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000
FXUS61 KBUF 201911
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
311 PM EDT Sat Apr 20 2024

.SYNOPSIS...
A trough will continue to produce scattered showers and windy
conditions across the area through this afternoon. A few of the
stronger showers may produce some small hail and graupel. High
pressure then builds in across the area tonight bringing mainly dry
weather that will last through the first part of the new work week.
Temperatures will be below average through Monday, before returning
to near normal levels by Tuesday.

&&

.NEAR TERM /THROUGH SUNDAY/...
Regional radars showing stable lake shadows setting up nicely with
the majority of the scattered shower activity along and inland of
any lake breeze convergent boundaries. Steep lapse rates within a
well mixed environment will keep gusty winds going through the
afternoon hours, before relaxing some this evening with the loss of
daytime heating and a weakening of winds off the deck.

Weak surface trough that crossed the area this morning is now
pushing into eastern NY. This reinforcing shot of cooler air behind
this feature has actually caused temperatures to slowly drop through
the day. Cool enough in fact that some wet flakes have mixed in
across the higher terrain with some of the scattered shower
activity. Otherwise, strong April sun will continue to interact with
the core of the upper cold pool and moisture associated with upper
level trough moving across the the region this afternoon. The bulk
of the activity still looks to be across two main areas. First,
along a lake breeze convergence zone south of Lake Ontario,
stretching from the Niagara Frontier over to central NY. Second area
is across the Saint Lawrence Valley where northern edge of Lake
Ontario lake breeze interacts with upper level support and better
moisture that will drive scattered showers through that region,
mainly north of Watertown. Despite temperatures ranging from the
upper 30s to mid 40s this afternoon, cold air just off the deck
(850Ts -5C) will allow any stronger showers the potential to produce
some small hail or graupel, of which we have already seen a few
reports early this afternoon...or even some higher terrain plain wet
snow showers. Winds will continue to gust 30-35 mph, with a few 40
mph gusts not out of the question.

Upper level trough axis moves east of the area, while surface high
pressure starts to build in from the west tonight, causing shower
activity to taper off quickly this evening. A weak surface trough
will cross the area overnight, possibly producing an isolated rain
or wet snow shower, otherwise mainly dry conditions expected with a
light westerly breeze. Lows tonight a bit below normal with upper
20s across the higher terrain and low to mid 30s elsewhere.

Surface high pressure will be control for Sunday with mainly dry
conditions expected. However, with the main upper level trough
remaining in place aloft expect below normal temperatures and breezy
conditions to develop once again, but not as windy as today. Highs
will be mainly range through the 40s, with some low 50s for the
traditionally warmer spots. Another cold front will approach late
Sunday, however any precipitation associated with the boundary will
remain north of the area through the end of the day.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
A cold front albeit dry (moisture starved) is advertised to drop
south out of Canada Sunday night. We might see an isolated rain or
snow shower focused mainly across the St. Lawrence valley. Have low
end PoPs (20% or less) there, elsewhere it is `likely` to remain
dry. With its passage...a colder air mass will quickly sweep in
behind the front with 850H temps briefly down to -10C by Monday
morning. Modification of this chilly airmass then quickly occurs by
Monday afternoon. Given full late April sunshine we should see temps
push into the 40s east of Lake Ontario, with a range of 40s to low
50s found elsewhere.

Dry weather will persist Monday night with the ridge of high
pressure overhead slowly drifting to the eastern seaboard. Cold
night expected with lows in the 30s for most locales.

