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000
FXUS61 KBUF 110909
AFDBUF
Area Forecast Discussion
National Weather Service Buffalo NY
409 AM EST Wed Dec 11 2019
.SYNOPSIS...
Moving bands of lake effect snow will bring a few brief rounds of
heavy snow and blowing snow today through this evening east of Lakes
Erie and Ontario. Lake effect snow will end tonight east of Lake
Erie, and continue through Thursday morning southeast of Lake
Ontario. High pressure will then bring a return to dry weather later
Thursday through Friday. Low pressure moving northward along the
east coast will then bring rain and warmer temperatures to the
region Friday night through Saturday, with rain changing back to
snow Sunday as colder air moves back into the area.
&&
.NEAR TERM /THROUGH TONIGHT/...
Lake effect snow continues to be the main concern through tonight. A
clipper will pass by well north of the region across Quebec today,
with the trailing cold front crossing the eastern Great Lakes during
the early to mid afternoon. The clipper cold front itself will do
little, with very limited moisture and forcing to work with. It will
introduce a more favorable lake effect environment however, with
lake induced equilibrium levels rising to around 12K feet around the
time of the cold frontal passage. A favorably deep mixed phase layer
will be found within the boundary layer, yielding dendritic growth.
Convergence along the clipper cold front will merge with pre-
existing bands of lake effect convergence, maximizing low level
forcing. This should result in strong, but short lived bands moving
onshore from both lakes. The one limiting factor will be a relative
lack of synoptic scale moisture compared to some events. This may
limit the maximum intensity of the bands, but the very favorable
thermodynamics and low level forcing should overcome this.
Off Lake Erie...
A fairly healthy band of snow is moving slowly north along the
Lakeshore from Dunkirk to Angola early this morning. The heaviest
snow is close to the lake, with lighter snow extending inland across
the higher terrain. This band of snow will begin to accelerate
northward through daybreak as boundary layer flow quickly backs to
the SSW. The snow will cross the Buffalo Metro area during the early
to mid morning, just in time for the morning commute. As is often
the case with northward moving bands in a somewhat dry environment,
the heaviest snow will be confined to near the lakeshore, with
lighter snow inland from the lake.
The band of snow will make it all the way north to Grand island and
central Niagara/western Orleans counties for a few hours late
morning and midday. The clipper cold front will then capture the
band, and force it to move quickly back to the southeast and across
the Buffalo Metro area through mid afternoon. The entire band will
move onshore from Buffalo all the way down to the Chautauqua County
shoreline, moving quickly inland across the higher terrain east of
the lake. This south/east moving band will be more intense than the
morning band, given the stronger thermodynamics and added boost of
convergence from the cold front. It will be moving fast however,
only lasting an hour or two at most for any one location.
Total accumulations from last night through this evening still look
to be in the 3-5 inch range from the Buffalo Metro area north and
east, and 4-7 inches from southern Erie County down the Chautauqua
County lakeshore and inland across the higher terrain. Much of this
snow will fall in a few quick bursts.
The east end of the afternoon band will extend quite far inland. It
is possible a few segments of the band may detach and be carried
eastward by the cold front across the Genesee Valley and western
Finger Lakes, producing brief, heavy snow squalls.
The Lake Erie snow will quickly weaken during the early to mid
evening across the western Southern Tier, with snow showers then
ending completely overnight.
Off Lake Ontario...
Expect a similar trend a few hours later. Most of the snow this
morning will be over the lake with weak, disorganized flow in place.
By midday lake snow will be carried onshore near Kingston Ontario
and Cape Vincent. This area of snow will consolidate and intensify
into a more focused band by early to mid afternoon. The band will
then be captured by the cold front and carried south and east across
the eastern Lake Ontario region.
This initial band may move inland, followed by a brief lull. A band
of lake effect snow should then re-develop near the southeast corner
of the lake this evening. This band will settle south across Oswego
County as boundary layer flow becomes WNW. Unlike Lake Erie, this
band will last longer with a more favorable environment over Lake
Ontario through early Thursday morning. High resolution model
guidance differs on how far south the band will get, with some
models moving it into northern Cayuga and northeast Wayne counties
for a few hours in the middle of the night. If this occurs,
advisories may need to be extended into this area. Late tonight and
early Thursday morning the band will then move back north across
Oswego County.
