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000
FXUS61 KBUF 230843
AFDBUF

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

.SYNOPSIS...
High pressure that supplied us with beautiful weather on Monday is
now drifting off the East coast. A strengthening southerly flow in
its wake will now transport milder air and increased moisture into
our region. This will lead to thickening clouds today with a slow
moving frontal system promising to generate a quarter to a half inch
of rain for us tonight into Wednesday morning. An expansive area of
Canadian high pressure will then assure us of fair dry weather
Thursday and Friday.

&&

.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 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 sfc convergence in the vcnty 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 pcpn
today...a 45kt low level jet within the warm advective pattern will
at LEAST partially mix to the sfc. This will allow sfc 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 IAG Frontier. A wind advisory has
thus been issued for Niagara and northern Erie counties where this
threat will be 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
sfc low will remain relatively weak and somewhat disorganized...
moderately strong lift provided by the aforementioned coupled jet...
and moreso by 100m hgt falls and sfc convergence ahead of a wavy sfc
front will lead to widespread rain over the forecast area. The
pcpn...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
moderately heavy rain at times. The only change from continuity is
that the slgt chc for thunder has been removed...largely due to poor
lapse rates and even less elevated CAPE than was previously
advertised.

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 pcpn 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 MONDAY/...
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 /09Z TUESDAY THROUGH SATURDAY/...
VFR conditions will remain in place through at least the first half
of today...although sfc winds will gradually increase as the day
matures. Sfc 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 Finger
Lakes after about 20z.

Widespread rain will then move across all of western and north
central 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...
Southerly winds will freshen throughout the region this morning
before becoming 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. The exception today is for the
western third of Lk Ontario (W of Hamlin Beach). Will issue a SCA
for that area only and carefully watch Lk Erie.

A wavy cold front will then slowly pass through the region tonight.
While winds and waves will briefly subside in the process (esp 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 be likely for this period.

&&

.FIRE WEATHER...
Dry conditions with gusty winds are expected again today. Min
RHs will fall below 30%. Wind gusts during the midday and
afternoon will reach 30 to 35 mph. With fine fuels continuing to
dry out today, an SPS has been issued for the lake plains and
Southern Tier.

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 later this
evening and overnight.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Wind Advisory from 8 AM this morning to 6 PM EDT this evening
     for NYZ001-010.
MARINE...Small Craft Advisory from noon today to 11 PM EDT this evening
         for LOZ042.

&&

$$

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