Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 281828

Area Forecast Discussion
National Weather Service Buffalo NY
228 PM EDT Fri Oct 28 2016

High pressure will briefly build across the region this evening with
fair weather. Low pressure will then move east across Ontario and
Quebec Saturday, with a trailing cold front sagging slowly south
across the region. This will bring scattered showers to the region,
which will be most persistent east of Lake Ontario. A wave of low
pressure will then move along the front and bring another period of
showers to the region Sunday.


Radar imagery showing a few scattered rain and wet snow showers
lingering across Lewis County early this afternoon in response to
upslope flow into the Tug Hill and western Adirondacks, and some
limited lake moisture. These will continue through mid afternoon
before ending as the moisture profile becomes more shallow.
Otherwise skies will remain cloudy across Central NY and the eastern
Lake Ontario region. Farther west, low level moisture has scoured
out nicely with increasing amounts of sunshine from the western
Finger Lakes westward across Western NY.

A narrow ridge of high pressure will briefly build across the region
this evening and provide a period of partly clear skies and light
winds. This high will move quickly to the east coast overnight as
low pressure moves across Lake Superior and into the Nickel Belt of
Ontario. Strong mid level warm advection will overspread the lower
Great Lakes overnight as a warm frontal segment develops and moves
east across the region. Isentropic upglide and increased moisture
will bring thickening clouds from west to east overnight. Ascent and
moisture become maximized late tonight across the North Country near
the nose of a 55 knot low level jet, and this may produce a few rain
showers late tonight east and northeast of Lake Ontario.

Low temperatures will occur early this evening as the surface ridge
is briefly overhead. Expect lows in the low to mid 40s across
Western NY and mid to upper 30s from the Genesee Valley to the
eastern Lake Ontario region. Overnight the warm advection and
increasing clouds will allow temperatures to rise, with low to mid
50s by daybreak across the lake plains of Western NY.

On Saturday the surface low will move east across Quebec, with a
trailing east/west oriented cold front sagging slowly south towards
Lake Ontario by late in the day. The stronger large scale forcing
associated with the mid level trough, and better low level
convergence on the nose of the low level jet, will be directed into
the eastern Lake Ontario region. This will combine with frontal
convergence and upslope flow to bring a likelihood of showers to
areas east of Lake Ontario. Farther south and west, both large scale
ascent and frontal convergence will be weaker, and should only be
capable of supporting a few brief/light scattered showers.

It will become quite breezy, especially in the typical areas from
the Lake Erie shore northeast across the Niagara Frontier to near
Rochester where winds will gust into the 30-35 mph range. Those
gusty winds will also bring very mild temperatures, with highs in
the mid 60s on the lake plains of Western NY, and mid to upper 50s
across the North Country.


Saturday night a cold front will sag southward across the region,
this from an area of low pressure that will reside near New
Brunswick through the night. The upper level flow will be nearly
zonal overnight, and without much lift along the slowing front we
will carry nothing more than chance wording for activity through
much of the night. Moisture will remain abundant through the night,
especially across southern zones and here there may be the
development of low clouds and fog across the hill tops.

Behind this front high pressure centered over Northern Plains
will funnel a shallow layer of cool air over the Eastern Great
lakes. While this northerly flow will supply some drier air, it may
not be enough to scour out lingering low level moisture such that a
northeast flow over Lake Ontario may bring some additional low
clouds and fog to the southern shoreline of Lake Ontario overnight.

A shortwave seen on water vapor imagery this Friday afternoon over
central California will transverse the country, and pass just south
of our region Sunday. This shortwave will produce a surface wave
along the stalling frontal boundary, with the wave reaching the
western mid Atlantic region Sunday afternoon. Additional lift along
both the surface wave, and upper level shortwave will bring a return
to rain showers. Highest confidence will lie across southern zones
where a layer of frontogenetic forcing within a saturated lower
layer ahead of the surface wave will bring rain showers. Activity
here may increase in coverage area just ahead of daybreak Sunday
morning. Farther to the north, and especially east of Lake Ontario
drier air associated with the upstream area of high pressure, and
the greater distance from the wave along the front to our south will
yield a much lower probability of rain showers during the day
Sunday. The Saint Lawrence Valley will likely remain dry Sunday.

