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693
FXUS61 KBUF 061735
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
135 PM EDT Thu Jun 6 2024

.SYNOPSIS...
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The second of two cold fronts will cross our region this evening...
and this will usher in a cooler and less humid airmass that will
stay in place through early next week. Unfortunately...the cooler
conditions will be accompanied by unsettled conditions with fairly
frequent showers. Warmer weather wil then finally return later next
week.
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&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
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The airmass east of Lake Ontario is certainly sub tropical in nature
with PWAT values arnd 1.8" and Td`s in the upper 60s...so there is
no doubt that convection in that area this afternoon will generate
some heavy rain. While the threat for severe weather has diminished
somewhat in that area because of the dense cloud cover and extent of
shower activity...there will still be the risk for isolated
thunderstorms that contain wind gusts in excess of 40 mph.

Otherwise...partial clearing will continue to take place over the
western counties.

The second of two cold fronts will push through the area tonight.
THIS...front will lead the charge of a cooler and less humid
airmass. While the vast majority of the region will experience fair
dry weather tonight...deeper moisture circulating around a deep
longwave trough over eastern Canada will nose across the far western
counties after midnight. This will support the chance for some
nuisance showers over the far western areas...and with H85 temps
forecast to drop to arnd 6c...there could actually be some lake
enhancement east of both lakes. Otherwise...it will be a night to
open those windows to allow the fresh new airmass indoors. Mins will
range from the mid and upper 50s across the lake plains to the lower
50s across the bulk of the Srn Tier and across the Tug Hill.

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.
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&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
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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.
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&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
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 /18Z THURSDAY THROUGH TUESDAY/...
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VFR conditions will be in place across the western counties for the
remainder of the afternoon...while numerous showers and
thunderstorms east of Lake Ontario will promote MVFR conditions for
sites like KART and KGTB.

Mainly VFR weather will then be in place for tonight...despite the
passage of a second front.

Deepening moisture rotating around the base of a large trough will
encourage Cigs to drop to MVFR levels on Friday. The lowering cigs
will be accompanied by some showers and possibly a thunderstorm or
two.

Outlook...

Saturday through Monday...VFR/MVFR with mainly daytime showers
likely with possible thunderstorms.
Tuesday...VFR conditions.
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&&

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