Amherst, New York 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

712
FXUS61 KBUF 180827
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
327 AM EST Sat Jan 18 2025

.SYNOPSIS...
A strong cold front will move across the region today. A mix of rain
and snow will accompany the front with all snow across the higher
terrain. Any rain will change over to all snow by tonight. Minor
accumulations are expected through tonight. Temperatures will
plummet through the first half of the new work week. The coldest air
in more than five years will build over the region Monday through
Wednesday and this will result in dangerously low wind chills
regionwide...along with accumulating lake snows east and northeast
of the lakes.

&&

.NEAR TERM /THROUGH TONIGHT/...
Water vapor imagery shows a deep trough digging into the Plains and
Upper Great Lakes region this morning. Cyclogenesis can be inferred
across the lower Tennessee Valley with increasing moisture
approaching the eastern Great Lakes region. A cold front extends
from an area of low pressure near James Bay and is draped across
northern Ontario into Illinois. Dry and mild conditions reside
across the forecast area early this morning, with some areas
climbing to the low 40s F across the lower elevations. Gusty winds
will be possible through morning.

Moisture will continue to move northward ahead of the approaching
strong cold front and surface low near the Tennessee Valley. Kata
frontal precipitation will enter far western NY around day break and
spread across the remainder of the forecast area through morning.
Based on thermal profiles, a mix of rain and snow will move into the
lower elevations while all snow will be found across the higher
elevations. A southwest wind will lead to downsloping across the
Finger Lakes region and therefore less precipitation is expected in
this area. Surface temperatures will fall a few degrees as
evaporative cooling occurs but with the cold front still to the
west, temperatures won`t move much through early afternoon. The
front will quickly cross the forecast area late this afternoon/early
evening. Winds will become westerly and surface temperatures will
take a nose dive behind the front. The strong low level jet will be
well to the east with weakening winds aloft as the front moves
through the region. Wind speeds will pick up some behind the front
but relax into the evening hours. The falling temperatures will
change any leftover precipitation to all snow across the lower
elevations. Most of the precipitation will be ahead of the front
which will limit issues.

A very dry airmass will move into the forecast area tonight. This
will erode the snow with only lingering snow showers across the
western Southern Tier and Tug Hill region. Plummeting temperatures
will result in low temperatures in the teens across western NY to
the single digits east of Lake Ontario overnight.

Snow accumulations will be elevation dependent today with 2-4"
across the higher terrain including the Chautauqua Ridge into the
Boston Hills/Ski Country. Similarly, the same can be said east of
Lake Ontario/Tug Hill. As rain transitions to snow later today 1-2"
is possible across the Niagara Frontier and hill tops of the Finger
Lakes region. Warmer temperatures and less snow will lead to little
to nothing in the Genesee Valley to the lower elevations of the
Finger Lakes region. Tonight, an additional inch or two is possible
across the higher terrain east of Lake Erie and on the Tug Hill.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
...BECOMING BITTERLY COLD WITH LAKE EFFECT SNOW EARLY NEXT
WEEK...

Deep troughing will engulf across much of the CONUS heading into
Sunday as cross-polar flow allows a frigid arctic airmass to dig
southward across the Upper Midwest. To the southeast, the cold front
now moving into the Carolinas will be interacting with a warm
maritime airmass off the Southeast coast, leading to a strengthening
area of low pressure. The sfc low is then expected to ride northeast
off the Mid-Atlantic coast by Sunday evening, arriving in the
Canadian Maritimes by Monday morning. A general northern trend noted
among the latest guidance packages in the system`s track, with an
increase in overall QPF as well, though the Canadian model continues
to be the outlier as it advertises a much further westward track.
Given the notably higher 75th-25th percentile spread in the GEPS and
that the further eastward ENS/GEFS are in much better agreement with
one another, will continue to lean on the latter. This would favor
the greatest direct impacts from this system remaining well south
and east of our area, though it is looking increasingly likely that
some lighter synoptic snow will manage to spread into the region on
Sunday. Daytime snowfall amounts should be minor, generally up to an
inch in most areas, though enhancement from the lakes could lead to
a few swaths of 1-2" totals. Otherwise...Highs on Sunday will be
cold, ranging from the teens to low 20s.

As the system continues to move northeast towards the Canadian
Maritimes Sunday night, it will begin to wrap the arctic air to our
west into the Great Lakes. Though, it will already be plenty cold
enough aloft heading into the night to support additional lake
effect and upslope snows as the flow backs from north to
northwesterly overnight. Some of the hi-res guidance (CMCreg/NAM)
advertise a mesolow moving through overnight, which could also bring
additional snow showers outside the main lake effect areas. Winds
will become more well-aligned down the long axis of both lakes as
the frigid air pours into the region along an arctic front during
the day Monday. The west-northwesterly flow will initially direct
steadier lake snows into the Southern Tier and southeast of Lake
Ontario Monday morning. As winds turn more southwesterly (260/250)
across the lakes, off Lake Erie this should place the band between
northern Chautauqua/Cattaraugus and the Buffalo Southtowns, while
off Lake Ontario the favored placement looks to be in the vicinity
of the Oswego/Jefferson county line. At this juncture, it looks as
though the bands will persist in these general regions through
Monday night, though it should be stated here that there is still
uncertainty in exact band placement and intensity. Model soundings
indicate marginal amounts of moisture through the DGZ over Lake Erie
in particular, which could prove to be a limiting factor, as well as
the potential for the band to edge a little further north into
Northern Erie county.

