Area Forecast Discussion
Issued by NWS Albany, NY

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000
FXUS61 KALY 161941
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
241 PM EST Sat Dec 16 2017

.SYNOPSIS...
Below normal temperatures will continue through the
weekend. The threat for lake effect snow showers will linger this
afternoon especially in the western Mohawk Valley. Dry weather for
Sunday with chances of light snow returning Sunday night.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Quick updated to increase pops across Berkshires for upslope snow.
Visibilities are reduced at KSPF and KAWQ in snow.

Previous Discussion...Lake effect snows continue however it has
weakened considerably and has shifted south of the advisory
area so the winter weather was dropped a bit early. Mesoscale
guidance indicates lake effect should persist much of this
afternoon with some upslope snow. The snow is expected to
quickly diminish by early this evening in northwesterly flow in
the wake of the cold front moving through. Have light
accumulations of around an inch in the western Mohawk Valley
with up to an inch possible for some locations in the southern
Green and northern Berkshires. Another day with below normal
temperatures and the western

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
Quiet weather is expected tonight and Sunday as the ridge of
high pressure builds across the region and then shifts east by
late in the day on Sunday. It will be a chilly night tonight as
air from Canada flows into the region. Expect lows tonight to
generally range from 5 below to 15 above zero. Highs on Sunday
will be similar to Saturday generally ranging from the upper
teens to lower 30s.

Sunday night through Monday night will feature the chances for
some light snow or even rain showers on Monday as the forecast
area will be in a warm air advection pattern as a warm front
moves from the Ohio Valley Sunday evening through our region
Monday night. Lows Sunday night will be in the upper single
digits to mid 20s with highs on Monday in the upper 20s to lower
40s. Lows Monday night will be in the mid 20s to lower 30s.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Much of the long term will be dominated by an increasingly zonal
northern stream flow, although there remains at least some potential
with some southern stream interaction at times.

To start the period, one PV anomaly is expected to move across the
northern Great Lakes into Quebec for Tuesday-Wednesday. Warm
advection should bring at least some light precipitation to northern
areas Tuesday-Tuesday evening, initially driven by some warm
advection. Forecast thermal profiles suggest some light snow, or a
light wintry mix may occur Tuesday morning, before changing to
mainly rain by afternoon, with precipitation chances greatest for
areas mainly north of I-90. Showers may expand south and east
Tuesday evening with a cold front. In the wake of the front, some
Lake Effect snow showers will be possible across the western
Adirondacks/Mohawk Valley later Tuesday night into Wednesday
morning. It should become quite windy Wednesday as a fairly tight
low level gradient develops. Tuesday highs should occur late in the
day, with 30s to lower 40s expected, warmest in valley areas. Some
temperatures could reach well into the 40s across portions of the
mid Hudson Valley. Temperatures will be cooling later Tuesday night,
with lows mainly in the 20s to lower 30s by daybreak Wednesday.
Wednesday highs should be mainly in the 20s to mid 30s, although
highs may occur in the morning before falling in the afternoon with
strengthening cold air advection.

High pressure may build across the region for Wednesday night into
Thursday. However, the one caveat is some southern stream energy,
which most 00Z/16 deterministic models and ensembles track from the
Gulf Coast region to the mid Atlantic coast. This track would keep
any associated precipitation well south/east of the region, however
will need to closely watch any northward trends as we approach, as
we have seen other southern stream systems track farther north and
west thus far this cold season than initially expected. Assuming the
more southern track occurs, expect cold and dry conditions, with
highs Thursday in the 20s to lower 30s, and overnight lows Wednesday
night/Thu morning in the single digits and teens.

For Thursday night-Friday, most 00Z/16 deterministic models and
ensembles track the next system developing over the southern Plains
northeast toward the Great Lakes. This may allow light precip,
mainly in the form of snow, to develop across the southern
Adirondacks and Mohawk Valley region later Thursday night, with more
widespread precipitation possible Friday, especially for areas north
of the I-90 corridor. Although there likely will be warming aloft
with this possible low track, shallow low level cold air may be
tough to dislodge across northern areas, so mixed precipitation
could occur in these areas, with a mix changing to rain farther
south. Lows Thursday night mainly in the 20s, although possibly
rising late; highs Friday potentially in the 30s for northern areas,
with some 40s possible across central and especially southern areas.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
Lake-enhanced light snow showers are ongoing downwind of Lake
Ontario and some may drift across the terminals from time to
time this afternoon. Not enough evidence to include a vsby
restriction at the terminals, except for KPSF where upslope
contributions may focus it a bit more. IFR vsby at KPSF cannot
be ruled out and will handle with amendments if it appears
likely. Elsewhere, have VCSH this afternoon. Drier air will
infiltrate from north to south, ending snow shower chances
between about 21-23Z. Outside of any heavier snow shower,
conditions are expected to remain VFR.

Tonight, high pressure builds in with clearing skies. Cannot
rule out a brief period of low stratus/freezing fog at KGFL as
was seen the last couple of mornings, and perhaps at KPOU as
well, toward 12Z Sun. Later TAF packages can assess this
potential for possible inclusion in the TAFs.

Winds this afternoon will be from the west to west-southwest
at around 10 kt with some gusts around 20 kt. Winds will become
light and variable overnight into Sunday morning.

Outlook...

Sunday Night: Moderate Operational Impact. Chance of SN.
Monday: Moderate Operational Impact. Chance of SHRA...SHSN.
Monday Night: Moderate Operational Impact. Chance of SHSN.
Tuesday: Moderate Operational Impact. Chance of SHRA...SHSN.
Tuesday Night: Moderate Operational Impact. Chance of SHRA...SHSN.
Wednesday: Low Operational Impact. Breezy NO SIG WX.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.

&&

.HYDROLOGY...
No hydrologic problems are expected into early next weekend. Ice
will continue to form on areas lakes and streams. Any snowfall
will be light with the exception of moderate accumulations of
lake effect snow across portions of the western Adirondacks into
this morning.

For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...IAA/Thompson
NEAR TERM...IAA/Thompson
SHORT TERM...11
LONG TERM...KL
AVIATION...Thompson
HYDROLOGY...IAA/11


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