Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
717 am EST Tuesday Dec 10 2013
limited lake effect snow showers will be ongoing east of the lakes
through today with minor accumulations expected. A westerly flow of
colder air will then set the stage for significant lake effect snow
east of the lakes tonight through Wednesday night. Some lake effect
snow will continue through the end of the week before an area of low
pressure potentially brings a more widespread general snowfall this
weekend. Temperatures will be below average the entire period.
Near term /through tonight/...
significant lake effect snows expected tonight through midweek east
of lakes Erie and Ontario...
Current radar loops are showing lake snow bands east of both lakes
Erie and Ontario under southwest flow this morning. The Lake Ontario
band focused across the Tug Hill plateau is much better organized
than the Lake Erie band which is positioned between Buffalo and
Jamestown. The radar is also picking up the northern edge of some
synoptic snow associated with a surface wave of low pressure
shifting across the middle Atlantic region.
The lake effect snows will remain fairly tame through today as weak
surface ridging builds from the Ohio Valley across western and
central New York keeping lake inversion heights limited to under
10kft. Southeast of the forecast area the surface wave will shift
across the middle-Atlantic region to New England with little impact on
our forecast other its gradient keeping breezy winds and some
scattered light snow or flurries observed across along the New York/PA
state line and southern Finger Lakes. The limited lake snows will
be more of a focus today across the southern tier and Eastern Lake
Ontario regions with a general one to three inches of snow through
the day at each location possibly more over the Tug Hill. Temperatures
will be chilly today as colder air continues to build across New
York. High temperatures will be limited to the 20s with breezy winds
making it feel more like the teens to single digits.
Lake effect snows will increase this evening as a middle level
shortwave and weak clipper low crosses north of the Great Lakes. This
feature will provide better synoptic moisture and lift across the
lower lakes region along with a shot of colder air behind its
accompanying Arctic front. This colder shot of air will raise lake
inversion heights to near 15kft with extreme lake induced instability
developing beneath this inversion. Lake surface to 700mb lapse rates
will raise to 8+c/km. These parameters with the addition of gusty
winds developing ahead of the clipper will bring significant lake
snows with blowing and drifting east and northeast of the lakes
beginning this evening for which lake effect snow warnings and
advisories have been issued as outlined beneath the marine section.
The only change to the headlines was the addition of a lake effect
Snow Advisory for Allegany County as lakes snows are expected to
impact mainly western portions of the County.
Lake effect off Lake Erie tonight...
lake effect snow will increase in intensity toward the evening
commute and as the clipper approaches winds will back to the
southwest. This will lift the lake effect snow from the southern
tier northward to the Buffalo southtowns with its northern extent
probably even reaching metropolitan Buffalo toward Tonawanda...Amherst and
clarance. The lake band will bring accumulating snow...low
visibilities and snow covered roadways. By late evening winds are
forecast to veer back toward westerly which will swing the lake band
back south to the Buffalo southtowns and western southern tier.
Across northern Erie and Genesee County two to four inches of snow
could accumulate in the brief times that the snow band lifts north
but this coming during the evening commute will bring a larger
impact across the greater Buffalo region. Longer residence time of
the band across the southtowns and southern tier will allow for
better accumulating snows of 3 to 6 inches or More.
Lake effect off Lake Ontario tonight...
east of Lake Ontario a well organized long axis parallel lake snow
band will bring more significant snows tonight. Impact here will be
focused across northern Oswego...southern Jefferson and Lewis
counties under a mainly westerly flow. Forecast models are not
showing a similar shift in the lake band tonight due to backing
winds with the approaching clipper as what we see for Lake Erie.
There may be some meandering of the more persist snows but overall
the focus will remain over the east end of the lake through the
night. Snow accumulations of 7 to 13 inches are possible tonight
with the higher amounts across the Tug Hill plateau. Accumulations
will sharply tapper off toward the outer edges of the band.
Developing gusty winds tonight with the approach of the clipper will
cause blowing and drifting of snow tonight. Significant travel delay
are expect along Interstate 81 due to snow covered roads and low
visibilities in the lake band.
Outside of the lake effect areas some minor snow accumulations may
occur as the clipper low passes across New York. Lows tonight will
drop into the teens with gusty winds making for wind chills inn the
single digits and perhaps below zero across the southern tier.
Short term /Wednesday through Thursday Night/...
Lake effect snows will be ongoing as we open Wednesday morning.
Persistent west-southwest flow off Lake Erie combined with abundant cold air
and 850mb temperatures dropping to -16c will focus activity across
southern Erie and Wyoming and to a slightly lesser extent along
the Chautauqua ridge. Snowfall rates will really pick up during
the late afternoon into the evening hours as lake effect will be
augmented by synoptic lift as a potent shortwave trough approaches
the lower Great Lakes. The heaviest activity will likely become
more focused on the Chautauqua ridge later on Wednesday night with
flow veering to the west-northwest as the shortwave moves overhead.
