003
FXUS61 KBUF 271037
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
637 AM EDT Mon May 27 2024

.SYNOPSIS...
While the majority of today will be rain free...a relatively deep
storm system moving out of Lower Michigan will push a pair of
frontal systems through our area that will result in several rounds
of showers and drenching thunderstorms. Some storms may have the
potential to generate damaging wind gusts...mainly across the Finger
Lakes and Eastern Lake Ontario regions. The unsettled will persist
into mid week...while there is high confidence that it will become
progressively cooler.

&&

.NEAR TERM /THROUGH TUESDAY/...
...Strong Thunderstorms and Drenching Downpours Likely Today...

An unusually deep (once in a 10 yr period) storm system over Lower
Michigan this morning will track to western Quebec by this evening.
In the process...it will push several fronts/boundaries through our
forecast area. The first is a warm front that will exit the North
country this morning. Showers and isolated thunderstorms with this
feature should completely move out of that area by mid morning.

Meanwhile...a convectively enhanced shortwave over Ohio will make
its way to the northeast during the morning. A relatively large area
of showers and thunderstorms associated with this mid level forcing
will cross the western counties between 8 AM and 12 Noon with a new
moisture rich airmass (PWAT values ~ 1.6") being supportive of
locally heavy rains within the convection. This scenario will result
in a pre frontal sfc  trough that will cross the Finger Lakes and
Eastern Lake Ontario region during the afternoon and early evening.

As is typically the case in western New York...it is the pre frontal
troughs that usually generate the greatest forcing for strong
convection...rather than the ensuing cold frontal passage. This case
will be no different. While instability (SBCAPE) ahead of this next
boundary is only forecast to reach 500-1000 j/kg...bulk shear values
of at least 30-40 kts are anticipated. Additional incalculable
shear should be added by the remnants of the previously
mentioned MVC (convectively enhanced shortwave) moving through
the region. Should convection become organized over the Finger
Lakes and particularly the Eastern Lake Ontario region...it
would not be difficult for stronger downdrafts to funnel 40-45kt
winds aloft to the sfc...especially given a forecast of DCAPEs
in the vcnty of 1000 j/kg. The Storm Prediction Center has thus
outlined the Finger Lakes and Eastern Lake Ontario region within
a slight risk for severe convection for today. While more
widely separated showers and drenching thunderstorms will still
be possible back over the far western counties this
afternoon...the risk for strong to severe convection will be
notable lower.

While breaks of sun will be possible for some areas today...we can
anticipate a fair amount of cloud cover with noticeably higher
humidity...courtesy of Td`s reaching into the mid 60s. Its worth
noting that any breaks of sun will only increase the risk for strong
to severe thunderstorms...especially for the Finger Lakes and
Eastern Lake Ontario regions.

There will also be the potential for localized hydro concerns...as
the sub tropical airmass combined with short MBE vectors will lend
itself to torrential downpours. This could lead to smaller basins
receiving an inch or two of rain in an hours time...which is right
where current one hour flash flood guidance is positioned. The
highest risk for this scenario coming to fruition will be once
again be over the Finger Lakes and Eastern Lake Ontario regions.

The deep area of low pressure will be over western Quebec by late
this afternoon/early evening. At this time...it will push a cold
front through the region. While a few more showers and thunderstorms
will be possible with its passage...this will certainly be anti-
climactic after the stronger convection from the pre-frontal trough.

Significant mid level drying in the wake of the cold front later
tonight will bring an end to the showers and evening storms...
although some showers could linger east of Lake Ontario into the wee
hours of Tuesday morning. Some areas could even experience at least
partial clearing.

