081
FXUS61 KBUF 060730
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
330 AM EDT Thu Jun 6 2024

.SYNOPSIS...
A slow moving cold front will press through the region with
showers likely today, and thunderstorms possible this
afternoon. Today will be the final day of this stretch of
summery-like weather as temperatures are slated to average below
normal from Friday through Monday of next week. The cooler
weather will be accompanied by fairly frequent shower activity.

&&

.NEAR TERM /THROUGH TONIGHT/...
Surface analysis shows a deep low pressure system over south-central
Canada this morning. There are two cold fronts that extend southward
from this low pressure system, the westward one extends south across
Michigan while the eastern cold front extends south across Lake Erie
and Ohio this morning. Regional radar shows showers ahead of these
two cold fronts, and locally, these showers are across western and
north central NY this morning. The airmass is saturated and any
showers will produce heavy downpours. The western Southern Tier
continues to get the bulk of the heavier showers with rain gauges
across Chautauqua county reporting 0.75-1.25 inches overnight.

It will be the last day of our summery stretch of weather as a deep
low pressure system the Great Lakes region today. The forecast area
remains on the warm side of an approaching cold front this morning.
Muggy conditions persist with dewpoints in the 60s across the
region. Lightning has dropped off overnight, however an area of 500-
1000 J/kg of MLCAPE exists immediately upstream and may move into
western NY this morning. This will keep a low chance of
thunderstorms through mid-morning. The cold front will enter western
NY between 6-8am this morning. There will be a wind shift from south
to west-southwest with an uptick in winds behind the front. Most
showers will end from west to east with partial clearing across
western NY this morning. Post-frontal conditions are favorable for
additional cumulus and showers to develop along a convergence zone
from the Niagara Frontier to Rochester, mainly north of the City of
Buffalo into this afternoon.

As dry conditions move in behind the front, daytime heating and
dewpoints in the 60s will be ahead of the front. Mid-level winds
will increase ahead of an approaching trough and conditions will
become favorable for thunderstorm development from the Finger Lakes
region to north central NY this afternoon. There is a Marginal Risk
of Severe thunderstorms and isolated severe thunderstorms are
possible within this corridor. The increase in winds will also cause
southwest winds to gust up to 35 mph east of Lake Erie this
afternoon. Elsewhere, gusty winds around 25-30 mph are possible.
Highs will reach the mid to upper 70s across the region today.

The aforementioned deep trough will move across the eastern Great
Lakes region tonight. Cold air advection will spread eastward and
the switch to cooler weather will arrive for Friday. Moist, cyclonic
flow will also move into the region and showers will increase in
coverage by Friday morning. Lows will reach the 50s.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
A very unsettled pattern will continue Friday through the weekend as
a mid level closed low moves very slowly from near Georgian Bay
Friday morning eastward across southern Quebec over the weekend. A
multitude of shortwaves will round the base of the closed low and
bring periods of enhanced ascent and deeper moisture to our region,
producing frequent rain chances. These smaller scale shortwaves
become more difficult to place in time and space beyond a few days,
with the finer details of the forecast becoming more uncertain
beyond Saturday.

Friday, the base of the mid level low will move across the eastern
Great Lakes, bringing with it a period of deep moisture and ascent.
Cool temperatures aloft will support steepening lapse rates with
modest diurnal heating. The coverage of showers should still be
rather sparse early in the morning, but expect a quick expansion of
shower coverage and intensity by late morning into the afternoon as
the deeper moisture and forcing arrive and interact with steepening
lapse rates. Instability will be weak, but still may support some
isolated thunder in the afternoon and evening. Stable lake shadows
will keep shower coverage lower east and northeast of Lake Erie and
Lake Ontario, but the synoptic forcing may be strong enough to
overcome the lake shadows to some extent.

Friday night, showers will continue as the trough moves slowly east.
Temperatures aloft become cool enough to support lake enhanced
showers east of the lakes, especially east of Lake Ontario overnight
as 850MB temps fall to around +5C or so. This is a rarity in June,
but the cool temperatures aloft combined with well above normal lake
temperatures will bring our first lake effect rain showers of the
2024-2025 season.

Saturday through Sunday, the closed low and trough axis will
continue to move slowly east. Cyclonic westerly flow will continue
across the Great Lakes, along with a series of difficult to time mid
level shortwaves. The 00Z model guidance suggests the most notable
of these waves will move across the eastern Great Lakes Saturday
night, bringing a greater chance of more organized rainfall.
Otherwise, weak diurnal instability, lake breeze boundaries, and
general weak large scale forcing will continue to support scattered
to numerous showers and possibly a few isolated thunderstorms
Saturday through Sunday.

Temperatures will run below average through the period with the
persistent trough and cool air aloft in place. Highs Friday through
Sunday will generally be in the 60s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
The same general longwave pattern will remain in place across North
America through early next week, with an expansive ridge in the west
and a trough in the east. The trough and associated forcing, deeper
moisture, and cool air aloft will continue to support showers and
cool temperatures through at least Monday. By Tuesday, forecast
model guidance continues to show the trough axis making some
eastward progress to along or just off the east coast. There may
still be a few spotty showers, especially in the afternoon across
higher terrain inland from the lakes, but the coverage of showers
should be much lower than previous days.

Tuesday night and Wednesday height rises will spread across the Ohio
Valley and eastern Great Lakes ahead of another trough digging into
the upper Great Lakes. This will bring a brief interlude of dry
weather, but shower chances may start to increase again as early as
Wednesday afternoon with the approach of the upstream trough.
Temperatures will warm through midweek as the pool of cool air aloft
exits.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
VFR conditions will become MVFR/IFR by this morning as showers move
across western and north central NY overnight. While the threat for
TS has reduced significantly as showers have moved into a more
stable airmass, the threat continues as a cold front approaches the
region. The cold front will slowly cross the region today with winds
becoming westerly. Overall, flight conditions will improve from west
to east across western NY through this afternoon. Additional cumulus
and showers are possible from KIAG/KBUF To KROC along a convergence
zone this afternoon. This may produce a brief period of MVFR
conditions. Southwest winds will increase east of Lake Erie with
gusts up to 30kts from KBUF To KGVQ this afternoon.

Showers will continue east of Lake Ontario through this afternoon.
The threat for thunderstorms increases east of Lake Ontario this
afternoon which may result in heavy downpours and gusty winds at
KART. Flight conditions will improve to VFR tonight.

Outlook...

Friday through Monday...VFR/MVFR with mainly daytime showers likely
with possible thunderstorms.

&&

.MARINE...
A cold front will cross the Lower Great Lakes this morning. Showers
will continue with the threat for thunderstorms increasing across
the eastern half of Lake Ontario this afternoon. SW to WSW winds
will freshen on both Lakes today through 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, especially across eastern Lake Erie.

&&

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

&&

$$

SYNOPSIS...HSK/RSH
NEAR TERM...HSK
SHORT TERM...Hitchcock
LONG TERM...Hitchcock
AVIATION...HSK
MARINE...Apffel/HSK/JM/TMA