774
FXUS61 KBUF 080219
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1019 PM EDT Sun Jul 7 2024

.SYNOPSIS...
High pressure centered over Lake Erie will slowly drift east and
provide us with fair dry weather through Monday night. A slow
moving cold front will then sag across and stall over our region
late Tuesday and Wednesday. Remnants from Beryl will circulate
up across the forecast area during this period to help set the
stage for the potential of some areas to receive multiple inches
of rain.

&&

.NEAR TERM /UNTIL 6 PM MONDAY EVENING/...
Another pleasant...star filled night can be expected overnight with
temperatures mostly settling into the upper 50s to lower 60s. As was
the case this morning...the clear skies and light winds will
encourage fog to form in the Southern Tier valleys...as well as
within the Black River valley in Lewis county.

High pressure wedged from New England to West Virginia will then
guarantee another sunny day to start the new work week. Temperatures
aloft will nudge upwards into the mid teens C...so that will allow
Mondays max temperatures to climb WELL into the 80s to near 90.

While fair dry weather will persist Monday night...it will be a
notably warmer night with lows ranging from the mid 60s across the
Southern Tier and North country to nearly 70 degrees elsewhere.

&&

.SHORT TERM /6 PM MONDAY EVENING THROUGH WEDNESDAY NIGHT/...
...Significant Rains from Beryl Possible Wednesday...

A warm and unsettled, though not overly active day expected Tuesday
as weak troughing remains upstream over the central Great Lakes.
With weak moisture advection and leading shortwave energy moving
into the region, expect some widely scattered convection to develop
in the afternoon mainly focused on lake breeze boundaries during
peak heating hours. While there will likely be more mid and high
cloud cover around, expect daytime temperatures well into the mid
and upper 80s, even a few low 90s across the typical warm spots in
the Genesee Valley and Finger Lakes regions.

While convection will likely wind down with the setting sun Tuesday
evening, rain chances will increase later in the night ahead of the
next complex system emerging to our west, though the vast majority
of the night is expected to be dry. Overnight lows will range from
the mid 60s across the hilltops to the low 70s across the Lake
Plains.

A complex rainfall forecast is shaping up for the midweek timeframe.
Weak, positively tilted longwave troughing initially across the
Upper Midwest and Great Lakes region Tuesday morning will slowly
translate eastward and de-amplify New England Tuesday night. Broad
upper level troughing will remain over the western Great Lakes as
reinforcing shortwave energy slides southeast out of Manitoba and
into the Dakotas. It is this shortwave energy that is expected to
interact with what will then be post-TC Beryl through the course of
the day Wednesday, causing a sharp mid-level trough and attendant
sfc cyclone to emerge over the Upper Midwest/western Great Lakes,
which will then slowly trudge northeast. A belt of warm tropical
moisture advection with PWATs surging to 2-2.5" will extend
northeast out ahead of the system and move into the eastern Great
Lakes as it does so. The main slug of heavy rain looks to come
sometime between Wednesday afternoon and late evening as this deep
tropical moisture overlaps sharp mid-level convergence along an 850H
warm front under diffluent flow aloft. There will also likely be
embedded thunderstorms that will locally enhance rainfall rates and
amounts, though severe potential looks to be lower than the rainfall
threat at this time. The bands of heaviest precip should begin to
shift east out of western NY and into the North Country late
Wednesday night.

It should be stated here that with the large amount of dynamics in
play, how exactly these features will interact will have a large
impact on the sensible weather and thus the deterministic forecast,
especially in regards to expected rainfall amounts and timing. The
timing of the reinforcing shortwave trough and the track of Beryl`s
remnants will be crucial to where the axis of heaviest QPF sets up
over our region, and there remains ample uncertainty in these
details at this range. However, given the overall synoptic setup and
PWATs climbing to near the daily maximum for the time of year, large
swaths of rainfall totals of 1.5-2" are very well possible, with
locally higher amounts certainty not out of the question especially
with any embedded thunderstorms. This could lead to poor drainage
flooding issues as well as minor rises on area waterways, though the
dry antecedent conditions should be a mitigating factor here.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
A mid-level closed low over Upper Great Lakes region Thursday will
move towards the eastern Great Lakes region while opening up as a
weaker wave by Friday. Deep, southerly flow and tropical moisture
with become squeezed over the eastern seaboard, between the
advancing trough and a prominent Atlantic ridge. Post T.S. Beryl
will weaken and move northeast of the region Thursday. This
surface reflection will become elongated near the eastern Lake
Ontario region and heavy showers and thunderstorms are possible
through Thursday afternoon. Drier air will work into western NY
Thursday, however diurnally driven circulations will trigger
some showers and thunderstorms through the early evening.

The axis of tropical moisture will be east of the forecast area
Friday. Drier air will continue to move into the region, however the
mid-level wave will be overhead and diurnally driven showers and
thunderstorms will be possible, albeit the threat of heavy rain will
be less. A mid-level ridge will move across the region Friday night
through Sunday and mostly dry conditions are expected across the
region. There is a low chance of showers in the afternoon through
early evening Saturday and Sunday, mainly inland from the lakes and
near lake breeze boundaries.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Surface high pressure slowly moving across the region will guarantee
fair and largely VFR weather through Monday.

The one exception to this will be within any valley fog that
develops in the Southern Tier and east of Lake Ontario late tonight.
This will likely cause reductions down to IFR at KJHW between
07z/08z to 12z. Any fog will then quickly lift and dissipate after
sunrise Monday, with a return to areawide VFR that will last through
the rest of Monday and Monday night.

Outlook...

Tuesday..Mainly VFR. A low chance of showers and thunderstorms.
Wednesday...MVFR with showers and thunderstorms likely. Restrictions
to IFR possible in heavy showers.
Thursday...Restrictions possible with a chance of showers and
thunderstorms.
Friday...Mainly VFR with a low chance of showers and thunderstorms.

&&

.MARINE...
High pressure draped across the Lower Great Lakes will drift east to
New England Monday...then off the east coast Monday night and
Tuesday. This will bring a period of generally quiet weather and
light winds/minimal wave action through Tuesday. The light
prevailing flow will allow local lake breeze circulations to once
again develop during Monday afternoon.

More unsettled conditions - featuring widespread rain and some
embedded thunderstorms - are then expected to develop on Wednesday
as an area of low pressure (the remnants of Tropical Cyclone Beryl)
track northeastward across the Ohio Valley.

&&

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

&&

$$

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