856
FXUS61 KBUF 050801
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
401 AM EDT Sun May 5 2024

.SYNOPSIS...
A mid level disturbance will cross the region today with widespread
rain moving from southwest to northeast across the area. The
widespread rain will be followed by a few more showers this
afternoon and this evening, and possibly a few isolated
thunderstorms in Western NY. Rain will then end from west to east
later tonight, with high pressure bringing a return to dry weather
Monday. The dry weather will last through most of Tuesday before a
warm front brings a chance of showers and thunderstorms late Tuesday
through Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Radar imagery showing a solid area of widespread rain covering most
of the area early this morning. The widespread rain will continue
through early to mid morning. Most of the rain is light, although
there will be a few pockets of moderate rain at times.

A mid level shortwave will cross the eastern Great Lakes through the
first half of today, with DPVA ahead of the wave bringing a period
of large scale ascent to the region. A 40 knot SSW low level jet
will continue to aid in low level moisture transport through this
morning. The combination of forcing and moisture will continue to
support widespread rain east of the advancing mid level trough axis.
The widespread rain will last through early to mid morning across
Western NY, midday for the Genesee Valley and western Finger Lakes,
and mid to late afternoon east of Lake Ontario.

Expect a general drying trend for several hours after the widespread
rain tapers off, although a few spotty showers may continue. An
upstream cold front will reach Western NY early this evening. A
narrow axis of modest diurnal instability will develop just ahead of
the cold front, supporting a broken line of showers and a few
thunderstorms over southern Ontario and also northeast Ohio and
northwest PA by late afternoon. This broken band of showers and a
few thunderstorms will enter Western NY early this evening. The cold
front will continue east overnight, with the broken band of showers
crossing the Genesee Valley late evening before reaching the eastern
Lake Ontario region after midnight. Diminishing instability will
bring an end to the thunder potential by late evening.

Low level flow will become quite weak along and behind the cold
front tonight, and drier air will lag behind by several hours.
Abundant low level moisture and weak flow will likely allow areas of
fog to develop from late evening through the overnight, with some of
this fog possibly lasting through early Monday morning.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Monday and Monday night, a few lingering showers/sprinkles over the
far eastern portions of the forecast area will be possible early in
the morning behind a passing cold front. Otherwise, mainly dry
conditions for the rest of the area with increasing sunshine from
northwest to southeast as an area of elongated high pressure and
increased ridging pushes into the region. Daytime highs in the low
60s for the higher terrain to the east of Lake Ontario and for areas
along both lakes where onshore flow will cool temperatures. Low 70s
expected for the lower elevations. Nighttime lows in the low to mid
40s.

On Tuesday the surface ridge axis will slowly drift east to New
England weakening in the process...while the leading edge of a
sprawling mid level trough and associated surface low over the north-
central states slowly works its way into the Upper Mississippi
Valley. As this does so...a warm frontal boundary snaking
southeastward from this system will slowly push northeast across the
Ohio Valley. While this latter feature could draw close enough to
support the potential for a couple widely scattered showers across
the Southern Tier later on in the afternoon...the day should
otherwise feature continued dry weather with just a modest increase
in cloud cover across far western New York. With our airmass
starting to warm again highs should generally range through the
70s...though it will again be a bit cooler along the lakeshores due
to onshore flow.

Tuesday night the various guidance packages suggest that the warm
frontal boundary will lift further northeastward and into our region
while also becoming increasingly wavy as a supporting mid-level
shortwave ripples eastward across the central/eastern Great Lakes.
This will bring a general southwest-northeast increase in cloud
cover and eventually the likelihood of some showers as the evening
progresses...with a few thunderstorms also becoming possible due to
the arrival of some weak elevated instability. Otherwise it will be
a notably milder night with lows ranging from around 50 across the
North Country to the mid and upper 50s south of the NYS Thruway.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The long term period continues to look wet with at least a chance of
showers for the entire forecast area each day. A mid/upper level low
over the northern Rockies will slowly track east, opening to a large
scale trough through the second half of the week.

Earlier in the week with the trough/mid-level low to the west,
periods of weak ridging over the region will give way to developing
sfc lows and shortwave troughs that will bring an influx of GOMEX
moisture north into the region. Moisture and large scale synoptic
lift will provide for periods of showers with some breaks in the
precip.

The larger trough will setup over the region by Friday, and persist
through at least the weekend. This will provide for several rounds
of showers, especially as different shortwave troughs track
through/around the larger trough. Cyclonic flow and the trough in
general over the region will also result in cooler temperatures.

Embedded thunderstorms will be possible at times, especially during
the middle of the week when instability will be a bit better than
later in the week.

Temperatures will start out above normal with highs in the mid 60s
to upper 70s from the higher terrain east of Lake Ontario to the
lower elevations of WNY respectively. Day-to-day cooling is then
expected through the rest of the period as the trough moves into the
region. Below normal high temperatures are expected for Saturday
with temperatures only reaching the low 50s to near 60 for the
afternoon.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
A mid level shortwave will cross the region from southwest to
northeast this morning, producing areas of rain in the process. The
most widespread rain will fall across Western NY through mid
morning, across the Genesee Valley and western Finger Lakes through
midday, and east of Lake Ontario through mid afternoon. Following
the widespread rain, a cold front will move into Western NY late
this afternoon and evening, then move east across the remainder of
the area overnight, producing a few more showers. The cold front may
produce a few isolated to widely scattered thunderstorms as well,
mainly across Western NY from late afternoon through mid evening.
VSBY will be VFR most of the time, although any pockets of heavier
rain will produce short lived VSBY restrictions.

CIGS will deteriorate to widespread MVFR with higher terrain IFR
before daybreak as the low levels saturate with widespread rain. The
widespread lower elevation MVFR CIGS and higher terrain IFR CIGS
will continue most, if not all of today. The lower elevations will
likely deteriorate further to IFR this evening along and behind the
cold front. IFR CIGS will continue to linger overnight following the
weak cold front. Weakening surface winds and abundant low level
moisture may also allow areas of fog to develop overnight with areas
of IFR VSBY.

Outlook...

Monday...Areas of IFR in low stratus and fog early, improving to
VFR.

Tuesday...VFR.

Tuesday night and Wednesday...VFR/MVFR. Chance of showers with a
chance of thunderstorms.

Thursday...VFR/MVFR. Showers likely with a chance of
thunderstorms.

&&

.MARINE...
Moderate southeast winds through this morning will produce choppy
conditions on the lakes, mainly in the offshore and Canadian waters
given the largely offshore wind component. Winds will then become
southwest and decrease from west to east today as a weak trough
moves across the eastern Great Lakes. There may be some marine layer
fog over Lake Erie and Lake Ontario this afternoon through tonight
as a warm/moist airmass overlays the cold lake waters.

Generally light winds are then expected Monday through Tuesday with
a weak pressure gradient in place across the eastern Great Lakes.

&&

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

&&

$$

SYNOPSIS...Hitchcock
NEAR TERM...Hitchcock
SHORT TERM...JJR/SW
LONG TERM...SW
AVIATION...Hitchcock
MARINE...Hitchcock