Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 061735

Area Forecast Discussion
National Weather Service Albany NY
1235 PM EST Tue Dec 6 2016

High pressure over the region will shift off to the east during
the day today. A quick moving low pressure system will bring
the area another period of light snow to the area tonight into
early Wednesday morning. Another low pressure system will move
across the region Thursday with lake effect snow developing in its
wake as much colder air is ushered in across the relatively warmer
waters of the Great Lakes.


As of 1230 PM EST...Pesky stratus clouds linger across Lake George
Glens Falls areas per observations and 1km satellite visible
imagery. In addition, canopy of high clouds was advecting in from
the southwest in advance of our event tonight. Regional radar
reveals the leading edge of the precipitation was south of I80 and
per extrapolation, would seem we can hold off the mention of
precipitation until after 6 pm. Otherwise, near term grids were
updated to reflect current trends and observations.


Another round of light snow tonight into early Wednesday morning.

The short wave will dampen out as it moves off the coast and the
coastal low will become the primary low as it tracks eastward out
to sea. The precipitation is expected to be light across the local
area. A period of light snow is expected with likely pops
overspreading the forecast area from southwest to northeast in the
evening. Looking at 1 to 2 inches of snow by around sunrise and
for the morning commute with the higher amounts across the central
and southeastern Catskills. The snow will taper off during the
morning and with rising temperatures rain will mix with a
changeover possible before ending. Will have a lull in precipitation
Wednesday afternoon night as the region is between systems.

A large stacked low is move gradually eastward across the Great
Lakes and eastern Canada through Thursday. Short waves will be
rotating about the low and southern stream energy will join in
resulting in secondary development beginning off the northern New
England coast by late in the day Thursday. With height falls
across the region expecting increasing chances for showers, mainly
snow showers with low level flow becoming favorable for lake
enhancement of snow into the western Adirondacks; the far
northwest corner of the forecast area.

Overall temperatures will be seasonable for early December.


Cold air advection continues Thursday night into Saturday as the
upper trough moves overhead, with 850 mb temperatures falling to
near -15C by 12Z Saturday. This airmass will be the coldest of the
season thus far, with low temperatures Friday and Saturday night in
the single digits and teens, and highs in the 20s and 30s. A
moderate wind will cause wind chills to feel even colder. The cold
air will result in a good lake effect response - Lake Ontario
average surface temps around 8C result in surface to 850 mb delta-T
values increasing to 20 to 25C. Westerly flow Thursday night will
favor northern Herkimer and Hamilton Counties for accumulating snow.
Models suggest a surface trough causing the low-level flow to veer
to northwesterly early Friday, which should result in accumulating
snow shifting southward into the Mohawk Valley and Catskills, and
perhaps some upslope snow into higher terrain of the
Greens/Berkshires as well. Expect some degree of snow shower
activity to continue into Saturday, especially over western portions
of the forecast area.

High pressure should build in briefly Saturday night, but active
weather looks to resume Sunday into early next week as medium-range
deterministic models and ensembles indicate a wave zipping through
the fast upper flow and amplifying over the eastern CONUS. Still
plenty of uncertainty as to where this amplification occurs, but
potential is there for widespread precipitation developing in the
period centered around Sunday night. With antecedent cold airmass in
place, a frozen p-type looks probable, but will leave the door open
for liquid as well if the system develops over the western Great
Lakes (e.g., 00Z GFS) and puts us in the warm sector.


Mainly VFR conditions this afternoon as high clouds spread across
the region ahead of the next system timed to affect our region
overnight. Stubborn clouds around KGFL anchored to the Lake
Champlain and northern Lake George area will break up this
afternoon. There is a good consensus from most sources of guidance
suggests snow spreading from southwest to northeast through the
evening.  A mix of snow and rain is expected to begin at KPOU around
03Z-05Z, then snow starts at KALB around 04Z-06Z and finally KGFL
and KPSF 05Z-07Z. Once the mix at KPOU and snow everywhere else
starts, ceilings and visibilities will rapidly drop to IFR levels,
by 06Z-08Z everywhere.

The system producing the snow and mix is expected to move quickly
and by 14Z-16Z the snow and mix should end. Visibilities are
expected to increase to VFR at that time but ceilings will be slow
to lift. Ceilings will be in the process of lifting out of IFR and
into the MVFR range after 14Z.

Light north to easterly flow at 6 kt or less this afternoon will
become variable tonight and south to southeast Wednesday morning.


Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: Moderate Operational Impact. Chance of SHRA...SHSN.
Thursday Night: Moderate Operational Impact. Chance of SHSN.
Friday: Moderate Operational Impact. Chance of SHSN.
Friday Night: Moderate Operational Impact. Chance of SHSN.
Saturday: No Operational Impact. Slight Chance of SHSN.


Active week with unsettled weather as a couple more systems impact
the region followed by the development of a lake effect snow event
Thursday night into Friday night. Precipitation will fall mainly
as snow.

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




LONG TERM...Thompson
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