222
FXUS61 KBUF 041340
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
940 AM EDT Sat May 4 2024

.SYNOPSIS...
A weak trough will dissipate over the region today. While this
feature may produce a few spotty showers, much of the time will be
rain free. A wave of low pressure will then move from the Ohio
Valley this evening across the eastern Great Lakes overnight through
Sunday, bringing a round of widespread rain to the region. The rain
will gradually taper off to scattered showers from west to east
Sunday, before ending entirely Sunday night. High pressure will then
build into the Great Lakes Monday with a return to dry weather.

&&

.NEAR TERM /THROUGH SUNDAY/...
Radar shows some scattered showers east of Lake Ontario and
in the Genesee Valley and Finger Lakes this morning. These
showers are quite sparse in coverage.

The weak trough will wash out today over the eastern Great Lakes.
Lingering mid level moisture will keep plenty of cloud cover in
place, but overall the lack of forcing will only support spotty
showers at best. Most areas will stay dry, but can`t rule out
scattered showers this afternoon.

A well defined mid level shortwave will then move from the Ohio
Valley this evening northeast across the eastern Great Lakes
overnight, generally following the path left by the remnants of the
trough that washes out over the area today. A 40+ knot southerly low
level jet ahead of the trough will bring a period of enhanced
convergence and low level moisture transport overnight. This will
combine with forcing from the shortwave to produce a fairly
widespread area of rain moving from southwest to northeast across
the region. Low stratus may intersect some of the higher hills
overnight through Sunday morning, resulting in patchy fog across
higher terrain.

Sunday, the mid level trough and associated forcing and deep
moisture will continue to move slowly northeast. Widespread rain
early in the day will gradually taper off to scattered showers from
west to east. The widespread rain should end in Western NY fairly
early in the day, while it will continue most, if not all day east
of Lake Ontario.

While the widespread rain will end across Western NY, an upstream
cold front will move into the far western end of the state by late
afternoon. This will combine with modest diurnal instability and
lake breeze convergence zones to support a few more scattered
showers in the afternoon and evening. Enough instability may develop
to support a few thunderstorms as well across Western NY.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
The synoptic set up heading into Sunday night will feature a upper
level trough just north of the Great Lakes. The axis of this trough
will then pivot across the Canadian provinces of Ontario and Quebec
by Monday morning. A potent shortwave diving south into the trough`s
base Monday will cause the longwave trough to rotate east into the
Canadian Maritimes Monday night.

Down at the surface, low pressure centered over eastern Quebec will
continue to track northeast into the Canadian Maritimes, dragging
its associated surface cold front across the region Sunday night.
Meanwhile, surface high pressure across the central Great Lakes will
begin to advect east towards the eastern Great Lakes. Rain showers
ahead of the front will then finish crossing from west to east
Sunday night.

Surface high pressure will continue to advect east across the area
Monday and Monday night, resulting in a period of dry weather. Skies
will clear from northwest to southeast throughout the day, however a
disturbance passing east across the Ohio Valley towards the Mid-
Atlantic will support clouds to linger across the New
York/Pennsylvania state line.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
A broad mid and upper level low over the northern Rockies and Upper
Plains Tuesday will gradually drift east across the northern half of
the contiguous United States throughout the remainder of the work
week. The track and progression of this low continues to have timing
and placement differences which also impacts the strength, timing
and placement of shortwave disturbances rotating through this
feature. This being said forecast confidence continues to remain
low.

Overall at the time of this update, expect this system to result in
unsettled weather with frequent opportunities for showers and some
thunderstorms throughout the Wednesday through Friday timeframe.
This being said the whole timeframe will not be a wash out, and a
few breaks in shower activity will be likely.

Now regarding temperatures for the end of the week, expect highs to
continue to average between 5 to 10 degrees above normal.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
VFR will prevail for the bulk of the area, although some
MVFR/IFR low stratus will continue across the higher terrain of
the Southern Tier through mid to late morning. There will
continue to be a few spotty showers today, but much of the time
will be rain free as the trough washes out overhead. VFR will
prevail with a wealth of mid level clouds.

Another wave of low pressure will move from the Ohio Valley this
evening across the eastern Great Lakes tonight. This will bring a
period of fairly widespread rain spreading from southwest to
northeast across the area from late evening through the overnight.
CIGS will deteriorate to widespread MVFR/IFR shortly after the rain
begins. Any pockets of moderate rain will bring short term VSBY
restrictions, and the low stratus may intersect some of the higher
hilltops overnight through Sunday morning with some patchy
fog/mountain obscuration across the high terrain. A 40+ knot low
level jet will also produce some low level wind shear overnight.

Outlook...

Sunday...Widespread MVFR/IFR in the morning in rain. Improving to
mainly VFR from west to east in the afternoon and evening as the
rain tapers off. Chance of a few widely scattered thunderstorms in
the late afternoon and evening across Western NY.

Monday and Tuesday...VFR.

Wednesday...VFR/MVFR. Chance of showers with a slight chance of
thunderstorms.

&&

.MARINE...
Moderate southeast winds today through Sunday 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 Sunday as a weak
trough moves across the eastern Great Lakes.

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...Apffel/Hitchcock
SHORT TERM...EAJ
LONG TERM...EAJ
AVIATION...Hitchcock
MARINE...Hitchcock