Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Buffalo New York
955 am EST Thursday Dec 12 2013
a very cold airmass will remain in place over eastern Canada and the
Great Lakes region through Friday...and this will continue to
support impressive plumes of lake effect snow. While the lake snows
will taper off as we head into the upcoming weekend...a storm system
passing over the Middle Atlantic States will produce a widespread
accumulating snowfall across our forecast area Saturday and Saturday
night. Temperatures are expected to remain below normal through at
Near term /through tonight/...
regional radars this morning display an increasing band of lake
snows off Lake Erie across the southern tier and ski country. Off
Lake Ontario...while still weak there are stronger returns over the
Open Lake...and expect this band to also begin to increase in
strength later this morning.
During the course of this morning...the low level flow will
become better aligned with a rising cap supporting renewed plumes of
moderate to heavy lake snow. These plumes will lift north during the
midday into the early evening hours...with heavy snows approaching
both Buffalo and Watertown. Getting into some specifics...
Off Lake Erie...
moderate to extreme instability will be in place over the lake today
with moderately sheared 280 flow producing multiple bands of light
to moderate snow over the majority of the western southern tier.
Several inches of fresh snow will fall by lunchtime...mainly south
of the Boston Hills. As we progress through the afternoon...the
lake snows will consolidate into a plume of heavy lake snow that
will lift across the southern half of Erie County...likely impacting
the south towns (orchard Park/East aurora) and the southern Buffalo
suburbs late in the afternoon and particularly during the evening
rush hour. Snowfall rates of 1 to 3 inches an hour will be possible
with this activity...with the northern portion of the band possibly
reaching Buffalo and its eastern suburbs during the early evening
hours. Very difficult driving conditions are expected for the
evening rush hour...particularly south and east of downtown Buffalo.
As we work through tonight...the steering winds will veer to about
280 degrees with the steady heavy lake snows dropping back south
across the southern half of the County. While conditions will
improve in the Buffalo metropolitan area...treacherous driving conditions
will become re established over southern Erie County and portions of
northern Chautauqua and northwestern Cattaraugus counties where
fresh snowfall accumulations could approach a foot.
Through this 12 hour period...it will likely be too cold to allow
for significant mixed phase cloud depth off Lake Erie...so am not
anticipating any lake induced thundersnow.
Off Lake Ontario...
by lunchtime...a rising cap and a realigning 270 flow will direct a
consolidating band of moderate to heavy lake effect snow over the
Tug Hill...with snow fall rates once again increasing to more than
an inch per hour forecast through the afternoon.
Late today and early tonight...the band may lift to between
Watertown and the Tug Hill before settling back to the south across
the tug during the overnight hours. With a cap approaching 15k feet...
it is not out of the question that a limited mixed phase cloud layer
could induce a bit of lightning...but again...this specific event is
on the cold side for lake induced electrification.
Fresh snowfall across the Tug Hill is expected to range from one to
two feet later today and tonight...so very difficult travel
conditions can once again be expected on I-90 between the I-81
exchange and Watertown.
Outside the lake bands...it will eb quite cold today and tonight with
flurries and scattered snow showers. Temperatures will be some 10 to
15 degree f below normal with highs today will only reach into the
teens to near 20. Wind chill values will be within a few degrees of
Short term /Friday through Sunday/...
during the course of Friday...low pressure over New England will
exit eastward across the Canadian Maritimes...while dragging its
trailing cold front southward across New York state. As a result...
significant lake snows still ongoing east of the lakes at the start
of the day will get shunted southward and weaken dramatically as the
low level flow veers more northerly and much drier air/a lowering
cap gets introduced behind the surface boundary...though not before
dropping at least some additional advisory-type accumulations east
of the lakes. The diminishing trend will affect the Lake Ontario
lake snows first...with the lake effect band initially getting
shunted south across much of the South Shore of the lake and
dropping some additional minor accums of 1-3 inches across the
Niagara-Cayuga County corridor...before rapidly breaking up as it is
pushed further inland and away from its moisture source.
