for precipitation to enter back into the forecast.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
VFR flight conditions will prevail overnight and Thursday...along
with largely dry weather. Meanwhile initially light winds will
freshen out of the southwest during Thursday as a weak cold front
approaches...with this likely leading to some 25-30 knot gusts
downwind of Lake Erie late Thursday afternoon into early Thursday
evening.

The weak cold front will then cross our area Thursday evening. For
most locations this will merely be marked by a modest increase in
cloud cover and a transition to lighter westerly winds...though
areas east of Lake Ontario should see a brief period of scattered to
numerous rain and snow showers and possible MVFR. Following the
passage of the front...dry and mainly VFR conditions will then
return for the balance of Thursday night.

Outlook...

Friday...VFR initially...then deteriorating to MVFR/IFR south of
Lake Ontario with rain showers becoming likely across far WNY by
later Friday afternoon.
Friday night through Sunday...MVFR/IFR with periods of rain, with
mixed precipitation likely at times east of Lake Ontario.
Monday...VFR/MVFR with rain showers likely.

&&

.MARINE...
Small Craft Advisories remain in place for the southeast portion of Lake
Ontario through 4 AM...otherwise high pressure nosing up across the region
will support weakening winds and subsiding waves through the first half
of Thursday.

Another cold frontal passage will bring another uptick in winds late
Thursday and Thursday night which may require a 6 to 9 hour period
of Small Craft headlines. This will be followed by another ridge
of high pressure late Thursday night and Friday.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 4 AM EDT early this morning for
         LOZ043-044.

&&

$$

SYNOPSIS...JJR
NEAR TERM...JJR
SHORT TERM...JM/JJR
LONG TERM...EAJ
AVIATION...JJR
MARINE...Apffel/JJR