Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 290038
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
738 PM EST Fri Feb 28 2020

.SYNOPSIS...
A swath of moderately heavy snow will accompany the passage of a
cold front tonight...while accumulating lake snows will persist east
of both lakes. A cold northwest flow will support additional snow
showers on Saturday for all areas except the North Country.
Significant day to day warming can then be expected for Sunday and
Monday.

&&

.NEAR TERM /THROUGH SATURDAY/...
Tonight and Saturday vertically stacked low pressure over Quebec
will slowly meander its way eastward to northern New England and the
Canadian Maritimes. This feature will push a secondary cold front
southward across our area this evening...with a modified shot of sub-
arctic air then following in its wake later tonight and Saturday.

The resulting cold cyclonic flow across our region will continue to
maintain lake effect and lake enhanced snows across our region
through Saturday...with the activity generally sliding southward to
areas southeast of the lakes and weakening over time as the initial
westerly flow out ahead of the cold front turns more northwesterly
and becomes a bit more sheared. The passage of the secondary cold
front will also generate a round of more widespread light to briefly
moderate snow tonight...resulting in general additional inch or two
of accumulation outside of the main lake effect areas.

Off Lake Erie...ongoing lake snows east of the lake will continue to
briefly ratchet up in intensity through this evening as the secondary
cold front approaches and provides a boost in moisture and large-scale
lift...though the presence of at least some directional shear should
still help keep this more diffuse in nature. Expect this to peak
during the late evening/early overnight hours...before weakening and
settling southward across the higher terrain through the remainder
of the night and Saturday as the flow turns more northwesterly and
the fetch across the lake shortens. Expect additional accumulations
across southern Erie and Wyoming counties and the western Southern
Tier to range from 4 to 7 inches tonight and 2 to 3 inches on
Saturday...for which Lake Effect Snow Warnings remain in effect.
Further north...the more immediate Buffalo southtowns and far
southern sections of Genesee County could pick up an additional 1 to
3 inches before the activity settles back southward later this
evening...with total amounts in most areas likely to stay under
advisory criteria.

Meanwhile off Lake Ontario...a single intense band will once again
be draped across the entire length of the lake to the Watertown area
and Tug Hill region at the start of the evening. This will quickly
get shunted bodily southward by the advancing secondary cold
front...with the band sinking across the entire south shore of the
lake and possibly bringing a brief burst of heavier snow to the
Niagara-Northern Cayuga county corridor that could produce a quick
few inches of accumulation. After that time...the strong single band
will break apart...with the general west-northwesterly flow in the
wake of the front and an increase in shear leading to a larger area
of weaker...multibanded lake snows for the remainder of tonight
and Saturday. In terms of additional accumulations...areas east of
Lake Ontario and Wayne/Northern Cayuga counties will likely see an
additional 4-7"/3-5" respectively through tonight...with an additional
2-3" then falling across the Wayne-Oswego County corridor during
Saturday. For this reason...Lake Effect Snow Warnings and Winter
Weather Advisories remain in effect for these areas as outlined
below. Further west...far northeastern portions of Monroe county
could also see localized lower-end advisory-criteria amounts...with
the areal coverage of these currently appearing too low to warrant
an additional headline.

Outside of the lake snows and general snowfall mentioned above...
tonight and Saturday will feature a return to much lighter winds but
also well below normal temperatures...with lows tonight dipping into
the single digits across the North Country and the mid teens
elsewhere...and highs on Saturday struggling to get much above the
upper teens to mid 20s.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
Lake effect snows will be in the process of weakening and winding
down during this period. Lake Erie will see this occur first as
equilibrium levels fall below 5K aided by a lowering subsidence
inversion and warming mid-levels. Off lake Ontario, deeper moisture
and upstream connections may keep lake snows going further into the
night with some minor additional accumulations. Otherwise, there too
lake snows will be in the process of weakening and by Sunday morning
should all but wrap up shortly after sunrise. In terms of
temperatures, lows will be found from the single digits east of Lake
Ontario to the teens across the rest of the region by sunrise
Sunday.

Winter doesn`t stick around too long again with a rapid warming
trend. A mid-level shortwave tracking across the Canadian Prairies
will push a warm front into and across the region on Sunday. Warm
advection processes and H850T climbing to 0C/-3C across the region
will result in high temperatures pushing near to a little above
normal. As the warm front crosses the region there will also be a
chance for some light showers. Otherwise, Look for highs in the
upper 30s to lower 40s across the Genesee Valley and far Western NY.
East of Lake Ontario, where the warm front won`t have quite made it
through highs will be a bit cooler and in the upper 20s to near 30F.

