Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 171011

Area Forecast Discussion
National Weather Service Buffalo NY
511 AM EST Wed Jan 17 2018

Light lake effect snow will fall east of the lakes today through
Friday before a pronounced day to day warming trend commences for
the start of the weekend and into early next week. This warming will
bring back chances of rain and snow with rain likely by Monday.


Widespread light synoptic snow has largely shifted east of Central
New York this morning as a low level inverted trough pushes east of
Lake Ontario. Across western NY, narrow multi-banded snow extends
off the nearly ice-covered Lake Erie. A southwest (220deg) wind is
directing two snow bands mainly between Grand Island into eastern
Niagara County and Metro Buffalo and the Southtowns into western
Genesee County. Cold air advection in the wake of the inverted
trough will send H85 temps down toward -18C which will help continue
to support limited lake effect snows off Erie today and eventually
develop lake effect to the east and northeast of Lake Ontario as
well. Lake-induced equilibrium levels will rise to 5-6K feet off
both lakes.

Lake Erie, Winds should remain Southwest today but lift will be weak
keeping the majority of the light lake effect directed over portions
of the Niagara Frontier including Greater Buffalo. The 91% ice cover
on Lake Erie will help keep snow accums limited mainly to between
one and three inches. Visibilities within the narrow multi-bands
will still be greatly reduced despite the light snow accums
forecast. Later today, BUFKIT profiles show equilibrium levels over
Lake Erie will fall to 3-4kft which should be too shallow to support
continued lake effect tonight.

Lake Ontario, Lake snow will continue to organize early this morning
as cold advection deepens. BUFKIT profiles indicate equilibrium
levels will peak 15-18z then fall toward 4kft late today into this
evening. Sufficient synoptic lift and moisture will continue to
support lake snow east of Lake Ontario through today and into
tonight. Flow will be Southwest to west directing the snow band or
bands from Watertown and occasionally drifting toward the Tug Hill.
Snow accumulations should not top 1-2 inches today and again tonight
owing to the shallow depth of the bands. 24 hour totals through
tonight will average 2-4 inches.

Outside of the lake effect areas later today and tonight, low level
ridging will continue fair weather but under mostly cloudy skies.
Temperatures will average 5-10 degrees below normal, with lows this
morning in the single digits to mid teens and highs this afternoon
in the upper teens to lower 20s. Tonight, lows are forecast largely
in the teens. Wind chills will range within a few degrees either
side of zero.


Limited lake snows will be ongoing, mainly off Lake Ontario Thursday
morning, within an aligned westerly flow in between ridging to
our south and a northern stream shortwave/low approaching from
the northern Great Lakes. This activity will weaken through the
day as lake induced equilibrium heights remain very low. Outside
of lake effect areas it will be mainly dry Thursday, with
variable amounts of clouds.

The pressure gradient between the two systems will result in
rather breezy conditions with somewhat milder temperatures in
the mid to upper 20s, but wind chill values in the single digits
can be expected.

The northern stream shortwave/low dropping down through the flow
will bring a quick shot of colder air. This feature will have
limited moisture with just a few scattered snow showers expected
across portions of the region. The environment will be a bit better
for lake effect snows east of Lake Ontario, with deeper moisture and
a little higher inversion height. This may produce a few more inches
of accumulation across the Tug Hill region late Thursday night and
Friday morning. All of this will slowly taper off and end later
Friday with warm advection bringing lowering inversion heights.

The warm advection pattern resumes in earnest by Saturday as
the flow becomes zonal across the United States, with warm
advection spreading east across the Ohio Valley and Great Lakes.
High temperatures will reach the lower to mid 40s by Saturday


January thaw, round 2, continues for the start of next week,
followed by cooler, but seasonable, temperatures returning for mid
to late week.

Fairly zonal, pacific influenced flow will be in place across the
CONUS on Sunday, as a trough exits from the Four Corners region. The
increasing southwesterly flow and rising heights aloft across the
forecast area ahead of the approaching trough will usher in warmer
temperatures from Sunday into Monday. High temperatures will run in
the 40s, both days, with perhaps a few locations near the 50 degree
mark by Monday. Expect to see showers develop in the vicinity of the
warm front across the region on Sunday along with ample cloud cover,
although it will not likely be a washout with plenty of dry time.
South of Lake Ontario, this would mainly be rain, with a mix of
either rain, freezing rain or snow for eastern Lake Ontario. An
approaching cold front Monday, tied to the ejecting trough moving
from the central plains to the eastern Great Lakes, will usher in
widespread, soaking rain showers. There will be ample moisture to
work with as the trough taps into a rich subtropical moisture source
from the Gulf of Mexico. Cooler air will rush back into the region
with blustery southwest to west winds behind the cold front passage,
bringing a return to more seasonable temperatures for mid-week.


Mixed mainly MVFR/IFR conditions this morning. Widespread light snow
is exiting east across Central NY. Lake Effect snow had developed off
Lake Erie impacting KBUF with IFR and will eventually impact KART as
the snow band develops later this morning.

Later today, MVFR conditions will gradually give way to VFR weather.
This will mainly be the case outside of the lake effect snows which
will be found east of both lakes impacting mainly KBUF and KART.
Lake snows should wane east of Lake Erie later today with
improvements expected at KBUF but should continue overnight east of
Lake Ontario with KART in and out of IFR.


Thursday through Friday...localized MVFR to IFR possible in
scattered to occasionally more numerous lake effect snow showers
east of the lakes...with mainly VFR conditions elsewhere.
Saturday...Mainly VFR.
Sunday...MVFR with a chance of light rain (mixing with snow
east of Lake Ontario).


Much cooler air behind an upper level trough axis will filter across
the Eastern Great Lakes through today and linger for much of
the rest of the week. This will bring an extended period of
small craft conditions that will eventually end Saturday after a
period of strong southerly winds.


MARINE...Small Craft Advisory until 10 PM EST Saturday for LEZ040-041.
         Small Craft Advisory from 1 PM this afternoon to 4 AM
         EST Sunday for LOZ042>044.



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