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636
FXUS61 KBUF 080010
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
810 PM EDT Tue May 7 2024

.SYNOPSIS...
A warm front will move across the area tonight, with an area of
showers and a few thunderstorms crossing the area from
southwest to northeast. The showers will exit the eastern Lake
Ontario region Wednesday morning. Dry weather will then prevail
most of the time for the rest of Wednesday, although a few more
showers and thunderstorms are possible later in the afternoon
and evening, especially east of Lake Ontario. Unsettled weather
will then last Thursday through the weekend with a series of low
pressure systems crossing the region.

&&

.NEAR TERM /THROUGH TODAY/...
-- Changed Discussion --
Tonight through early Wednesday morning a mid level trough will move
northeast across the Great Lakes, with an associated warm front
moving northeast across our area overnight. A 40+ knot southwesterly
low level jet in the warm sector will impinge upon the warm front
and enhance moisture transport and isentropic upglide. The quality
of forcing and moisture continue to support the idea of an organized
area of showers and some embedded thunder (currently located over SE
Lower Michigan and western Ohio as of 00z) moving from southwest to
northeast across the area overnight. Model guidance remains in good
agreement bringing this into Western NY around midnight, into the
Genesee Valley and western Finger Lakes during the early overnight
hours, and areas east of Lake Ontario during the pre-dawn hours.
While conditions here will be nowhere near as unstable as what is
currently seen upstream...enough elevated instability should be in
place to support a few embedded garden-variety thunderstorms...
especially during the first half of the night. Any storms we do see
could produce brief periods of heavy rain, but they`ll be moving
along quickly enough to prevent any real flooding concerns.

Wednesday, the warm front will still be over the eastern Lake
Ontario region early in the morning with showers and a few isolated
thunderstorms. Rain will have already ended across Western NY as the
better forcing and moisture move east. It`ll be quite breezy
with wind gusts around 35 mph downwind of Lake Erie. This will
result in a lake shadow which should keep most of Western NY
rain free. The exception will be just south of Lake Ontario on
the northern fringe of the shadow where limited instability may
spark a few afternoon thunderstorms.

There may be a brief break in the showers east of Lake Ontario
late Wednesday morning, but chances there will increase again
when a strong mid level shortwave moves across southern Ontario.
The best chance for showers and thunderstorms will be along the
boundary which will be across northern Jefferson and Lewis
Counties. In addition, instability to the south of this will
feed into it, and potentially produce some stronger storms with
heavy rain. SPC just clips this area with its Marginal Risk in
the Day 2 Outlook.

Finally, an increasingly moist airmass crossing the cold lake waters
will likely produce marine layer fog late tonight through Wednesday
morning. Some of the Lake Erie fog will likely move onshore into
downtown Buffalo for a few hours Wednesday morning. Some of the Lake
Ontario fog may move onshore into Jefferson County as well.

A weak area of low pressure will be east of the forecast area
Wednesday night. The vast majority of the night will be rain-
free with only small chances for showers east of Lake Ontario
early and across the Western Southern Tier late.
-- End Changed Discussion --

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
The main challenge for this period will be periodic embeded
shortwaves and the positioning of the H850 thermal boundary.
This feature is advertised to set up near the eastern Great
Lakes, or even become draped across the region. This will impact
temperatures, shower activity, and even thunderstorm potential
through Friday. What is certain, it is looking `likely` that it
will be very unsettled through at least Friday. Given the
unsettled weather anticipated...it would be highly recommended
to have an umbrella handy through Friday. As was mentioned
temperatures will be impacted...we could find ourselves on the
cooler side of the thermal boundary with below normal
temperatures. This will result in highs on Thursday only in the
60s, and then a tad bit cooler Friday with a range of 50s. May
find a few spots in the low 60s.

Friday night...it looks like we will see a general decrease in
shower coverage but can`t completely rule out some showers
overnight.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
A broad upper level trough will become nestled across much of the
Northeast through the weekend, and possibly will begin to retreat
early next week. This pattern will `likely` continue the theme of
unsettled weather (showers), and also cool conditions (slightly
below normal) across much of the region for this time of year.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
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High pressure across New England will maintain VFR flight conditions
through this evening. A warm front will then quickly push across the
region overnight and early Wednesday morning...bringing a rough 3-4
hour period of showers and a few embedded thunderstorms to most
locations. As this occurs...mainly VFR conditions initially will
tend to deteriorate to MVFR/IFR (mainly in lower ceilings) as the
lower levels become increasingly saturated to the rainfall and the
advection of greater lower level moisture into our region from the
southwest.

Very late tonight and into early Wednesday morning some patchy fog
and/or low stratus still appears to be a distinct possibility in the
vicinity of KBUF/KART as the low level flow veers to southwesterly
and off the cooler waters of Lakes Erie and Ontario. Any fog/stratus
that forms should then dissipate during the mid to late morning
hours. After that time...mainly VFR conditions are expected south of
Lake Ontario through the rest of the period with just a low-end
chance of a few more widely scattered afternoon showers/storms along
a developing low-level convergence zone just south of that lake.
Meanwhile...areas east of Lake Ontario should see another round of
showers/storms and associated lower-end VFR to MVFR conditions
develop during the afternoon.

Outlook...

Wednesday night...VFR/MVFR.

Thursday and Friday...Mainly MVFR. Showers likely and MVFR stratus.

Saturday and Sunday...VFR/MVFR. A chance of showers.
-- End Changed Discussion --

&&

.MARINE...
Moderate ENE winds will produce choppy conditions on Lake Ontario
west of Rochester through the first half of tonight...however winds
and waves are expected to remain below Small Craft Advisory criteria.

WSW winds will then increase late tonight and Wednesday. This will
particularly be the case across Lake Erie...where winds and wave
action will be sufficient to support Small Craft Advisories as
outlined below. Elsewhere choppy...but sub-advisory conditions can
be expected.

An increasingly moist airmass crossing the cold lake waters will
likely produce marine layer fog late tonight through Wednesday
morning on Lake Erie and Lake Ontario with visibility restrictions.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory from 8 AM to 8 PM EDT Wednesday for
         LEZ020.
         Small Craft Advisory from 5 AM to 11 PM EDT Wednesday for
         LEZ040-041.

&&

$$

SYNOPSIS...Apffel/Hitchcock
NEAR TERM...Apffel/Hitchcock/JJR
SHORT TERM...AR
LONG TERM...AR
AVIATION...Apffel/JJR
MARINE...Apffel/Hitchcock/JJR