Area Forecast Discussion
Issued by NWS Buffalo, NY

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FXUS61 KBUF 160632

Area Forecast Discussion
National Weather Service Buffalo NY
132 AM EST Sat Dec 16 2017

Lake effect snow bands will drift southward overnight, with
periods of heavy lake effect snow falling across the Southern
Tier and Tug Hill region. High pressure will push towards our
region Saturday and Saturday night, ending lake effect snow
while maintaining the cold temperatures through the weekend.


Lake effect snows continue to impact areas downwind of both Erie and
Ontario early this morning, as the region remains underneath cold
cyclonic flow aloft. Bands will continue to affect warned areas
through the night, and winter weather headlines remain unchanged.
Outside of lake bands, an area of dry air aloft is allowing from
breaks in the clouds, and expect partly cloudy skies overnight. In
spite of the fact that temperatures are considerably warmer than
last night, brisk westerly winds will keep wind chills in the teens
to single digits across the forecast area.

A secondary front will drop across Lake Ontario Saturday
morning, and this feature may briefly intensify lake effect
snow. This secondary front will also shove lake snows
southward, with light snow showers possible along the entire
southern Lake Ontario shoreline.

As high pressure drops southward later Saturday it will bring drier
air, along with lowering inversion levels...such that lake effect
snow will diminish through the day.

Temperatures will remain cold, with overnight lows in the teens.
West winds will bring wind chill values down into the single digits.
Saturday high temperatures will range across the mid to upper 20s.


During Saturday night high pressure centered over western Quebec
will briefly ridge southward across New York State. Subsidence and
drier air associated with the surface high will result in a largely
dry night...though at least some leftover clouds will persist across
areas south of Lake Ontario...which will like closer to a lingering
weak warm frontal boundary. Expect low temps to range from around zero
across the North Country where skies will be the mid
and upper teens south of Lake Ontario.

On Sunday the surface ridge will slide eastward into eastern Quebec
and New England. Increasing warm air advection on its backside will
result in clouds increasing across our region from southwest to
northeast through the day...with the chance of a few rain showers
arriving across the Southern Tier late as moisture and shortwave
energy pool along the slowly re-energizing warm front draped along
the NY/PA border. Otherwise daytime highs will finally begin to
rebound given the ongoing warm air advection regime...with afternoon
highs ranging from the mid 20s across the North Country to the 30s
across most areas south of Lake Ontario.

Sunday night and Monday broad warm air advection will continue across
our region...with the aforementioned warm front slowly lifting north
across the area. This will result in plenty of cloud cover and
general chances for some snow showers Sunday night...with these then
transitioning over to mainly rain showers on Monday as the atmospheric
column continues to steadily warm. With respect to temperatures...
lows will range from around 20 across the North Country to the
upper 20s and lower 30s across most areas south of Lake Ontario
Sunday night...with highs on Monday then reaching into the mid to
upper 30s east of Lake Ontario and to around 40 elsewhere.

Monday night our region will again be under the influence of broad
warm air advection out ahead of a modest mid level trough/attendant
surface low pushing into the Upper Great Lakes. This will result
in continued plentiful cloud cover and scattered shower potential...
with the column likely remaining warm enough to support mostly rain.
At the surface...nighttime lows will range from the lower to mid 30s
east of Lake Ontario to the mid and upper 30s elsewhere.

Finally...during Tuesday the aforementioned trough/surface low will
make their way further eastward and slowly push their attendant
cold front across our region...along with some scattered to numerous
rain showers. The antecedent mild airmass in place out ahead of
the front will result in one more day of milder temperatures with
area highs reaching into the lower to mid 40s areawide...before
steady cold air advection in its wake pushes readings back down
into the mid and upper 20s Tuesday night. Coupled with an eventual
increase in moisture...the ongoing cold advection regime will also
result in the redevelopment of some lake snows east and southeast of
the lakes Tuesday night...for which some likely PoPs remain in play
from continuity.


On Wednesday lake effect snows should continue southeast of both
lakes (especially Lake Ontario) before winding down Wednesday night
as surface-based ridging and drier air build into the region. Meanwhile
temperatures will run a little below average...with highs mainly in
the lower 30s on Wednesday followed by lows ranging from the teens to
lower 20s Wednesday night.

After that...the medium range guidance packages remain in general
agreement on another low pressure system developing northeastward
across the Great Lakes and Northeastern states late in the week...
though considerable discrepancies remain as to the exact strength...
timing...and track of the low. In a general sense...this system
should bring a warming trend for the latter portions of the work week
along with renewed precipitation chances...with an initial ptype of
snow gradually giving way to more in the way of rain over time as
temperatures warm.


Lake effect snows will continue to affect areas downwind of
Lake Erie and Ontario overnight and through much of the day on
Saturday. Westerly flow will gradually veer more northwesterly
through the period, and this will keep bands south of
KBUF/KIAG/KART, however KJHW will continue to see MVFR/IFR
conditions through 18Z. The passage of a final upper level
disturbance will shove the Lake Ontario band south of the lake
around 18Z, bringing a brief period of -SHSN and potential
MVFR/IFR conditions to KROC. Otherwise, outside of lake bands,
expect VFR/MVFR conditions to persist through the TAF period.


Saturday night and Sunday...VFR.
Sunday night...MVFR with a chance of snow showers.
Monday...IFR/MVFR with a chance for rain and snow showers.
Tuesday...IFR/MVFR with rain likely.
Wednesday...IFR in lake effect snow likely SE of the Lakes,
MVFR/VFR in chance of snow elsewhere.


A cold front will cross the waters overnight, with winds veering
to west and then northwesterly. Waves will continue to increase
behind the cold front with small craft advisories in place for
the lakes and the Upper Niagara River.

High pressure will nose southward from Canada on Saturday, and bring
lighter winds and an end to the SCA. Light winds and waves will
continue Saturday and into Sunday.


NY...Lake Effect Snow Warning until 10 AM EST this morning for
     Lake Effect Snow Warning until 1 PM EST this afternoon for
     Lake Effect Snow Warning until 4 PM EST this afternoon for
     Winter Weather Advisory until 1 PM EST this afternoon for
     Winter Weather Advisory until 4 PM EST this afternoon for
MARINE...Small Craft Advisory until 1 PM EST this afternoon for LEZ040-
         Small Craft Advisory until 4 AM EST early this morning for
         Small Craft Advisory until 7 PM EST this evening for



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