690
FXUS61 KBUF 121018
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
618 AM EDT Mon May 12 2025

.SYNOPSIS...
High pressure will move off the east coast today, bringing much
warmer air into the area to start the new work week. Dry weather
will continue today, then a broad diffuse area of low pressure and
moisture will spread northward across the Ohio Valley and Great
Lakes, bringing a chance of a few showers starting Tuesday and
lasting through the end of the week.

&&

.NEAR TERM /THROUGH TUESDAY/...
Surface high pressure across New England this morning will move off
the east coast today. Much warmer air will be felt across most of
western and north-central NY today. A light gradient wind will open
the door for lake breezes to move onshore today. High temperatures
will be in the mid 70s to low 80s across most of the area, but highs
will only reach 60-75 around Lake Ontario and along the immediate
Lake Erie lakeshore. High clouds will increase from south to north
across the region today.

Tonight will be a transition period with showers entering the
western Southern Tier late tonight. An upper level trough will move
across the Pacific Northwest and aide in dislodging a broad upper
level trough across the Mississippi and Tennessee Valleys. Further, a
broad area of moisture will advance northward and enter western NY
tonight. Initially, clouds will thicken and produce overcast skies
across the forecast area. A tight moisture gradient and isentropic
lift along an exiting mid-level ridge axis will advance light rain
showers into the western Southern Tier late tonight. There is
uncertainty as to how far north these showers make it overnight. If
they do advance into the Buffalo metro and Finger Lakes region they
will likely encounter more low-level dry air and be in the form of
isolated showers and sprinkles. Dry conditions will continue from
the northern Finger Lakes to the eastern Lake Ontario region. The
combination of clouds and showers will limit cooling tonight, with
lows in the upper 50s to low 60s.

Deeper moisture will advance northward across most of the forecast
area as the upper low moves into the Ohio Valley Tuesday. 850mb
moisture transport will advect anomalously high PWATS into the
northern Mid-Atlantic region . While we might not tap into the core
of the highest PWATS, forecast amounts are still above the 90%
percentile for mid-May across western NY. There is uncertainty in
the location of upstream precipitation and the potential for
embedded shortwave troughs. Daytime heating and deep moisture
underneath the trough will increase instability Tuesday. Scattered
to potentially numerous showers are possible across western NY,
however confidence is low in coverage and location. A few
thunderstorms can`t be ruled out Tuesday afternoon. The upper level
ridge axis will persist across eastern New York into New England and
keep low chances of showers across Jefferson and Lewis counties
Tuesday. A steady south-southeast wind will allow areas that were on
the cooler side Monday, such as near the Lakes, to reach the 70s,
and the low 80s across the Saint Lawrence Valley Tuesday. Cooler
across the higher terrain east of Lake Erie with highs in the 60s.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
A mid level closed low over the lower Ohio Valley Tuesday evening
will move very slowly northeast, gradually opening up into a
negatively tilted trough that will deamplify with time as it moves
across the Great Lakes. A moist airmass will remain in place through
the middle of the week, with surface dewpoints well into the 50s and
possibly lower 60s at times. Weak shortwaves will traverse through
the larger scale mid level trough, with each one providing a
periodic increase in large scale ascent, with more localized low
level forcing from lake breeze boundaries and terrain driven
circulations. The weak forcing and moisture will maintain a chance
of showers at times through the middle of the week, but there will
be plenty of rain free time as well.

Temperatures will remain warm through the middle of the week,
running 5-10 degrees above average for mid May.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
The weakening, slow moving trough that reaches the Great Lakes
during the middle of the week will linger Thursday, then drift
towards New England Friday. Weak forcing associated with the trough,
moisture, and diurnal instability will support a chance of a few
showers and isolated thunderstorms Thursday with uneven/spotty
coverage.

Friday, a mid level closed low is forecast to move into the upper
Great Lakes, then move slowly east across Ontario and Quebec next
weekend. A warm, moist, and somewhat unstable airmass will remain in
place Friday ahead of this next system, maintaining the chance of a
few scattered showers and thunderstorms. A cold front associated
with the mid level system will cross the eastern Great Lakes
Saturday, with another round of showers and thunderstorms possible.

Sunday, the mid level trough will become established from the Great
Lakes into New England, with a cooler post-frontal airmass advecting
into the area. Lingering moisture and forcing from the trough will
support a chance of a few more showers.

&&

.AVIATION /10Z MONDAY THROUGH FRIDAY/...
VFR conditions will continue today as surface high pressure across
New England moves off the east coast. Lake breezes will likely
develop east and south of Lake Erie and Lake Ontario, with
winds becoming north-northeast at KROC and possibly at KIAG by
Monday afternoon.

Mostly clear skies will continue through this morning. High clouds
will increase from south to north through this evening. Low to mid
clouds and rain showers will enter western NY late tonight.
Sub-VFR conditions will move into the western Southern Tier
after 6z.

Outlook...

Tuesday...VFR/MVFR with a chance of showers.

Wednesday...Areas of MVFR with showers likely.

Thursday...VFR/MVFR with chance of of a few showers and
afternoon/evening thunderstorms with local/brief restrictions.

Friday...VFR/MVFR with showers likely and afternoon/evening
thunderstorms with local/brief restrictions.

&&

.MARINE...
High pressure draped across southern New England this morning will
drift off the east coast later today...with generally light to
modest winds and minimal wave action prevailing.

Tuesday through Thursday, winds will generally be east to southeast
on the lakes with a light to moderate chop at times, but no Small
Craft Advisory conditions are expected through the week. There is a
low chance of thunderstorms during this time.

&&

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

&&

$$

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