504
FXUS61 KBUF 181707
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
107 PM EDT Wed Jun 18 2025

.SYNOPSIS...
Showers and thunderstorms continue this afternoon and early evening,
with heavy rainfall and gusty winds being the main hazards. The cold
front to our west will cross our region late tonight through
Thursday with showers, thunderstorms and gusty winds before lower
humidity and more comfortable conditions settle into the region for
Thursday night and Friday. Unseasonably warm temperatures and
increased humidity begin late this weekend through the start of the
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Latest satellite and radar shows storms quickly developing along a
lake breeze boundary east of Lake Erie early this afternoon.
Additional storms have been developing across southwest Ontario that
will continue to move east towards Niagara Co over the next few
hours. Per the latest CAMs, showers and thunderstorms will continue
this afternoon across western NY with the prefrontal environment as
well as with another round potentially overnight with the cold
frontal passage. Latest SPC mesoanalysis has 1000-1500 J/kg of
MLCAPE with up to 30 kt of effective shear more conducive of
multicellular convection with heavy rainfall (more details below)
and strong downburst winds as the main hazards. SPC`s Marginal Risk
for Severe Thunderstorms that clips Chautauqua Co is more focused on
the remnants of convection over the Midwest with a progressive
shortwave. Plenty of uncertainty surrounding upstream development
with considerable spread highlighted in the CAMs, but any remaining
storms with the convective complex will likely not arrive across
western NY until after 11 PM Wednesday.

Heavy Rainfall: Latest NAEFS and EC guidance shows abnormally high
PW values across western NY this afternoon. and forecast soundings
continue to suggest moist profiles through the column with skinny
CAPE and warm cloud layer depth >10kft. Additionally, experimental
guidance has suggested that precipitation accumulations with
afternoon thunderstorms could exceed flash flood guidance,
specifically around the Finger Lakes region headed into this
evening. One limiting factor will be that storm motions will be
close to 20 kt reducing residence time over specific areas, however
initial storm motions have be parallel to the lake breeze boundary
off of Lake Erie with training storms. Will need to continue to
monitor storm development through this afternoon and evening for any
potential flash flooding hazards as MRMS QPE with initial storms
have shown the capability of 1.5+ inch per hour rates.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
Gusty winds are expected across the Niagara Frontier Thursday
morning with a 998mb surface low to our northwest traversing across
southern Ontario. 850mb winds will be above the climatological 99th
percentile for mid-June, around 45 kt. Low-level CAA behind the
front will support vertical momentum transport enabling winds
gusting 40-50 mph. Latest NBM has been slowly trending upward with
probability of wind gusts exceeding 41 kt still low (15-25%).
Decided to hold off on any headlines for portions of the Niagara
Frontier east towards Rochester, but upcoming shifts will continue
to monitor the potential need for an advisory.

With the cold front still moving through the area, showers and
thunderstorms look to develop midday across the Southern Tier
through the Finger Lakes region where MLCAPE will be marginal (~500
J/kg), but forcing will be enough to support development. Shear and
instability profiles will be better for development of organized
convection farther east, especially in north-central NY east of Lake
Ontario. Strong downburst winds and heavy rainfall will be the main
hazards once again. By late Thursday afternoon into the evening, the
500mb trough axis will be passing overhead with any storms
associated from the surface cold front well off to the east of the
CWA, but a few lingering showers may persist.

As height rises begin across the central CONUS, a few shortwave
disturbances still appear to pass in the flow before temperatures
warm up across western NY late in the weekend. The first of these
disturbances will pass Friday afternoon into the evening with
showers developing under northwest flow aloft.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
...Dangerous Heat Sunday Through Tuesday...

A strong ridge will build into the eastern half of the CONUS during
the period. This will lead to increasing heat and humidity through
the weekend and into the first half of next week. While the ridge
and associated sfc high will provide dry weather for a large chunk
of the period, there will be the potential for showers and
thunderstorms early on in the period from Saturday afternoon into
the first part of Sunday morning. A ridge-runner complex of
thunderstorms within a northwest flow will cross a portion of the
area during this time. Confidence in the exact track/location is low
still among guidance with a variety of solutions still, but the main
focus is from Rochester and points east, including far enough north
to miss most of the North Country as well.

500 hPa heights building to around 596dm will support hot and humid
conditions. Afternoon high temperatures will reach the mid 80s to
mid 90s for Sunday through Tuesday. Some upper 90s will be possible
for the warmer interior lower elevations on Monday and Tuesday. Heat
index values in the mid 90s to around 100 degrees will also be
possible for Sunday through Tuesday in some locations.

Shower potential will increase for late Tuesday into Wednesday as
the next system approaches from the northwest, but guidance is still
uncertain on this potential. Wednesday also looks a bit cooler, but
above normal. Temperatures for Wednesday are also still uncertain
somewhat as well and dependent on the potential for a cold front to
move through the region.

&&

.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
MVFR ceilings this morning have lingered around KBUF and KIAG, but
satellite imagery as of this morning has shown thinning of low-level
clouds. Showers and thunderstorms have been developing across
western NY early this afternoon and will continue into the evening.
Thunderstorms moving overhead any terminals will result in
significant reductions in visibility due to heavy rainfall along
with gusty winds. These storms will continue to move east from the
Lake Erie shoreline with another round of overnight showers and
thunderstorms likely, especially for KBUF, KIAG, KJHW, and
surrounding terminals after 03z. Gusty southwest winds up to 40 kt
are expected Thursday morning through the early afternoon from the
Niagara Frontier east towards KROC.

Outlook...

Thursday Night...VFR/MVFR with showers and thunderstorms likely.
Breezy morning synoptic winds.

Friday...Mainly VFR. A chance of showers and thunderstorms, mainly
east of KROC.

Saturday...Mainly VFR. Increasing chances for showers and
thunderstorms.

Sunday and Monday...Mainly VFR.

&&

.MARINE...
A cold front will stall to our west today, with a southwest push of
wind across the Lower Great Lakes that generally will remain 10
knots or less through the day as lake breeze circulations become
established with the inland warming. A light chop will be found on
the northeast portions of the Lakes.

Tonight a wave of deepening surface low pressure on this stalled
front, advancing from the Ohio Valley to northwest of the Lower
Great Lakes will bring an increase in the southwest winds late
tonight and into Thursday morning. Sustained southwest winds well
over 15 knots will bring likely small craft advisories to the Lower
Great Lakes Thursday.

These winds will veer to westerly and then northwesterly tomorrow
night behind the cold front, with ample speed to support waves of 4
feet or great on Lake Ontario deep into Thursday night.

&&

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

&&

$$

SYNOPSIS...Brothers/Thomas
NEAR TERM...Brothers
SHORT TERM...Brothers
LONG TERM...SW
AVIATION...Brothers
MARINE...Thomas