Area Forecast Discussion
Issued by NWS Buffalo, NY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
FXUS61 KBUF 160123

Area Forecast Discussion
National Weather Service Buffalo NY
823 PM EST Fri Dec 15 2017

A cold front will advance across the region this evening,
strengthening lake effect snow bands east of the Great Lakes. These
lake effect snow bands will drift southward tonight behind the cold
front, with periods of heavy lake effect snow falling across the
Southern Tier and Tug Hill region. High pressure will push towards
our region tomorrow and tomorrow night, ending lake effect snow
while maintaining the cold temperatures through the weekend.


An area of low pressure will track from southern Ontario
province this evening into southern Quebec late tonight. This
will result in lake effect snow from an associated cold front
and enhanced mid-level moisture.

At 800 p.m. radar showed a band of heavy snow across ski
country and rapidly moving into the Western Southern Tier.
Snowfall rates up to 2 inches an hour are possible, but the band
is a bit less intense than earlier this evening as it is
temporarily disrupted by the wind shift. Lake effect snow will
re-develop late this evening and continue to focus across the
Western Southern Tier.

Two headline changes were made on the last update. The advisory
for Niagara and Northern Erie counties was dropped since the
snow has moved out of these areas. Also, based on the strength
of the current band and lingering lake effect snows on Saturday,
we have issued an advisory for Allegany county.

A similar story will play out a few hours later off Lake
Ontario. Heavy snow will move through Watertown between 10 p.m.
and 1 a.m. Expect a slightly slower motion and more moisture to
result in a quick 3 to 6 inches for the metro area, even though
its arrival will be well after the evening commute in the
Watertown area. After this, a well aligned westerly flow will
focus heavy snow across the traditional snow belts east of Lake
Ontario. Snowfall rates of 3 inches an hour are likely on the
Tug Hill where upsloping will be a factor. This will result in
extremely poor travel conditions along these portions of
Interstate 90 late tonight.

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.


There is high confidence that heavy snow associated with lake
effect snow will drop southward of the BUF terminal around 00Z.
This band will continue to move south, eventually impacting JHW
between 01-02Z and weakening but remaining in that area into
Saturday morning. This will result in variable vsby at JHW
ranging from 1/4SM to 1SM during this time.

Heavy lake effect snow will also impact ART, with heavy snow
and 1/4SM vsby roughly between 04Z and 06Z. The band will also
drop south of ART after this, with mainly VFR conditions for the
remainder of the TAF period.

Saturday morning, lake effect snow will remain south of all TAF
sites expect for JHW where lake effect snow will linger into the
afternoon hours while gradually weakening.


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.


The cold front will cross the waters this evening, 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 Saturday for NYZ007.
     Lake Effect Snow Warning until 1 PM EST Saturday for NYZ006-
     Lake Effect Snow Warning until 4 PM EST Saturday for NYZ019-
     Winter Weather Advisory until 1 PM EST Saturday for NYZ012-085.
     Winter Weather Advisory until 4 PM EST Saturday for NYZ021.
MARINE...Small Craft Advisory until 1 PM EST Saturday for LEZ040-041.
         Small Craft Advisory until 4 AM EST Saturday for LEZ020.
         Small Craft Advisory until 7 PM EST Saturday for



MARINE...APFFEL/THOMAS is the U.S. government's official web portal to all federal, state and local government web resources and services.