Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 201128

Area Forecast Discussion
National Weather Service Buffalo NY
628 AM EST Sat Jan 20 2018

Windy conditions will persist through today as our region remains
sandwiched between a low pressure system passing to our north across
eastern Canada, and a broad area of high pressure across the
Southeast. Winds will diminish this evening, as high pressure noses
across the region. A warm front will then lift across the lower
Great Lakes on Sunday, bringing a chance for light precipitation.
More significant rainfall is expected Monday, as a large storm
system tracks into the Great Lakes, with temperatures warming well
into the 40s ahead of this system.


Western and central New York continues to experience windy
conditions this morning, as the area remains caught in a tight
pressure gradient between a 986mb centered to our north, over
northwestern Quebec, and an expansive area of high pressure centered
over the southeastern states. The sharp gradient extends upwards
into the atmosphere, where a 60kt 850mb jet streak is currently
transiting the region. Though the presence of a robust inversion at
around 950mb is preventing the strongest winds from mixing down to
the surface, we are nonetheless seeing gusts of 30 to 45 mph across
the forecast area this morning. These stronger winds should persist
through the morning hours before gradually coming down this
afternoon, as the core of the low-level jet passes off to the
southeast. While the windiest conditions will be found this morning,
it will still be breezy this afternoon, with gusts of 20 to 30 mph
still possible.

Aside from the windy conditions, it should be a largely quiet day
across much of the forecast area, with just passing high clouds
associated with the jet stream, centered just to our north. A weak
upper level disturbance ridging this jet stream may bring a little
bit of enhanced moisture and light precipitation, mainly in the form
of drizzle/sprinkles, if anything, to the upslope areas of the North
Country. Otherwise, increasing surface ridging should keep
conditions dry elsewhere. Temperatures across most areas will only
warm slightly today from the seasonably mild values this morning, as
diurnal heating will be offset by weak cold advection associated
with the aforementioned upper level disturbance. The one exception
will be across the Genesee valley, where the brisk southwesterly
winds will aid in downsloping, pushing temperatures well into the
40s, particularly around Dansville.

Winds will continue to diminish tonight, as the low rapidly tracks
away from the region and high pressure noses across the lower Great
Lakes. This high pressure should make for an uneventful night, with
temperatures cooling into the lower 30s, with upper 20s in the North


Sunday into Sunday night, a mid-level cut off low will shift from
near Las Vegas east to the Central Plains states forcing a surface
low to form and deepen while tracking across Kansas. This system
will be responsible for our expected warmup Sunday through Monday.
Deep southwesterly flow ahead of the system into Western and Central
NY will bring this warming with High temps ranging from the upper
30s to low 40s. Despite a decent moisture connection to the Gulf of
Mexico, lift will remain rather weak Sunday only increasing slightly
into Sunday night. Slight chance POPs for drizzle or where colder, a
potential of flurries/freezing drizzle Sunday increase to a chance
of rain with perhaps some sleet spreading from the western Southern
Tier north and east later Sunday into Sunday night. The potential
for freezing drizzle would be due to a lack of cold enough temps
within the low level moisture and lift axis as shown on BUFKIT
profiles although mid-level seeder clouds could allow for more in
the way of light snow/flurries. Low temps Sunday night will range
from the mid 30s in WNY to mid 20s east of Lake Ontario.

A stalled or slowly moving warm front is forecast to make a lift
north into and across western NY into the North Country Monday into
Monday night. Very mild air in the wake of the warm front should
help boost temps into the mid/upper 40s in WNY with lower 40s more
likely east of Lake Ontario by later Monday and Monday night. Have
adjusted POP grids to reflect a trend of POPs increasing from likely
along the warm front to categorical ahead of the cold front. P-type
will be plain rain across WNY with rain/snow/mix changing to rain in
the North Country. Expecting the cold front and associated leading
low level jet, both tied to low pressure lifting across Michigan,
will force widespread rain Monday night. GFS PWATs are still holding
near 3/4 of an inch, which is above the 90th percentile for late
January per SPC sounding Climo, should bring some moderate to
possibly heavy rainfall. Temperatures ahead of the cold front will
run very mild Monday night lingering in the 40s before falling some

As has been pointed out previously...the combination of the above
rainfall and increased snowmelt from higher temperatures and dewpoints
may eventually bring some flood concerns by later Monday and Monday
night. While this warm-up is not as dramatic as that of last weekend
and overall rain amounts are also likely to be lower given the fast
passage of the cold front...there may still be some potential for
ice jam flooding in the late Monday-Monday night-Tuesday time
frame which will continue to be highlighted in the Hazardous
Weather Outlook.


