319
FXUS61 KBUF 081923
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
323 PM EDT Mon Jul 8 2024

.SYNOPSIS...
An axis of high pressure stretching across the region this evening
will slowly push east across New england overnight and Tuesday.
While this will guarantee fair dry weather for the vast majority of
the region...we will experience an increase in high and mid level
clouds along with a shift back to more humid conditions. The remnants
of Beryl will then move into the region late Tuesday night into
Wednesday night when a soaking rainfall can be expected. Most areas can
expect one to two inches of rain...although higher amounts will be
possible across the Southern Tier and Eastern Lake Ontario region.

&&

.NEAR TERM /THROUGH TUESDAY NIGHT/...
Fair dry weather will persist throughout the region tonight...as an
axis of high pressure will slowly exit across New England. High and mid
level clouds will start to stream into the region on the backside of
the high pressure...while a deepening southerly flow will allow more
humid air to return. As a result...tonight will be a warmer night with
mins generally in the mid 60s to as high as 70.

Warm and increasingly humid conditions are then anticipated for
Tuesday...as a weak cold front approaching from the north will
basically dissolve over our region during the afternoon and evening.
While fair weather will generally be the rule on Tuesday...we should
have a fair amount of mid level (alto-cu) cloud cover. This will help
to hold temps down a few degrees from where they would otherwise
be...but despite this highs will range from 85 to 90. Given afternoon
Td`s within a few degrees of 70...this could support apparent temps in
the low to mid 90s for the usual corridor from IAG county to the
Finger Lakes region.

In regards to pcpn...slight and low chc pops will remain in place for
mainly orographically initiated convection within a destabilizing
synoptic environment. This would mainly be for the swath stretching
from the western Southern Tier and Finger Lakes region to the southern
slopes of the Tug (incl srn Lewis co).

A tropically enhanced warm front extending eastward from the sfc
remains of Beryl will approach our region Tuesday night. PWAT values
that will already be in the vcnty of 1.75" Tuesday evening will surge
to over 2" by daybreak...as tropical moisture associated with Beryl
will pour across our forecast area from the Ohio valley. This deep feed
of moisture will ride up across the aforementioned warm front and
result in increasingly widespread showers during the course of the
overnight. The rain could become heavy over the far western counties.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
...Significant Rains from the Remnants of Beryl Likely Wednesday...

Model guidance continues to come into better agreement on the track
of the remnants of Beryl...with an eastward-translating mid level
trough capturing and lifting these northeastward across the Ohio
Valley and Lower Great Lakes Tuesday through Wednesday night. During
this portion of the forecast period...the corresponding surface
reflection looks to slowly deepen as it tracks from Indiana at the
start of Wednesday to Lake Erie by Wednesday evening...then
gradually fill as it drifts across the Lower Great Lakes Wednesday
night...then across southern Ontario/Quebec Thursday.

The remnants of Beryl will be accompanied by a pronounced swath of
tropical moisture (precipitable water values of 2.0 to 2.5 inches)
Wednesday and Wednesday night...with the latter supporting a risk
for heavy rainfall. This rich moisture field will be initially
lifted by a diffluent flow aloft and a northward-advancing warm
front during the day Wednesday...followed by the system`s trailing
cold front late Wednesday and Wednesday night. This will bring about
a near certainty of periods of rain and some embedded thunderstorms
Wednesday and Wednesday night...with the aforementioned frontal
boundaries potentially also serving as foci for training storms and
corridors of enhanced rainfall/resultant flooding risk. Current
multimodel consensus supports the potential for a fairly widespread
1.5-2 inches of rain across the area...with the potential for more
localized amounts of up to 3 inches within any corridors of
training/enhanced rainfall that might develop. Given these expected
totals...the relatively dry conditions of the past week...the 18 to
24-hour nature of the expected rainfall and current 6-hourly FFG
values of 2 to 2.5 inches...still feel that we should be able to
handle the bulk of this without issues...and as such will continue
to hold off on the issuance of any Flood Watches for the time being.

