-- Discussion containing changed information from previous version are highlighted. --
265
FXUS61 KBUF 041930
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
330 PM EDT Tue Jun 4 2024

.SYNOPSIS...
Mid summer weather will be found throughout the region this
afternoon...as most areas will top out in the mid 80s with a touch
of humidity. This will be followed by a warm dry night...then
conditions will deteriorate Wednesday and Wednesday night. A slow
moving cold front will work its way through a notable more humid
airmass at that time...nearly guaranteeing showers and drenching
thunderstorms. Significant day to day cooling can be expected for
the remainder of the week...along with fairly frequent showers.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
Partly to mostly sunny skies will be found across the region this
afternoon...as the axis of a mid level ridge will be centered over
the Lower Great Lakes. The associated subsidence should all but
guarantee issue free weather...but unlike yesterday (Mon) when we
had a cap arnd 750mb...there is nothing to prevent isolated towers
from `going up` in a diurnally destabilized airmass. This would be
more the case across the Finger Lakes...Genesee valley and portions
of the western Southern Tier.

Otherwise...it will be quite warm this afternoon. High pressure in
the lower levels based off the Jersey shore will help to circulate
H85 temps of 16-18C into our region. Simple adiabatic warming will
allow our mercury to climb to the mid 80s for most areas...with
spots like Dansville and some of the Southern Tier valley sites
tickling the 90 degree mark.

Any isolated convection from the afternoon will collapse early this
evening. This will leave a fair dry night with temps running at
least 5 degrees higher than those from last night. Mins will thus
range from 60 in some of the Srn Tier valleys and in parts of Lewis
county...to the mid and upper 60s most elsewhere.

Conditions will deteriorate on Wednesday...as the ridge axis of the
previously mentioned mid level ridge will slowly push to our east.
Immediately in its wake...an initial shortwave (pseudo warm front)
will lift northeast across our region. This elevated boundary will
essentially be the leading edge of a sub tropical airmass that will
include PWAT values that will climb to near 2 inches by late
afternoon. The boundary will prompt scattered showers and
thunderstorms over the western counties in the morning and midday to
become likely by late afternoon. Have added the mention of heavy
rain to the likely pops. Otherwise...Wednesday will be warm and
increasingly humid with Tds reaching into the mid and upper 60s.

Wednesday night will be quite unsettled throughout the region...as a
large negatively tilted trough over the Upper Great Lakes will push
the first of two cold fronts through our forecast area. Given the
moisture rich airmass that will be in place...the forcing from the
front will generate numerous showers and thunderstorms...most of
which will include pockets of heavy rain. Categorical pops will be
in place regionwide...with the most widespread activity found over
the western counties thorugh midnight...then east of Lake Ontario
during the second half of the night.

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
-- Changed Discussion --
Deep troughing extending from central Canada across the Great Lakes
will draw a much cooler and more unstable airmass across our region
Thursday through Friday. Multiple spokes of shortwave energy and
upticks in synoptic moisture rippling through this trough will also
maintain at least low-end chances for showers and thunderstorms for
much of the period, though there should be plenty of dry time in the
mix as well.

Thursday should start out mainly dry for areas west of the Finger
Lakes as a weak region of surface high pressure slides across the
region. More widespread soaking rain ahead of a cold front should
slide east and out of the North Country through the morning hours.
Increasing moisture and diurnal instability should then cause
scattered showers and possibly a few thunderstorms to blossom late
Thursday morning through the afternoon, mainly across areas outside
of the stabilizing effects of the lakes. Otherwise, daytime
temperatures should be closer to `normal` for early June Thursday
with highs ranging in the 70s.

Lingering convection will taper off after sunset Thursday night as
temperatures begin to fall through the 60s and dip into the 50s by
the pre-dawn hours. Shower chances then ramp up fairly quickly again
on Friday as another cold front is driven through the region.
Steepening lapse rates within the cooling airmass aloft and residual
synoptic moisture should allow plenty of diurnal showers and a few
thunderstorms to redevelop by the afternoon, which should then taper
back off in coverage late Friday evening.

Friday will also mark the first day in a stretch of below normal
temperatures for our area, with highs only in the 60s to low 70s.
Low temperatures Friday night will fall back into the 50s, though
upper 40s are likely across the higher terrain areas of the Southern
Tier and North Country.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
A large closed low pressure system aloft will wobble about the
eastern Great Lakes through at least the weekend before slowly
transitioning to New England early next week. This will maintain the
cool, unsettled pattern across the region with chances for showers
and thunderstorms. Coverage and intensity will `likely` follow the
diurnal insulation trend each day, generally being greatest in the
afternoon hours and away from any stabilizing influence from the
lakes. While waves of shortwave energy will continue to wobble
through the low aloft and bring upticks in synoptic moisture from
time to time, PWATs don`t look to become anomalously elevated at any
point which should preclude the develop of more widespread impactful
storm complexes. The one possible exception to this may come as the
system`s main trough axis and cold front drop southward and generate
some heavy rain across the region sometime in the second half of the
weekend, but at this juncture uncertainty is high in this occurring.

As alluded to previously, temperatures will run below normal this
period. Highs Saturday and Sunday will only manage to top out in the
60s for most, though warm a few degrees for Monday and Tuesday with
low 70s becoming more common. Lows each night will mainly be in the
low/mid 50s, with upper 40s possible further inland away from the
influence of the lakes.
-- End Changed Discussion --

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
VFR conditions will be in place through Wednesday morning...although
isolated convection cannot be ruled out across the Finger Lake and
western Southern Tier THIS afternoon.

Outlook...

Wednesday...Mainly VFR with some showers and thunderstorms,
especially over the western counties.
Wednesday night and Thursday...Areas of MVFR with showers and
thunderstorms.
Friday through Sunday...VFR/MVFR with showers likely and possible
thunderstorms.

&&

.MARINE...
A weak pressure gradient will continue to maintain light to modest
winds and minimal waves into midweek.

A cold front will cross the eastern Great Lakes Wednesday night and
Thursday with a few rounds of thunderstorms likely. West to
southwest winds will increase on the lakes behind the cold front
Thursday through Friday with choppy conditions developing.

&&

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

&&

$$

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