Total accumulations east of Lake Ontario will generally be 3-5
inches in most locations. The Tug Hill may see up to 6 inches as the
strongest forcing late this afternoon interacts with upslope flow.
Oswego County may also see up to 6 inches if the overnight band
remains in one location long enough.
Finally, winds will become quite gusty today as the pressure
gradient tightens across the eastern Great Lakes. Expect gusts of
around 40 mph on the lake plains northeast and east of the lakes,
and up to 30 mph farther inland. Where lake effect snow develops,
the strong winds will produce blowing and drifting snow and very
poor visibility for short periods of time. The combination of brief
bursts of heavy snow and blowing snow will be the greatest impact
from this event.
&&
.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
Thursday, winds will back as surface high pressure passes just to
our south, with this feature also sending a wealth of mid level dry
air across the eastern Great Lakes. A few flurries are possible
early Thursday near Buffalo on a southwest flow, while east of Lake
Ontario a weakening band of lake effect snow will likely continue to
add to modest accumulations. Another inch or so of snow is possible,
generally along and to the west of I-81. The backing winds will send
a weakening band of snow from near Oswego County in the morning, to
near the Thousand Islands by Thursday afternoon...where it will be
in a much weaker state.
Fair weather will then occur Thursday night through Friday as this
surface high pressure slides to the east. Behind the surface high a
southerly flow will develop, and aid in sending Friday's
temperatures into the 40s, with mid 40s likely through the Genesee
Valley.
While our region is under fair weather, two upstream shortwave
troughs will be advancing towards our region...and develop a surface
low that will be our next weekend weather system.
The first wave, within the southern branch of the jet will be
streaming across the Central Plains Friday, while a second shortwave
will be dropping southward across Manitoba. These two waves will
carve a deep trough over the eastern US, with this trough replacing
a downstream ridge (which help to give us fair weather Friday).
Friday night a surface low will be forming just off the Carolina
coastline. A deep southerly and southeasterly flow will transport
both Gulf of Mexico and Atlantic moisture northward...with the core
of the moisture along a LLJ that will remain well to our east across
eastern NY and New England. Still we will have PWAT values rising to
three-quarters of an inch Friday night and Saturday, with initial
warm air advection, and isentropic lift rain moving across our
region Friday night and Saturday. There may be enough initial cold
air on the onset of precipitation that a little snow may fall over
the Tug Hill region early Friday night. Overall rainfall with this
system again looks to be manageable for our region, with minor rises
in creeks and streams.
Later Saturday and into Saturday evening a deformation axis rain
shield will cross the region, that should primarily fall as plain
rain across WNY before the cold air deepens and precipitation type
changes to snow. There is still uncertainty with the timing of the
colder air and change to snow..but we could see several inches of
synoptic snow east of Lake Ontario if the colder air before the
deformation band of precipitation ends.
Under the onset of cold air advection Saturday night (850 hPa
temperatures falling to around -6 to -8C, and still under moist
cyclonic flow aloft, and the passage of the upper level trough axis
rain showers will transition to light accumulating snow for our
region. Highlighted will be the colder, higher terrain where
orographic lift maintains light snow through the night with a
coating of snow across the hills of SW NYS, and additional snow on
top of the deformation band of snow for areas east of Lake Ontario.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
Sunday, cold northwesterly flow will continue across our region as a
now phased upper level trough, and deepening surface low are across
Atlantic Canada. A few wind gusts could near 40 mph along the
southern and eastern shoreline of Lake Ontario with this departing
surface low. Continued cold air advection, with 850 hPa temperatures
dropping down towards the negative teens range through the day will
limit any surface warming. Highs Sunday will only be a few degrees
warmer than the early Sunday morning lows. There will still be
enough moisture around to continue now lake effect snow showers,
highlighting areas to the south and southeast of the Lakes. There
will also be some blowing snow within these stronger wind
gusts...and will add this to the forecast for Sunday. As a ridge of
high pressure draws towards the region Sunday night, drier air will
end snow showers...while also inducing some clearing. East of Lake
Ontario clearing skies will help bring a chilly night with lows
dropping down into the lower teens, and possibly into the single
digits in the coldest of spots.
Monday a surface ridge will pass across our region, ending any
lingering lake effect snow early, and bring a quiet December weather
day across the region with temperatures in the afternoon around the
freezing mark.