The scenario will be much the same on Lake Ontario...just with
greater snow amounts across the Tug Hill plateau where we could see
close to a foot of snow on Wednesday thanks to the greater upslope
component and longer westerly fetch off Lake Ontario. As with Lake
Erie...suspect we shall see a strong burst of snow later in the
evening with the approach of the upper level trough before flow
veers northwesterly later in the evening. After midnight suspect
that band will briefly move onto the South Shore of Lake Ontario
before falling apart as fetch decreases and vertical profile becomes
increasingly sheared/disorganized in the wake of the shortwave with
widespread...but less intense snow showers south of the lake through the
rest of the night as we transition to a multi-band regime.
For Thursday...westerly flow becomes re-established behind upper
level trough by Thursday afternoon. With better aligned vertical profiles in
the boundary layer...expect band to reorganize and focus on
Chautauqua ridge off Lake Erie and on the tug off Lake Ontario. The
tug could easily see another foot or more Thursday/Thursday
night...particularly if a Georgian Bay connection can develop...but
not as much on Chautauqua ridge where there will not be as much upstream
moisture to work with. Some guidance suggests Lake Erie band could
shift back to the north into Buffalo metropolitan later Thursday night as
low level flow veers southwesterly in response to high pressure over
the Ohio Valley moving to the Piedmont.
It will be quite cold through the period as 850mb temperatures will be
running in the -16 to -18c range. The passage of the aforementioned
shortwave trough and associated Arctic front will push temperatures
down with highs in the 20s Wednesday dropping to highs only in the
teens to lower 20s Thursday. Look for lows to range from the teens
along the lake plains with single digits across the north country
and higher terrain of the southern tier. Once the persistent
sustained winds of 15 to 20 miles per hour with gusts as high as 30 miles per hour are
factored in...wind chills are likely to drop into the single digits
below zero at times.
Long term /Friday through Monday/...
considerable discrepancies persist to end the work week right
through the weekend as latest medium range continue to differ on the
handling of the developing baroclinic zone across the Great Lakes.
This scenario would set the stage for a prolonged period of snow
showers...with at least some lake contribution at times...although
the actual mean flow is too hard to forecast at this time. Therefore
have maintained generic chance probabilities. Temperatures are
expected to remain cold with highs in the upper teens to middle 20s and
lows in the upper single digits and teens.
Aviation /12z Tuesday through Saturday/...
lake effect snow bands have developed this morning east of the
lakes. Under a southwest flow the heavier snows are for the most
part remaining clear of the taf sites to the north of kjhw and south
of kart...kbuf...kiag...kroc. IFR ceilings and visible should be expected
within lake bands with VFR/MVFR ceilings outside of the lake bands.
Later this afternoon into the Evening Lake effect will lift north
towards kbuf and kart as a clipper low approaches the region. A
brief period of IFR is likely from roughly 22z-01z...with a brief
relaxation at kjhw. The lake band will then settle back to the south
across the southern tier after 02z Wednesday with low MVFR or IFR
conditions at kjhw again.
Tuesday night through Wednesday night...VFR except areas of IFR east
of the lakes in heavy lake effect snow.
Thursday...VFR except MVFR/IFR in lake effect snow showers southeast
of the lakes.
Friday...VFR except MVFR/IFR in lake effect snow showers east of the
Saturday...MVFR/IFR with a chance of snow.
breezy southwest winds are keeping choppy conditions across the
lakes today with small craft advisories in effect. Later this
afternoon winds will increase to gale as a clipper low crosses the
lower lakes. Gale warnings have been raise across the lakes from
this evening through the overnight. Through Wednesday winds will
relax some with Gale Warning expected to drop back to small craft
advisories on the near shore waters. Gusty westerly winds will
continue through the rest of the week with a pressure gradient
remaining across the region.
New York...Lake effect snow warning from 6 PM this evening to 4 am EST
Thursday for nyz006>008-012-019-020-085.
Lake effect Snow Advisory from 6 PM this evening to 3 am EST
Thursday for nyz021.
Lake effect Snow Advisory from 4 PM this afternoon to 1 am EST
Wednesday for nyz010-011.
Marine...Small Craft Advisory until 6 PM EST Wednesday for lez020.
Small Craft Advisory until 4 PM EST this afternoon for
Gale Warning from 4 PM this afternoon to 7 am EST
Wednesday for lez040-041.
Small Craft Advisory until 6 PM EST Wednesday for
Small Craft Advisory until 6 PM EST this evening for
Gale Warning from 6 PM this evening to 1 PM EST Wednesday
Gale Warning from 6 PM this evening to 10 am EST Wednesday