000
FXUS61 KBUF 231524
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1124 AM EDT Tue Apr 23 2024

.SYNOPSIS...
High pressure that supplied us with beautiful weather on Monday will
drift off the East Coast this afternoon. A strengthening southerly
flow in its wake will now transport milder air and increased
moisture into our region. Clouds will continue to thicken and lower
through the afternoon ahead of a slow moving frontal system
approaching from the upper Great Lakes that promises to generate a
quarter to a half inch of rain for us tonight into Wednesday morning
with chilly temperatures on Wednesday. An expansive area of Canadian
high pressure will then assure us of fair dry weather Thursday and
Friday, before chances for showers return this weekend. Temperatures
remain chilly on Thursday, followed by day-to-day warming with
readings soaring to well above normal levels by the second half of
the weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Our short stint of fair dry weather is about to come to an end, as
the area of high pressure that supported a nice day on Monday is now
drifting off the East Coast. While most of the region will be able
to enjoy some sunshine through increasing high clouds through
midday, a strengthening southerly flow ahead of a wavy frontal
boundary will encourage clouds to lower and thicken during the
afternoon. Unfortunately, there will be enough lift provided by a
coupled H25 jet and surface convergence in the vicinity of a
pre-frontal trough to encourage some showers to develop over the
western counties by mid to late afternoon.

Along with the increased cloud cover and eventual resulting
precipitation today, a 45kt low level jet within the warm advective
pattern will at least partially mix to the surface. This will allow
surface winds to gust to at least 30 mph across the region, with
gusts as high as 45 to 50 mph possible for parts of the Niagara
Frontier. A Wind Advisory remains in effect for Niagara and northern
Erie counties where the threat is greatest.

Its not all bad news for todays weather though, as moderately strong
warm advection will prompt temperatures to climb well into the 60s
for the afternoon. These readings will be a solid 10 to 15 degrees
higher than those from Monday.

Tonight, a very robust mid level shortwave and attendant storm
system will gradually cross the Lower Great Lakes. While the main
surface low will remain relatively weak and somewhat disorganized,
moderately strong lift provided by the aforementioned coupled jet,
and moreso by 100dm hgt falls and surface convergence ahead of a
wavy surface front will lead to widespread rain over the forecast
area. The precipitation which should be more showery in nature early
on, will transition into a 3-5 hr period of steady rain to the tune
of a quarter to one half inch (basin avg). Localized higher amounts
will be possible as PWAT values approaching one inch should support
embedded areas of moderately heavy rain at times.

While colder air will seep southwards into our region on the
immediate backside of the wavy front towards daybreak, the cold
advection is not as robust as earlier projected. Will thus slow any
transition to wet snow showers until after sunrise.

The wavy frontal boundary will push off to our east Wednesday
morning. While notably drier air will quickly overspread our
forecast area in the process, some leftover light rain should be
expected up until about midday. This will especially be the case for
the Eastern Lake Ontario region where a quarter inch of rain will be
possible. Some of this leftover precipitation will become mixed with
wet snow as a shallow and short lived DGZ should become established.

As we work our way through Wednesday afternoon, skies should yield
at least partial sunshine with the sunniest skies opening near and
east of Lake Ontario. Temperatures should reach their peak at some
point in the morning before remaining steady or slowly falling
during the afternoon.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
Sprawling Canadian high pressure will settle directly across our
area Wednesday night and Thursday...before slowly drifting east and
off the New England coast later Thursday night and Friday. We can
therefore expect tranquil and dry weather to dominate our region
throughout this period...along with mainly clear/mostly sunny skies.

The coldest temperatures of the period will come Wednesday night as
the core of the high settles directly overhead and provides ideal
conditions for strong radiational cooling. This will allow temps to
tumble into the mid to upper 20s across the lake plains...the lower
20s across the interior Southern Tier...and even to around 20 east
of Lake Ontario (the current forecast min temp of 20F for Watertown
is just a couple degrees shy of the record low for 4/25...which is
18 degrees set in 1972). Strong late April diurnal influences will
then begin to modify our chilly airmass on Thursday...allowing highs
to mostly recover into the upper 40s to mid 50s...though a
developing onshore flow off Lake Ontario will help to keep areas
along the south shore of that lake confined to the mid 40s.

