538
FXUS61 KBUF 151110
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
710 AM EDT Wed May 15 2024

.SYNOPSIS...
Unsettled weather will continue today as a frontal boundary remains
stalled over the Lower Great Lakes, producing occasional showers and
a few scattered thunderstorms. The greatest coverage of rain will be
this afternoon inland from the lakes, with lower coverage of showers
close to Lake Erie and Lake Ontario. Weak high pressure will build
into the Lower Great Lakes later tonight and Thursday with mainly
dry weather before another front brings rain back to the region
later Friday through Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Weak mid level circulation and associated vorticity maxima drifting
across PA early this morning, is producing an area of showers that
is slowly moving northward across southcentral NY into central NY.
Meanwhile a weak surface cold front is slowly settling
south/southeast of Lake Ontario across western and northcentral NY.
This is providing increased low level convergence along the far
northwestern edge of this shower activity with a few light scattered
showers found across the Southern Tier and just clipping southern
and eastern Lewis County early this morning. Otherwise, mainly dry
weather with areas of patchy fog expected through the start of the
day, especially across areas south of Lake Ontario where a northeast
low level flow may advect fog over the lake inland.

The weak mid level circulation over eastern PA this morning will
consolidate into a mid level closed low over New Jersey by evening.
Meanwhile, the weak surface front will continue to linger over NY
through most of the day. Deep moisture and weak forcing will again
combine with modest diurnal instability to support increasing
showers and a few embedded thunderstorms through the day. The best
coverage of rain will start from the Southern Tier into the Finger
Lakes in the morning, then gradually spread north through the day.
Similar to today, the lowest chance of rain will be close to Lake
Erie and all but far eastern Lake Ontario where stable lake cooled
air lowers instability. Low level northeasterly flow will aid in
lake stabilized air off Lake Ontario making further inroads which
will help limit shower activity from the Niagara Frontier over to
Rochester as well. Overall flow will again be weak, supporting slow
storm motion with any thunderstorms and the risk for some locally
heavy downpours.

Tonight, lingering showers across inland areas will gradually
diminish and end as high pressure surface and aloft moves from the
Upper Great Lakes into the Lower Great Lakes overnight. Some patchy
fog may develop again, especially in areas that receive rainfall.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Drier conditions should take hold Thursday as a mid level low
pushes off the Mid Atlantic coast and ridging starts to build
into the region. Exception may be for areas east of Lake Ontario
and possibly the Finger Lakes, as Atlantic moisture wraps in on
the northern side of the departing low. This may allow for a
few showers or even an isolated thunderstorm to develop as weak
diurnal instability develops. High temperatures mainly in the
upper 60s to lower 70s, but northerly flow will keep the south
shore of Lake Ontario cooler.

Mid level ridge builds into the region Thursday night, any lingering
shower activity will end with a brief dry period for Thursday night.

Mid level ridge departs on Friday with moisture starting to increase
ahead of the next upper trough progressing into the eastern Great
Lakes Friday and Friday night. The associated surface low will lift
to near James Bay Friday night dragging a cold front toward the
region. Warm/moist advection and isentropic ascent ahead of the
front will drive increasing chances for showers from west to
east Friday into Friday night. Some marginal instability will
develop with the potential for some embedded thunder.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Shower activity continues through most of the long term period. A
trough moving through the area early Saturday will continue the
potential for showers through the morning. As the trough departs to
the east, shower activity will diminish through the day on Saturday.

The potential for showers will continue through the period, but to a
lesser extent then Saturday morning as a few different systems pass
by mainly to the north and south through the rest of the long term
period. A larger trough and mid-level low over the mid-Atlantic will
keep showers in or near the forecast area for much of the forecast
period. The driest day as of now looks like Sunday, but there is
still much variability among the models for the later portion of
the long term and into the new work week.

Temperatures during the period will be mainly above normal with
highs in the low to upper 70s for the lower elevations inland from
the lakes. For the higher terrain and areas closest to the lakes
with onshore winds highs will be in the low 60s to near 70.
Currently, Saturday will be the coolest day of the period, with some
warmer temperatures for Sunday-Tuesday with most of the three days
around the same temperatures for afternoon highs.

&&

.AVIATION /11Z WEDNESDAY THROUGH SUNDAY/...
Worst conditions early this morning are found across portions of
the Niagara Frontier and lower Genesee Valley where a moist
northeasterly upslope flow is producing LIFR/IFR CIGS and VSBY.
Other than IFR found across interior portions of the Southern Tier,
mainly VFR conditions across the area. A weak surface cold front is
slowly will settle south/southeast of Lake Ontario across western
and northcentral NY this morning. A few light scattered light
showers have developed across the interior Southern Tier, with just
a few widely isolated light showers found east of Lake Ontario early
this morning. Expect CIGS to deteriorate to mainly low VFR/MVFR
levels through the early morning hours for those locations currently
seeing VFR flight conditions.

Otherwise, low stratus will continue much of the day with mainly low
VFR/MVFR CIGS lower terrain and IFR CIGS higher terrain...and
possibly continuing well into the morning hours south of Lake
Ontario owed to moist northeasterly upslope flow. Patchy areas light
fog (marginal MVFR) may persist as well, mainly from the Genesee
Valley eastward. Showers will again increase in coverage, with the
greatest coverage of rain across inland areas and the lowest
coverage close to Lake Erie and all but far eastern Lake Ontario. A
few thunderstorms may develop again in the afternoon that will have
the potential to produce localized brief reductions in VSBY.

IFR/MVFR CIGS will continue into tonight with fog likely to expand
in coverage through the overnight once again. Lingering showers
across inland areas will taper off through the late evening/early
overnight hours.

Outlook...

Thursday...MVFR/IFR improving to VFR through the morning.
Friday...VFR. A chance of showers late.
Saturday...Areas of MVFR with showers likely.
Sunday...Mainly VFR with a chance of showers.

&&

.MARINE...
Generally light winds will continue through the remainder of the
week. Northeast winds in the 10-12 knot range will produce mainly
light chop on Lakes Erie and Ontario through tonight. Otherwise,
light winds will return Thursday as weak high pressure builds over
the eastern Great Lakes. An offshore flow will then develop Thursday
night and Friday with gentle to moderate southeasterly breezes in
advance of the next system approaching from the west.

&&

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

&&

$$

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