Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 170609
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
209 AM EDT Sun Mar 17 2024

.SYNOPSIS...
A cold front will plow across northcentral NY overnight producing a
brief period of widespread rain along with delivering an initial
shot of colder air for the second half of the weekend. Saint
Patrick`s Day will be chillier with a brisk wind and persistent
clouds that could yield a few nuisance rain or snow showers. Looking
further ahead, the airmass will continue to grow colder with below
normal temperatures and occasional rounds of lake effect snow
showers anticipated through much of the upcoming work week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A strong cold front will plow across western and central NY
overnight, bringing the initial shot of cold air that will only grow
colder with time and will have some staying power. Moisture pooling
along and ahead of the boundary along with good dynamical forcing
both surface and aloft will bring a several hour period of steady
rain to the region as the front passes through. Deepening cold air
may allow for some wet snow to mix in across the higher terrain by
morning, with little or no accumulation. Lows will still be above
normal with lows mainly in the mid to upper 30s, possibly down near
the freezing mark across the highest terrain. Damp and breezy
conditions will make it feel quite raw though.

Weak cold advection will continue through the day Sunday, especially
off the deck with 850Ts falling to around -8C to 9C by late in the
day. This will mean daytime highs in the mid to upper 30s higher
terrain to low and mid 40s elsewhere. Despite a chillier day, the
strong mid march sun angle will help to counteract cold air
advection near the surface which will allow for some fairly steep
low level lapse rates to develop by late morning into the afternoon.
With the cold cyclonic flow aloft, this will bring the chance for
some convective showers to develop, with any stronger cells possibly
producing some graupel. Would not rule out a few wet flakes as well,
especially across higher terrain as cold air continues to slowly
deepen aloft. Best chance for shower activity will be across an area
of low level convergence that sets up from the Niagara Peninsula
east to southern Oswego County, and also across the western Southern
Tier.

Meanwhile, the strong differential heating and subsequent influence
on low level lapse rates will allow stable lake shadows to develop
over and ENE of Lake Erie and Lake Ontario, with less cloud cover
and lower chances of showers downwind of the lakes from late morning
through the afternoon. If going out for St. Patrick`s Day
activities, dress warmly as wind chills will generally range from
the mid 20s to the mid 30s courtesy of a stiff westerly breeze
gusting upwards of 30-35 mph.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
Through this period a deep upper level low will settle across the
Great Lakes region. The base of this trough will pass across our
region Monday night. At the surface low pressure will maintain
across Atlantic Canada. A secondary cold front will drop across the
region later Monday and Monday night.

Temperatures at 850 hPa will drop from around -7C to around -10 to -
12C this period, with the coldest air aloft following the base of
the upper level trough aloft. There could be a mix of rain and snow
early, becoming all snow later Sunday night. Lake effect snow will
carry on Monday and Tuesday carried inland by oscillating winds.
Most favorable time period for lake effect snow will be Monday night
and into Tuesday, when deeper synoptic moisture is available within
the core of the cold air aloft. The mid March sun angle, and
steepening mid level lapse rates may allow for some graupel later
Monday and Tuesday...and an isolated lightning strike.

An upstream connection to Georgian Bay will all for snow to become
moderate to briefly heavy on the Tug Hill Monday night as the
secondary surface trough drops through. Could see snow totals
pushing into advisory level range, and will add the Tug Hill region
into the HWO for snow later Monday and Monday night. This secondary
trough will push the heavier lake snow off Lake Ontario towards the
southeast end of the Lake Tuesday morning before winds back sending
the snow back towards the Tug Hill later Tuesday and Tuesday night.
Lake snows Tuesday will weaken and become more cellular with daytime
insolation.

Off Lake Erie snow will focus upon the higher terrain south of
Buffalo Monday and Monday night. A northwest flow Monday night will
bring snow across the northern Niagara Frontier and towards the
Genesee Valley. The backing winds Tuesday may allow for the lake
snow to accumulate around metro Buffalo before snows weaken Tuesday
afternoon with the loss of synoptic moisture. Lake effect snow
continues Tuesday night off Lake Erie, but lacking deep moisture,
and also 850 hPa temperatures not as cool, lake snow will be weaker
in nature, likely across areas south of Buffalo.

Maximum temperatures will be below normal this period...or in
perspective, about 15 to 20 degrees colder than what the region has
averaged the first half of March. Clouds at night will keep
overnight lows close to normal. A brisk wind Monday and Tuesday,
gusting 25 to 35 mph will make these daytime highs feel even
colder, generally in the upper teens to 20s through the day.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Chilly, winter-like weather will continue across western and north
central NY into the first week of spring. An upper level trough will
remain across the Great Lakes region and Northeast. Another shot of
cold air (even colder than early in the week) will arrive by
Thursday. Forecast adjustments were made to lower temperatures
during this period, especially on Thursday.

Cold, cyclonic flow will maintain chances for snow showers across
the region Wednesday through Thursday. A shortwave trough may
intensify these snow showers with localized snowfall accumulations
possible. Synoptic moisture looks to diminish while warm air
advection starts across the region Thursday night into Friday. This
will bring temperatures up and likely lead to drier weather.

Uncertainty in the forecast grows moving into next weekend.
Consensus and most ensemble packages are leaning towards drier
weather with surface high pressure across the region and a coastal
low developing off the Carolinas. The 12z GEFS members and GFS have
a northern stream system interacting with the coastal low which
would bring widespread rain and snow to the region as early as late
Friday.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
A 40 mile swath of moderately heavy rain will push across western
and north central during the remaining pre dawn hours. The rain wil
be accompanied by MVFR cigs...although IFR to LIFr conditions will
be found across the Srn Tier where the rain could end as a period of
wet snow.

Sunday...areas of MVFR CIGS in the morning will improve to mostly
VFR by midday through the afternoon. Scattered showers will
continue, especially along a strip from near KIAG to KROC to KSYR
and also across the western Southern Tier from midday through the
afternoon as a convergence zone develops. Precip type will mostly be
rain, although some wet snowflakes or graupel/small hail may mix in
at times. It will be quite windy Sunday, with gusts of 25-30+ knots
areawide.

Outlook...

Monday through Wednesday...Occasional lake effect snow showers with
local/brief IFR conditions. MVFR/VFR outside of lake effect.
Thursday...MVFR/VFR with a chance of snow showers and associated
brief/local IFR.

&&

.MARINE...
Moderate southwesterlies will continue overnight with winds and
waves gradually building on Lake Erie and Lake Ontario. In the wake
of a cold front, winds will become westerly and freshen during the
course of the overnight, with winds and waves building to Small
Craft conditions on Lake Erie and Lake Ontario overnight through
Sunday morning.

Moderate to strong west to southwest winds will then continue Sunday
through much of the upcoming week as cold air deepens over the
eastern Great Lakes. This will bring a very long period of Small
Craft Advisory conditions.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory from 10 AM this morning to 11 PM EDT this
         evening for LEZ020.
         Small Craft Advisory until 8 PM EDT Tuesday for LEZ040-041.
         Small Craft Advisory from 8 AM this morning to 8 PM
         EDT Tuesday for LOZ042.
         Small Craft Advisory from 8 AM this morning to 5 AM EDT
         Wednesday for LOZ043>045.

&&

$$

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


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