033
FXUS61 KBUF 060455
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1255 AM EDT Mon May 6 2024

.SYNOPSIS...
A cold front will push across the region overnight, producing a few
scattered showers from the Genesee Valley east to the eastern Lake
Ontario region. Areas of fog will also continue overnight. High
pressure will bring a return to dry weather Monday. The dry weather
will last through most of Tuesday before a warm front brings a
chance of showers and thunderstorms late Tuesday through early
Wednesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A cold front will continue to move slowly east across the area
overnight with a few scattered showers from the Genesee Valley
eastward. The most likely areas to see measurable rain overnight
will be east of Lake Ontario and also across Allegany County. Areas
of fog will continue overnight. The most widespread fog will be
driven by advection as a warm/moist airmass crosses the cold lakes.
Expect the Lake Erie fog, currently in the Buffalo Metro area, to
move south before daybreak into the western Southern Tier as
boundary layer flow veers to the northwest and north, with improving
conditions in Buffalo by daybreak. Fog will also develop over and
east/southeast of Lake Ontario late tonight and early Monday morning.

Weak surface high pressure will then build across the region on
Monday and Monday night. There will be a north to south clearing
trend during the day Monday. Fair weather Monday night, with
mostly clear skies outside of some lingering clouds near the
Pennsylvania state line which will be close to the stalled
frontal boundary.

Despite the cold frontal passage, afternoon sunshine will allow
temperatures to rise into the upper 60s to lower 70s on Monday.
Good radiational cooling Monday night with lows mainly in the
40s. Forecast hedges towards a wider diurnal spread (warmer
highs and cooler lows) due to the clear skies and light winds.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
On Tuesday the axis of surface-based ridging will slowly drift from
New York State to New England...while the leading edge of a
sprawling mid level trough and associated surface low over the north-
central states slowly works its way into the Upper Mississippi
Valley. As this does so...a warm frontal boundary snaking
southeastward from this system will slowly push northeast across the
Ohio Valley...with this feature drawing close enough to support the
potential for a few widely scattered showers/an isolated
thunderstorm across the Southern Tier later on in the afternoon.
Otherwise...the day should feature continued dry weather with just a
modest increase in cloud cover across far western New York. As for
temps...the general warm air advection pattern across our region
will allow highs to range through the 70s in many areas...though an
onshore flow will keep the south and southeastern shores of both
lakes notably cooler.

Tuesday night the warm frontal boundary will make its way across
western New York while also becoming increasingly wavy over time as
a supporting mid-level shortwave ripples eastward across the
central/eastern Great Lakes. This will bring a continued southwest-
northeast increase in cloud cover and eventually the likelihood of
some showers as the night progresses...with a few thunderstorms also
becoming possible due to the arrival of some weak elevated
instability. Otherwise it will be a notably milder night with lows
ranging from around 50 across the North Country to the mid and upper
50s south of the NYS Thruway.

On Wednesday the aforementioned shortwave will slide further east to
New England...with one or more surface waves along the now-stalling
frontal boundary eventually consolidating into a single broad
surface low over southeastern NY and southern New England. As this
occurs...any synoptically-driven showers and any embedded storms
should tend to taper off from west to east through the day. Latest
guidance suggests that this diminishing trend may even be quick
enough to support largely dry conditions across far western New York
for much of the day...though even there cannot completely rule out a
few additional widely scattered afternoon showers/storms as a
developing lake breeze convergence zone interacts with diurnally-
driven instability. High temps are a bit of a tricky call at this
juncture as the various guidance packages all show differing degrees
of cooling aloft behind this system...though a rough model consensus
suggests that readings may end up ranging from the mid-upper 60s
across the North Country to the mid-upper 70s across interior
portions of the Finger Lakes and Southern Tier.

Wednesday night a weak bubble of high pressure will slide across New
York State...before giving way to a sharp mid-level trough/surface
low making their way east from the Upper Midwest/Lower Ohio Valley
later on in the night. As a result we can expect partly cloudy skies
and largely dry/quiet weather Wednesday evening to eventually give
way to increasing clouds and renewed chance of showers across
Western New York by later on in the night. Otherwise...lows will
generally be in the upper 40s to lower 50s.

On Thursday the mid-level trough will make its way across the
central Great Lakes...with its attendant surface low gradually
becoming better organized as it slides east across the Upper Ohio
Valley and into far southwestern New York. Increasing moisture and
DCVA/isentropic upglide out ahead of this system will bring an
increasing likelihood of showers across our area from southwest to
northeast...with some weak instability also possibly supporting a
few embedded thunderstorms across the Southern Tier. With the
increased cloud and pcpn coverage expected...highs on Thursday will
be cooler than those of the preceding few days...with maxes ranging
from the lower 60s across the higher terrain to the mid and upper
60s elsewhere.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
A potent shortwave trough and surface low pressure system will track
along the 850H mid-level thermal boundary Thursday night though
Friday. This system will likely bring widespread chances for showers
and even some embedded rumbles of thunder. Cyclonic flow and along
with the trough overhead will result in overall cooler temperatures.
Highs will be found in the 50s for most locales Friday.

Chances for showers decrease Friday night and especially during the
day Saturday as shortwave ridging builds in and then moves through
the eastern Great Lakes.

After Saturday...the next upstream upstream trough approaches but
there are fairly large differences amongst the various guidance
packages. Will for now hold close to NBM guidance with the potential
for more unsettle weather beginning Sunday into next week.

Overall...this period will end on the cool side with below normal
highs temperatures(50s to low 60s).

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
A cold front will continue to move slowly east across the region
early this morning, exiting the eastern Lake Ontario region by 12Z
Monday. The front will continue to produce a few scattered showers
through daybreak, mainly east of Lake Ontario and near KELZ.

The bigger impact will be fog and low stratus through early morning
with areas of IFR/LIFR. Most of the fog is being driven by
advection, with a warm/moist airmass crossing the cold lake waters.
Off Lake Erie, the current area of fog directed towards KBUF/KIAG
will continue for a few more hours before moving south into the
western Southern Tier (including KJHW) before daybreak. Forecast
soundings show drier air quickly arriving at KBUF/KIAG by around 09Z
with quickly improving conditions for the busy morning push. The fog
will last through 12-13Z at KJHW before improving.

Some fog and low stratus will also form over and east/southeast of
Lake Erie through early morning, with some of this possibly
impacting KROC and KART briefly.

All of the fog and low stratus will scatter out by mid morning as a
much drier airmass moves into the eastern Great Lakes behind the
departing cold front. VFR will then prevail for the rest of today and
tonight with areas of cirrus.

Outlook...

Tuesday...VFR.

Tuesday night and Wednesday...VFR/MVFR. A chance of showers and
thunderstorms.

Thursday...VFR/MVFR. Showers likely with a chance of thunderstorms.

Friday...MVFR. Showers likely.

&&

.MARINE...
Negligible winds and waves through Tuesday. There may be some marine
layer fog over Lake Erie and Lake Ontario through early this morning
as a warm/moist airmass overlays the cold lake waters.

&&

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

&&

$$

SYNOPSIS...Apffel/Hitchcock/TMA
NEAR TERM...Apffel/Hitchcock/TMA
SHORT TERM...JJR
LONG TERM...AR
AVIATION...Hitchcock
MARINE...Apffel/Hitchcock