Sunday night, warm frontal boundary extending back into the Ohio and
mid Mississippi valley will provide the avenue for a weak low to
track along overnight. Deep moisture transport aided by a +45 knot
LLJ and DPVA will lead to increasing chances of precipitation as we
head into Monday. While the main p-type looks like rain, there maybe
a brief period of mix precipitation before it transitions to all
liquid on Monday. Precipitation amounts will generally be light and
less than a quarter of an inch across area basins.

In terms of temperatures, low temperatures will range from the teens
to low 20s east of Lake Ontario into the 30s across the Finger Lakes
and Western NY sunrise Monday. Highs on Monday, look for
temperatures to climb into the 40s areawide.

Monday night, the first wave exits the area and a weakening cold
front approaches the region from the northwest. There will be a
brief lull in the precipitation overnight before a series of weak
waves ripple by to our south. This will bring additional chance of
precipitation on Tuesday. Otherwise, lows overnight will be found in
the mid to upper 30s across the region.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Multiple shortwave disturbances and attendant waves of low pressure
rippling through the deep west to southwesterly large-scale flow
will continue to potentially bring frequent chances for rain Tuesday
into Thursday. This in combination with snowmelt from warmer
temperatures and the subsequent rainfall could pose an elevated risk
of flooding.

The last in the series of surface waves looks to cross our region
sometime between Wednesday and Wednesday night with a shot of colder
air (but nothing unusually cold for early March) then following for
Thursday. This would knock temperatures back closer to average for
the tail end of the period while also possibly allowing a little wet
snow to mix in on the backside of the system with any lingering rain
showers.

While the large scale pattern is in general agreement, there is
considerable difference with the small scale feature which could
potentially impact our region. The GFS shows a fast moving clipper
system Thursday night-Friday with accumulating snows across Western
NY. Meanwhile, the ECMWF plunges this little clipper system well to
our south. It then merges it with a low exiting off the coast. This
solution would have little if any impact on our region. For now,
have kept low end chance POPs for the tail end of the week.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
A cold front will push south across the region tonight...and this
will generate a swath of moderately heavy snow that will translate
into IFR to LIFR conditions for all of western New York. Meanwhile...
a band of heavy lake snow near KART at 00Z will push south. This
will allow for significant improvement for KART and KGTB by late
evening.

On Saturday...Continued general IFR/MVFR can be expected southeast
of the lakes in numerous snow showers and areas of lighter lake
effect snow...while the North Country should experience a mix of
MVFR to lower-end VFR conditions.

Outlook...

Saturday night and Sunday...Improvement to VFR with lingering lake
effect snow showers southeast of the lakes coming to an end.
Sunday night...MVFR/VFR with scattered rain and snow showers.
Monday through Wednesday...MVFR/VFR with scattered to numerous
rain showers.

&&

.MARINE...
Slowly departing deep low pressure over Quebec will maintain rather
brisk westerly to west-northwesterly winds across the Lower Great
Lakes through Saturday evening...for which Small Craft Advisories
are in effect as outlined below. Calmer conditions will then return
later Saturday night and Sunday as high pressure builds directly
across the region.

&&

.TIDES/COASTAL FLOODING...
A period of strong west winds in wake of strong low pressure will
continue to produce lakeshore flooding over eastern Lake Ontario,
now lingering into early this evening. There...the combination
of high lake levels, strong onshore westerly winds, and high
waves will produce some lakeshore flooding in bays and inlets at
the east end of the lake along with some minor shore erosion.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Lake Effect Snow Warning until 4 AM EST Saturday for
     NYZ006>008.
     Winter Weather Advisory until 1 PM EST Saturday for NYZ004-005.
     Lake Effect Snow Warning until 10 AM EST Saturday for NYZ012-
     019-020-085.
     Winter Weather Advisory until 10 AM EST Saturday for NYZ021.
MARINE...Small Craft Advisory until 4 AM EST Sunday for LEZ040-041.
         Small Craft Advisory until 1 AM EST Saturday for LEZ020.
         Small Craft Advisory until 4 AM EST Sunday for LOZ043-
         044.
         Small Craft Advisory until 1 AM EST Sunday for LOZ042-045.

&&

$$

SYNOPSIS...RSH
NEAR TERM...JJR
SHORT TERM...AR
LONG TERM...AR/JJR
AVIATION...JJR/RSH
MARINE...JJR
TIDES/COASTAL FLOODING...JLA/JJR


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