Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 221928
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
328 PM EDT Mon Apr 22 2024

.SYNOPSIS...
Expansive high pressure ridged across the area will keep dry weather
and light winds intact through tonight. A southerly flow will
gradually pick up overnight, with breezy to windy conditions
developing on Tuesday, but also warmer temperatures. The fair dry
weather will last through at least the first half of Tuesday, then a
slow moving cold front will produce a general soaking rainfall with
a quarter to a half inch of rain Tuesday night into Wednesday
morning. Dry weather will return for Wednesday night through Friday,
before chances for showers return for the weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
Diurnal heating has helped mix down drier air off the deck, which
has aided in the dissipation of most of the cu field that was
present across the Genesee Valley/Finger Lakes region earlier.
Otherwise, expansive high pressure ridged across the region will
provide a pleasant finish to the day with abundant sunshine. Highs
this afternoon will remain a bit below normal with low to mid 50s
across the western counties, and mid 40s to near 50 across the
northcountry.

High pressure will slide east of the area tonight, but remain in
firm control of our weather providing a dry night. Southerly return
flow will gradually strengthen through the night. This will help
keep us warmer than Sunday night with lows mainly in the mid and
upper 30s, and low to mid 40s across lower terrain over far western
NY aided by downslope flow.

High pressure will drift to the East Coast Tuesday. Meanwhile,
strengthening low pressure moves east into the western Great Lakes
with a pre-frontal trough nearing western NY later Tuesday. This
will mean at least a dry first half of the day before moisture and
lift increase ahead of the of the approaching pre-frontal trough
with showers possibly entering far western NY by mid afternoon, then
becoming likely across areas west of the Genesee Valley late in the
day into the early evening. A 40-50 knot low level jet will move
into the area ahead of the trough. A well mixed environment from
later morning on will allow for some breezy to windy conditions to
develop as we at least partially mix down some of those stronger
winds off the deck with many areas seeing gusts up of 25-30 mph,
with gusts up to 40-45 mph across portions of the Niagara Frontier.
However, one positive of the strong southerly flow will be warmer
weather, with temperatures expected to reach into the low to mid 60s
for all but the higher terrain, where some mid and upper 50s will
hang on.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Forecast remains on track for the next slug of widespread soggy
weather this period, quickly followed by a rush of cooler
temperatures. This will come as a positively-tilted mid-level trough
slides from the central Great Lakes to New York State Tuesday night,
then on to New England during Wednesday. In the process...this
system will push its attendant and rather elongated/wavy surface low
across our area later Tuesday night...with this system then quickly
departing off the New England coastline Wednesday.

On the front flank of this system...lead shortwave energy entering
our region from the Ohio Valley will act in concert with a modest
low level jet and leading prefrontal trough to bring increasingly
widespread showers into our region from southwest to northeast
Tuesday evening. The showers will then evolve into a 3-6 hour period
of steadier moderate rainfall during the late evening and early
overnight hours as the wavy cold front approaches and a coupled
upper level jet structure develops aloft...with these two features
helping to more strongly lift the plume of GOMEX-based moisture that
will be in place across our region.

Wednesday morning the main cold front will then slice through our
region from northwest to southeast, bringing some additional showers
and perhaps even a few embedded thunderstorms given the presence of
some weak instability during this time frame. Following the passage
of this front, much colder and drier air will then flood across our
region during Wednesday as Canadian high pressure begins to rapidly
build in behind the departing frontal boundary. While latest
guidance has generally trended a couple of hours later with the
arrival of this front and some minor discrepancies persist with
respect to exactly how cold our airmass will get...the expected
degree of cold advection should be enough (when coupled with
plentiful cloud cover and lingering pcpn) to support a non-diurnal
temperature trend Wednesday morning. This should result in
widespread readings ranging through the 40s at the start of the day
falling back to the mid to upper 30s in most areas...save for
perhaps interior portions of the Finger Lakes and areas near the
NY/PA border. As we push through the afternoon...further drying and
the re-introduction of at least some partial sunshine will then help
to slow or temporarily reverse this trend...with this particularly
true across our northwestern periphery where temps may actually
recover into the lower to mid 40s for a time.

