Area Forecast Discussion
Issued by NWS Albany, NY

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000
FXUS61 KALY 130853
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
353 AM EST Wed Dec 13 2017

.SYNOPSIS...
In the wake of our storm, cold and brisk conditions are
expected into Thursday. A weak clipper type system may bring some
light snow to areas from the Capital District southward late
tonight into Thursday morning.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Winter Storm Warning continues for southern Herkimer county for
heavy lake effect snow through today.

Winter Weather Advisory continues for Fulton, Montgomery, and
Schoharie counties for lake effect snow through today.

Wind Advisory issued for the Mohawk and Schoharie Valleys,
eastern Catskills, Greater Capital District, northern and
central Taconics and Berkshires.

As of 330 AM EST...Regional and local radar returns show very
light activity and per the NY Mesonet web cams, flurries at best
across the higher terrain. Per coordination, we have made
several changes to the going headlines with previous warnings
for the Dacks and southern Greens have been dropped. Lake
effect snow was redeveloping downwind of Lake Ontario and
perhaps a mesolow was developing per radar/velocity signatures
just to the east of Oswego. Heart of the upper trough axis was
across Upstate NY this early Wednesday morning per the H2O vapor
loop. Cold advection was well underway under this trough axis
as H850 temperatures drop back toward -20C. This will continue
with the LES, however, per mesoscale models, seems this band
will impact mainly the western Mohawk Valley and portions of the
Schoharie Valley with inland penetration appearing to be
further reduced as inversion heights per BUFKIT profiles drops
to less than 3K feet. Then we focus on the winds as mixing layer
heights suggest we tap into the 40kt range of wind magnitudes
as no changes to the current wind headlines. Temperatures today
will be chilly with mainly 20s and wind chill values into the
single digits with below zero readings into the higher terrain.
By late this afternoon, lake effect and any residual upslope
will subside as those inversion heights lower further and drier
air entrainment.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
Another Alberta Clipper system quickly tracks through the
Dakotas and along the I80 corridor tonight. Unlike its
predecessor, this system is more open and faster which will
limit both its moisture content and any light snow/flurries
overnight mainly around the I90 corridor and points southward.
QG forcing is notable yet specific humidities are quite low
hence QPF from the various models are quite light with the
slightly higher values into the terrain of the Catskills,
Taconics, Litchfield Hills and portions of the Berkshires.
Snowfall amounts less than 1 inch expected.

Lake effect snow may start to re-develop late Thursday afternoon
and into the night, as west-northwest winds align with
continued sufficient lake induced instability. Main area of
concern could be western Mohawk Valley and into the western
Adirondacks and Schoharie Valley. Will continue to monitor the
potential. Outside of lake effect, dry and cold conditions will
persist.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
The long term period will remain fairly active as upper level
impulses embedded in the northern stream traverse the broad trough
situated over the northeast CONUS. There are differences in guidance
and ensembles in the timing and track of these embedded impulses.
Each upper impulse will enhance lake effect snow bands into the
southern Adirondacks and western Mohawk Valley and at times areas of
scattered snow showers will break off and effect eastern NY and
western New England.

Timing of the individual impulses is difficult but it looks like we
will receive a quick shot of energy and chances for snow Friday
night into Saturday as an upper low passes north of the region. High
pressure builds into the region on Sunday for a brief reprieve from
active weather.

The broad upper troughing in our region is expected to slowly
flatten as southern stream upper ridging builds north Sunday night.
Temperatures are expected to moderate Saturday through Tuesday so
that by Monday and Tuesday, temperatures could be a slightly above
normal.

The next chance for precipitation arrives Sunday night as a
southern stream impulse gets wrapped into the broad trough and lifts
northeastward into New England. A warm front is expected to move
through the region during the day Sunday but temperatures appear
cold enough for mainly snow, with perhaps a rain/snow mix in the Mid-
Hudson Valley. Snow chances continue into Monday as a cold front and
the upper trough shift through the region. Once this system exits,
the broad upper trough gets reinvigorated once again Tuesday with
another upper impulse digging southward from Canada. This should
enhance lake effect snows across the Adirondacks.

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
Gusty west to northwest winds will continue to increase
throughout the morning with sustained winds up to 20 to 25 mph.
Gusts up to 40 mph are possible throughout the day as well.

Chances for snow showers will continue through the early
morning, mainly at KGFL/KPSF, but cannot rule out a stray snow
shower at KALB.

CIGS will generally be VFR but may drop to MVFR at times due to
a long fetch of moisture off the Great Lakes well east and
upslope into the Berkshires.

Outlook...

Wednesday Night: Low Operational Impact. Breezy NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: No Operational Impact. NO SIG WX.
Friday Night:  Slight Chance of SN.
Saturday: Low Operational Impact. Slight Chance of SN.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: Low Operational Impact. Slight Chance of SN.

&&

.HYDROLOGY...
No hydrologic problems are expected through the weekend.

Cold weather with periods of snow and snow showers are forecast
much of the time. Some moderation of the temperatures is
expected later in the weekend.

Ice will form and thicken on area lakes and rivers and some
river gauges may start to show erroneous readings due to ice by
the end of the week.

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...Wind Advisory from 7 AM this morning to 7 PM EST this evening
     for NYZ038>040-047>054-058-061-063-082.
     Winter Weather Advisory until 6 PM EST this evening for NYZ039-
     040-047-082.
     Winter Storm Warning until 6 PM EST this evening for NYZ038.
MA...Wind Advisory from 7 AM this morning to 7 PM EST this evening
     for MAZ001-025.
VT...None.

&&

$$
SYNOPSIS...BGM
NEAR TERM...BGM
SHORT TERM...BGM
LONG TERM...NAS/JVM
AVIATION...JVM
HYDROLOGY...BGM/JPV



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