Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 082343
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
643 PM EST Thu Dec 8 2016

.SYNOPSIS...
Scattered snow showers are possible across the region,
with lake effect snowbands expected across portions of the western
Adirondacks through Friday morning. Snow showers will gradually
diminish by late Friday night. Colder air will start to move into
the region by the end of the week.  The next chance of widespread
snowfall will be late Sunday into Monday.

&&

.NEAR TERM /THROUGH FRIDAY/...
Lake Effect Snow Warning for northern Herkimer/Hamilton
Counties remain in effect until 7 AM EST Fri...

As of 630 PM EST, main snowband has remained a bit south of Rte 28
in Herkimer/Hamilton Cos, although has expanded back slightly
northward over the last few radar scans from KTYX. It is shifting
back slight southward over eastern Lake Ontario, so expect the
most persistent moderate/heavy snowfall through this evening to be
mainly just south of Rte 28, between Old Forge, Mckeever and
Atwell in Herkimer CO, and about midway between Raquette Lake and
Hoffmeister/Piseco in Hamilton Co. In these areas, snowfall rates
of 1-3 inches are possible over the next 2 to perhaps 3 hours,
before the band begins settling southward. So, expect at least an
additional 6-10 inches in some areas this evening. Areas farther
north and east should receive less overall, despite a few heavier
bursts of snow, with an additional 2-5 inches possible just east
and south of Big Moose, and perhaps extending to Speculator.

Farther south and east, another area of snow showers, in
association with an extension of a Lake Erie snowband, continues
to move east southeast across central/southern Berkshire CO, the
southern Taconics and northern Litchfield CO. This area may
decrease in areal coverage as it continues tracking E/SE, but a
quick coating to a few tenths of an inch of snowfall will be
possible. This could even extend into portions of the mid Hudson
Valley, mainly east of the Hudson River, and central/southern
Litchfield CO between 7 and 830 PM.

Later tonight, a trough will move southeast across the region
after midnight. Wind flow will become more northwesterly. Lake
trajectories will be favorable early tonight for snowfall across
Hamilton/Herkimer counties. With the northwesterly flow, the
snowband will begin to shift southward across the Catskill and
Mohawk Valley region by around 9z Friday. With the flow more
northwesterly and not along the axis of the lakes, the band may
break into a multi banded structure. Snowfall rates will
eventually diminish as the night progresses. The best area of
accumulation will be across the Northwestern Adirondack zones and
Catskill region. As you get further eastward into the warning
area, intensity will be much less.

Friday, with northwesterly flow and moisture, snow showers will
continue Friday and into early Friday night. The snow showers
should be light with most areas seeing a coating or less, except
for localized squalls.


&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
Temperatures Friday night into Saturday morning will drop into
the teens as colder air drop into the region with 850 temperatures
around -15 to -17C.

Saturday, 500mb flow is zonal over the northern portion of North
America.  A surface tough will move across the Northeast on
Saturday.  This will bring more cold air into the region.  Scattered
snow showers will be possible on Saturday.  Below normal
temperatures will continue on Saturday as 850 mb temperatures are
around -14 to -17 degrees celsius.  High temperatures on Saturday
will have a difficult time reaching 30. Low temperatures Saturday
night will drop into the teens across most locations with the
higher terrain areas of the Adirondacks seeing lows below 10
degrees.

Sunday, High pressure will move off the East coast as A warm
front associated with an area of low pressure will approach from
the south and west. The best warm air advection looks to occur
later in the afternoon on Sunday into the evening. There will be a
chance of snow showers Sunday afternoon onward.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Still expecting an active upper pattern with coldest weather so far
this season but there is a broad consensus that the core of the
coldest air stays north and west of our region through the next 7
days.  It will be cold enough for any precipitation to be primarily
snow through the period.

First, strong warm advection, low level jet energy, isentropic lift
and moisture advection Sunday night through Monday. There are hints
that there will be a brief period of boundary layer temperatures
near or just above freezing for the southern half of our area Monday
afternoon.  Before any potential rain/snow mix, there is an
increasing consensus in sources of guidance and ensembles for a
light to moderate snowfall accumulation across the region.  So, any
potential mix Monday afternoon will not reduce the total snowfall
expectations much. Highs Monday in the lower to mid 30s but upper
20s higher terrain. Steadier precipitation ends Monday night and
some lake effect snow shower activity possible the rest of the night.

Much more spread in sources of guidance beyond Monday night through
Thursday. Some guidance suggests more quick moving upper impulses
contributing to some periods of larger scale synoptically forced
snow, while other guidance supports more periods of lake effect snow
shower activity. With those sorts of uncertainties, keeping isolated
to scattered snow shower activity in the usual lake effect snow
regions of the southern Adirondacks, western Mohawk Valley Schoharie
Valley, eastern Catskills and southern Green Mountains with isolated
snow shower activity around those areas of terrain. There could be a
more organized band of snow showers along the leading edge of the
strong cold front Wednesday or Wednesday evening.

Again, the one general agreement in the sources of guidance is that
the core of the coldest air should stay north and west of our
region, However, the northern stream upper pattern is amplified
enough that we will still see the coldest air so far this season,
especially after a strong cold front tracks through in the Wednesday
or Wednesday night time frame.

During the transition period before the strong cold front tracks
through our region, highs Tuesday and Wednesday in the 30s with 20s
higher terrain. Highs Thursday in the 20s with teens higher
elevations.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
A secondary cold front will settle southeastward across the TAF
sites overnight.

As the front approaches and passes, scattered snow showers and
flurries will be possible, mainly between 04Z-09Z/Fri. There could
be brief periods of MVFR/IFR as any snow showers pass through.
Otherwise, mainly VFR conditions outside of any snow showers.

During Friday, the bulk of lake effect snow should remain well
west of the TAF sites. However, some scattered flurries of snow
showers may still occur, especially at KALB and KPSF. Brief
periods of MVFR/IFR visibilities will be possible within any snow
showers.

West to southwest winds of 8-12 KT and some gusts of 20-25 KT will
shift into the NW after midnight as the trough passes. Some gusts
up to 30-35 KT could occur as the winds shift. NW winds will
remain 8-12 KT with some gusts up to 25-30 KT possible on Friday.

Outlook...
Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: Moderate Operational Impact. Chance of SHSN.
Sunday Night: Moderate Operational Impact. Likely SN.
Monday: Moderate Operational Impact. Likely SN.
Monday Night: Moderate Operational Impact. Chance of SN.
Tuesday: Low Operational Impact. Slight Chance of SHSN.

&&

.HYDROLOGY...
Lake effect snow will continue tonight into Friday across areas
north and west of the capital region. The area for the highest
probability of snow will be across areas north and west of the
Mohawk valley. Lake effect snowfall is expected for the western
Adirondacks...with light accumulations for the Western Mohawk
Valley and Eastern Catskills.

Snow is possible Sunday night into Monday. At this time,
confidence is not high on QPF or snow amounts.

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...Lake Effect Snow Warning until 7 AM EST Friday for NYZ032-033.
MA...None.
VT...None.

&&

$$
SYNOPSIS...VTK
NEAR TERM...VTK/KL
SHORT TERM...VTK
LONG TERM...NAS
AVIATION...KL/NAS
HYDROLOGY...VTK


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