Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 230626

Area Forecast Discussion
National Weather Service Buffalo NY
226 AM EDT Sun Oct 23 2016

Rain will linger across the Eastern Lake Ontario region through
tonight, mixing with and changing to snow across the higher
elevations of the Tug Hill Plateau. Things will dry out Sunday
before another disturbance brings a chance of showers Sunday
night. Otherwise, cool northwesterly flow will keep temperatures
below average into the middle of the week, with a chance of lake
effect rain showers southeast of the lakes.


Rain will continue into tonight across the eastern Lake Ontario
region as the wrap-around moisture on the western flank of the
departing low pressure system continues to slide across the area.
As temperatures across inland portions of the North Country fall
well into the 30s, we will see snow across the higher elevations
of the area, with an accumulation of up to three inches possible
across the highest portions of the Tug Hill and the Western
Adirondacks overnight.

Elsewhere, expect plenty of lake-effect cloudiness to persist.
Temperatures will fall into the mid to upper 30s in the Southern
Tier, with lower 40s near the lakes, though a continued brisk west-
northwest flow will drop wind chill values into the 20s.

Cyclonic flow will continue to slowly depart the area Sunday with
much of the day expected to be dry. Lingering cold northwest flow
could bring some light precipitation southeast of the lakes early in
the day. Band of warm air advection develops into the region with an
increase in cloud cover during the afternoon. A solid improvement in
the temperature department, although still a bit below normal with
most highs Sunday in the lower 50s, expect 40s across the North


Sunday night...a fast moving shortwave will quickly slide from Lower
Michigan to Long Island...with an associated weak surface low passing
along or just south of the New York/Pennsylvania border. These two
features will bring a quick shot of scattered to numerous rain
showers to areas along and south of Interstate 90...with the most
numerous activity found across the Southern Tier where some likely
PoPs remain in play. Elsewhere...conditions should be cloudy and mainly
dry aside from some scattered/limited lake effect rain showers east-
southeast of Lake Ontario...with these tending to fade overnight as
some modest drying develops in the wake of the departing shortwave.

After that...our weather for the remainder of this period will be
dominated by persistent upper level troughing...the core of which
will only slowly drift from Quebec Province to the Canadian Maritimes.
This feature will feed a continued northwesterly to northerly flow of
colder Canadian air across our region...which will result in temps
averaging solidly below normal through midweek. More specifically...
expect daytime highs mostly in the upper 40s to lower 50s on Monday
to pull back into the lower to mid 40s for both Tuesday and Wednesday
as our airmass cools...while nighttime lows mostly ranging through the
30s Monday night will drop off into the upper 20s and lower 30s Tuesday
night...quite possibly resulting in a killing freeze in those areas
where the growing season has not yet ended.

Precipitation-wise...the continual northwesterly to northerly flow of
Canadian air will also result in a potential for some lake effect
precipitation southeast and south of the lakes. This stated...the
combination of the short fetch...a fairly low (4-5 kft) capping
inversion...and less than impressive moisture below this level should
all help to keep any such activity fairly limited/scattered in nature.
As such...have kept PoPs confined to the 20-40 range...with the highest
values indicated southeast of Lake Erie Monday night/early Tuesday...
where and when moisture will be a little bit more favorable. The
predominant ptype with this should be rain...except at night and early
each morning when the boundary layer should be cool enough to support a
little wet snow inland from the lakes and/or across the higher terrain.
Any lake effect activity that does form should then come to an end
during the day on Wednesday...when surface-based ridging settles
directly overhead along with increasing large-scale subsidence and


A progressive sinusoidal flow over the country...dominated by Pacific
based air...will support a minimal day to day warming trend during
this time frame. While this will be accompanied by mainly unsettled
conditions...significant weather is not anticipated.

High pressure nosing south across the Lower Great Lakes Wednesday
evening will stubbornly give way to a deepening storm system over
the Mid West during the overnight. In the process...a tightening
baroclinic zone will advance across our western counties. This will
certainly lead to an increase in cloud coverage...with some rain
showers possible west of the Genesee Valley. The strengthening warm
advection ahead of the sfc low should encourage a non diurnal temp
trend...with the mins generally occuring around midnight. This will
especially be the case over the far western counties...assuring that
any pcpn that falls will be in the form of rain.

All of the guidance packages are in agreement that the storm system
will then track by to the west of our forecast area on Thursday...
while significant hgt falls will accompany the passage of an actual
warm front and relatively deep swath of moisture. Have bumped 50
pops to likely for the afternoon.

Thursday night...the associated cold front will make its way across
our region with more showers being generated as a result. Again...
all of the pcpn should be liquid as H85 temps in the single digits
will only drop to around zero c by daybreak.

On Friday...the core of the chilliest air will move across our
region as the base of the supporting negatively tilted trough will
make its way from the Lower Great Lakes to the Upper St Lawrence
Valley. There should also be plenty of `wrap around` synoptic
moisture in place within a deep cyclonic flow. This will support
scattered showers as midday temperatures will struggle to near 50f.

As we head into the start of the weekend...the medium range
ensembles diverge fairly significantly. While one `camp` suggests
that a weak shortwave ridge will cross our region on Saturday...
another favors the passing of a robust shortwave. Experience has
this forecaster leaning towards the former...with brief ridging
supporting a dry day on Saturday. Confidence with this Day 7
forecast is lower than normal.


Cold northwesterly flow is continuing to generate lake-effect clouds
south and east of the lakes, with ceilings mostly greater than 3kft.
Expect bkn stratocu to scatter out south and east of Lake Ontario
this morning as a shortwave ridge crosses the forecast area from the
northwest...however clouds should fill back in later this afternoon
as another upper level disturbance approaches the area.

The aforementioned disturbance will likely trigger rain showers
across the Southern Tier, along with potentially reinvigorating lake-
effect showers southeast of Lake Ontario, from 00Z onwards. IFR
conditions associated with these showers will be possible across
the Southern Tier after 02Z, with MVFR cigs possible farther north
across the Niagara Frontier and elsewhere south of Lake Ontario as
the lake-effect clouds return, with a few showers possible south of
the lake.


Monday...VFR/MVFR with a chance of lake effect rain showers.
Tuesday...Mainly VFR.
Thursday...MVFR/IFR with rain showers likely.
Friday...MVFR with a chance of lake effect showers.


Surface low pressure will deepen as it moves north across Maine
and into Quebec through tonight. The tightening gradient between
this low and a narrow ridge of high pressure moving into the
central Great Lakes coupled with increasing cold air advection
will allow northwesterly winds to freshen to gale force tonight
across central Lake Ontario, and appropriate warnings remain in
effect. Elsewhere, the brisk northwesterly flow will keep small
craft advisories in play well into Tuesday before high pressure
moves overhead Tuesday night into Wednesday.


MARINE...Small Craft Advisory until 2 AM EDT Monday for LEZ041.
         Small Craft Advisory until 3 PM EDT this afternoon for
         Gale Warning until 11 AM EDT this morning for LOZ043-
         Small Craft Advisory until 11 PM EDT this evening for
         Small Craft Advisory until 7 PM EDT this evening for



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