000
FXUS61 KBUF 270701
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
301 AM EDT Sat Apr 27 2024

.SYNOPSIS...
A warm front will push across areas south of Lake Ontario Saturday
and the North Country Saturday night...and in the process will
bring our region some showers. Following its passage...late
spring to summerlike warmth will then overspread our region for
both Sunday and Monday... before a passing cold front brings our
next opportunity for more widespread showers and a few
thunderstorms Monday night and Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Weakening low pressure will lift across Minnesota overnight...while
slowly pushing its attendant warm front in our direction. This
boundary will only make slow eastward progress as it rams up against
the sharp upper ridge in place across our region...with its mainly
light and poorly organized shower activity at present likely
struggling to make it much past Chautauqua county by daybreak.
Otherwise our area will just see a general west to east increase in
mid and high cloud cover...along with notably milder temperatures
than the past couple night as a southeasterly to southerly return
flow of milder air strengthens across our region. Many locations
have already reached their lows for the night...with temps likely to
be mostly steady or slowly rising through the 40s across the eastern
half of the area...and in the upper 40s to mid 50s across the
western half. It will be mildest right along the Lake Erie shoreline
in Chautauqua and Southern Erie counties...where the downslope flow
will be strongest (with gusts to 35-40 mph) and where readings will
thus mostly hover in the upper 50s to lower 60s.

On Saturday the cutter-type low over Minnesota will continue to
weaken as it lifts across Lake Superior and into central Ontario
Province...with its trailing warm front also weakening as it pushes
across western New York and becomes further displaced from its
parent/encounters continued resistance from upper level ridging
aloft. Consequently...the numerous light to modest showers attendant
to the front will tend to become weaker and more scattered as the
boundary pushes across western New York...and have continued to
reflect this in the forecast with a general west-east decrease in
PoPs along the boundary as it makes its way eastward. Given the
current lack of any lightning upstream and the absence of any
instability amongst the bulk of the guidance...have pulled any
slight chance of thunder from the forecast today as the potential
for this appears rather minuscule.

With respect to high temperatures Saturday...these will be coolest
from the interior southern Tier across the Finger Lakes with the
front and showers/thickest cloud cover expected to cross these areas
during peak heating...resulting in highs there remaining confined to
the mid 50s to lower 60s. Further east across the North Country...
the later arrival of the thicker clouds and showers and downsloping
will allow highs there to reach into the lower to mid 60s. The
warmest overall readings are most likely to be found across far
western New York...where the clouds and showers should tend to thin
out at least somewhat as the warm sector starts to become
established later on in the day...and where the combined effects of
downsloping and a warmer airmass should help to boost readings
higher than what is currently suggested by the vast majority of the
guidance. While the temperature forecast across far WNY has some
significant forecast bust potential (in both directions...as it
could turn out notably cooler if the clouds/showers hang on longer
than expected...or notably warmer if we get any sun given the warmth
of the incoming airmass)...at this point still expect highs to reach
the mid-upper 60s across Niagara County and the lower elevations of
Erie County... and the lower 70s along the Lake Erie shoreline of
Chautauqua county.

Moving on into Saturday night...the warm frontal boundary will
continue to weaken and eventually lose its identity as it crosses
the North Country...with any showers along it continuing to
generally weaken and become more scattered over time. Meanwhile
further west the warm sector will continue to establish itself
across the remainder of the region. While much of the guidance tries
to redevelop some additional showers across western New York
overnight...feel that is is overdone given the apparent lack of a
significant trigger for additional convection. While a few more
widely separated showers cannot be ruled out given the broad/weak
warm advection regime that will be in place aloft...feel that these
are currently not worth much more than some slight chance PoPs...and
have thus continued to undercut guidance values. Otherwise...the
very mild incoming airmass and a continued decent south to south-
southwesterly breeze will result in low temperatures more typical of
late May or June...with mins expected to range from around 50 across
the North Country to near 60 along the Lake Erie shoreline.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
A weak warm front will carry northward to start this period, with
showers and a few thunderstorms over the eastern end of Lake Ontario
and points eastward.

Aloft a mid level ridge will begin to build over our region Sunday
- Monday. At the surface Sunday a frontal boundary will lie to our
west and north Sunday...to be pushed southward Monday as a shortwave
well to the north near James Bay crests the mid level ridge.
Marginal instability may allow for a few showers or thunderstorms
Sunday and Monday. Tough to time and place such storms, but daytime
period will be favored with the building instability.

