Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 270811
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
411 AM EDT Sun May 27 2018

.SYNOPSIS...
An area of showers will cross the Southern Tier this morning with a
weak wave passage, then a few widely scattered showers and
thunderstorms will develop inland from the lake breeze across
Western NY this afternoon. Mainly dry conditions will return Monday
through Wednesday as high pressure moves across the region. The
chance for widespread soaking rainfall returns Thursday into Friday
as the remnants of Alberto move through the eastern Great Lakes.

&&

.NEAR TERM /THROUGH TONIGHT/...
An area of showers have blossomed across the Southern Tier of New
York in response to a plume of weak low-level moisture advection.
This area of showers will slowly evolved eastward toward central NY
through the morning hours. A few pulses of lightning cannot be ruled
out as there have been some strikes upstream across Lake Erie, and
this area of weak mid-level instability will advect across the
region with these showers.

Also through this early morning, with dewpoints pushing into the low
60s there may be areas of fog forming over the lakes, especially
Lake Ontario. Light flow will keep any fog largely over the waters,
though an easterly component to these light winds may push some fog
along the immediate shoreline of Niagara-Orleans-Monroe.

A subtle shortwave will cross western NY today, which will help
reinforce an area of surface convergence across western NY as the
surface pressure falls locally support the developing lake breeze
boundary. This will be the main focus for potential convective
initiation this afternoon, as instability grows with the mid 60s dew
points advecting into the region and daytime heating. Convective
mode will be fairly disorganized broken line of slow moving showers
and thunderstorms drifting off toward the southeast. While a lone
stronger / organized storm is possible with a localized area of 35
knots of deep layer shear in the proximity of the surface boundary,
expect the storms to remain sub-severe. There may also be a
localized heavy rain threat given the slow storm motions. However,
most locations, will see ample dry time today. Areas near the lake
shores are likely to remain completely dry with the afternoon lake
breezes in place, and even those locations across western NY in the
best place to see some storms will just have to deal with a passing
threat.

Temperatures will be in the upper 70s to mid 80s today, coolest near
the lake shores and in the North Country. Light northeast winds
south of Lake Ontario near the convergent boundary will actually
help Buffalo one of the warmer spots.

Tonight, any lingering showers and storms will quickly diminish with
the loss of diurnal heating. A few isolated showers may accompany
the weak frontal passage across the North Country, but the rest of
the area will remain dry overnight. Temperatures will remain mild,
in the upper 50s to mid 60s, with dew points staying high. Where
enough clearing occurs across western NY, especially wherever gets a
decent shot of rainfall, there may be some areas of fog developing.
There may also be some redevelopment of fog over the lakes with the
continued high dew points.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
On Memorial Day a weak surface trough will cross the region,
reaching Western NY by mid to late morning, then moving to Central
NY during the afternoon. This feature has little upper level
support, but may produce just enough low level convergence when
combined with lake breeze boundaries to support a few isolated
showers and thunderstorms. Stable lake shadows will keep anything
that does develop away from the lakeshores, and this stable, drier
air will spread southeast during the afternoon following the passage
of the trough. Highs will reach the mid 80s again for lower
elevations, with lake breezes keeping areas within a few miles of
the lakes cooler.

Another weak backdoor cold front will move south across the area
late Monday night and Tuesday morning. This system also has little
upper level support, and given the poor diurnal timing will likely
move through the area dry with just a modest increase in clouds.
This front will settle south across PA later Tuesday, with a push of
drier and less humid air arriving on northeast winds. Modest cold
advection behind the front will bring temperatures down just a
little, with highs in the upper 70s to lower 80s.

High pressure will settle from Quebec to northern New England
Tuesday night and the first half of Wednesday. This will bring a
period of dry weather before clouds and moisture begin to increase
from southwest to northeast later Wednesday. A few showers may reach
the southwest corner of NY by late afternoon Wednesday. High
temperatures will move back into the low to mid 80s as a warmer
airmass moves quickly back into the region.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
Wednesday night and Thursday our attention turns to the remnants of
Alberto. Model guidance has been in excellent agreement with the
track and timing of this over the past few days, with the remnant low
moving through the central Great Lakes. While the low will track
well to our west, a plume of deep sub-tropical moisture will move
northward through the Ohio Valley and into the eastern Great Lakes,
supporting a few periods of showers from Wednesday night through
Thursday. While deep tropical moisture will cross the region, the
lack of forcing from a mid latitude synoptic front or other feature
will likely prevent a heavy rainfall risk.

Friday through Saturday the remnant low is forecast to interact and
merge with a northern stream trough, with a closed upper level low
developing over the eastern Great Lakes or Northeast States by later
Friday and Saturday. If this materializes it would bring unsettled
weather going into next weekend, with temperatures trending cooler.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
An area of showers with isolated thunder will move across the
Southern Tier of New York early this morning with localized MVFR
visibility restrictions in heavier rain. This will move into central
NY through mid morning, exiting the forecast area. MVFR cigs will
develop at JHW this morning as this area of rain departs. Outside of
this area of showers, widespread VFR conditions will continue.

This afternoon, scattered showers and thunderstorms are expected to
develop across WNY inland from the eastern Great Lakes. Localized
MVFR/IFR conditions are possible within the heavier rains, however
mainly VFR conditions expected to prevail outside of these storms.

Outlook...

Sunday night and Monday...Mainly VFR with isolated showers. Patchy
fog possible.
Tuesday and Wednesday...VFR.
Wednesday night and Thursday...VFR/MVFR. A chance of showers and
thunderstorms.

&&

.MARINE...
High pressure will remain anchored off the coast of the southeast
states through Memorial Day, with a weak pressure gradient in place
across the eastern Great Lakes. This will promote light winds and
flat wave action the majority of the time.

There may be a few widely scattered thunderstorms at times with
locally higher winds and waves.

&&

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

&&

$$

SYNOPSIS...Church
NEAR TERM...Church
SHORT TERM...Hitchcock
LONG TERM...Hitchcock
AVIATION...Church
MARINE...Church



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