With the aforementioned uncertainties, estimating snowfall amounts
within these bands are still a bit difficult to pin down at this
range. The setup over Lake Ontario looks better in regards to the
potential for more significant snowfall amounts and rates,
especially later Monday and Monday night. Depending on how
stationary the band is, could see totals in the vicinity of the Tug
Hill Plateau quickly approach or even exceed a foot by daybreak
Tuesday. Totals are currently much lower in comparison off Erie,
though this will ultimately hinge on band residence time and if
enough moisture will be available to support higher rates.

In regards to temperatures...850H temps around -20C to start the day
Monday are expected to crater down to around -25C by Monday night.
With a stiffening pressure gradient between high pressure nosing in
from the Ohio Valley and the low over the Canadian Maritimes, wind
chill values are expected to be sub-zero east of Lake Ontario by
Sunday evening, then everywhere else by early Monday morning.
Apparent temps are expected to remain below zero through Monday
night, and be WELL into the negative teens by Tuesday morning.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
...FRIGID COLD AND BOUTS OF LAKE EFFECT SNOW CONTINUE THROUGH EARLY
NEXT WEEK...

An arctic airmass will remain over the forecast area Tuesday through
at least Wednesday night as deep longwave troughing remains
entrenched across much of the Lower 48. Air temperatures to start
this period will be in the low single digits across the lower
terrain and sub-zero elsewhere, with wind chills well into the
negative teens and even negative 20s. 850H temps around -25C will
greatly inhibit how warm it will get at the sfc, with highs only in
the single digits to low teens Tuesday and Wednesday, though
Wednesday will likely be a few degrees "warmer" in comparison.
Tuesday night looks to be the coldest period during this arctic air
outbreak, with air temps expected to be below zero just about
everywhere and wind chills from -15F to -25F overnight.

In addition to frigid wind chills, lake effect snows are expected to
continue through the mid-week timeframe. Higher uncertainty in this
timeframe on exact placement of the bands and therefore potential
snowfall amounts, though west-southwesterly flow should direct the
heavier snows east to northeast of both lakes into Tuesday night.
Long range guidance indicates that these snows could impact the same
areas as those that received snow later Monday and Monday night with
the continued potential for more impactful accumulations and
snowfall rates, especially off Lake Ontario on or near the Tug Hill.

A sfc-850H ridge will then build over the lakes later Wednesday into
Thursday. This will not only weaken and shift the overall lake
response further north but also lead to a warming trend. That is to
say, temperatures are expected to remain below normal, though highs
Thursday and Friday are expected to range in the 20s as opposed to
single digits.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
A southerly low level jet and VFR conditions will continue across
western and north central NY this morning. Wind gusts around 25 kts
are possible at the TAF sites with higher gusts along the Lake Erie
shoreline. Low level wind shear will be present for those places not
mixing by daybreak.

A strong cold front will move across the region later today.
Precipitation will move into western NY this morning and spread east
across the forecast area. Marginal surface temperatures will result
in a rain and snow mix at lower elevations and snow across higher
elevations including KJHW. Flight conditions will deteriorate and
widespread MVFR/IFR conditions are expected at the TAF sites. Model
guidance is showing a lot of IFR conditions this afternoon. Leaned
less aggressive in pre-frontal conditions as downsloping will likely
keep them at MVFR.

Any mix of rain and snow will transition to snow late this afternoon
into the evening. Widespread snow will move east with lingering lake
effect and upslope snow showers tonight. MVFR/IFR conditions will
continue across the TAF sites tonight.

Outlook...

Sunday...VFR/MVFR with a chance of snow showers.
Monday through Wednesday...Local LIFR in lake effect snow east
of the lakes, mainly VFR elsewhere.

&&

.MARINE...
Occasional moderate southwest to west winds will continue to bring
Small Craft Advisory conditions on Lake Erie much of the time today.
A cold front will move across the Lower Lakes this afternoon into
this evening. West winds will briefly pick up with a brief period of
Small Craft Advisory conditions on the southern shore of Lake
Ontario this afternoon through tonight. Winds relax on the Lakes
late tonight through Sunday night.

A prolonged period of Small Craft Advisory conditions will occur
next week.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Storm Watch from Monday afternoon through Wednesday
     morning for NYZ006>008.
     Winter Storm Watch from Monday morning through late Tuesday
     night for NYZ010-011.
     Winter Storm Watch from late Sunday night through Wednesday
     morning for NYZ012-019-020-085.
MARINE...Small Craft Advisory until 10 PM EST this evening for LEZ040-
         041.
         Small Craft Advisory from 1 PM this afternoon to 8 AM
         EST Sunday for LOZ042.
         Small Craft Advisory from 6 PM this evening to 8 AM EST
         Sunday for LOZ043-044.
         Small Craft Advisory until 8 AM EST Sunday for LOZ045.

&&

$$

SYNOPSIS...HSK/RSH
NEAR TERM...HSK
SHORT TERM...PP
LONG TERM...PP
AVIATION...HSK
MARINE...EAJ/HSK/JJR