Under this ridge warm air advection aloft will promote temperatures
above normal for Sunday in the low to mid 70s. For Monday, with
southwesterly flow and 850 hPa temperatures 12-13C, widespread upper
70s and lower 80s air temperatures, and even mid 80s in the Genesee
Valley are expected. This southwest flow will keep downtown Buffalo
a bit cooler. Also depending upon how far southward the front sags
Monday across the southern and eastern waters of Lake Ontario, a
possible northerly component to the wind may keep the south-
southeast shoreline along the Lake a bit cooler.

Monday night a cold front will edge its way closer to our region.
Showers and perhaps a few thunderstorms will become likely later in
the night across WNY. Also a few showers are likely east of Lake
Ontario as a stalled frontal boundary is forced northward ahead of
the next system. Will side towards the warmer temperature solutions
of guidance for Monday night with a steady southerly flow and
increasing cloud cover.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
An anomalously strong ridge over Northeast will move off the east
coast by Tuesday, and based on multiple ensemble systems there is
medium to high confidence that zonal flow will set-up across the
Great Lakes region through mid-week. Confidence lessens towards the
end of the work week with consensus showing a subtle trough over the
Northeast, however some ensemble members show the potential for a
ridge to build into the region.

For more sensible details, a cold front will move across the eastern
Great Lakes region Tuesday. There is good agreement that the front
will move through during daylight hours which increases the
probability (55-75%) for showers and thunderstorms across a portion
of the forecast region. Surface high pressure will move into the
region Wednesday and result in mostly dry weather, however there is
a low (20-30%) chance for showers or thunderstorms in the afternoon.
Another cold front may approach the region Thursday and Friday.
Surface high pressure may linger into Thursday, however the forecast
will maintain a higher chance (30-40%) as moisture increases ahead
of the cold front. The cold front may move into the region Friday
which will continue the chance for showers and thunderstorms.

Temperatures will remain above normal through the work week.

&&

.AVIATION /07Z SATURDAY THROUGH WEDNESDAY/...
Overnight...expect continued VFR conditions with only a general west-
to-east increase in mid and high cloud cover out ahead of a slowly
approaching warm front.

On Saturday...weakening low pressure over Minnesota will lift
northeastward to central Ontario...while pushing the warm frontal
boundary east across western New York. The warm front will bring
thickening/lowering clouds and a period of fairly numerous showers
from west to east through the course of the day...though the front
and showers should both tend to weaken with increasing eastward
extent. Expect ceilings to lower to the IFR to MVFR ranges across
the higher terrain and to the lower VFR range across the lower
elevations...where a stiffening southerly downslope flow will tend
to keep cloud bases somewhat higher than indicated by guidance. The
strengthening southerly flow will also help generate some wind gusts
of 30-35 knots at times...with these greatest across and immediately
downwind of our higher terrain.

Saturday night the warm front and its showers will continue to
weaken while traversing the North Country...where flight conditions
will range from IFR/MVFR across the higher terrain to MVFR/VFR
across the lower elevations. Meanwhile further west...any showers
should greatly diminish in coverage with mainly dry weather
prevailing for much of the night...with flight conditions ranging
from IFR/MVFR across the higher terrain of the Southern Tier to VFR
elsewhere.

Outlook...

Sunday and Monday...Mainly VFR with a chance of showers and
thunderstorms.
Monday night and Tuesday...MVFR/VFR with showers becoming likely
along with a chance of thunderstorms.
Wednesday...Mainly VFR.

&&

.MARINE...
Overnight and Saturday low pressure will track from Minnesota to
central Ontario Province...while slowly pushing its attendant warm
front east and across the Lower Lakes region. This will result a
moderately brisk south-southeasterly to southerly flow continuing to
overspread the Lower Great Lakes...though the increasingly offshore
nature of the flow will help to direct the greatest wave action
across Canadian waters. Consequently...conditions are expected to
remain below advisory criteria.

Following the passage of the warm front...a general southerly flow
across the Lower Great Lakes will weaken some while turning more
southwesterly Saturday night and Sunday. This will result in
conditions remaining below advisory criteria. This being said...a
few thunderstorms will become possible Sunday afternoon and evening.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...JJR
NEAR TERM...JJR
SHORT TERM...Thomas
LONG TERM...HSK
AVIATION...JJR
MARINE...JJR