Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 192106
AFDBUF

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

.SYNOPSIS...
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.

&&

.NEAR TERM /THROUGH MONDAY/...
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.

&&

.SHORT TERM /MONDAY NIGHT THROUGH THURSDAY/...
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
flow.

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.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
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.

&&

.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
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.

Outlook...

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

&&

.MARINE...
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.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...HITCHCOCK
NEAR TERM...HITCHCOCK
SHORT TERM...CHURCH
LONG TERM...JJR/RSH
AVIATION...HITCHCOCK
MARINE...HITCHCOCK



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