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000
FXUS61 KBUF 290625
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
125 AM EST Sat Feb 29 2020

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

&&

.NEAR TERM /THROUGH TODAY/...
Currently as of 6Z, the Lake Ontario lake band is dropping across
the counties just south of the lake. This is occuring as a trough
drops south across the lake. Localized reductions in visibility will
be possible in this band of snow as it moves south, but the band is
weakening the farther inland it travels.

Early this morning through today, 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
early this morning...with a modified shot of sub-arctic air then
following in its wake.

The resulting cold cyclonic flow across our region will continue to
maintain lake effect and lake enhanced snows across our region
through today...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 early this morning...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 morning 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 through the early morning hours...before weakening and
settling southward across the higher terrain through the remainder
of the day 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 through early this morning and 2 to 3 inches on
today...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 this
morning...with total amounts in most areas likely to stay under
advisory criteria.

Meanwhile off Lake Ontario...a single intense band 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 bringing a brief burst of heavier snow to the Niagara-
Northern Cayuga county corridor that could produce a quick few
inches of accumulation. 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 today. In terms
of additional accumulations...Wayne/Northern Cayuga counties will
likely see an additional 3-5" through the early morning...with an
additional 2-3" then falling across the Wayne-Oswego County corridor
today. 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...
today will feature a return to much lighter winds but also well
below normal temperatures...with lows this morning dipping into the
single digits across the North Country and the mid teens
elsewhere...and highs today struggling to get much above the upper
teens to mid 20s.

&&

.SHORT TERM /TONIGHT 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 /07Z SATURDAY THROUGH WEDNESDAY/...
A cold front will continue to 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. With the front and associated lake effect pressing south
of the eastern Lake Ontario region, expect marked improvement to VFR
overnight at KART.

On Saturday...Continued general MVFR (with IFR at times at KJHW) 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 this evening...for which Small Craft Advisories are in
effect as outlined below. Calmer conditions will then return later
tonight and Sunday as high pressure builds directly across the
region.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Lake Effect Snow Warning until 4 AM EST early this morning for
     NYZ006>008.
     Winter Weather Advisory until 1 PM EST this afternoon for
     NYZ004-005.
     Lake Effect Snow Warning until 10 AM EST this morning for
     NYZ012-019-020-085.
     Winter Weather Advisory until 10 AM EST this morning for
     NYZ021.
MARINE...Small Craft Advisory until 4 AM EST Sunday for LEZ040-041.
         Small Craft Advisory until 4 AM EST early this morning 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/SW
NEAR TERM...JJR/SW
SHORT TERM...AR
LONG TERM...AR/JJR
AVIATION...JLA/JJR/RSH
MARINE...JJR/SW