000
FXUS61 KBUF 191731
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
131 PM EDT Fri Apr 19 2024

.SYNOPSIS...
A cold front will exit to the east of the area by this evening, with
rain showers ending from west to east. Another trough will pass over
the eastern Great Lakes Saturday with scattered showers. A few of
these showers may produce some small hail or graupel. Dry weather
will return Sunday through much of Tuesday as high pressure builds
east across the Ohio Valley and Mid Atlantic. Cool temperatures and
gusty winds this weekend will give way to a warming trend early next
week.

&&

.NEAR TERM /THROUGH SATURDAY/...
Radar imagery showing the most concentrated area of rain moving into
the eastern Lake Ontario region this afternoon, with lighter showers
extending back into the Genesee Valley. The cold front and mid level
trough supporting this rain will continue to move east through the
rest of the afternoon, with showers gradually diminishing from west
to east. Rain has already ended for the western end of the state,
with mainly dry weather prevailing the rest of today. Breezy
conditions will continue this afternoon, with gusts occasionally
reaching 25-35 mph.

Tonight, the main cold front will move east of the area this
evening, with the associated area of rain exiting Lewis County by
early to mid evening. A weaker secondary cold front and mid level
trough will cross Western NY this evening, and may produce a few
spotty light showers east/northeast of Lake Erie. This boundary will
cross the eastern Lake Ontario region overnight, and may support a
few more scattered light showers. Ongoing cold advection will drop
temperatures back into the low 40s in most locations, with mid to
upper 30s across higher terrain.

Saturday, a sharp mid level trough will move from the central Great
Lakes in the morning to western New England by evening, with a
strong vorticity maxima crossing the eastern Great Lakes in the
afternoon. An associated cold front will cross the region in the
afternoon. While forcing will be strong with this feature, it will
be moisture starved.

Cold air aloft will contribute to strong low/mid level lapse rates
with daytime heating and support diurnal showers from late morning
through early evening. Expect a classic lake breeze boundary and
stable lake shadow configuration to the showers Saturday. The most
concentrated band of showers will likely be from the Niagara
Frontier extending ESE into the western Finger Lakes where enhanced
and channeled WSW flow off Lake Erie converges with WNW flow found
just south of Lake Ontario. The cold air aloft and steep lapse rates
suggest a few of these showers may contain graupel or small hail,
even in the absence of thunder. Meanwhile, stable lake shadows over
and east of Lake Erie and Lake Ontario will keep shower chances
lower, and the amount of sunshine higher for areas east of the
lakes.

Temperatures Saturday will run close to 10 degrees below average,
with highs ranging from the upper 40s for lower elevations to the
low to mid 40s across higher terrain. It will be quite breezy again
as well, with gusts of 25-35 mph across the area.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
Broad mid-level troughing across the lower Great Lakes and the
Northeast Saturday night will allow a shortwave trough to round the
base of the trough Sunday. The passage of the shortwave will pull
the longwave trough northeast, allowing for mid-level ridging to
spread across the Great Lakes.

Despite the deep cyclonic flow overhead, expansive high pressure
centered over the Central Plains and expanding east across the Ohio
Valley will support mainly dry weather throughout the weekend into
the start of next week. However, with the passage of the shortwave
and the longwave trough axis aloft, a couple of moisture starved
cold fronts will push southwards across the region Saturday night
and then Sunday night. While both of these fronts will be
precipitation free, cold air will advect into the region supporting
below normal temperatures Sunday and Monday. Highs Sunday and Monday
will range in the 40s across the North Country and upper 40s to low
50s elsewhere.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Unlike the previous several days...this bulk of this period is
guaranteed to be unsettled and ultimately much chiller...including
the potential for some accumulating wet snow.

