668
FXUS61 KBUF 050138
AFDBUF

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

.SYNOPSIS...
A warm dry night on tap before conditions deteriorate Wednesday and
Wednesday night as a slow moving cold front works its way through a
notably more humid airmass at that time, nearly guaranteeing showers
and drenching thunderstorms. Significant day to day cooling can then
be expected for the remainder of the week, along with fairly
frequent showers.

&&

.NEAR TERM /THROUGH TONIGHT/...
Warm and dry this evening with temperatures slowly falling through
the 70s. Fair dry weather will then continue through the remainder
of the overnight with temperatures running at least 5 degrees higher
than those from last night. Minimums will thus range from 60 in some
of the Southern Tier valleys and in parts of Lewis County, to the
mid and upper 60s most elsewhere. This is some 10-15 degrees above
average for most locations.

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 subtropical 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 by later in the morning and
midday. Shower and storm chances will expand northeastward through
the afternoon hours as instability builds owed to diurnal heating
and increased moisture, with coverage becoming likely by late in the
day across southwestern NY as a cold front approaches from the west.
Have added the mention of heavy rain to the likely PoPs. Otherwise,
Wednesday will be warm and increasingly humid with highs again well
into the 80s for the bulk of the region and Tds climbing 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 through midnight, then east of Lake Ontario
during the second half of the night. A very warm and humid night on
tap with lows mainly in the mid and upper 60s once again, although
some cooler/less humid air will start to filter into far western NY
very late Wednesday night behind the boundary.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
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.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Widespread VFR conditions tonight with a mainly light south to
southeast flow becoming established overnight. In terms of cloud
cover, just some passing cirrus through the overnight.

VFR conditions will persist through at least midday Wednesday, with
just a thickening and lowering of mid level decks from southwest to
northeast across areas from the Genesee Valley westward through the
morning hours. Mid level decks will continue to thicken and lower
through the second half of Wednesday, with mainly VFR CIGS expected
to persist through the end of the TAF period. The exception will be
across the western Southern Tier (KJHW), where low VFR CIGS by mid
afternoon may deteriorate to MVFR CIGS by very late afternoon/early
evening.

In terms of precipitation, a few showers or an isolated storm
possible across western NY by late Wednesday morning, before more in
the way of scattered showers and storms are anticipated for the
afternoon and early evening hours. Brief reductions in VSBY will be
possible in any heavier showers or storms.

Outlook...

Wednesday night...Areas of MVFR/IFR with showers and thunderstorms.
Thursday...Becoming mainly VFR with scattered showers and
thunderstorms, especially during the afternoon.
Friday through Sunday...VFR/MVFR with showers likely and possible
thunderstorms.

&&

.MARINE...
A light southerly flow will develop tonight, then slowly strengthen
some Wednesday into Wednesday night ahead of a slow moving cold
front approaching from the west. With the flow being mainly
offshore, the main impact will just be a bit of an uptick in light
chop as you move toward the open waters.

The cold front will then cross the lower Great Lakes late Wednesday
night and Thursday morning, however expect a threat for
thunderstorms Wednesday afternoon through Thursday. SW to WSW winds
will freshen on both Lakes Thursday and Friday in the wake of the
cold frontal passage with choppy waters developing. Conditions may
possibly near Small Craft Advisory criteria for a couple of brief
periods Thursday and Friday afternoon, especially across eastern
Lake Erie.

&&

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

&&

$$

SYNOPSIS...JM/RSH
NEAR TERM...JM/RSH
SHORT TERM...PP
LONG TERM...PP
AVIATION...JM
MARINE...JM