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Area forecast discussion
National Weather Service Buffalo New York
945 PM EST Wed Nov 13 2019

a weak cold front will cross the lower Great Lakes Thursday
afternoon and evening, producing wet snow and rain showers northeast
of the lakes in the process. A second cold front will move south
across the area late Friday. This may produce a few light snow
showers and will bring one last push of very cold air to start the
weekend. A warming trend will then begin Sunday through the first
half of next week.


Near term /through Thursday/...
a warm front will move northeast across the lower Great Lakes
tonight, and this will spread a wealth of mid/high clouds across our
region. The low levels remain quite dry, so any light snowfall
should be limited to the north country. Temperatures will drop into
the upper teens to lower 20s in western New York this evening, and single
digits to low teens east of Lake Ontario. Ongoing warm advection
will then allow temperatures to warm overnight.

Thursday...a mid level trough and associated weak surface cold front
will move from the central Great Lakes to the eastern Great Lakes by
late in the day. This system will be moisture starved, so from a
synoptic standpoint it will have little opportunity to produce much
precip. It will remain cold enough aloft to support some lake
enhancement however. Lake enhanced precip will develop first across
southern Ontario in south-southwest flow late tonight and Thursday morning. The
Lake Erie band will then move into the Niagara Frontier by
afternoon. The Lake Ontario band will move into Jefferson County by
mid to late afternoon. Temperatures aloft are quite cool still, so
the majority of this will be wet snow with the possible exception of
along the lakeshores where some rain may mix in. Accumulations will
be minimal however as surface temperatures warm above freezing, with
highs in the mid 30s across lower elevations. Winds may gust to 25-
30 mph northeast of the lakes Thursday as the pressure gradient
tightens ahead of the approaching cold front.


Short term /Thursday night through Saturday night/...
Thursday night a weak mid level trough and its attendant surface
trough over southern Ontario will continue to deteriorate as they
push eastward and across our area. Given the rather weak nature of
this system...for the most part it will only produce some widely
scattered light rain and snow showers as it crosses our region...
with interior portions of the southern tier and Finger Lakes more
than likely to remain totally dry. The above said...temperatures
aloft will still remain sufficiently cold enough to support some
areas of lake enhancement northeast of lakes Erie and Ontario...with
more numerous showers consequently affecting the Niagara Frontier
and Jefferson County...where forecast temperature profiles will
support mainly snow and possible fresh accumulations of an inch or
two away from the immediate lakeshores. Later on in the night...the
Lake Erie activity should tend to weaken and become more scattered
in tandem with warming aloft and a resultant lowering of the capping
inversion to around 3 kft.

On Friday yet another (and stronger) mid-level trough will pass by
to our north...with its attendant cold front pushing southward and
across our region. With very limited synoptic moisture and upper
level support...this second boundary will also only be capable of
generating some widely scattered rain and snow showers on its own...
though cold-enough temperatures aloft will still support some areas
of lake enhancement east of the lakes...with these drifting southward
over time as the low level flow gradually veers. Off Lake Erie a
relatively low cap of 3-4 kft will help to keep the lake enhancement
more limited than off of Lake Ontario...where a 2 kft-higher cap and
the longer westerly fetch across the lake should support more numerous
rain and snow showers. With only marginal temperature profiles in
place for rain vs. Snow...any notable snowfall accumulations should
remain confined to the higher terrain...with the Tug Hill and western
Adirondack foothills possibly picking up fresh accums of an inch or
two. Otherwise...high temperatures will mostly range between 35 and
40 degrees.

Following the passage of this last shot of much colder
but also rather dry air will build across our region for Friday
night and Saturday. The dry nature of the colder airmass and short
northwesterly to northeasterly fetch will help to confine any lake
response to some scattered snow showers and flurries southeast and
south of the lakes Friday night...with these followed by fair dry
weather Saturday and Saturday night as the surface ridge crests
across our region. Meanwhile temperatures will fall back to well
below average levels...with lows Friday and Saturday nights ranging
from the single digits across the north country to the mid to upper
teens south of Lake Ontario...and highs on Saturday struggling to
get much above the mid to upper 20s south of Lake Ontario...and the
lower to mid 20s across the north country.


Long term /Sunday through Wednesday/...
in the long term portion of the forecast...the core of the strong
surface high will slide eastward to northern New England and the
Canadian Maritimes on Sunday...where it will then remain in place
through Monday. With weaker ridging still extending all the way back
across our region through this time...we should experience continued
fair dry weather through Monday. With respect to temperatures...the
developing warm air advection pattern on the backside of the ridge
axis will result in a steady day-to-day warming trend...with highs
mainly in the upper 30s/lower 40s on Sunday mostly climbing into the
lower to mid 40s on for the north country which will
be a bit cooler both days.

By Tuesday the medium range guidance packages still suggest that
the aforementioned low level-ridging will give way to another broad
mid-level trough and its associated surface trough approaching from
the upper Great Lakes. Increasing lift and moisture out ahead of
these features may provide the impetus for some scattered showers...
with the bulk of these likely falling in the form of plain rain
given the continued warm air advection pattern across our region.
Speaking of which...the latter will also help temperatures to
continue trending upward...with daytime highs reaching the mid to
upper 40s in most locations.

Finally...the mid level trough and surface trough should finish
crossing our region between Tuesday night and Wednesday...with
precipitation chances trending back downward following its passage.
Otherwise...weak to modest cool air advection on the backside of
of this system should help to temporarily halt or bring about a
slight reversal to the warming trend of the previous few days...
with highs mainly in the lower to middle 40s expected.


Aviation /03z Thursday through Monday/...
while there will be a wealth of Alto-cu tonight as the result of a
warm frontal passage...VFR conditions will remain in place. The
exception could be at kart where a little light snow before 06z
could briefly knock vsbys down to MVFR levels.

Fair uneventful weather will then stay in place across the majority
of the region on a weak cold front will approach from
the upper Great Lakes. Conditions will deteriorate somewhat though
at kbuf and kiag during the course of Thursday cigs
will lower to MVFR levels with a mix of rain and wet snow possibly
reducing vsbys to IFR levels after 21z.

Thursday night...MVFR/IFR in lake enhanced snow showers northeast of
the lakes, tapering off overnight. VFR outside of lake enhanced
Friday...a chance of lake effect snow showers east of the lakes with
local MVFR/IFR. Otherwise VFR.
Saturday through Monday...mainly VFR.


the axis of a surface ridge will exit across New England tonight.
This will maintain a relatively weak south to southeast flow over
the lower Great Lakes into Thursday morning.

A cold front will then approach the area during the midday and
afternoon on Thursday before crossing the region Thursday evening.
Freshening southwest winds ahead of the front will support another
round of Small Craft Advisory conditions from on Lake Erie and the
northeast end of Lake Ontario. Small craft conditions will likely
continue at the east end of both lakes through Friday.


Buf watches/warnings/advisories...
New York...none.
Marine...Small Craft Advisory from 1 am Thursday to 4 PM EST Friday for
Small Craft Advisory from 7 am to 7 PM EST Thursday for
Small Craft Advisory from 1 am Thursday to 10 PM EST
Friday for loz045.




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