In addition to the rainfall...there is also a secondary concern for
the potential for some stronger to potentially severe storms across
our southernmost two tiers of counties later Wednesday afternoon
into Wednesday evening. Some guidance (most notably the NAM and GFS)
continues to suggest the potential for the system`s warm front to
push across or even north of these areas Wednesday afternoon...which
if realized could allow for the development of moderate amounts of
instability. Given the presence of fairly strong deep-layer shear (0-
6 km bulk shear values of 40-50 knots) and veering wind profiles
aloft...this could result in an environment possibly supportive of
some multicell/supercell storms in the above areas...with damaging
wind gusts being the primary severe weather threat. With this in
mind have opted to add a mention of gusty winds to the forecast for
the Southern Tier and interior of the Finger Lakes Wednesday
afternoon and evening...which lines up well with the Marginal Risk
area depicted in SPC`s Day 3 Convective Outlook.

As for high temperatures Wednesday...these will be highly dependent
upon the northward progress of the system`s warm front. To its
north...a general ENE flow and more widespread/persistent pcpn will
likely keep readings confined to the 70s...while to its south temps
could easily surge well into the 80s. What is more certain are the
humidity levels...as the burgeoning tropical airmass will likely
send surface dewpoints surging into the oppressive lower to mid 70s
in many areas.

The widespread tropical rains will wind down from west to east
during the course of Wednesday night and early Thursday as the
system`s center and trailing cold front pass through our longitude.
In their wake...there will be a lingering chance of much more
scattered/weaker showers and a few more isolated storms on
Thursday...before high pressure and drier air build in Thursday
night and usher in a return to quieter and drier weather to close
out this period. Otherwise...we can expect temperatures to average
out a bit above normal...along with continued muggy conditions
(though humidity levels will likely not be quite as oppressive as
what we`ll see during Wednesday).

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
A trough over the central Great Lakes will track toward and across
the forecast area through the first half of the weekend, weakening
in the process. This will result in the potential for some showers
across the area, especially the eastern portions of the area where
increased Atlantic moisture is expected. For the period through the
first half of the weekend, there is still plenty of model
uncertainty among all the guidance, especially on the timing of the
trough crossing the region. Some guidance brings the trough through
quicker before moisture increases to the east, resulting in less
shower potential. Some other guidance is slower with the trough,
allowing the moisture to expand north and west, resulting in
increased shower potential for north central NY.

Shower potential will increase later Sunday into the new work week
as a few shortwave troughs track across the area within a mainly
zonal flow over the region. A cold front tracking southeast across
the Great Lakes and into the forecast area Monday afternoon into
Tuesday morning will increase the potential for showers during this
timeframe. Again though, there is plenty of uncertainty among
guidance for timing and shower coverage.

Daytime temperatures during the long term period will be 5 to 10
degrees above normal for the entire area.

&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
Widespread fair/dry/VFR conditions will continue through early
Tuesday afternoon...along with generally light winds. Scattered
diurnal cumulus inland from the lakes this afternoon will fade with
the loss of heating this evening...then high and mid clouds will be
on a gradual increase from west to east overnight and Tuesday as mid
and upper level moisture begins streaming across our area well out
ahead of the remnants of Beryl. A few widely scattered diurnally-
driven showers and storms will then become possible inland from the
lakes Tuesday afternoon.

Outlook...

Wednesday...MVFR/IFR with tropical rains and a chance
of thunderstorms.
Thursday...MVFR/VFR with a chance of showers and a few isolated
thunderstorms...with the showers possibly a bit more numerous east
of Lake Ontario.
Friday...Mainly VFR with a low chance of showers and thunderstorms
inland from the lakes.
Saturday...Mainly VFR with a low chance of showers and thunderstorms
well inland from the lakes.

&&

.MARINE...
Light to gentle southeasterlies will become southerly overnight...while
negligible wave action will persist.

Gentle to occasionally moderate breezes and minimal waves on Tuesday
will remain favorable for recreational boating. While conditions will
stay below small craft advisory criteria Tuesday night...there will be
an increasing risk for thunderstorms...especially on Lake Erie.

Wednesday will be quite unsettled...as the remnants of Beryl will move
through with times of heavy rain and possibly some gusty thunderstorms.
The active weather will be accompanied by moderate to occasionally
fresh northeasterlies.

&&

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

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...JJR
LONG TERM...SW
AVIATION...JJR
MARINE...RSH