459
FXUS61 KBUF 282347
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
747 PM EDT Fri Jun 28 2024

.SYNOPSIS...
Showers will develop across the region overnight as a warm front
approaches the area. The warm front will finish crossing the area
Saturday, with a trough quickly following later in the day,
resulting in occasional showers and scattered thunderstorms. A few
storms will contain locally torrential downpours along with the risk
of isolated strong wind gusts. Cooler and less humid weather will
return Sunday, although there will still be a few scattered showers.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
...Conditional Severe Weather Risk and Torrential Downpours on
Saturday...

Mid level clouds are thickening and lowering this evening across the
region. Regional radars show returns aloft moving into Western NY,
but an extensive layer of dry air is resulting in plenty of sub-
cloud evaporation. Expect mainly virga through the evening hours,
although some light showers may start to reach the ground by late
evening.

Tonight, a shortwave trough east of the Northern American Rockies
will move across the Northern Plains. A broad area of low pressure
will become more compact as it moves into the Upper Great Lakes. A
large pool of moisture across the Central Plains to Ohio Valley will
move east as additional moisture moves north from the southern
Atlantic and GOMEX. A southwest flow will increase with a 45kt low
level jet approaching the region overnight. The strengthening low
level jet and commensurate increase in isentropic upglide and
moisture transport will trigger shower development across the
region, especially later tonight. Forecast soundings show weak
elevated instability above a defined warm nose where warm air
advection will be taking place. A few isolated thunderstorms can`t
be ruled out overnight.

Heavy Rainfall...

Plume of deep moisture will settle into the eastern Great Lakes
Saturday. PWATS are forecast between 2-2.25 inches which is well
above the 90th percentile and could reach maximum values per KBUF
sounding climatology data. Additionally, high freezing levels and a
deep warm process layer will result in efficient rainfall rates in
any showers and thunderstorms that develop across the region. Given
the abundant moisture and organized forcing, there is a low chance of
localized flooding if storms train over the same areas repeatedly.
MBE vectors are quite small as well, suggesting the potential for
slowly propagating clusters of storms with locally heavy rainfall.
There is a Slight Risk of excessive rainfall across the western
Southern Tier and North Country where the heavy rainfall signal is
the strongest in high-res guidance, and a Marginal Risk of excessive
rainfall elsewhere.

Severe Weather Potential...

Moderate to strong low/mid level flow will overspread the eastern
Great Lakes overnight as the warm front approaches, with elevated
flow continuing through Saturday. This will result in a favorable
low level shear environment, with 0-1km SRH exceeding 200 m2/s2
overnight through a portion of Saturday. While the highest SRH will
be found along and ahead of the warm front, low level shear will
remain elevated even as the warm sector becomes established in the
wake of the warm front.

While shear will be quite impressive, instability (or lack thereof)
may end up being a limiting factor in severe weather potential.
Model guidance suggests widespread low clouds Saturday, along with
occasional showers. This would greatly limit instability if it
verifies. The severe weather risk is therefore conditional on
sufficient instability developing. If it does, all hazards may be on
the table with the potential for isolated damaging wind gusts, hail,
and even an isolated tornado.

The plume of moisture will move east of the region as a cold front
approaches Saturday night. Showers and thunderstorms will remain
possible, however the threat for severe storms and heavy rain will
slowly diminish from west to east with the departure of the deepest
moisture and loss of diurnal instability.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
A shortwave trough will round the base of the mid-level trough
causing the longwave troughing pattern to pull east out of the lower
Great Lakes by Monday. This pattern aloft will support a secondary
surface cold front to pass from west to east Sunday, bringing with
it continued chances for showers and thunderstorms.

Surface high pressure and associated dry air will begin to filter
east across the Great Lakes Sunday night. High pressure will then
slide east across the lower Great Lakes into New England Monday and
Tuesday. With the dry air filtering in across New York Sunday night,
showers and thunderstorms will scatter out from west to east. Then
dry and quiet weather will persist through Tuesday.

With regards for temperatures late this weekend and into the start
of the week, expect a cool Sunday with highs in the upper 60s and
low 70s across Western New York and the North Country, however low
to mid 70s will lie across the Genesee Valley and northern Finger
Lakes. Low to mid 70s will then linger Monday before a rebound in
temperatures on Tuesday with highs in the upper 70s to low 80s due
to exiting high pressure.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
A mid level shortwave trough passing across southern Canada will
push a cold front slowly across our region Wednesday night, with
this front lingering near the NYS/PA state line Thursday and Friday.
Shower and thunderstorms through this period, and muggy, with
dewpoints in the low to mid 60s.

Wednesday will be the hottest day, with 850 hPa temperatures in the
upper teens (potentially topping 20C per the 12Z ECMWF) supporting
mid 80s to lower 90s. Clouds and storms around Thursday and Friday,
along with slightly cooler air aloft behind the front, will keep
temperatures in the 80 degree range.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
VFR conditions will continue through most of tonight with thickening
and lowering mid level clouds. A few scattered light showers will
develop by late evening, with showers becoming more widespread
overnight through Saturday morning as a warm front crosses the
eastern Great Lakes. A 40+ knot low level jet will cross the region
overnight through Saturday, with a period of low level wind shear.

Saturday, the warm front will finish crossing the region, quickly
followed by another trough in the afternoon. This will result in
occasional showers and scattered thunderstorms, coming in several
different rounds from morning through evening. Abundant moisture
will allow some showers to become heavy, with VSBY restrictions in
areas of heavier rainfall. CIGS will deteriorate to widespread MVFR
Saturday, with areas of IFR across higher terrain and east of Lake
Ontario.

Outlook...

Sunday...VFR/MVFR with scattered showers.
Monday and Tuesday...VFR.
Wednesday...Mainly VFR.

&&

.MARINE...
An area of high pressure will move off the east coast
tonight...a warm front will approach the region from the southwest.
Winds will respond by swinging around to the south and increasing
overnight.

It will then become quite unsettled on Saturday. Widespread showers and
possible strong thunderstorms will develop in the wake of the
aforementioned warm front during the course of the day...while fresh
to strong southerlies will generate more pronounced wave action. The
offshore wind for most shorelines will keep the larger waves in
offshore waters, but it will be quite choppy nonetheless. Small
Craft Advisory conditions will develop over the northeast end of
Lake Ontario where the wind direction is at least shore parallel,
allowing for more fetch to build waves.

Fresh southwesterlies Saturday night will then increase further and
become westerly on Sunday when SCA`s will be more likely...
especially on Lake Ontario.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory from 7 AM Saturday to 2 AM EDT Sunday for
         LOZ045.

&&

$$

SYNOPSIS...Hitchcock
NEAR TERM...Hitchcock/HSK
SHORT TERM...EAJ
LONG TERM...Thomas
AVIATION...Hitchcock
MARINE...Hitchcock/HSK/RSH