Tuesday there becomes considerable model spread with the track of
the next storm system. The 00Z GFS takes a classic high wind profile
track of a deepening low pressure to our west and north, while the 00Z
ECMWF and Canadian maintain this low to our south, keeping a colder
airmass over our region and possible snow.
&&
.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
The lake effect snow off Lake Erie will move quickly north early
this morning, before moving quickly back south during the afternoon.
The band will produce IFR and VLIFR conditions with moderate to
heavy snow as it migrates across the region. The fast movement will
make for very changeable conditions, with the low VSBY not lasting
for more than an hour or two at any one location. The same will
occur off Lake Ontario, with lake effect snow developing over Canada
at the northeast end of the lake late this morning, then moving
quickly south and east across the east end of the lake during the
afternoon and evening. This band will also produce IFR and VLIFR
conditions with brief periods of moderate to heavy snow.
Outside of lake effect areas VFR will prevail most of today,
although a few very brief snow showers and IFR are likely this
afternoon with a cold frontal passage. Winds will gust up to 35
knots northeast of Lakes Erie and Ontario, and around 25 knots
farther inland.
The lake effect snow off Lake Erie will quickly diminish this
evening across the western Southern Tier and end overnight. The Lake
Ontario band will last longer, and center on Oswego County overnight
with areas of IFR. Outside of lake effect areas VFR will prevail
tonight.
KBUF Airport...Lake effect snow will move north across the airfield
during the early to mid morning. This first batch will produce IFR,
but VSBY below airfield minimums is not expected. The band of snow
will then be north of the airport for a few hours before moving back
south across KBUF during the early to mid afternoon. This second
round of snow is likely to be heavier and accompanied by more
blowing snow, with VSBY below airfield minimums possible for a brief
(around 1 hour) period. Conditions will improve rapidly by 21Z as
the band moves south of the airport.
Outlook...
Thursday...Lake effect snow southeast of Lake Ontario with local IFR
in the morning, ending in the afternoon. Otherwise VFR.
Friday...VFR.
Saturday...MVFR. Rain likely.
Sunday...Areas of MVFR/IFR in snow showers, especially southeast of
the lakes.
&&
.MARINE...
A clipper low will pass by well north of the region today, with its
trailing cold front crossing the eastern Great Lakes during the
early to mid afternoon. A brief period of marginal gales will
accompany the cold front on both lakes, with a few hours of
sustained winds near 35 knots. Winds will quickly diminish tonight
as the pressure gradient relaxes across the eastern Great Lakes.
&&
.TIDES/COASTAL FLOODING...
A period of low end gale force winds will develop this afternoon
and evening on Lake Ontario. The strong onshore winds, high
wave action, and high lake levels will bring an increased risk
of lakeshore flooding along the Lake Ontario shore at the east
end of the lake. The Lakeshore Flood Watch was upgraded to a
Warning for Jefferson, Oswego, and northern Cayuga counties
this afternoon through tonight. This event will not be as
significant as the Halloween night lakeshore flooding, but still
may be high enough to result in some flooding in flood prone
areas and more shoreline erosion.
&&
.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory until 10 PM EST this evening for
NYZ012-085.
Lakeshore Flood Warning from 3 PM this afternoon to 4 AM EST
Thursday for NYZ005>007.
Winter Weather Advisory from 11 AM this morning to 1 AM EST
Thursday for NYZ007-008.
Winter Weather Advisory from 4 PM this afternoon to 4 AM EST
Thursday for NYZ006.
Winter Weather Advisory from 8 AM this morning to 3 PM EST
this afternoon for NYZ001-002.
Winter Weather Advisory until 1 AM EST Thursday for NYZ019-020.
Winter Weather Advisory until 7 PM EST this evening for NYZ010-
011.
MARINE...Small Craft Advisory until 10 PM EST this evening for LEZ020.
Gale Warning from 9 AM this morning to 7 PM EST this
evening for LEZ040-041.
Small Craft Advisory until 10 PM EST this evening for
LOZ030.
Small Craft Advisory until 7 AM EST Thursday for LOZ042-
043.
Gale Warning from 3 PM this afternoon to 1 AM EST Thursday
for LOZ044-045-063>065.
Gale Warning from 1 PM this afternoon to 10 PM EST this
evening for LOZ062.
Small Craft Advisory from 2 PM this afternoon to 10
PM EST this evening for SLZ022-024.
&&
$$
SYNOPSIS...Hitchcock
NEAR TERM...Hitchcock
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