Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 191929

Area Forecast Discussion
National Weather Service Buffalo NY
229 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.


Visible satellite imagery shows full sunshine across the entire
region this afternoon with just a few thin patches of cirrus
crossing the North Country. Expect sunshine to continue through the
end of the day for most of the region. Across the North Country a
few lower clouds may develop toward evening across the higher
terrain as low level moisture and upslope flow begin to increase.
Temperatures will reach the low to mid 50s across most of Western
NY, with mid 40s across the eastern Lake Ontario region. These highs
will likely occur early this afternoon, with temperatures then
starting to drop mid to late afternoon as cold advection increases.

Tonight a mid level trough will dig southeast across New England.
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
boundary layer flow becomes northwest and north. 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 mostly cloudy tonight for most areas from the Genesee
Valley eastward, with clouds more patchy across far Western NY.
Temperatures will turn a little colder behind 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.


Temperatures will remain solidly above normal during this period...
as a blocked flow will persist across the northern hemisphere. The
main feature within the obstructed flow will be a Rex Block that
will be anchored between Alaska and the Hawaiian Islands. This will
naturally keep a trough over the western half of the country while
general ridging will be found further downstream (over the east).
While the pattern will attempt to break down towards the end of this
forecast period with the trough broadening across the country...but
any semblance of winter will be short lived as the various ensemble
packages are suggesting that the longwave trough will then become re-
established over the west.

In terms of 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. Such 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.

While there is high confidence of the general pattern and its
corresponding impacts on our temperatures...the same cannot be said
about the timing of the individual storm systems. This will lead to
some broad brushing of chc pops...especially later in the period.
Will thus refrain from getting too specific with the use of likely


VFR will prevail through the end of the afternoon with mainly clear
skies across the region. A backdoor cold front will drop south
across the area this evening, with low level moisture increasing in
it`s wake as low level flow becomes northwest and eventually north
late tonight. This will pick up some limited moisture off Lake
Ontario, and also produce more upslope flow into the higher terrain.
This will bring areas of MVFR CIGS, first by early evening east of
Lake Ontario, and eventually overnight for the rest of the area. The
MVFR CIGS will linger into Monday morning before quickly scattering
out as high pressure builds southeast across Quebec and northern New
England, bringing a return to VFR.


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


West to southwest winds early this afternoon will slowly veer to the
northwest during the late afternoon and evening as a backdoor cold
front moves south across the Lower Great Lakes region. This will
bring choppy conditions to the east end of Lakes Erie and Ontario,
but winds and waves will generally stay just below Small Craft
Advisory Criteria. Winds will become north and then northeast Monday
as high pressure builds across Quebec and New England.

Relatively light winds will then continue through the first half of
the week.





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