A robust...Pacific based shortwave will cross the Upper Mississippi
valley on Tuesday...while strong frontogensis over the Upper Great
Lakes will lead to a wavy sfc frontal boundary that will extend to
the southern plains. Meanwhile...high pressure wedged along the
Eastern seaboard will be pushed out to sea. The resulting deepening
southerly flow between the two systems will start to direct rich
GOMEX moisture across the Ohio valley towards the Lower Great Lakes.
While the start of Tuesday will be pcpn free...some rain is expected
to work its way into the forecast area during the course of the
afternoon and evening. Guidance packages remain at odds though over
the amount of phasing that could take place between the
aforementioned Pacific based energy within the sub tropical jet and
an already established upper level storm system in the vcnty of
James Bay. From the 00z guidance...the GFS is a little faster and
much more aggressive with phasing than the more trustworthy ECMWF.
This would lead to rain moving in faster on Tuesday with QPF in the
vcnty of a quarter inch across the western counties. Will lean on a
compromise between the ECMWF and ensemble solution which will yield
Tuesday pops ranging from low chc over the Finger lakes and much of
the Eastern Lake Ontario region to high likely near Lake Erie.

As the strong shortwave energy digs across the Upper Great Lakes
Tuesday night...the wavy frontal boundary will ease across our
forecast area. While there will be a near 100% chance for some
rain...the amount of phasing and the placement of the last wave
along the sfc boundary will determine whether we experience
widespread showers or a period of steadier soaking rain. This swath
of rain could also be delayed by some six hours if the notably
slower ECMWF solution works out...placing the steadiest pcpn over
our region late Tuesday night and Wednesday morning. Will thus `drag
out feet` with the lowering of pops early Wednesday by aiming abv
most of the guidance packages.

In the wake of the wavy frontal boundary...colder air will make its
way across our region during the second half of Wednesday. As is
typically the case...it will be a race between the cold air and the
residual low level moisture as to the potential for a little wet
snow. Previous guidance packages were more impressed with the
potential for a little accumulation...but the models have since
backed off with that train of though. In any case...mixed pcpn
should be tapering off across our area later Wednesday and Wednesday
night with brisk northwest winds and falling temperatures reminding
us of the season that is still clearly visible in our rear-view
mirrors.

Sfc based high pressure just to our west on Thursday should then
promote fair dry weather...although it will be on the chilly side of
normal with the mercury struggling to get out of the 40s.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
A cold front will exit the area to the east later this afternoon and
evening. Showers from the western Finger Lakes to the eastern Lake
Ontario region will gradually end from west to east through the rest
of the afternoon and early evening. Several hours of MVFR CIGS will
continue along and behind the cold front, generally lagging the rain
by a few hours. There will be some IFR across higher terrain as
well. The MVFR/IFR CIGS will improve to VFR from west to east late
this afternoon through this evening as drier air arrives. Wind gusts
in the 20-30 knot range will continue through the rest of the
afternoon.

Tonight, a secondary cold front may produce a few more spotty light
showers, but VFR will prevail once the last of the lower CIGS moves
east of the eastern Lake Ontario region this evening. Winds will
diminish after sunset.

Saturday, a sharp mid level trough will cross the eastern Great
Lakes. This will combine with steep low/mid level lapse rates to
produce scattered showers from late morning through early evening.
The most concentrated area of showers will likely be found from the
Niagara Frontier (near KIAG and KBUF) ESE into the western Finger
Lakes where lake breeze convergence maximizes. A few of these
showers may contain some small hail and/or graupel given the cold
air aloft. VFR will prevail, but any heavier showers may contain
brief CIG/VSBY restrictions.

Outlook...

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

&&

.MARINE...
A cold front will move east of the area this afternoon and evening.
A brief period of gusty WSW winds in the wake of the cold front will
produce Small Craft Advisory conditions on Lake Erie and the eastern
portion of Lake Ontario through this evening before winds diminish
overnight.

Another trough will cross the eastern Great Lakes Saturday,
producing another round of solid westerly flow Small Craft Advisory
conditions on Lake Erie and Lake Ontario. Winds will temporarily
diminish again Saturday night, 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 9 PM EDT this evening for LEZ020.
         Small Craft Advisory until midnight EDT tonight for LEZ040-
         041.
         Small Craft Advisory until 9 PM EDT this evening for
         LOZ044-045.

&&

$$

SYNOPSIS...Hitchcock
NEAR TERM...Hitchcock
SHORT TERM...EAJ
LONG TERM...RSH
AVIATION...Hitchcock
MARINE...Hitchcock