Another rather chilly (though not quite as cold) night will then
follow Thursday night as the high begins to slide off to our
east...with mins ranging from the mid 20s across the North Country
to the lower 30s across the lake plains of far western New
York...where a the beginnings of a southeasterly return flow will
develop as the night progresses. As the high drifts further east of
our region on Friday...the SSE return flow will strengthen and
spread milder air back across our region...allowing highs to bounce
back to around 60 east of Lake Ontario and to the lower to mid 60s
elsewhere...with the warmest readings found in areas of favored
downslope flow along the Lake Erie shoreline.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Friday night and Saturday an initial weakening cutter-type system
will lift northeastward across the northern Plains and Upper Great
Lakes. A warm frontal boundary snaking southeastward from this low
will approach from the west Friday night before partially crossing
our region during Saturday...while tending to weaken over time as it
pushes further out ahead of its also-weakening parent low. Current
model consensus continues to suggest an associated band of showers
approaching/crossing far western New York late Friday night/Saturday
morning...with this activity then at least somewhat weakening/
diminishing in coverage as it pushes further east Saturday
afternoon. With this in mind will continue to carry a period of
likely PoPs across far western New York Saturday morning...before
dropping these back to the chance range as the afternoon progresses.
Otherwise...broad warm air advection across our region will result
in a continued upward arc in temperatures...with lows in the lower
40s east to around 50 west Friday night followed by widespread highs
in the 60s Saturday. Should the showers diminish across far WNY as
currently thought during Saturday afternoon...850 mb temps of +9 to
+10C and a stiffening southerly downslope flow could easily support
highs breaking into the lower 70s along the Lake Erie shoreline and
across the Niagara Frontier...even in spite of what should still be
fairly cloudy skies.

Saturday night and Sunday the initial surface low will continue to
weaken as it pushes northeastward across Quebec Province...with its
trailing cold frontal boundary now looking increasingly likely to
stall out well to our north as a second and stronger cutter-type low
develops across the Upper Mississippi Valley...and upper-level
ridging noses northward across New York State. With daytime heating
on Sunday...cannot rule out some additional scattered showers/a few
thunderstorms as our region becomes more firmly embedded within the
warm airmass on the east side of these two systems...however with
the main surface boundary remaining to our north areal coverage
should be lower than on Saturday...with drier weather tending to be
more predominant. The much bigger story will be temperatures...as
850 temps will surge to between +11C and +13C and support late
spring to early summerlike warmth across our region. Expect temps to
range through the 50s Saturday night...then climb well into the 70s
south of Lake Ontario on Sunday...with a few of our normal warm
spots in the Genesee Valley likely even breaking the 80 degree mark.
This being said it will be a bit cooler east of Lake Ontario...as
well as immediately downwind of Lake Erie owing to a southwesterly
breeze off that lake.

Sunday night and Monday the second and stronger cutter low will make
its way across the Upper Great Lakes and into Ontario Province...
with this next system eventually pivoting its trailing cold front
toward our area during Monday. Consequently generally dry weather
should prevail Sunday night...with the approaching front then
bringing an uptick in shower and thunderstorm potential on Monday.
Otherwise we can expect late spring to early summertime warmth to
continue...with lows of 55-60 Sunday night followed by fairly
widespread highs in the mid 70s to lower 80s on Monday.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
VFR conditions will remain in place through this afternoon, although
surface winds will gradually increase as the day matures. surface
wind gusts will reach at least 30 knots for all of the TAF sites
today, with gusts as high as 40 knots at KBUF and KIAG.

During the course of this afternoon, VFR level clouds will gradually
lower and thicken with showers expected west of the Genesee Valley
by late in the afternoon or early evening.

Widespread rain will then move across all of western and
northcentral New York tonight, as a slow moving frontal system will
make its way through the region. CIGS will lower to MVFR levels
during the evening, then to IFR levels for many areas during the wee
hours of Wednesday morning.

Outlook...

Wednesday...MVFR to IFR CIGS with rain ending early.
Thursday and Friday...VFR.
Saturday...VFR/MVFR. A chance of showers.

&&

.MARINE...
Freshening southerly winds will gradually become more southwesterly
this afternoon. This would typically favor Small Craft Advisory
conditions, but the early season cold dome effect is likely coming
into play as model guidance is holding waves down for most areas,
however there will still be some decent chop on the waters. The
exception today is for the western third of Lake Ontario (W of
Hamlin Beach), where a SCA for that area remains in effect. Will
continue to monitor Lake Erie as winds slowly veer more
southwesterly through the afternoon.

A wavy cold front will then slowly pass through the region tonight.
While winds and waves will briefly subside in the process
(especially on Lake Ontario), a notable but short-lived increase in
northerly winds can be expected on Wednesday. While the fetch will
not be overly favorable for significant wave increases, the
combination should be more than enough to generate rough conditions.
Future Small Craft Advisories will likely be needed for this period,
especially on Lake Ontario.

&&

.FIRE WEATHER...
Dry conditions with gusty winds are expected again this
afternoon. Min RHs will fall below 30%. Wind gusts during the
midday and afternoon hours will reach 30 to 35 mph. With fine
fuels continuing to dry out today, an SPS remains in effect for
all but far western NY.

RH values will quickly recover late this afternoon and evening
though, as showers will develop ahead of a slow moving cold
front. The showers will transition into a widespread rain later
this evening and overnight.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Wind Advisory until 6 PM EDT this evening for NYZ001-010.
MARINE...Small Craft Advisory until 11 PM EDT this evening for LOZ042.

&&

$$

SYNOPSIS...JM/RSH
NEAR TERM...JM/RSH
SHORT TERM...JJR
LONG TERM...JJR
AVIATION...JM/RSH
MARINE...JM/RSH
FIRE WEATHER...JM/RSH