Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 271748
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
148 PM EDT Sun May 27 2018

.SYNOPSIS...
A few 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/...
Early this afternoon, a weak shortwave across central New York
will continue to exit to the east. This shortwave is subtle,
but there is some very weak ridging behind it, which is limiting
the development of convection behind it. The most impressive
area of showers and thunderstorms is in far northern Jefferson
county which was well handled by mesoscale guidance. Otherwise,
the only other showers shown on radar are scattered showers
across the western Southern Tier which have been overdone by
guidance thus far. These should intensify along the lake breeze
boundary through mid afternoon before tracking east and
weakening late this afternoon. Based on this, have lowered PoPs
with the latest forecast update, due to the sparse nature of the
convection. The severe risk remains minimal due to weak winds
aloft, however locally heavy rainfall is still a possibility in
a few storms.

Temperatures will be in the mid 70s to lower 80s this
afternoon, coolest near the lake shores and in the North
Country.

Tonight, any lingering showers and storms will quickly diminish with
the loss of diurnal heating. The moist boundary layer air with
dew points in the mid 60s will result in fog development
tonight. This should be limited to areas west of Rochester since
a modest southerly flow will result in downsloping there. Winds
will be weaker to the west of this, allowing radiational fog to
develop in the Southern Tier valleys. Also, interaction with the
relatively cool waters on Lake Erie will result in fog and
stratus on the lake which will likely spread into the Niagara
Frontier tonight. Temperatures will remain mild with lows in
the upper 50s to lower 60s.

&&

.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 /18Z SUNDAY THROUGH FRIDAY/...
There will be patchy MVFR cigs this afternoon, with otherwise
mainly VFR conditions. Scattered showers and thunderstorms will
develop, but should largely be inland from TAF sites. Localized
IFR conditions are possibly in any showers or storms.

For tonight, the potential for fog is the main concern. For
ROC/ART a southerly flow should downslope which is likely to
prevent any fog. It`s a different story at BUF/IAG where a light
SSW flow will likely bring lake fog and stratus onshore. This
is a challenging forecast, but this is likely to result in a
period of IFR or lower conditions late tonight, lasting well
into the morning hours on Monday. Meanwhile, valley fog will
develop which is likely to impact JHW. In each case, there is a
potential for locally dense fog.

Outlook...

Monday night...VFR.
Tuesday and Wednesday...VFR.
Wednesday night...VFR/MVFR. A chance of showers and thunderstorms.
Thursday and Friday...MVFR. Showers and thunderstorms likely.

&&

.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.

Areas of fog will develop tonight and last through Monday. There
also may be a few widely scattered thunderstorms at times with
locally higher winds and waves.

&&

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

&&

$$

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



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