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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBUF 150908
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
508 AM EDT Mon Apr 15 2024

.SYNOPSIS...
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A weak boundary will linger near the Saint Lawrence Valley,
bringing a few showers to the North Country today. Otherwise,
high pressure will build across the region with a return to
drier weather for the start of the new work week that will last
through at least Tuesday. Some unsettled weather will return by
midweek as a weakening area of broad low pressure moves into the
Great Lakes.
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&&

.NEAR TERM /THROUGH TUESDAY/...
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A few scattered light showers moving across the Saint Lawrence
Valley early this morning, with the southern edge just scraping
northern portions of the North Country. Otherwise, surface high
pressure building into western NY keeping things dry elsewhere to
start the day.

Ridging will continue to build into the region today in the wake of
the cold front, keeping a mainly dry forecast intact from the Finger
Lakes westward. Meanwhile, the base of an upper level trough will
linger across northern New York. A shortwave rotating southeast
through the base of the trough will send a secondary boundary toward
the Saint Lawrence Valley. This may develop some scattered light
showers from time to time, mainly across the eastern Lake Ontario
region, with best chances toward the Saint Lawrence Valley and far
northern NY closer to the surface boundary. Expect seasonable
temperatures with highs lower to mid 50s east of Lake Ontario, and
mid 50s to near 60 across western New York, with some lower 60s for
the traditional warmer spots.

Upper level trough pushes east into New England tonight making way
for ridging surface and aloft to build east across western and
northcentral NY. Surface ridge builds right over our area Tuesday,
while the axis of an amplifying upper level ridge will slowly slide
east from the upper to central Great Lakes during this same
timeframe. This will bring a well-deserved period of dry weather and
relatively light winds to our region. Airmass will modify some by
Tuesday allowing daytime highs to climb into the 60s for many areas
south of Lake Ontario, with 50s right along the Lake Ontario
shoreline into the eastern Lake Ontario region.
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&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
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Surface high pressure over Hudson Bay will extend south across the
eastern Great Lakes Tuesday night. As this area of high pressure
slides east, a weakening low pressure system is expected to slowly
move across the Midwest and into the Great Lakes region Wednesday
through Thursday. Thereafter, it will be engulfed by a secondary low
pressure system over Manitoba, leading to a shallow but stubborn
upper level troughing pattern across much of the Northeast.

This will system will ease a pair of warm frontal boundaries through
the forecast area from the southwest Tuesday night into Wednesday,
followed by a increasingly diffuse cold front late Wednesday night
into Thursday morning. While Tuesday night will be dry albeit
increasingly cloudy as surface high pressure remains in control over
the region, precipitation chances will ramp up from the west
Wednesday morning and remain elevated as a slug of GOMEX-based
moisture is drawn northward into the system. The main warm frontal
boundary is expected to slow, if not completely stall out over the
region as it runs up against the strong ridge over New England. This
will cause sharply lower precip chances for the far North Country
compared to areas south and west. That is, until Thursday when the
cold front working in from the west forces the main swath of showers
through the region. Slightly better dynamic and instability
parameters with this front could bring a few embedded thunderstorms
to WNY Wednesday afternoon and evening, though any storms or heavier
showers are expected to weaken as they move east. Far western NY is
then expected to begin drying out by Thursday evening.

Temperatures through the midweek timeframe will heavily depend on
the timing of the frontal passages and precipitation. Tuesday night
in particular will feature a wide spread in low temperatures as the
primary warm front nears the region, ranging from the upper 40s
along the Lake Erie shoreline to the low 30s across the North
Country. Thereafter, temperatures should average on the mild side
Wednesday through Thursday with highs in the upper 50s to low 60s
both days.
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&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
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A progressive, narrow ridge of high pressure will quickly move into
the region Thursday night leading to a brief period of drier weather
across the region overnight. By Friday, a larger secondary low
pressure system will be in the process of stacking in the vicinity
of James Bay. This increasingly positively tilted trough will swing
a pair of cold fronts through the region between Friday and
Saturday. This will lead to renewed chances for rain showers by the
end of the week as well as a day-to-day cooling trend. Drier weather
is expected to arrive by Sunday, though a fast-moving shortwave
racing ahead of the building ridge over the nation`s midsection may
bring a few additional showers.

While temperatures are expected to still average above
climatological norms Thursday night through Friday night, by Sunday
temps are expected to sink a few degrees below normal. Temps may
even cool enough Saturday night to support a few wet flakes across
the higher terrain east of the lakes.
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&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
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Other than some passing mid and upper level clouds at times,
high pressure will bring VFR conditions for the bulk of the area
through the 06Z TAF period.

The exception will be across the Lake Ontario region (KART) through
this morning, owed to a lingering surface boundary across the Saint
Lawrence Valley that will bring some low VFR/MVFR CIGS to the lower
areas (KART), with IFR CIGS for the higher terrain inland from Lake
Ontario through mid to late morning. Some patchy fog may also reduce
VSBYS to MVFR at times. There may also be a few passing scattered
light rain showers across the North Country. CIGS at KART should be
predominantly low VFR this afternoon, then become VFR sometime this
evening.

Winds will generally remain light, although there may be some gusts
of 15-20 knots late this morning into the afternoon, with a few
gusts to 25 knots not out of the question.

Outlook...

Tuesday...Mainly VFR with a chance of showers late Tuesday night
over western NY.
Wednesday and Thursday...MVFR/VFR with showers likely.
Friday...MVFR/VFR with a chance of showers.
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&&

.MARINE...
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High pressure building across the lower Great Lakes will support
mainly gentle to moderate breezes on the Lakes, keeping waves 2 feet
or less on Lake Erie. However, westerly breezes will be a bit
stronger on Lake Ontario today as a boundary slides into the Saint
Lawrence Valley tightening up the surface pressure gradient some as
the area of high pressure continues to build in from the west. This
will cause some choppy conditions, especially across the eastern
half of Lake Ontario where conditions will approach Small Craft
Advisory criteria. However, current forecast keeps conditions just
shy of headline criteria.

High pressure will further build over the both Lakes for Monday
night and Tuesday with mainly light to gentle breezes and no more
than some light chop.

Pressure gradient will tighten Tuesday night as strong high pressure
ridge remains across eastern NY and New England and an area of low
pressure moves from the upper Mississippi Valley eastward into the
upper and central Great Lakes. Winds will veer from westerly to
easterly on both Lakes and strengthen. This will be especially the
case across Lake Ontario where Small Craft Advisories will likely be
needed for the mid week timeframe. Easterly flow will produce the
highest waves across the western half of Lake Ontario.
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&&

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

&&

$$

SYNOPSIS...JM
NEAR TERM...JM
SHORT TERM...PP
LONG TERM...PP
AVIATION...JM
MARINE...JM