Given the expected trends in temperature profiles during Wednesday
there will be at least some potential for rain showers to mix with
and/or changeover to wet snow before ending. That stated, given the
generally slower start to the changeover and the fact that it will
also be in a race against the precip tapering off rather quickly
from northwest to southeast as the surface high and much drier
air/subsidence rapidly build in behind the departing cold
front...the potential window for wet snow to be limited and fairly
narrow...with this and the high late April sun angle helping to
largely confine any spotty minor accumulations to our higher
terrain.

Wednesday night the core of the Canadian surface high will settle
directly across New York State...with largely clear skies...light
winds...and the chilly airmass allowing temps to tumble into the mid
to upper 20s areawide...and possibly even to the lower 20s across
interior sections of the Southern Tier and North Country.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Fair weather expected for Thursday and much of Friday as a sfc high
pushes into the region and ridging increases. Temperatures on
Thursday in the mid 40s to upper 50s will warm on Friday to the mid
50s to mid 60s as winds shift out of the east and then southeast.

Shower potential increases later Friday evening into the night from
west to east as a warm front approaches from the southwest. The
front is associated with a weakening sfc low and trough that will
cross from the central plains to the central Great Lakes from Friday
evening through Saturday. The trailing cold front will track toward
the region but stall out near or just north of the area. The area
along the stalled frontal passage will have the best chance for
lingering showers, otherwise areas south of the stalled front will
have longer breaks in precip after the warm front passes. Still a
good amount of uncertainty with showers timing for Friday night into
Saturday and how much precip with the warm front. Some models are
coming in drier than previous runs having the showers move through
quicker and with less coverage.

Another sfc low takes a similar track to the early weekend system
but on Monday & Monday night, pulling the stalled frontal boundary
over/near the region back north as a warm front and then pushes a
cold front through around the late Monday night/first half of
Tuesday timeframe.

All the above mentioned, showers each day of the weekend and into
the start of the new work week is expected, along with some daytime
thunderstorms with the forecast area in the warm sector of the two
different systems. Guidance still hinting at a few hours of some
steadier showers with the warm frontal passage. Plenty of breaks in
showers though, especially if the stalled front stays north of the
area.

Temperatures over the weekend continue to warm from the mid 50s and
upper 60s on Saturday to the low 60s to upper 70s for Sunday and
Monday.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Widespread VFR conditions will remain in place through the TAF
period.

Mainly clear conditions and mainly light winds will continue through
the evening hours. Southerly flow will start to pick up second half
of tonight, with VFR conditions prevailing.

VFR conditions will continue through midday Tuesday with mid and
upper level decks increasing across western NY through the morning
hours. Of note will be the increasing winds through the day, with
wind gusts of 25-30 knots for much of the area from late morning on,
with upwards of 35 knots possible across the Niagara Frontier
(KBUF/KIAG) through the afternoon.

Looking a bit past the end of the TAF period, expect flight
conditions to deteriorate to low VFR and possibly near MVFR by late
Tuesday, along with increasing shower chances across western NY.

Outlook...

Tuesday night into Wednesday...MVFR to IFR CIGS with rain.
Thursday and Friday...VFR.
Saturday...VFR/MVFR. A chance of showers.

&&

.MARINE...
High pressure nosing across the lower Great Lakes from the Ohio
Valley will support generally light winds and negligible waves
through early tonight. During the course of the overnight, southerly
winds will freshen somewhat as the aforementioned surface high moves
off the East Coast.

Fresh southerlies Tuesday morning will become southwesterly in the
afternoon. While this will lead to choppy conditions on portions of
Lake Erie and Lake Ontario, the highest wave action will be in
Canadian waters. This should minimize the potential for any Small
Craft Advisories, although it will be close across western Lake
Ontario.

A slow moving frontal boundary will cross the lower Great Lakes
Tuesday night. Moderate to fresh southwesterlies are expected with
waves below Small Craft Advisory criteria. Winds pick up and switch
to the north behind a cold front Wednesday with Small Craft Advisory
conditions possible, especially on Lake Ontario.

&&

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

&&

$$

SYNOPSIS...JM/RSH
NEAR TERM...JM
SHORT TERM...JJR/PP
LONG TERM...SW
AVIATION...JM
MARINE...JM/RSH


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