Forecast Discussion

000
FXUS61 KBUF 091436
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1036 AM EDT Fri Jun 9 2023

.SYNOPSIS...
A persistent area of low pressure over Maine will circulate several
disturbances over our area during the next couple days, and this
will result in a few showers this afternoon and possibly an isolated
thunderstorm. The greatest coverage of the showers will be today,
with mainly dry and warmer weather for the weekend. A stronger area
of low pressure and cold front will then move into the area Sunday
night and Monday with a good chance of widespread, beneficial
rainfall.

&&

.NEAR TERM /THROUGH SATURDAY/...
Radar imagery showing an area of rain over southern Ontario heading
south, with the more concentrated area of showers missing our area
to the west. A few sprinkles will cross far Western NY through the
rest of the morning. Elsewhere, a few scattered showers are
developing with the onset of diurnal heating, and these will
continue to gradually expand in coverage through early afternoon.

The persistent upper level storm system that has been anchored over
Maine and the St Lawrence valley the past few days will circulate a
robust shortwave southwards across our region today. As the impulse
of energy crosses Lake Ontario during the course of the morning...
the associated synoptic forcing will combine with a conditionally
unstable airmass to allow showers to blossom across the region.
There may also be a few isolated thunderstorms...mainly during the
afternoon when any sunny breaks will provide additional instability
to our airmass. While there will be a fair number of showers around
today, most areas will not see enough rain to be beneficial. The
showers will help to precipitate smoke particles out of the airmass
locally.

Speaking of smoke...guidance is suggesting that the concentration
will drop off CONSIDERABLY during the course of the day...but it is
not expected to clear our completely. Despite the general
improvement...an air quality alert for fine particulates will remain
in effect through today into this evening for the far western
counties (generally west of the Genesee valley).

Subsidence in the wake of the aforementioned shortwave will coincide
with a loss of diurnal instability this evening...and this will lead
to a significant reduction in the areal coverage of showers. Much of
the overnight will be pcpn free...but clouds will be stubborn to
clear.

The upper level storm system that has been pushing Canadian
wildfire smoke southwards into our region the past several days will
finally move east across the Canadian maritimes on Saturday. Subtle
hgt rises in the wake of the system and a general lack of any
shortwaves in the backing mid level flow should support mainly dry
weather across our region...although some lingering showers will be
possible across the Eastern lake Ontario region...mainly in the
afternoon. It will be milder with temperatures averaging some 5 to
10 deg f higher than those from today (Fri).

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/...
The large upper low that impacted our weather for much of this past
week will be located over the Canadian Maritimes at the start of the
period. This will allow for a change in our general wind flow
pattern, finally ending any lingering smoke issues. Meanwhile, the
next upper trough will be digging south out of Ontario Province into
the upper Great Lakes Saturday night, before evolving into another
large cutoff upper low on Sunday. In between these two features lies
the good news in the form of a weak induced upper ridge that will
move east across our region Saturday night and Sunday. This will
provide a mainly dry and warm finish to our weekend. A late day
shower cannot be ruled out across far western NY as the next system
approaches from the west. Otherwise, comfortable sleeping conditions
Saturday night with lows in the upper 40s to mid 50s. Highs on
Sunday will then be a bit above average, with highs mainly in the
upper 70s to lower 80s. Mid 70s across the higher terrain.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Large upper low completely cuts off from the main flow while
continuing to slowly deepen as it spins across the Great Lakes
region to open the period. Model consensus remains in good agreement
that this system will bring our region some much needed beneficial
rain for the start of the new work week. An associated surface low
will develop over the mid Mississippi valley on Sunday and track
northeast into the lower Great Lakes by Monday morning. This low
will then begin to rapidly occlude on Monday as it wraps up while
sliding northwest to a position directly beneath its parent upper
low, as the system becomes vertically stacked. As it does so, it
will send an attendant slow-moving cold front eastward across
western and northcentral NY Monday into the first half of Monday
night. A plume of very moist air will surge north across our area
ahead of the front, with PWATs rising to between 1.5 to 1.75 inches.
Latest guidance also suggesting that a wave may form and slowly move
north along the boundary as it moves east across the area. Putting
it all together, a widespread soaking rainfall is looking more and
more likely. In fact, WPC has our entire area outlined in a Day 4
Marginal Risk for Excessive Rainfall, which looks like it would be
mainly localized in any stronger convection. At this point, basin
average rainfall amounts of at least a half to an inch are possible.

Upper low remains nearly stationary to our west through Tuesday,
while the cold front will have cleared to the east of our area. This
should provide at least a decent period of dry time sometime later
Monday night and/or Tuesday. Can`t rule out a few showers during
this time though owed to the cool moist cyclonic flow residing
aloft, especially during the peak diurnal heating hours.

Cutoff upper low finally starts to make a move to the east Tuesday
night and Wednesday. This will bring the next likelihood for some
additional rainfall as it moves across NYS, although much lower
amounts than what fell on Monday.

Main upper low pulls east of the area by Thursday before becoming
hung up across New England. Impulses rotating about the periphery of
the upper low in the cool moist cyclonic flow aloft will keep at
least the chance for showers going into at least Thursday.

Otherwise, temperatures overall during the long term period will be
near, to a little below normal.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
Showers will increase in coverage from late morning through the
afternoon as an upper level low spins over the northeast US. The
initial cumulus development has been MVFR in some areas, especially
across higher terrain and east of Lake Ontario. Most areas will
return to VFR this afternoon for the majority of the time, although
any of the heavier showers will produce brief VSBY/CIG restrictions.

The vast majority of any lingering showers late today will end this
evening. This will leave mainly VFR weather over the region...
although cigs may lower to MVFR levels east of Rochester late.

Outlook...

Saturday and Sunday...Mainly VFR.
Sunday night and Monday...Restrictions likely in showers and
possible thunderstorms.
Tuesday...Restrictions possible in scattered showers.

&&

.MARINE...
Generally quiet conditions are expected on the both Lake Erie and
Lake Ontario into this weekend...as a weak gradient persist across
the Lower Great Lakes. The will allow for a daily cycle of weak
onshore/offshore breezes. Stronger southerly component winds will
develop on the lakes by early next week.

&&

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

&&

$$

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

NWS BUF Office Area Forecast Discussion