666
FXUS61 KBUF 280600
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
200 AM EDT Fri Jun 28 2024

.SYNOPSIS...
Beautiful weather will be in place today...as high pressure overhead
in the morning will drift off the coast of Long Island by this
evening. Conditions will then deteriorate tonight and particularly
on Saturday...as low pressure crossing the Upper Great Lakes will
push several frontal boundaries through the region. Scattered
showers late tonight will become much more numerous on Saturday when
a sub tropical airmass will support some heavy rain as well. Not a
good day at all for outdoor activities. Sunday will offer some
improvement...but a few showers will still be possible.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure overhead early this morning will gradually make its
way to the east during the course of the day...eventually moving off
Long Island by this evening. While some cirrus will stream across
the far western counties today (Fri) and actually thicken somewhat
during the afternoon...beautiful weather can anticipated today to
end the work week. It will be comfortable with continued low
humidity... but warmer by some 5 to 10 degrees as afternoon
temperatures will reach 75 to 80. The higher end of that range will
be near Lake Erie and in the downslope areas west of Rochester.

As the sfc high moves further off the East coast Friday night...a
deepening southerly flow featuring a modest 30-35kt low level jet
will become established over our area ahead of a mid level shortwave
and attendant sfc warm front. Lift provided by the low level jet
over the sfc boundary will promote scattered shower activity after
midnight...mainly over the western counties. Elevated CAPE averaging
200 j/kg could be enough within a synoptically forced environment to
support a thunderstorm or two...with values as high as 500 j/kg over
the Southern Tier being the most favored area. It will be notably
warmer tonight than the past two...as the aforementioned deepening
southerly flow and associated pronounced warm advection only
allowing the mercury to drop to between 65 and 70 across the lake
plains to the lower 60s most elsewhere. Back to summer.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Scattered showers and a few rumbles of thunder Saturday morning
will only increase in coverage area as moisture deepens, and a
mid level convective shortwave trough passes across our region.

The early evening timing of the pre-frontal trough, cloud cover
holding elevated instability back to around 1000 J/KG or less and
poor mid level lapse rates under 6 C/KM are not favorable for strong
to severe storms. However, 0-6 km bulk wind shear values 35 to 45
kts could aid in strength and structure to better organized storms
such that stronger wind gusts within such storms remains possible.
SPC has our region within a marginal risk for severe storms for
Saturday. Hail should be little to none. Wetbulb zero heights are
just too high, around 15K and a very moist airmass encouraging
melting on the way down will make for smaller hail stones if they do
develop. It will be humid Saturday with dewpoints in the low to mid
70s.

Perhaps the bigger threat will be heavy rainfall Saturday afternoon
and evening. Pwats on the 12Z GFS/NAM/ICON/GEFS are forecasted to
near or even exceed 2.00 inches. A measured PWAT of 2.00 inches is
uncommon for late June on radiosondes launched at the Buffalo
Airport. Only 7 instances (12Z or 00Z) of a PWAT of 2.00 inches or
more have been recorded since 1948. The time period for heavy rain
will be roughly noontime through 10 pm when peak heating of the day
can increase instability, and 0-6 km bulk shear increases to 50
knots allowing for better storm structure. Clusters of showers and
thunderstorms collecting ahead of a convective shortwave will be
moving owing to the wind fields aloft, but any thunderstorm can
quickly deposit an inch or more of rainfall in a short period of
time, and any training to cells will aggravate the potential for
poor drainage flooding.

A wind fields weaken aloft through the night and instability lowers,
as well as the eastward shift to the axis of deeper moisture,
thunderstorms, becoming scattered showers will diminish through the
night. It will remain muggy Saturday night, with patches of fog
forming as the cold front will remain off to our west.

Sunday the cold front will slice across our region. Temperatures
around 14 to 15C at 850 hPa Sunday morning will fall to the upper
single digits by late Sunday afternoon. We could still see a few
showers Sunday along the front, with chances higher to the east as
increasing instability will encourage showers growth. Dewpoints will
be falling through the day, with a much more comfortable afternoon
in store with temperatures in the low to mid 70s.

Cool Sunday night as a ridge of high pressure passes overhead. The
850 hPa temperatures around 7C over the warm lakes may encourage
some lake induced clouds within a northerly flow. Towards the west
fog will likely form within the river valleys. Lows will drop back
into the 50s, and in the colder locations of the inland Southern
Tier and Tug Hill may even reach the upper 40s.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Surface high pressure will move across the eastern Great Lakes
region Monday through Monday night. This will bring a period of dry,
and seasonable weather for the region Monday through Tuesday. Then,
warmth and humidity will increase as the high shifts to the east
Tuesday through Thursday. Weak troughing will replace weak ridging
and a cold front is expected to move across the region Wednesday
through Thursday. This will increase the chance for showers and
thunderstorms during this time.

Temperatures will begin below normal Monday with highs in the low to
mid 70s. Day to day warming will occur Tuesday through Wednesday
with highs averaging the upper 70s to low 80s Tuesday to the mid to
upper 80s Wednesday. Temperatures Thursday will depend on the timing
of the cold front with high temperatures ranging from the low to
upper 80s. Humidity values will increase Wednesday.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
While there may be some valley fog across parts of the Southern Tier
early this morning...fair VFR conditions with light winds will be in
place through the upcoming day...courtesy of high pressure that will
move from western New York to Long Island by this evening.

VFR weather will remain in place through the first half of Friday
night...then an approaching warm front will help to generate
scattered showers late...mainly over the western counties. Alto-
cu cigs this evening will lower to VFR level strato-cu overnight
in most areas...although MVFR cigs will become likely towards
daybreak Saturday across the Srn Tier.

Outlook...

Saturday...Localized restrictions likely in increasingly widespread
showers and scattered thunderstorms...some of which may produce
locally heavy rainfall.
Sunday...A chance of a leftover shower or two...otherwise mainly VFR.
Monday and Tuesday...VFR.

&&

.MARINE...
Winds on the lower Great Lakes tonight will become light and
variable as high pressure from the western Great Lakes builds into
the region. Mainly easterly winds at 12 knots or less will
develop Friday as the high departs across New England, but some
local onshore breezes will likely develop during the afternoon.

Southeasterly winds early Friday night will veer to southerly as
a warm front lifts into the lower Great Lakes. These southerly
winds may increase to over 15 knots Saturday, but wave heights
in US waters likely remaining 3 feet or less.

A cold frontal passage will bring scattered thunderstorms Saturday
afternoon and Saturday evening with the potential for locally
gusty winds and higher waves. Behind the frontal passage,
westerly winds will strengthening to near 20 knots with a period
of advisory conditions possibly developing Sunday on both Lake
Erie and Lake Ontario.

&&

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

&&

$$

SYNOPSIS...RSH
NEAR TERM...RSH
SHORT TERM...Thomas
LONG TERM...Hitchcock/HSK
AVIATION...RSH
MARINE...TMA