Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 150322

Area Forecast Discussion
National Weather Service Buffalo NY
1022 PM EST Sun Jan 14 2018

High pressure will bring dry weather tonight through most of Monday.
Temperatures will be cold again tonight, although winds will be
light. Low pressure will then move through the Great Lakes region
Monday night and Tuesday, with periods of light snow and minor
accumulations. Some lake effect snow will develop following
this clipper Tuesday night through Wednesday night.


Regional satellite imagery late this evening shows cirrus
overspreading the area from the south in association with warm
advection aloft. This thin but increasing cloud cover is enough to
put the brakes on the falling temperatures, and readings should not
fall too much more once the clouds move overhead, thanks in part to
the insulating effects of said clouds in addition to ongoing warm
advection across the area. With this in mind, expect lows in the
single digits above zero across most areas, with the exception of
the North Country, where a slightly longer window of clear skies
will allow for temperatures to fall to 0 to 10 below before leveling
out after midnight.

The initial round of cirrus will pass north across our area
overnight, with more high clouds thickening and lowering from west
to east through the day on Monday in advance of an upper level low
dropping out of the upper Midwest into the central Great Lakes.
Light snow is expected to arrive over far western New York by the
end of the day, as an 850mb jet transporting deeper moisture and
associated isentropic ascent arrives over the area. Increasing
southerly flow and associated warm advection will yield a warmer day
across the forecast area, with highs in the low to mid 20s, with
slightly cooler readings in the upper teens to around 20 in the St.
Lawrence valley.


The center of a clipper-type low will be centered near Lake Michigan
Monday evening with widespread light snow pushing across western NY
supported by warm advection ahead of the low. The weak low will pass
just north of Lake Erie through Monday night with light snow pushing
across central NY. Temps Monday night should hold fairly steady to
slowly rising in the low 20s for western NY to teens in the North

A cold front with dry slot is forecast to push across western NY
Tuesday afternoon bringing an end to the widespread snow west to
east. Not expecting a significant snowfall from the clipper but
could be enough to make a tricky Tuesday morning commute. A general
1-3 inches is expected due to the dryness of the airmass. Lake snows
then look like they will begin to develop later Tuesday. Wind gusts
behind the front will reach above 20 mph Tuesday which could bring
some blowing and drifting of freshly fallen snow. Temps on Tuesday
should be able to reach into the 20s to near 30 ahead of the cold
front with falling temps in its wake.

By Tuesday night and Wednesday, cyclonic flow and lift associated
with a passing mid-level trough will combine with decent synoptic
moisture to likely bring some weak low topped lake snows in
southwest veering to west flow. 850mb temps of around -16C will help
push lake induced equilibrium levels to between 5kft and 8kft
supporting the lake snows with peak intensity spanning Wednesday
and tapering down Wednesday night. Additionally, winds look to again
be able to gust over 20mph Wednesday and Wednesday night as the GFS
shows a strong low level jet approaching and dropping across the
eastern Great Lakes. These gusts could again cause blowing and
drifting snow. While still too early to be nailing down snow
accumulations, it is interesting to point out that the NAM 212 mean
COOP snow from the 0114/12z CIPS Analogs shows 72 hour snowfall of 8-
12 inches off Lake Erie and 12-18+ inches near the Tug Hill. Based
on this guidance, confidence is high enough to include the eastern
Lake Ontario Counties in the Hazardous Weather Outlook.

Low temps Tuesday night and Wednesday night will range in the single
digits to teens with Highs on Wednesday forecast to run in the teens
to 20s.


During the first 24 hours of this period...increasing ridging will
lead to leftover weak lake snows east of Lake Ontario continuing to
steadily diminish. Otherwise the remainder of the area will just be
dry and quiet with below normal highs in the mid to upper 20s
Thursday followed by lows in the mid teens to lower 20s Thursday

After that...another significant pattern change still appears in
store as the medium range guidance packages remain in good agreement
on the large-scale flow across North America first turning more
zonal on Friday...before evolving into a western CONUS trough/
eastern CONUS ridge next weekend. For our region this will result in
a marked day to day warming trend...with readings possibly making it
all the way back into the 50s by Sunday should some current model
projections verify.

While the ongoing warm air advection regime could also result in
some lower-end precipitation chances during portions of this
period...overall amounts currently look to be light and thus
generally insignificant. With respect to ptype...snow would be the
most likely ptype on Friday...before giving way to predominantly
rain over the weekend as conditions warm.


High pressure will gradually move out of the region over the next 24
hours. While VFR conditions will persist for the bulk of the period,
high clouds will move across the region overnight, and will
thicken/lower into a mid-level deck during the day on Monday, as a
low pressure system approaches the region. Light snow will develop
across far western New York near the end of the TAF period in
association with this low, resulting in MVFR conditions at
KBUF/KIAG/KJHW after 23Z Mon.

Monday night...Light snow with areas of IFR.
Tuesday through Friday...A chance of snow showers with spotty MVFR
to IFR, especially east of the lakes with local lake effect snow.


Winds will remain relatively light through Monday as high pressure
drifts slowly east down the Saint Lawrence Valley. Winds will
increase on Lake Ontario later tonight and Tuesday, but the ESE wind
direction will direct the greater wave action into Canadian waters.

A clipper system will then cross the eastern Great Lakes late Monday
night and Tuesday. This will bring an increase in winds on Lakes
Erie and Ontario, with Small Craft Advisory conditions possible from
later Tuesday through Wednesday.





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