559
FXUS61 KBUF 161516
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1116 AM EDT Tue Jul 16 2024

.SYNOPSIS...
Another cluster of strong to severe thunderstorms will cross the
region from west to east today, with localized torrential rainfall
and damaging winds possible. A few more showers and isolated
thunderstorms will continue tonight through Wednesday as a cold
front slowly crosses the eastern Great Lakes. High pressure will
build into the Great Lakes Thursday and remain through next weekend,
with an extended period of dry and less humid weather.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
...LOCALIZED SEVERE THUNDERSTORMS LIKELY AGAIN TODAY...

Our focus once again today is on severe weather potential. A
large and well defined MCV is emerging from a decaying MCS over
southeast lower Michigan late this morning is forecast by all
guidance to cross the eastern Great Lakes today. Overall, the
setup is very similar to yesterday, with the most notable
difference being the timing of the feature, roughly 3 hours
earlier in the diurnal cycle than the MCV yesterday. The MCV
will move across Western NY through early afternoon, possibly
too early to allow for sufficient destabilization to support
robust severe weather potential. The arrival time from the
Genesee Valley east into Central NY and the eastern Lake Ontario
region will be late enough to allow for a window of sufficient
destabilization to support a better chance of severe weather.

Update nudged back timing slightly but otherwise a severe
weather potential remains. SPC has issued a Severe Thunderstorm
Watch for most of the area, and has also upgraded Central NY to
an enhanced risk for severe weather.

Severe Weather Potential...

The strong MCV crossing the region today will again locally enhance
the severe weather potential, with the mesoscale circulation
providing more favorable low/mid level shear and convergence,
particularly in the southeastern quadrant of the MCV. The early
arrival of clouds and convection will limit destabilization in
Western NY, with SBCAPE of up to 1000 J/kg by mid to late morning.
Greater instability will develop from the Genesee Valley eastward
with a few extra hours of diurnal heating before convection, with
SBCAPE of 1500 J/kg or better. 0-6 km deep layer shear will be on
the order of 30-40 knots based on the latest HREF mean, although
locally higher values are possible as the MCV augments the low/mid
level wind fields.

Expect thunderstorms to expand rapidly across Western NY through
early afternoon. The initial lack of strong instability may
keep these storms sub- severe at first, although gusty winds and
locally heavy rainfall is certainly possible. The instability
and shear parameters along with organized mesoscale forcing from
the MCV suggest the initial development across Western NY will
grow upscale by midday to early afternoon, with high-res CAMS
guidance suggesting storm mode evolving into short bowing
segments with localized damaging wind risk from the Genesee
Valley into Central NY and the eastern Lake Ontario region.
Damaging winds will be the primary risk, with a secondary risk
for large hail, and a low but non-zero risk of an isolated
tornado given the influence of the MCV on the low level shear
environment.

The severe weather risk will end by early afternoon in Western NY,
mid afternoon in the Genesee Valley, and late afternoon or early
evening east of Lake Ontario.

Heavy Rain Potential...

PWAT values will remain in the 1.75"-2.0" range today. The very
moist environment and relatively deep warm cloud depth will continue
to support torrential downpours with any strong convection. The MCV
if moving quite fast, and should allow the storms to maintain enough
forward speed to keep the risk of flash flooding low. Nonetheless,
any training may support a localized minor flood risk.

A few more scattered showers and thunderstorms may develop later in
the afternoon and evening along the southern edge of the Lake Erie
breeze, mainly from the western Southern Tier into the Finger Lakes.
These will gradually taper off through the evening.

Overnight, the mid level trough and associated cold front will
approach slowly from the northwest. Increasing large scale ascent
and low level convergence ahead of these features will support an
increasing chance of showers and a few isolated thunderstorms again
late tonight, but with less coverage and intensity than today.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
A cold front will start this period on our western counties
doorstep, with the front slicing across the region through the
morning and early afternoon hours. A few showers, and later
thunderstorms will remain possible along and ahead of this front.
Greatest possibilities for thunder will be the Finger Lakes and east
of Lake Ontario where greater daytime insolation and developing CAPE
(MUCAPE of 500 J/KG) will be realized.

A longwave trough will enter into our region Wednesday night with
showers ending across eastern zones, and clouds thinning. Some
patches of fog will be possible with still a fair amount of humidity
to start the night.

A much drier airmass will build across our region later Wednesday
night and Thursday on a light northerly flow behind the passage of
the upper level trough. This will promote fair weather for Thursday
and Thursday night. Though temperatures will only be a few degrees
cooler Thursday than Wednesday, the dewpoints at least 10
degrees cooler will be more noticeable.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
This will be a spectacular stretch of weather, with a broad ridge of
high pressure expanding across the region. A weak cold front will
drop southward across the region Sunday, but its passage should
largely be rain-free with possibly an isolated shower east of Lake
Ontario. Otherwise, there`s good model agreement providing high
confidence in rain-free weather. Temperatures will be near normal
with daytime highs averaging in the mid 70s to lower 80s and
nighttime lows mainly in the mid 50s to lower 60s. A few colder
spots early Friday morning, and again early Saturday morning could
drop into the upper 40s east of both Lakes.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
An area of showers and thunderstorms associated with an upper
level disturbance will arrive in Western NY by late morning,
then move east across the rest of the area, reaching the eastern
Lake Ontario region by mid afternoon. This will bring a
likelihood of thunder and brief VSBY/CIG reductions across much
of the area, including all the terminals. Some storms may be
strong with localized high wind gusts. Mainly VFR conditions
will follow later today behind this round of showers and
thunderstorms. A few more storms may develop late afternoon
through evening from the Southern Tier into the Finger Lakes,
mainly east of KJHW and south of KROC.

Tonight, the evening showers and thunderstorms across the Southern
Tier and Finger Lakes will taper off. Overnight, an approaching cold
front and mid level trough may produce a few more showers and
thunderstorms with uneven coverage. Areas of MVFR/IFR CIGS will
develop later tonight through Wednesday morning.

Outlook...

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

Thursday through Saturday...VFR.

&&

.MARINE...
A period of moderate southwesterlies will develop on Lake Erie
today, with Small Craft Advisory conditions this afternoon.
Winds will be somewhat lower on Lake Ontario, but still enough
to produce a moderate chop this afternoon and evening.

Another cluster of thunderstorms will cross the eastern Great Lakes
today, with locally higher winds and waves. The timing is earlier
than yesterday, with the greatest chance of storms this morning
through early afternoon on Lake Erie and western Lake Ontario, and
midday through late afternoon for the eastern end of Lake Ontario.

A cold front will cross the eastern Great Lakes Wednesday. West to
northwest winds up to 15 knots will produce moderate chop at times
Wednesday through Thursday on Lake Ontario, but winds and waves are
generally expected to remain below Small Craft Advisory criteria.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Beach Hazards Statement until 8 PM EDT this evening for NYZ010-
     019-085.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LEZ020.
         Small Craft Advisory until 11 PM EDT this evening for
         LEZ040-041.

&&

$$

SYNOPSIS...Hitchcock
NEAR TERM...Apffel/Hitchcock
SHORT TERM...Thomas
LONG TERM...Apffel/Thomas
AVIATION...Apffel/Hitchcock
MARINE...Apffel/Hitchcock