Area Forecast Discussion
Issued by NWS Buffalo, NY

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000
FXUS61 KBUF 120226
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
1026 PM EDT Wed Oct 11 2017

.SYNOPSIS...
A low pressure system will exit into the Mid Atlantic region
overnight with rain tapering off to showers and drizzle through Thursday
morning. Dry weather will return later Thursday and last through
most of Saturday with temperatures returning to above normal.
Another low pressure system will cross the region Sunday, bringing
much above normal temperatures and chances for showers, before a
strong cold front passage ushers in temperatures slightly below
normal to start the next week.

&&

.NEAR TERM /THROUGH THURSDAY/...
Late this evening, radar shows a large area of rain and showers
across much of Western New York. This steady rain associated
with the upper level trough axis will move into Central New York
during the early morning hours. After this, there will still be
lots of low level moisture with lingering showers and drizzle as
well as patchy fog. This will be enhanced across the Niagara
Frontier due to the ENE flow at the surface. Temperatures will
only fall a few degrees overnight in most areas, with lows
around 50 in most locations. The exception is the north country
where temperatures will fall in cold air advection with
temperatures falling into the lower 40s.

Once this low moves past overnight, the remainder of Thursday
looks bleak in terms of cloud cover, but mostly dry otherwise.
There still may be some drizzle in the morning. This cloud
cover will likely last throughout the day as forecast
atmospheric profiles remain moist through 10kft. This will limit
diurnal heating with highs in the lower to mid 60s.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
Thursday night and Friday high pressure will remain anchored over
New England and the Canadian Maritimes. This will maintain southeast
flow from the Mid Atlantic into the Great Lakes, transporting
Atlantic moisture northwestward into the region. This will keep a
good amount of cloud cover across Western NY from the Genesee Valley
westward Thursday night, with additional cloud cover spreading into
the remainder of the region Friday as low/mid level flow turns more
southwesterly and transports moisture into the eastern Lake Ontario
region. While there will be some clouds around, an upper level ridge
and overall lack of large scale forcing should keep the area dry.
Some model guidance develops spotty very light precip Thursday night
and Friday, but this is likely just an artifact of the low level
moisture in the model.

The cloud cover will keep temperatures up in Western NY Thursday
night, with lows in the low to mid 50s. The eastern Lake Ontario
region will see more clearing, with radiational cooling allowing
temperatures to drop into the upper 30s to lower 40s. Any frost risk
appears to be farther east where the clear skies will last all
night. High temperatures on Friday will run above normal, with upper
60s on the lake plains of Western NY, and low to mid 60s across the
higher terrain of the interior Southern Tier and east of Lake
Ontario.

Friday night high pressure will drift farther east and out into the
North Atlantic. Meanwhile a cold front will move into the central
Great Lakes and Quebec. This system will remain upstream overnight
with a continuation of dry weather as any showers remain on the
Canadian side of the border. Increasing southwest flow will keep
temperatures very mild, with lows in the upper 50s on the lake
plains and low to mid 50s farther inland.

Saturday and Saturday night the upstream cold front will approach
Lake Ontario and then stall. The approaching front will force clouds
to thicken from northwest to southeast Saturday, with clouds
lingering into Saturday night. The bulk of the showers are likely to
remain on the Canadian side of the border where the deeper moisture
and stronger frontogenesis will reside. However, model guidance
continues to suggest a few showers may reach the Niagara Frontier
and North Country later Saturday, then areas from roughly the NY
Thruway northward on Saturday night. Saturday will turn quite warm
as deep southwest flow transports warm air into the region. Expect
highs in the mid to upper 70s. Saturday night stays very mild with
deep southwest flow and cloud cover, only allowing temperatures to
drop back into the lower 60s on the lake plains and upper 50s for
the interior.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Sunday a deepening surface low will be tracking by to our west and
north, with southwest winds rushing across our region. A strong LLJ,
50kts at 3k feet, will be found across our region...that with some
sunshine will bring strong wind gusts downwind from the
lake...possibly in the low end advisory range. There will be some
uncertainty as to how much sunshine (and thus the depth of the mixed
layer) as thicker clouds will be just to the west of the region
along a baroclinic boundary.

This cold front to the west will cross the region later Sunday and
Sunday night with showers and possibly a thunderstorm. Instability,
with air temperatures in the 70s to lower 80s, and dewpoints around
60F will bring CAPE values upward to 300 - 500 J/KG, and additional
lift along a strong cold front could yield a few rumbles of thunder.

A very noticeable change will be in store for Monday. Gone will be the
late summer warmth, and in place will be another brisk day with
temperatures in the upper 40s to mid 50s. Strong cold air advection,
and cyclonic flow aloft will maintain brisk westerly flow...that may
near gale force on the lakes. 850 hPa temperatures dropping down to
just below zero will generate lake effect activity, with rain
showers possible SE of the lakes. With a secondary trough
maintaining cool air aloft, this lake effect rain showers may linger
into Tuesday morning before drier, and warmer air arrives ahead of
an area of high pressure.

A dry forecast will then prevail for the remainder of Tuesday and
Wednesday with seasonable temperatures.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Widespread rain will taper off through the early morning hours,
but there still will be lots of low moisture with mainly MVFR
and IFR conditions overnight. The lowest conditions will
generally be across the Western Southern Tier (including JHW)
with lower cigs due to the higher terrain. There also will be
lower conditions across the Niagara Frontier due upsloping in
the ENE surface flow.

Conditions will improve slightly later tonight when winds shift
to the east which will promote a slightly drier boundary layer.
A more significant improvement is expected Thursday morning when
winds shift to the southeast. This will lead to downsloping at
most terminal locations with improving to VFR at most TAF sites.

Outlook...

Thursday night...Mainly VFR.
Friday and Saturday...VFR.
Sunday...VFR/MVFR with showers and possibly a thunderstorm.
Monday...Mainly VFR. A chance of showers.

&&

.MARINE...
Strong northeast winds will gradually diminish and shift to the
east overnight. Conditions will slowly improve Thursday into
Friday with high pressure in control. The next chance for
impacts on the lower Great Lakes comes Sunday into Monday as a
strong low pressure system moves by to our north and pushes a
strong cold front across the region.

&&

.TIDES/COASTAL FLOODING...
Strong northeast winds on Lake Ontario will continue through
tonight. Waves are near peak this evening and will diminish
along with the winds overnight.

The lake level is several feet lower than in the late spring, so
lakeshore flooding will not be as significant as earlier this
year. However, the shoreline is very fragile following all of
the erosion this year, so addition high wave action will result
in further erosion.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Lakeshore Flood Warning until 8 AM EDT Thursday for NYZ001>003.
MARINE...Small Craft Advisory until 5 AM EDT Thursday for LEZ040-041.
         Small Craft Advisory until 2 AM EDT Thursday for
         LOZ030.
         Small Craft Advisory until 5 AM EDT Thursday for LOZ043.
         Small Craft Advisory until 11 AM EDT Thursday for LOZ042.
         Small Craft Advisory until 11 PM EDT this evening for
         LOZ044.

&&

$$

SYNOPSIS...APFFEL/ZAFF
NEAR TERM...APFFEL/ZAFF
SHORT TERM...HITCHCOCK
LONG TERM...THOMAS
AVIATION...APFFEL/ZAFF
MARINE...APFFEL/ZAFF
TIDES/COASTAL FLOODING...CHURCH/HITCHCOCK



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