A low amplitude...Pacific air dominated pattern over the Lower 48 at
the start of this period will experience significant amplification
as we head towards the end of the week. The impetus for this
evolving pattern will be a series of strong shortwaves that will
slam into the West Coast and lead to broad troughing over the
western half of the country. This in turn will promote a burgeoning
progressive ridge over the Ohio Valley and Great Lakes regions that
will eventually pump another period of very mild weather into our
region for next weekend (just outside of the scope of this
forecast). Breaking this down on a day to day basis...

Tuesday into Wednesday, colder air will rush back into the region
behind a cold front with a blustery west wind developing. Rain ahead
of the front will mix with then changing to snow showers in its
wake. Expect a return to more typical mid-winter temperatures
following the front into Wednesday. Temps Tuesday morning ranging
from the mid 30s in the higher terrain to mid 40s toward the lakes
will fall through the day to near freezing by days end. Synoptic
moisture and lift associated with the cold front and a passing mid-
level trough axis will drive the chance for some scattered snow
showers Tuesday eventually transitioning into a likely potential
lake effect snow Tuesday night through Wednesday.

As ridging starts to build across the Upper Great Lakes on
Thursday...warm advection will begin over our region with
significant drying taking place between H925 and 850. This will
bring an end to the nuisance lake snows by early afternoon.

The axis of a large surface high will cross our forecast area
Thursday night and Friday...during which time steady warm advection
will push our H85 temperatures into positive territory. This will
set the stage for notably nicer weather across our
temperatures should climb back into the 40s across the western
counties for Friday afternoon.


Strong southwesterly winds continue to buffet area terminals due to
the combination of a tight surface pressure gradient across the
region and the presence of a strong low-level jet overhead.
Strongest gusts and LLWS threat will be over the next few hours
before gusts start to decrease later in the morning and into the
afternoon as the core of the LLJ moves away from the area and the
pressure gradient begins to relax. Nonetheless, it will remain breezy
for much of the day, with high clouds streaming overhead in
association with the nearby presence of the upper level jet stream.
Aside from the high clouds though, conditions should remain VFR for
the bulk of the TAF period. MVFR cigs will start to develop after
06Z however, as low level moisture begins to increase along an
approaching warm frontal boundary.


Sunday through Sunday night...Widespread MVFR ceilings persisting
through Sunday. A chance of rain/snow late.
Monday and Monday night...MVFR/IFR with rain showers developing.
Tuesday...MVFR/IFR with rain showers changing to snow showers before
ending...then areas of lake effect snow also developing east of the
lakes Tuesday night.
Wednesday...VFR/MVFR with a chance of snow showers.
Thursday...Mainly VFR.


A moderate to strong pressure gradient between an area of low
pressure crossing Southern Canada and surface high pressure over the
Southeast will maintain breezy conditions on the Lakes, and the
Upper Niagara River. A small craft advisory will remain in effect
for the Lakes, as well as the Upper Niagara River. High pressure
will reach the Eastern Great Lakes region Sunday that will relax the
winds and allow for wave heights to diminish.

Northeasterly winds will freshen on Monday, as a large area of low
pressure tracks from the lower Missouri valley towards the Great
Lakes. This will likely generate more small craft advisory
conditions on the western half of Lake Ontario. This low will then
track across the Great Lakes on Tuesday, sweeping a cold front
across the lower Great lakes late Tuesday into Tuesday night and
bringing a potential for gales on Lake Ontario behind the front
Tuesday night into Wednesday morning.


MARINE...Small Craft Advisory until 10 PM EST this evening for LEZ040-
         Small Craft Advisory until 1 PM EST this afternoon for
         Small Craft Advisory until 4 AM EST Sunday for



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