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000
FXUS61 KBUF 202140
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
540 PM EDT Tue Oct 20 2020

.SYNOPSIS...
Low pressure will pass to the north on Wednesday. This will
lift a warm front northward across the area early Wednesday
morning, which will quickly be followed by a cold front. This
will produce showers and possibly a few thunderstorms late
tonight and Wednesday. High pressure will then build across New
England which will provide a southerly flow with warm and dry
weather for the end of the work week.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
Conditions through the evening will be mainly dry as frontal
boundary has moved into eastern NY and south into Pennsylvania.

The frontal zone will remain stalled through this evening, with
nothing more than a few spotty light showers or patchy drizzle
through the first half of the night, especially toward the
Finger Lakes and Southern Tier. Late tonight through Wednesday
morning the frontal zone will move back quickly northward as a
warm front, forced by rapidly increasing southerly flow ahead of
a trough moving through the Upper Midwest. A 50+ knot low level
jet will support strong moisture transport and isentropic
upglide along the warm front, with showers blossoming late
tonight through Wednesday morning. 12Z model guidance supports
the best coverage of showers across the lakes and into the North
Country. Elevated instability of up to 500J/kg for parcels
rooted above the surface may also support a few scattered
thunderstorms as well.

Weak low pressure will pass by to the north of the region Wednesday.
The frontal zone will quickly return southeast as a cold front in
the afternoon, supporting another round of showers and possibly a
few scattered thunderstorms. Rain will begin to taper off from
northwest to southeast late afternoon and early evening following
the passage of the cold front.

Wind gusts may reach 30 knots northeast of Lake Erie and 20-25 knots
elsewhere Wednesday. Temperatures will briefly surge into the upper
60s across Western NY and lower 70s from the Genesee Valley to
Central NY by midday to early afternoon, only to fall again late in
the day following the cold front.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
A bubble of high pressure will pass across Ontario and Quebec
Wednesday night. The region will remain on the southern periphery of
the surface high which will rapidly diminish any of the residual
showers from the eastward progressing front from earlier in the day.

The front that moved through the region on Wednesday will make its
reprise Thursday though this time as a warm front. Strong warm air
advection will increase temperatures at 850mb to near +12C across
portions of Western New York Thursday afternoon, while reaching the
North Country Thursday night. Mostly dry conditions are expected
through Thursday night as the better forcing associated with the
warm front will be confined to a deepening area of low pressure over
the Mid-West. In regards to temperatures on Thursday, clouds will
limit the full heating potential, therefore highs are expected to
peak in the low to mid 60s across the North Country and Lake Plains,
whereas mid to upper 60s are expected across the Southern Tier.

Warm conditions will persist into Friday since southerly flow will
continue as the warm front continues to progress further northeast
into Quebec. Highs on Friday will climb up into the low to mid 70s.
The aforementioned surface low pressure will continue to track
northeast Friday. As such, its associated cold front will approach
the region from the west on Friday, therefore chances for showers
will increase across the western border of New York by Friday
afternoon.

The cold front will then track across the region Friday night into
Saturday. Showers will likely enter western New York Friday night
before diminishing as the front tracks east. A couple of rumbles of
thunder can`t be ruled out across the Niagara Frontier Friday
evening, though these chances are low due to the timing of the
frontal passage. It should be noted that if the front were to pass
earlier Friday evening, the chances for thunder will be better.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
The cold front from Friday night, will weaken into Saturday as the
surface low tracks further north into Canada. In its wake, high
pressure will build across the Great Lakes late Saturday and Sunday,
resulting in dry conditions Saturday night into Sunday.

An unsettled pattern for the remainder of this period as a deepening
upper level trough over Western CONUS propagates eastward and looks
to push a warm front through the area Monday morning. A cold front
then follows in its wake, crossing the area Tuesday morning. Model
guidance differs on the exact position and timing, but precipitation
looks to overspread the area with the passage of these fronts, hence
the widespread chance for rain showers through the start of the work
week.

&&

.AVIATION /22Z TUESDAY THROUGH SUNDAY/...
Widespread MVFR/lower VFR CIGS will prevail through the evening as
winds shift to the southeast and downsloping results in drier low
level air and lifting cloud bases. The exception will be KJHW, which
is expected to remain IFR most of the night since downsloping will
not be a factor there.

Late tonight the frontal zone that settled south of our area earlier
today will return northward as a warm front, with showers increasing
late tonight along with a few rumbles of thunder possible. A
strengthening low level jet will bring several hours of low level
wind shear late tonight.

Showers will continue on Wednesday, both with the warm front and
then with a cold front which will move through mid-day. Expect
mainly MVFR flight conditions through 18Z, with areas of IFR
possible in heavier rain and lower cigs. Conditions will
gradually improve Wednesday afternoon when drier air builds in
behind the cold front.

Outlook...

Wednesday night...Mainly VFR. Patchy IFR valley fog possible.
Thursday and Friday...VFR.
Friday night and Saturday...MVFR with showers likely, improving
to VFR Saturday afternoon.
Sunday...VFR.

&&

.MARINE...
North to northeast winds will continue through this evening on
Lakes Erie and Ontario, producing choppy conditions at times.
East winds may briefly increase on Lake Ontario later tonight as
a warm front moves north. This will be followed by a period of
gusty southwest winds Wednesday as another cold front crosses
the eastern Great Lakes. Issued a Small Craft advisory for Lake
Erie for Wednesday and Wednesday evening. Small craft headlines
are also likely to be needed for portions of Lake Ontario
Wednesday into Wednesday night.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory from 8 AM to 8 PM EDT Wednesday for
         LEZ040-041.

&&

$$

SYNOPSIS...Apffel
NEAR TERM...Apffel/Hitchcock/JLA
SHORT TERM...EAJ
LONG TERM...EAJ/PP
AVIATION...Apffel/JLA
MARINE...Apffel/Hitchcock