FXUS61 KBUF 160836

Area Forecast Discussion
National Weather Service Buffalo NY
336 AM EST Sat Feb 16 2019

High pressure centered over the Canadian prairies and a storm system
over northern Quebec will maintain a cold northwest flow across our
region into tonight. This will keep some light snow showers and
flurries in place southeast of the lakes...although generally fair
weather can be anticipated through the first half of Sunday. Low
pressure moving from the Tennessee Valley to the Mid Atlantic region
will bring us our next chance for widespread measurable snow late
Sunday into Monday.


A cold northwest flow in the wake of a deep storm system over
northern Quebec will generate some nuisance light snow showers and
flurries southeast of both lakes through the morning hours...but
given a staunch subsidence inversion under 5k ft...any accumulations
will be minimal. Otherwise...expansive high pressure centered over
the Canadian prairies will arch to the southeast across the Great
Lakes region for the afternoon. This will support fair uneventful
weather across our region...with nothing more than some flurries and
spotty light snow showers over the counties bordering the south
shore of Lake Ontario. Temperatures today will fall short of
normal....staying in the 20s for all but the normally milder
Genesee Valley.

Tonight...a low amplitude mid level ridge and an extension of the
aforementioned Canadian surface high over will guarantee a fair
night across the region. The only weather to speak of will be some
flurries that will be found over the counties lining the south shore
of Lake Ontario. It will be cold...with the mercury dipping into the
teens over the western counties and the single digits for sites
north and east of the Tug Hill.


As this period opens on Sunday a few spotty flurries may still be
ongoing along and a little inland from the south shore of Lake
Ontario...with these supported by leftover shallow low level
moisture and an east-northeasterly low level flow. These should
fade by mid to late morning...with dry conditions otherwise
prevailing through early to mid afternoon along with increasing
mid and high clouds out ahead of the next system.

Later Sunday afternoon and evening a modest southern stream system
will track from the Tennessee Valley to about Pittsburgh...from
which point onward it will slide eastward along the Mason-Dixon
line and off the mid-Atlantic coastline later Sunday night and
Monday morning. Over the past couple of days the various guidance
packages have universally trended northward and come into much
better agreement with the track of this system...with all guidance
now suggesting a rough 18 to 24 hour-long period of steady light
snow across much of our region between late Sunday afternoon/Sunday
evening and the first half of Monday. With this in mind have
continued the steady upward trend in PoPs...with these now raised
to categorical south of Lake Ontario and to likely/chance across
the North Country...where a fairly sharp northern cutoff to the
snow still looks to be in place.

Initially the snow should be forced by a combination of weak warm
air advection and DCVA...followed by weak deformation and upsloping
later on in the event. With the more northerly track to the system
and deeper moisture and somewhat better forcing consequently available
to work with...total snowfall amounts between late Sunday afternoon
and Monday have come up a bit more...and now look to range on the
order of 2-4 inches south of Lake Ontario to a half inch to an inch
near the Saint Lawrence River. Should the current northward trend
continue...it is not at all out of the question that amounts could
potentially reach the lower end of the advisory range in places
south of Lake Ontario...a mention of which will be added to the
HWO. Stay tuned...

Following the passage of this system...the cold but increasingly
dry northwesterly flow in its wake may support a few more flurries
or leftover snow showers Monday night and Tuesday...particularly
closer to Lake Ontario. Otherwise expansive high pressure initially
centered over the northern Plains states will steadily build
southeastward across the Great Lakes and southern Canada...while
bringing a return to dry and quiet weather to our region.

As for temperatures...these will remain at below normal levels
through this period...with daily highs ranging through the 20s...
and nightly lows mostly ranging from the single digits across the
North Country to the teens south of Lake Ontario.


During the latter half of next week the flow across the eastern
CONUS will become a bit more amplified as deepening large-scale
troughing over the Rockies and western Plains states drives the
development of downstream upper level ridging over the eastern third
of the nation and the far western Atlantic ocean. Southern stream
energy and another attendant broad/complex surface low ejecting
northeastward within this flow regime still looks to push across
the Ohio Valley and the Northeastern states between Wednesday and
Thursday...with the medium range guidance continuing to exhibit
some differences with respect to the track and timing of this
system. These differences notwithstanding...it still appears that
this system will bring at least the chance of precipitation to our
area Wednesday into Thursday...with a cold enough airmass for
primarily snow on Wednesday eventually warming enough to support
the potential for mixed precipitation or even rain Wednesday night
and Thursday. At the same time...the overall warm advection regime
should also allow temperatures to climb back to a little above
late February normals by Thursday.

Following the passage of this system...the ECMWF and GEM build
another large area of high pressure and plentiful dry air across
our region Thursday night and Friday...while the GFS quickly
tracks yet another southern stream system along the path of its
predecessor and across our region. Given our continuity and that
the latter solution remains an outlier...for now will continue to
aim more optimistic and indicate the return of fair and mainly
dry weather for the end of the week...along with continued near
to slightly above normal temperatures.


Cigs of 2500 to 3500 feet will be found across the majority of
western and north central New York for the remainder of the pre dawn
hours...with some light lake effect snow reducing vsbys to MVFR
levels at times for the counties lining the south shore of Lake
Ontario...including at KBUF.

After daybreak...cigs will gradually climb to VFR levels for most of
the region with the areas of light snow tapering off to flurries.
The exception will be between KROC and KSYR where lower cigs from
continued nuisance lake effect should persist.

Tonight...high pressure arching southeast across the Lower Great
Lakes will provide fair VFR weather across the majority of the
region. Again...the exception will be close to Lake Ontario where
some lake induced strato-cu will be found between 2500 and 3500


Sunday...VFR/MVFR with a chance of snow showers south of Lake
Ontario. Monday...MVFR with a weak system moving across the region.
Wednesday...MVFR with a chance of snow.


A relatively tight sfc pressure will remain in place over the Lower
Great Lakes through at least midday...as a deep storm system will
continue to move away via northern Quebec. This will keep small
craft advisories in place for the nearshore waters of Lake
Ontario...although the SCA for Lake Erie has been extended into the
early morning hours.

As we push through the morning into the midday...expansive high
pressure over the Canadian prairies will arch southeast across all
of the Great Lakes. This will allow winds and waves (in ice free
areas) to gradually subside below small craft advisory levels for
most of Lake Ontario. The exception will be from Hamlin Beach to
Mexico Bay where waves will likely remain elevated into the evening

The large Canadian high pressure system will then promote relatively
light winds and minimal waves later Saturday night into Sunday. As
we progress deeper into Sunday and Sunday night...northeast winds
will freshen...especially over Lake Ontario.


MARINE...Small Craft Advisory until 8 AM EST this morning for LEZ040-
Small Craft Advisory until 9 PM EST this evening for
Small Craft Advisory until 1 PM EST this afternoon for



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