Tuesday...dry weather will slowly give way to increasing chances for
showers as a potentially strong cold front drops southeast across
the upper Great Lakes region. At this point...there still remains a
fair amount of uncertainty as guidance shows a wave (elongated) or
waves of low pressure developing along the front. There is also
varying degrees of QPF, and then how cold does it may get behind the
front. The GFS is `very` cold (potential outlier) behind the front
to the tune of -11C to -13C at 850H. Thinking the GFS is way too
cold but just can`t completely write it off just yet. That said...
we will need to see more run to run consistency. Even so...it is
looking fairly wet with widespread rain Tuesday night as the front
works into the region.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Heading into Wednesday morning, a robust albeit weakening mid-level
shortwave will be sliding east across the region. This feature will
be partially coupled with a deeper closed low just east of Hudson
Bay, with an elongated wave of surface low pressure ahead of the
system`s primary cold front extending from the Ohio Valley to
northeastern Quebec. A more distinct area of cyclonic flow at the
surface in the vicinity of the eastern Lake Ontario region will
quickly move in tandem with the southernmost shortwave, sliding east
into New England by the afternoon. There remains some uncertainty in
the strength of this surface wave over the eastern Great Lakes,
which will likely influence additional rainfall amounts and the
speed at which this initial cold front exits the region. The overall
trend will support the steadier more widespread rain beginning to
taper off across the western zones through the day, though the
latest CMCNH/ECMWF solutions indicate a bit more in the way of low-
level moisture and lighter wrap around showers sticking around into
Wednesday evening. Otherwise, it will be notably cooler Wednesday
with highs only in the 40s to low 50s.

Extra cloud cover and a few lingering showers could be weakly forced
by a secondary cold front that will sag southward into the region
late Wednesday into early Wednesday night, though a large expanse of
surface high pressure building across the Great Lakes and
southeastern Canada will lead to mainly dry weather across the
region overnight. A much cooler airmass will filter into the region
behind the secondary front which will support a rather chilly night,
as well as perhaps a brief mix with wet snow before the precip
completely tapers off. Though as mentioned previously in the short
term discussion...There is still an enormous discrepancy in how cold
this airmass gets between the deterministic ECMWF/CMCNH and GFS
solutions, as well as their respective ensembles. While the former
have consistently advertised 850H temps dipping to around -5C
overnight, the GFS continues to show temps closer to -13C. Will
continue to lean on the former and the NBM which support lows in the
low 30s to upper 20s across the hilltops, as opposed to widespread
20s advertised by the latter.

Other than a stray upslope shower across the Tug Hill/Western Dacks
Thursday morning, expect another cool albeit much drier day as high
pressure at all levels builds east over the region. Next chances for
rain will arrive Friday night and last through Saturday as the high
moves east of the region near the end of the week, supporting a
strong warm front that will move into the region from the southwest.
This will also initiate a warming trend, with temps averaging above
normal Friday and especially Saturday.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Mainly VFR conditions are expected to prevail across western
and northcentral NY through the TAF period.

Upper level trough crossing the area this afternoon producing
scattered showers, mainly along and inland of lake breeze
boundaries. Best chance for scattered showers will be located mainly
from KIAG/KBUF to KROC and eastward. Small hail/graupel may mix in
with some stronger showers from midday through the afternoon
hours...with even some wet snow showers possible across the hilltops.
Best chance for a shower at KART will be late this afternoon.
Although prevailing VFR conditions are expected, CIGS will be
between 3-5 kft through late afternoon/early evening, especially
south of Lake Ontario. Westerly winds will gust 25-30 knots
through the early evening.

Showers will dissipate towards evening, with dry conditions tonight
through the first half of Sunday and mainly VFR conditions expected
along with lighter winds.

Outlook...

Monday...Mainly VFR.
Tuesday...Mainly VFR. A chance of showers later in the
afternoon.
Tuesday night and Wednesday...Areas of MVFR with showers.
Thursday...Mainly VFR.

&&

.MARINE...
Another trough will cross the eastern Great Lakes this afternoon,
producing another round of solid westerly flow Small Craft Advisory
conditions on Lake Erie and Lake Ontario. Winds will temporarily
diminish again tonight, then increase again Sunday with another
period of solid westerly flow Small Craft Advisory conditions on
Lake Erie and Lake Ontario. Overall, a poor weekend for boating with
chilly temperatures, strong winds, and high waves much of the time.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LEZ020.
         Small Craft Advisory until 11 PM EDT this evening for
         LEZ040-041.
         Small Craft Advisory until 11 PM EDT this evening for
         LOZ042-043.
         Small Craft Advisory until 2 AM EDT Sunday for LOZ044-045.

&&

$$

SYNOPSIS...JM
NEAR TERM...JM
SHORT TERM...AR
LONG TERM...PP
AVIATION...JM
MARINE...Apffel/Hitchcock/HSK