Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 192338

Area Forecast Discussion
National Weather Service Buffalo NY
638 PM EST Sun Feb 19 2017

High pressure will provide our region with fair weather through
Tuesday morning. A weak front will then cross the area later Tuesday
and Tuesday night with a period of showers. Mainly dry weather will
then return for Wednesday and Thursday before low pressure moves
into the Great Lakes Friday with the next period of rain.
Temperatures will remain well above average through the week before
colder air arrives next weekend.


A mid level trough will dig southeast across New England tonight...
and this will force a backdoor cold front to move south across
our region with steady low level cold advection. Low level
moisture will increase overnight in the wake of the backdoor
cold front as the boundary layer flow will becomes north to
northwest. This will pick up some limited lake moisture off
Lake Ontario...and also produce more upslope flow into the higher
terrain south of the lake. Expect skies to become partly to mostly
cloudy tonight for most areas from the Genesee Valley eastward...
with clouds more patchy across far Western NY. Temperatures
will steadily lower in the wake of the the backdoor cold front...
with lows around 30 in most areas and low to mid 20s for the
North Country.

On Monday...the backdoor cold front will stall and wash out
just to our south and west. High pressure will build south into
Quebec and northern New England with associated subsidence and
drying bringing another dry day. Some low stratus may linger in
the morning from the interior sections of Western NY eastward to
Central NY and Lewis County...but this should erode and give
way to sunshine as a dry low level airmass builds into the
region. Temperatures will be knocked back another notch with
highs in the lower to mid 40s across far Western NY...upper 30s
for the Rochester area and Finger Lakes...and low to mid 30s
across the North Country.


Monday night will be range from quite chilly (teens) across the
North Country, which will be closer to the departing cold airmass
over New England, to somewhat mild (low 30s) across WNY where warm
air will start to surge into the region ahead of the next
approaching weather system.

A progressive trough will cross the region Tuesday bringing a line
of showers across the area. Temperatures will be quite mild with no
real cold airmass nearby to tap into, and thus these showers will be
all rain with no precipitation type concerns. Yesterday`s model runs
trended toward faster timing, which has persisted with today`s model
runs. Thus have categorical PoPs crossing the region during the day
on Tuesday. Precipitation should end from west to east quickly
Tuesday night, but held back some chance PoPs especially for the
higher terrain where upslope flow may allow for some lingering
showers or drizzle into Tuesday night. Patchy fog will likely
develop Tuesday night across WNY in the wake of the rain showers,
and as dew points climb above the lake temperatures on southwesterly

Broad ridging across the central CONUS with cold air and troughing
to our north will support continued southwesterly flow Wednesday and
Thursday keeping an abnormally warm airmass in place across the
region, along with mainly fair weather. High temperatures will
likely push the low to mid 60s in the typical downslope prone
Genesee Valley and northern Finger Lakes, with upper 50s to near 60
across western NY and low 50s across the North Country. The nights
will also be rather mild with lows Tuesday night only falling into
the mid 30s in the North Country, and low 40s in WNY. Wednesday
night looks very mild ahead of an approaching frontal boundary, with
increased winds and cloud cover, temperatures might not fall below
the mid to upper 40s in WNY to about 40 in the North Country. Patchy
fog will likely also redevelop Wednesday night as mid-40 dew point
air advects across the colder Great Lakes.


During this period a blocked flow will persist across the northern
hemisphere...with a Rex Block remaining anchored between Alaska and
the Hawaiian Islands. Across the CONUS...this will favor large-scale
troughing across the western half of the country and broad/flat
downstream ridging over the east...which for our region will translate
into temperatures remaining above typical late winter averages. While
the overall pattern may break down a little early on with the trough
temporarily broadening across the country and consequently leading to
an incursion of seasonably colder air into our region next weekend...
this should be short lived as the various guidance packages still
suggest that the mean trough will become re-established over the west
by the end of next weekend or early next week.

In terms of the day to day weather...the upper level pattern described
above will be very conducive for `cutter` type storms to make their
way from the high plains to the Upper Great Lakes. This storm track
will keep the storm systems to our west...further enhancing the mild
weather with periodic injections of warmth from the GOMEX. During the
extended portion of the forecast...this will be the case Friday and
Friday night when a sub 990mb low will direct some late winter sub
tropical warmth (H85 temps 10 to 12c) across the Lower Great Lakes.
Following the passage of this low and its trailing cold front sometime
on Saturday...the aforementioned colder air will then filter across
our region through the remainder of the weekend...resulting in our
temperatures pulling back closer to normal...but still remaining a
bit above average overall.

With respect to precipitation potential...the cutter system referenced
above should bring general shower chances to our region Friday right
through Saturday...with these appearing most likely to peak sometime
during Friday night...when PoPs have been bumped up to the low likely
range. After that...drier weather should return for the rest of the
period...with any potential lake response east of the lakes likely
remaining greatly limited in scope by the dryness and marginally cold
nature of the incoming colder airmass.


VFR conditions will remain in place across the bulk of western
New York tonight...although the passage of a weak backdoor cold
front could be accompanied by some MVFR cigs across the Eastern
lake Ontario region. There may also be some MVFR cigs across
portions of the Finger Lakes towards daybreak.

As high pressure becomes re-established over the region on
Monday...widespread VFR conditions can be anticipated along with
light sfc winds.

VFR conditions will persist ahead of a frontal system Monday


Tuesday and Tuesday night...Showers likely with areas of MVFR.
Wednesday and Thursday...Mainly VFR.
Friday...Showers likely with areas of MVFR.


Veering winds along and behind a weak backdoor cold front will
promote north to northwest winds across the Lower Great Lakes

Winds will continue to veer to the northeast on Monday as high
pressure will become re-established over the region. The
northeast flow will create choppy conditions west of Hamlin
Beach on Lake Ontario...but winds and waves should remain small
craft advisory criteria.

While winds will gradually freshen with a continued veering flow
Monday night...the flow will be offshore and this will limit the
risk for small craft advisory conditions.





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