-- Discussion containing changed information from previous version are highlighted. --
287
FXUS61 KBUF 261041
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
641 AM EDT Sun May 26 2024

.SYNOPSIS...
While today will start off with some low clouds and fog in many
areas...weak high pressure will GUARANTEE that we can anticipate
delightful weather during the afternoon for outdoor activities.
Unfortunately...conditions will deteriorate tonight and particularly
on Memorial Day itself. An unusually strong storm system for this of
year will track across the Upper Great Lakes on Monday...pushing a
pair of fronts through our region in the process. This will result
in fairly widespread showers and likely some drenching...gusty
thunderstorms as well.

&&

.NEAR TERM /THROUGH MONDAY/...
Relatively wet antecedent conditions from Saturday afternoons
showers and thunderstorms...combined with light winds and a near
saturated airmass below H7...has resulted in fairly widespread
stratus and fog early this morning. These conditions will persist
through the initial daylight hours...after which time diurnal mixing
will allow notably drier air aloft to erode away the cloud cover.

Otherwise...weak sfc high pressure today will accompany a burgeoning
shortwave ridge that will pass over the region. This will guarantee
that we will experience a beautiful afternoon with a wealth of
sunshine...along with comfortable temperature and humidity levels.
Great weather for those outdoor holiday plans.

Conditions will significantly deteriorate tonight though...
particularly over the western counties. A very robust shortwave...
seen in WV imagery crossing Colorado at 07z...will work its way
across the Mid west tonight. The resulting sfc low will deepen to
under 1000mb while moving to Lower Michigan in the process. A warm
front extending from this storm system will lift north across our
forecast area during the course of the night...and this will support
a blossoming area of showers and possible thunderstorms. PWAT values
are forecast to climb to 1.5" as the boundary moves through...so
some of the showers could include some moderately heavy rain.

Unfortunately...Memorial Day will feature more wet...unsettled
weather. The anomalously deep area of low pressure over Lower
Michigan Monday morning will push nearly due north...while the
aforementioned warm front will slowly make its way across the North
Country. This will place western New York in the warm sector where
fairly widespread showers early in the day should give way to a few
hours of relatively "rainfree" weather during the midday and early
afternoon. Meanwhile...steadier rain will be found in the vcnty of
the advancing warm front over the North Country.

As we push through Monday afternoon...a cold front will gradually
make its across the far western counties. The airmass ahead of this
synoptic forcing will be more than unstable enough to support strong
convection...and with PWAT values hovering arnd 1.6" in an
environment with short MBE vectors...there will be an elevated risk
for torrential downpours and localized flooding concerns. While mid
lapse rates are NOT forecast to be very impressive (mainly <7 deg
c/km)...GREATLY minimizing the threat of large hail...30-35 kts of
bulk shear could support locally strong downburst winds within
stronger convection. Again...the larger concern will be the risk for
slow moving torrential downpours.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
The cold front associated with the sfc low over the central Great
Lakes will cross the area during the first half of Monday night. As
the front crosses the area, it will push the more organized showers
and storms east. Showers and thunderstorms should be more
concentrated across the eastern third of the forecast area during
the evening on Monday night, ahead of and along the front. Showers/
thunderstorms with gusty winds and heavy downpours will be possible
for these areas during this time. Behind the front, with the large
trough still over the region, showers will still be possible
through the rest of the night, but not nearly as organized or
with the heavier rainfall potential. Thunderstorms should either
push east out of the forecast area, or weaken entirely behind
the front by later in the evening. The best chance for a break
in showers overnight should be for areas south of Lake Ontario
as forcing over these areas weakens between the departing front
and ahead of the next shortwave trough. Temperatures should be
in the mid 50s to near overnight. Rainfall amounts of a few
hundredths to a third of an inch are possible from west to east.

Tuesday and Tuesday night, a large mid-level low and trough remain
over the Great Lakes and Ontario/western Quebec areas. Still some
uncertainty among guidance for how organized showers become with
passing troughs, but with a shortwave trough crossing the region
both during the day and overnight, showers in general should
increase in coverage. Some breaks between the passing troughs will
be possible for a few hours during the late afternoon and into the
evening on Tuesday. The next trough approaches, increasing showers
once again from northwest to southeast late in the evening and
overnight. Daytime heating, increasing instability some will also
bring the potential for a few thunderstorms as well for the
afternoon on Tuesday. Afternoon temperatures in the low 60s for the
higher terrain east of Lake Ontario to the mid 70s for lower
elevations of Finger Lakes. Temperatures on Tuesday night will dip
down to the upper 40s to mid 50s.

Wednesday, showers will continue to slowly fill in from northwest to
southeast during the morning as the trough continues to tracks
across the area. Showers will then taper off from west to east
during the afternoon hours. A few thunderstorms will be possible
with the daytime heating in the afternoon, but should be limited.
Afternoon highs on Wednesday will be in the upper 50s to mid 60s
from the higher terrain to lower elevations respectively.
Temperatures on Wednesday will be around 5 to 10 degrees below
normal.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
The long term looks mostly dry with fair weather as a large ridge
and sfc high build into the eastern half of the CONUS.

A few showers may linger early on Wednesday night, but otherwise dry
weather and day-to-day warming is expected into the first half of
the weekend. Temperatures remain below normal for Thursday, near
normal for Friday, and then above normal for Saturday.

Some guidance is hinting at one last trough the drops south for
Thursday across the region behind the departing larger trough, but
it should remain mainly dry with a large sfc high pushing into the
region, helping to cut down on any forcing with the trough.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
As we work our way through this morning...diurnal mixing will erode
the low stratus and dissipate the fog...likely by 15z. This will
leave VFR conditions for the midday and afternoon with light winds.

An approaching warm front tonight will encourage CIGs to drop to
minimal VFR levels for the western counties overnight. The lowering
CIGs will be accompanied by increasingly widespread showers...mainly
over the western counties where an isolated thunderstorm will also
be possible.

Finally...marginal low level wind shear conditions will be possible
over the western counties after 06z. They were not added to the TAFs
because of low confidence.

Outlook...

Monday...Restrictions likely with showers and thunderstorms.
Tuesday and Wednesday...Restrictions possible with showers.
Thursday...VFR.
-- End Changed Discussion --

&&

.MARINE...
The axis of the high will slide across our area this morning...then
off to our northeast this afternoon. This will result in light to
modest winds turning east-northeasterly under 10 knots...with fair
weather prevailing outside of any areas of dissipating early morning
fog.

More notable winds will occur on Monday into Tuesday with increasing
southerly winds early Monday taking on a more west-southwesterly
component Monday afternoon into Tuesday. Winds could nudge into the
15 to 25 knots range with possible small craft headlines needed
during this time period. Scattered gusty thunderstorms will also be
possible Monday.

Boaters should continue to monitor the forecast, especially given
the holiday weekend which will likely increase boating activity.
This will especially be the case on Monday as conditions on the
lower Great Lakes will likely deteriorate.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
NY...Dense Fog Advisory until 9 AM EDT this morning for NYZ001-002-
     010-011-085.
MARINE...None.
-- End Changed Discussion --

&&

$$

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