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000
FXUS61 KBUF 220013
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
813 PM EDT Sun Apr 21 2024

.SYNOPSIS...
A moisture starved cold front will cross the area tonight with one
more reinforcing shot of cooler air that will keep temperatures
below average through the start of the new work week, before warmer
weather returns for Tuesday. Otherwise, high pressure will build
across the area providing mainly dry weather through Tuesday, before
unsettled and much cooler weather returns by midweek.

&&

.NEAR TERM /THROUGH TODAY/...
Cyclonic flow associated with upper level trough will maintain
breezy conditions through early evening with west to southwest
gusts to 25-30 mph.

A moisture starved cold front will cross the area tonight bringing
one last shot of cooler air that will keep temperatures below normal
through the start of the new work week. Other than a stray light
rain or snow shower toward the Saint Lawrence Valley tonight, high
pressure builds across the region providing dry weather and lighter
winds for tonight through Monday. Chilly night on tap with mid and
upper 20s higher terrain and low to mid 30s elsewhere. As mentioned,
temperatures will remain below average for Monday, however airmass
will modify some. This will yield highs ranging from the mid and
upper 40s across the higher terrain, to the low and mid 50s
elsewhere.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
Main focus this period continues to be on the next round of
widespread soggy weather followed by a sharp cooldown around the
midweek timeframe.

High pressure will slowly shrink off the East Coast Monday night
through Tuesday. This will maintain dry and relatively milder
weather to start the period as warmer air advects into the region on
the backside of the high. Lows Monday night will range from the low
40s across far western NY to the mid/low 30s across the North
Country. As the area sits firmly within the next incoming system`s
warm sector, highs Tuesday should top out in the low to mid 60s. A
50kt 850H jet embedded within the WAA regime will likely lead to a
breezy day northeast of Lake Erie, with gusts of 30-35mph expected.

This system will come in the form of a robust mid-level shortwave
sliding east across the Great Lakes Tuesday. As it trudges eastward,
this shortwave is expected to partially phase with a deeper closed
low wobbling along the eastern shores of Hudson Bay, as well as a
weaker shortwave moving across the Mississippi Valley. This will
create a deeper longwave troughing pattern that will dig across the
Northeast through Wednesday before shifting to the Canadian
Maritimes by late Wednesday night. Several waves of surface low
pressure are expected to form ahead of the primary mid-level trough
axis, with broad-scale cyclogenesis allowing the system to tap into
a reservoir of GOMEX based moisture. While a few showers or a stray
thunderstorm could reach far western NY late Tuesday
afternoon/evening, a swath of soaking rain will move through the
region Tuesday night courtesy of broad scale ascent under the
poleward exit region of a 110kt upper level jet. Little to no
hydrological concerns at this juncture given the dry conditions
earlier in the week...Basin averaged QPF amounts through Wednesday
morning will average 0.25-0.5" in most areas, a bit higher at 0.5-
0.75" east of the lakes.

The system`s main cold front will begin to plow through the region
behind the rain Wednesday morning. Mid-range guidance is starting to
come into better agreement on the progression of this front and how
much cold air spills into the region behind it. Due to discrepancies
on the amount of phasing between the shortwave over the Great Lakes
and the low near Hudson Bay, previous runs of the GFS were
significantly colder (850H temps bottoming out around -12C) than the
deterministic CMCNH/ECMWF and their respective ensembles (closer to -
2C). While there remains uncertainty in the timing and true depth of
the cold airmass, the trend among the latest guidance has been
somewhere in the middle of these solutions, with the overall
consensus leaning colder. Should these trends hold, this will
support a strong non-diurnal temperature curve with the front
Wednesday, with temps sharply falling across the region from the 40s
early in the morning well into the 30s through the remainder of the
day. While temps at the sfc and aloft will support at least a
partial changeover to wet snow, this colder airmass also looks to be
quite a bit drier with most of the region precip-free by the
afternoon. This, combined with the strong late April sun angle,
should greatly minimize the threat of snow sticking anywhere other
than the highest hilltops south of Buffalo and east of Lake Ontario.

Within the post-frontal airmass and under mostly clear skies,
Wednesday night is expected to be downright cold. Lows will likely
be sub-freezing across the entire region, through bottoming out in
the low 20s across the higher terrain of the Southern Tier and North
Country.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
A large Canadian sfc high along with increased ridging will provide
dry weather for Thursday and most of Friday. The sfc high will
center over the forecast area by Thursday night and track to the New
England coast by Saturday morning.

A weakening trough and sfc low will track across the plains on
Friday and center over the Great Lakes on Saturday night. This will
result in increasing rain potential starting later Friday
evening/overnight as the warm front out ahead of the system
approaches/crosses the region. Showers and periods of steadier rain
will continue through much of Saturday as a plume of GOMEX moisture
pushes north across the Ohio Valley. With the warm sector of the
system over the region, there will be the chance for some
thunderstorms on Saturday, with the best chance for some storms over
the southwestern portions of the area. Still some uncertainty as far
as shower/rain amount goes among guidance with the GFS keeping the
sfc low track closer to the forecast area and keeping the trough a
bit stronger as well. Other forecast models limit the moisture
influx and pull the sfc low farther north, resulting in less precip
overall. Showers should continue into Sunday with more breaks,
especially into the afternoon.

Temperatures during the period will be below normal to start with
warming each day to above normal by the weekend.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
VFR CIGS to continue across all terminal tongiht. Winds will
slowly diminish but gusts up to 30 knots will be possible early.

Also...there may be a stray rain or or wet snow shower toward
the Saint Lawrence Valley as a moisture starved cold front
pushes south across the area but will have little impact on area
terminals.


Monday...dry weather is expected as high pressure builds in behind
the frontal boundary. VFR again will be found across area terminals.

Outlook...

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

&&

.MARINE...
Elevated westerly winds will maintain Small Craft Advisory
conditions on Lake Erie and the Upper Niagara River, as well as the
eastern end of Lake Ontario through much of tonight. Weaker winds
and waves will reside across the waters Monday through Monday night.
Southerly winds will freshen on the waters Tuesday and will likely
result in Small Craft Advisory conditions into midweek.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until midnight EDT tonight for LEZ020-040-
         041.
         Small Craft Advisory until 6 AM EDT Monday for LOZ044-
         045.

&&

$$

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