-- Discussion containing changed information from previous version are highlighted. --
264
FXUS61 KBUF 252036
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
436 PM EDT Tue Jun 25 2024

.SYNOPSIS...
Warm and humid conditions today will last into Wednesday, along with
increasing chances of showers and some thunderstorms, especially on
Wednesday. Cooler and less humid conditions expected Thursday and
Friday. Active weather returns Saturday as a cold front crosses the
region.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Surface ridge will continue to exit off to the east through this
afternoon. Strengthening southerly flow bringing wind gusts up to 40
mph this afternoon across far western New York. Earlier MCS has
nearly fall apart with some remnant showers moving across southern
Ontario/Lake Ontario. Some of this shower activity could brush the
eastern Lake Ontario region later this afternoon.

A weak cold front drops south into the region tonight with
additional chances for some showers or a isolated thunderstorm. The
best chances will again be found again across the North Country
closer to the support from the upper-level jet. Overnight low
temperatures should fall back into the 60s.

Wednesday should start off relatively quietly as the frontal
boundary working south overnight stalls out over the region. This
boundary waver back northward during the day as a frontal wave moves
north along it from the Ohio Valley. The western Southern Tier will
have the best chance to emerge into the warm sector, with the
potential that the warm sector lifts as far north as the I-90
corridor by afternoon. The coverage of thunderstorms and the
potential for severe weather will depend greatly on the position of
the frontal boundary with the degree of instability high depended
upon where the warm sector is located. Therefore, CAPE values remain
in question, but sufficient shear looks to be present, especially
along the Southern Tier, which lines up with the Marginal Risk for
severe storms maintained by the latest SPC Day 2 Convective Outlook.
Precipitable water values surge to near 1.5 inches bringing at least
some threat for heavy rainfall. The greatest risk of this will be
across the western Southern Tier which will lie closer to the track
of the passing frontal wave.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
-- Changed Discussion --
Steadier showers and storms will continue into Wednesday evening
from the western Southern Tier into the Finger Lakes region as a
wave of low pressure moves northeastward along the slow-moving wavy
frontal boundary draped across this region. Scattered lighter
showers will also be possible for areas north of the boundary before
the frontal wave responsible for all of this activity exits east of
the area by the early overnight hours, allowing this initial wavy
cold front to finally press southward out of our area. Another
shortwave trough will then dive southeastward out of the upper Great
Lakes, crossing the eastern Great Lakes region late Wednesday night
and Thursday. This feature will also help force a secondary cold
front southeastward through western and northcentral NY late
Wednesday night through the midday/early afternoon hours on
Thursday. With deeper moisture associated with the initial wave
having departed to our east, not expecting more than some scattered
lighter showers/isolated rumble of thunder as the boundary passes
through the area, mainly from the Genesee Valley eastward. Depending
on the speed of the front, a few showers may linger across eastern
areas through late morning/early afternoon Thursday, with areas
toward the North Country/SL Valley continuing with at least the
slight chance for a few diurnally driven light showers through late
in the day as the southern periphery of the passing shortwave aloft
grazes northern NY. Otherwise, a much more refreshing airmass will
advect in across the region in the wake of the frontal passage as a
dome of high pressure builds in from the west bringing dry weather
through Friday with comfortable temperatures and humidity levels. In
fact, below normal temperatures are expected Thursday with highs
ranging from the upper 60s to low 70s. Similar to the first part of
the work week, high pressure then slides east of the area Friday
with a warming southerly return flow boosting temperatures back near
normal with highs mainly in the mid 70s to low 80s.

A weak mid level ripple and associated low level warm frontal
segment will cross the area Friday night, with increasing chances
for showers and a few thunderstorms from west to east as the night
wears on. Of note will be the very humid airmass that advects into
the area behind the frontal passage. Dew points mainly in the
comfortable low to mid 50s range late Friday will surge into the mid
60s to near 70 Saturday morning. This will keep lows Friday night on
the warm side, especially across areas south of Lake Ontario with
low temperatures only falling back into the mid and upper 60s, a tad
cooler across the North Country.
-- End Changed Discussion --

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
A well defined shortwave trough will cross the Great Lakes Saturday,
deepening an area of surface low pressure that will advance from the
northern Great Lakes through southern Quebec Saturday. A deep
southerly flow ahead of this trough will advance moisture northward,
increasing PWATs to nearly 2 inches across the eastern Great Lakes
region. Showers and thunderstorms are expected to form Saturday and
continue through the evening hours of Saturday before a cold front
crosses the region from west to east late. The timing of the cold
front, cloud cover holding instability back to around 750 J/KG or
less and poor mid level lapse rates under 6 C/KM are not favorable
for strong to severe storms. However, 0-6 km bulk wind shear values
35 to 45 kts could aid in strength to the storm if any taller storms
can develop.

Behind the cold front a much drier airmass will settle upon the
eastern Great Lakes. We`ll still have to contend with a few showers
Sunday with the passage of the upper level trough, but drier air and
eventually cooler airmass (mid single digit Celsius 850 hPa
temperatures) will bring a cool night Sunday night with lows in the
mid 40s to mid 50s. Fair weather Monday, with comfortable dewpoints
in the 40s and 50s with high pressure nearby. Tuesday a return
southerly flow along with the approach of a shortwave from the west
may trigger a few showers or thunderstorms.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
Mainly VFR expected to remain across all area terminals into this
evening. South to southwest winds of 30 to 35 knots at KBUF and KIAG
and possibly KROC will diminish after 00Z.

Tonight...a mix of VFR/MVFR Cigs will be found across most area
terminals. Lower Cigs (IFR) may materialize across the S. Tier to
include KJHW.

Outlook...

Wednesday...MVFR/VFR with a chance for showers most area terminals.
Showers and a chance of thunderstorm across the Southern Tier.
Thursday and Friday...Mainly VFR.
Saturday...Localized restrictions with shower likely and a
chance of thunderstorms.
Sunday...Mainly VFR.

&&

.MARINE...
A south to southwest wind flow picks up across Lake Erie and the
western end of Lake Ontario today. Waves will be offshore, but a
period of Small Craft conditions will develop this afternoon into
the evening. SCAs remain in effect for Lake Erie beginning at 16Z
though 03Z this evening and for the Upper Niagara River until 00z.
Winds will remain elevated on area the lower Great Lakes tonight
producing light to moderate chop on both lakes.

Lighter winds and wave action is expected Wednesday but there will
be a better coverage of thunderstorms for Lake Erie.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
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...AR/TMA
NEAR TERM...TMA
SHORT TERM...JM
LONG TERM...Thomas
AVIATION...AR/TMA
MARINE...AR/TMA