Tuesday will be characterized by brisk winds...cooler and less humid
conditions...as a deep cyclonic flow will be in place across the
eastern half of the continent. A robust shortwave within this
pattern will rotate across the region while being accompanied by the
next surge of deeper moisture. This will combine with diurnally
enhanced instability to once again encourage showers and possible
thunderstorms to blossom over the region...especially during the
midday and afternoon. Temperatures on Tuesday will only climb into
the 60s to near 70...which will be JUST shy of normal values while
westerly winds will gust to 30 to 35 mph at times.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
A potent trough and then a cold front will track across the area
Tuesday night into early Wednesday morning. As the trough tracks
across the area, showers will continue through the first half of the
night, before becoming less organized. Forcing from the trough will
provide the main focus for showers during the evening and early
overnight, while the cold front will move through and continue the
potential for showers. Overall synoptic moisture ahead of the trough
will be generally low with PWats of around an inch, and lowering
some to around three quarters of an inch after it crosses the area.
With these lower moisture values and weaker forcing from the cold
front, showers that do linger into the morning on Wednesday will be
less organized. Most areas can expect less than a tenth of an inch
of rainfall, with the greatest amounts east of Lake Ontario where
forcing and moisture will be slightly better. Temperatures on the
night will be in the upper 40s for the higher terrain to the low 50s
for the lower elevations.

Wednesday, showers will linger across the area, with the best chance
for showers southeast of Lake Ontario toward the NY/PA border.
Showers will taper off and track out of the area from northwest to
southeast. By the afternoon, showers should be limited to a general
area from the NY/PA border, to the Finger Lakes & to the western
ADKs. Northwest flow over the region will help keep temperatures
below normal, with highs in the mid 50s to upper 60s from the higher
terrain to lower elevations respectively.

Wednesday night, earlier showers should be out of the area, minus a
few sprinkles for the Southern Tier and for areas well southeast of
Lake Ontario. Clearing skies from northwest to southeast, along with
a mostly northerly flow will bring one of the cooler nights the area
has seen in a while with overnight lows dropping to the low to
upper 40s.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
A large area of high pressure and stout ridge will build east into
the region during the long term period. This will provide mainly dry
and fair weather for most of the period. A trough will pass over the
region on Thursday/Thursday night, but synoptic moisture will be
limited and with the sfc high pushing into the region, any potential
for showers looks very limited. The sfc high and large ridge center
over the region from Friday afternoon through Saturday evening.

There are some timing issues with the next incoming trough and how
quickly the large ridge weakens and/or moves east. Due to this, some
guidance is bringing in the potential for showers starting on Sunday
morning, but with the lack of certainty, left at most slight chance
POPs.

Temperatures for the period will start out at least 5 degrees below
normal on Thursday and warm through the period to around 5 degrees
above normal.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
While mainly VFR conditions will be found across the region early
this morning...the next round of showers and thunderstorms will move
into the western counties between 12 and 16z. This area of pcpn may
be accompanied by MVFR cigs. The exception to this will be across
the Srn Tier...where MVFR cigs are already in place and where some
of the higher terrain could experience IFR cigs.

Cigs of 2500-3500 feet should then be common during the midday and
afternoon. There will be more showers and thunderstorms to contend
with...especially over the Finger Lakes and Eastern Lake Ontario
regions where the convection could become strong.

The showers and residual thunderstorms this evening will taper off
from west to east...as a cold front will press through the region.
MVFR cigs will remain in place across the western Southern
Tier...which cigs of 2500-3500 should remain in place elsewhere.

Outlook...

Tuesday...Restrictions possible with showers.
Wednesday...VFR to MVFR cigs with a chance of showers.
Thursday and Friday...VFR.

&&

.MARINE...
Southerly winds will freshen and gradually become southwesterly
throughout the Lower Great Lakes today...but with most areas
experiencing an offshore flow...the only area that will warrant a
small craft advisory will be on Lake Erie.

There will be thunderstorms throughout the region today...some of
which could become strong. The highest risk for significant
convection will be over the eastern half of Lake Ontario this
afternoon and evening. Mariners should be extra vigilant to any
statements or warnings regarding this activity.

Moderate to fresh southwesterlies are then expected throughout the
region tonight and Tuesday. These winds would very likely require
more small craft advisories.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory from 11 AM this morning to 11 PM EDT this
         evening for LEZ020.
         Small Craft Advisory from 2 PM this afternoon to 8 PM EDT
         Tuesday for LEZ040-041.

&&

$$

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