Sunday night, while the Pacific based shortwave will be racing to
our east, a slower more amplified shortwave will be dropping across
the northern portions of New York State and New England. This
feature will find a drier airmass over the region, but enough
moisture may linger for a few upslope light rain or snow showers
across the North Country overnight. Otherwise Sunday night should
feature a drying trend as an upper level ridge from the Central
Plains slides eastward. This ridge will build over the Great Lakes
region Monday and Monday night, bringing fair weather and warming
temperatures to our region.

There will not be much warming Sunday, this with thick clouds and
light northerly flow. Temperatures Sunday will likely only climb
about 3 to 5 degrees above their morning low...with temperatures
mainly in the mid 40s to mid 50s Saturday night and Sunday.
Partial clearing Sunday night will allow temperatures to drop back
into the 30s, with some inland areas again reaching the freezing
mark. Monday will start the work week on the cool note, with
temperatures again around 50F...this before much warmer air arrives
for Tuesday.


As we move into the longer-term portion of the forecast...the surface
ridge responsible for Monday`s fair weather will quickly slide east
and out to sea Monday night and Tuesday...allowing another northern
stream shortwave and surface low to quickly slide eastward across
Ontario and Quebec. Rapidly strengthening warm air advection out
ahead of this next system will likely result in another night with a
noticeable non-diurnal temperature trend Monday night...followed by
a rather warm day on Tuesday when readings will likely surge into
the 65 to 70 degree range south of Lake Ontario...and into the upper
50s and lower 60s across the North Country.

While this system will push its trailing cold front across our region
late Tuesday and Tuesday night...this feature still appears to be
rather weak and greatly starved for both moisture and upper-level
support...which should result in it coming through dry for the bulk
of our for the North Country which will lie closer to
the low track and where a few isolated showers may thus be possible.
Following the frontal passage...another bubble of high pressure and
somewhat cooler air will build across our region for Wednesday...but
even then temperatures will remain solidly above average with afternoon
highs in the upper 50s to lower 60s anticipated for most locations.

Looking out toward the end of the period...the medium range models
remain in decent agreement on another weak low crossing our region
sometime in the Wednesday night to Thursday time frame. This system
will bring us our next real chance for some showers...while temps
should continue to average out a bit above normal.


Extensive stratocumulus will continue through this evening east and
southeast of Lake Ontario with widespread MVFR CIGS and IFR across
higher terrain. A few light mixed rain/snow showers across the Tug
Hill region will end by mid to late afternoon with little impact on
VSBY. High pressure will bring a brief period of fair weather and
mainly VFR this evening.

Overnight a warm front will move east across the region with a
period of mid level clouds, and possibly a few rain showers late
tonight across the North Country with VFR prevailing in most areas.
On Saturday low pressure will move east across Quebec, with a
trailing cold front sagging slowly south towards Lake Ontario in the
afternoon. Showers will become most likely east of Lake Ontario with
VSBY possibly dropping to MVFR at times. Elsewhere expect just a few
widely scattered light showers. Extensive low level moisture will
stream into the area, with CIGS deteriorating to MVFR by late
morning and remaining MVFR through the afternoon. Some IFR may
develop in the afternoon across the higher terrain.


Sunday...Areas of IFR/MVFR with showers likely.
Monday through Wednesday...VFR.


Northwest winds continue to slowly diminish this afternoon, with
winds and waves dropping to below Small Craft Advisory criteria
along the south shore of Lake Ontario. A narrow ridge of high
pressure will briefly build across the Lower Great Lakes this
evening with a short period of lighter winds.

Overnight and Saturday low pressure will move east from Lake
Superior to Quebec. This will rapidly tighten the pressure gradient
as high pressure anchors along the east coast. Southwest winds will
rapidly increase on Lake Erie after midnight, then on Lake Ontario
late tonight and Saturday. This will bring another round of Small
Craft Advisory conditions to most of the Lake Erie and Ontario

A weak cold front will then sag slowly south across the Lower Great
Lakes Saturday evening, with winds becoming northwest and eventually
northeast by Sunday morning, and diminishing with waves subsiding to
below Small Craft Advisory levels.


MARINE...Small Craft Advisory from 5 AM to 5 PM EDT Saturday for LEZ020.
         Small Craft Advisory from 2 AM to 8 PM EDT Saturday for
         Small Craft Advisory from 5 AM to 5 PM EDT Saturday
         for LOZ030-042.
         Small Craft Advisory from 5 AM to 2 PM EDT Saturday for



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