Meanwhile...the Lake Erie activity will hang on a bit longer given
the later arrival of the front...but even this should weaken
noticeably during the late morning and afternoon. Outside of the
Main Lake effect areas...generally just expect some scattered snow
showers and minor accums of an inch or less in conjunction with the
frontal passage. Given the frontal passage...temperatures should exhibit a non-
diurnal trend...with morning highs ranging from the middle-upper teens
across the north country to the Lower-Middle 20s elsewhere...then
slowly dropping off during the afternoon.
Friday night...low level-ridging extending east across New York
state and New England will bring a relative minimum in snowfall
chances during the evening...before increasing warm advection/
moisture associated with developing low pressure over the Tennessee
Valley brings a renewed potential for some light snow to areas south
of Lake Ontario overnight. Given what should be colder air
and less cloud cover over the north country compared to areas south
of Lake Ontario...nighttime lows will exhibit a decent north-south
gradient...with readings ranging from the teens south of the lake to
between zero and 10 below across the north country.
Saturday through Sunday...our attention will shift back to the
synoptic scale as the aforementioned surface low over the Tennessee
Valley redevelops off the middle Atlantic coastline...then lifts
northeastward and out into the western Atlantic...while a weaker low
drifts across the Great Lakes. The warm air advection pattern in
advance of the main surface low will spread a shot of plentiful
moisture and lift across our region Saturday and Saturday
evening...with this then exiting off to our north and east later
Saturday night and Sunday morning. With our airmass likely remaining
cold enough for all snow....this system should bring a widespread
general snowfall to the area between Saturday and the first part of
Sunday. While the exact accums we can expect out of all this are
still uncertain...at this point a 00z operational model suite/wpc
blend suggests the potential for a decent advisory-type snowfall
areawide. Temperature- wise...readings should remain below average
right through the weekend...with highs generally in the upper teens
to middle 20s Saturday and Sunday...and nighttime lows dipping into the
10-20 range Saturday night.
Long term /Sunday night through Wednesday/...
once this weekend's synoptic system lifts off to the northeast...
another shot of cold air will push into the region with lake snows
redeveloping on a west-northwesterly flow...with the best potential
for these coming between Sunday night and Monday morning. After
this...high pressure ridging across the region should bring
diminishing lake effect potential Monday afternoon and night...
before the next clipper system crosses the Great Lakes Tuesday and
Aviation /15z Thursday through Monday/...
while disorganized bands of lake effect will produce MVFR conditions
east of both lakes Erie and Ontario this morning...VFR weather will
be found at the major taf sites. The exception will be at kjhw where
MVFR ceilings will be likely.
During the course of the midday and afternoon...the multiple bands
of lake effect will move north towards Buffalo and Watertown. By
late afternoon...consolidating plumes of moderate to heavy lake snow
will approach both metropolitan areas with conditions deteriorating to at
least MVFR. There will be the chance for vlifr conditions in heavy
snow at both kbuf and kart during the late afternoon and evening.
Otherwise...VFR conditions are expected. Significant delays will be
possible at both airfields as snowfall rates in excess of an inch
per hour will be possible.
Tonight...significant lake snows in the buf and Art metropolitan areas will
drift back to the south. General improvement will take place
overnight at these taf sites...while conditions will deteriorate to
at least LIFR at kjhw.
Friday...mainly VFR...except IFR in lake effect snow showers east of
Saturday and Sunday...MVFR/IFR with snow likely.
Monday...MVFR with a chance for snow showers.
with a deep pool of cold air over the eastern Great Lakes right into
the weekend...and passage of several surface waves/low pressures
across the Great Lakes solid advisory-level conditions will persist
through the end of the week. The exception will be the eastern half
of Lake Ontario where winds will become border line gale strength
overnight tonight and into the morning hours Friday. Will issue a
Gale Warning for the eastern half of Lake Ontario to cover for this
New York...Lake effect snow warning until 1 PM EST Friday for nyz007-008-
Lake effect snow warning until 4 PM EST Friday for nyz006.
Lake effect Snow Advisory until 1 am EST Friday for nyz011.
Lake effect snow warning from 1 PM this afternoon to 5 am EST
Friday for nyz010.
Marine...Small Craft Advisory until 7 PM EST Friday for lez040-041.
Gale Warning from 6 PM this evening to 10 am EST
Friday for loz043>045-063>065.
Small Craft Advisory until 6 PM EST this evening for
Small Craft Advisory until 7 PM EST Friday for loz042.