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000
FXUS61 KBUF 200810
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
410 AM EDT Sat Apr 20 2024

.SYNOPSIS...
A trough will pass over the eastern Great Lakes today with scattered
showers and gusty winds. 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 SUNDAY/...
Composite radar shows a broken line of weak echos stretching from
northern New York to northern Ohio this morning. This is mainly mid-
level moisture along a secondary cold front which is barely reaching
the ground. This activity will move east and weaken with partial
clearing across western NY to the Saint Lawrence Valley by daybreak.

Post-frontal conditions will be realized after daybreak as an upper
level trough moves overhead today. Cool temperatures aloft and
surface heating will result diurnally driven cumulus and strato
cumulus through the daytime hours. The stable airmasses over Lake
Erie and Lake Ontario will move onshore and scattered rain showers
will develop inland through the afternoon. There will be two main
area of scattered to numerous showers today. First will be along a
convergence zone south of Lake Ontario. This will be the best zone
for showers, stretching from the Niagara Frontier to central NY.
Second area will be across the Saint Lawrence Valley where upper
level support and better moisture will drive showers through the
region. Forecast soundings show the well mixed boundary layer to 8-
10k feet with 850mb temperatures down to -5C. While surface
temperatures will reach the upper 40s to low 50s this afternoon,
graupel/small hail is possible in stronger showers. Breezy today
with gusts reaching 30-35 mph. Showers will diminish in coverage
this evening and dry conditions will be present overnight. Clouds
will mostly clear out with the exception of some lake clouds east of
Lake Erie. Cool with temperatures in the low 30s across the higher
terrain, mid 30s closer to the lakes.

A large area of high pressure over the central plains will extend
into the eastern Great Lakes region Sunday. Dry conditions are
expected, however there is a slight chance rain showers make an
appearance across the Saint Lawrence River Sunday afternoon. Due to
low confidence, kept the forecast dry for now. Cool conditions will
persist Sunday with highs in the upper 40s to low 50s. It will be
breezy again but winds won`t be as strong as today. Westerly winds
with gusts up to 30 mph are possible across the Niagara Frontier and
Tug Hill region.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
Fair dry weather is promised for this period...as a progressive but
flattening mid level ridge and associated wedge of sfc high pressure
will traverse the Great Lakes region.

The only feature to keep an eye on though will be a moisture starved
cold front that will sweep through the area late Sunday night. While
our forecast area will experience a glancing blow of the colder air
in its wake on Monday...the vast majority of the colder air will be
directed into New England.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
High pressure will push off the eastern seaboard Tuesday...as a
positively tilted shortwave pivots out south-central Canada and into
the northern Plains/upper Midwest region. As this feature moves east
into the Great Lakes region Tuesday night, it will partially phase
with a deeper closed low wobbling about the vicinity of Hudson Bay.
This will cause the southern trough to dig southward and
progressively become more negatively tilted as it marches east
though Wednesday. Concurrent broad surface cyclogenesis will lead to
an elongated area of low pressure that will extend from the Midwest
all the way northeast across Quebec. Deep southerly flow out ahead
of the system`s main cold front will allow it to tap into a plume of
GOMEX based moisture, with a subsequent wide swath of rain showers
plowing through the region Tuesday night into Wednesday. Cooler air
will filter into the region behind the system, though strong high
pressure building across the Great Lakes should taper off the
potential for wrap-around precipitation fairly quick. With the loss
of sunlight and cooler air moving in, rain could briefly mix with
wet snow across the Tug Hill Wednesday night before ending. Mainly
dry weather and clearer skies are then expected Wednesday night
through Friday.

Long range guidance can be fairly sensitive to these types of
partial phasing setups, which can quickly lead to poor model
consensus and large run-to-run jumps in projected solutions. In this
case, the latest from the ECMWF/CMCNH are in decent agreement are
less bullish on the amount of phasing between the northern and
southern stream waves, in stark contrast to the operational GFS
which has consistently been more aggressive in this regard. Have
leaned on the former which show a slower arrival time of precip
Tuesday afternoon and evening. Both operational models advertise
areawide dry weather until rain showers move into WNY after sunset,
though have stayed close to NBM and left Chc PoPs for Tue afternoon
as there remains uncertainty in the exact timing at this range. Less
phasing of the two systems also implies the deeper cold air staying
confined to the north in Canada, with just seasonable cool advection
in the wake of the system. Should this favored trend hold, the
already tenuous potential for wet snow on the backside of the system
will be minimized even more.

&&

.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
Prevailing VFR conditions will persist across western and north
central NY this morning. The boundary layer will become well mixed
today as an upper level trough moves overhead. Diurnally-driven
stratocu and rain showers will form outside of the stable lake
airmasses. A convergence zone will likely set-up inland and south of
Lake Ontario where scattered showers will be located, mainly from
KIAG/KBUF to KROC and eastward. Small hail may mix in with some
stronger showers around midday. There is a lower chance of showers
at KART and KJHW today. Prevailing VFR conditions are expected
however ceilings will be between 030-050 ft especially south of Lake
Ontario. Showers will dissipate towards evening with dry conditions
tonight.

Outlook...

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

&&

.MARINE...
Another trough will cross the eastern Great Lakes today, 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 from 10 AM this morning to 8 PM EDT this
         evening for LEZ020.
         Small Craft Advisory until 11 PM EDT this evening for
         LEZ040-041.
         Small Craft Advisory from 10 AM this morning to 11 PM
         EDT this evening for LOZ042-043.
         Small Craft Advisory from 10 AM this morning to 2 AM EDT
         Sunday for LOZ044-045.

&&

$$

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