Area Forecast Discussion
Issued by NWS Albany, NY

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344
FXUS61 KALY 080602
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
102 AM EST Thu Dec 8 2016

.SYNOPSIS...
Colder air will build into the region through Friday. As
the cold air moves in, scattered snow showers and flurries will be
possible across the region, with heavy lake effect snowbands
expected across portions of the western Adirondacks through Friday
morning. Snow showers will gradually diminish late Friday into
Saturday, but temperatures will remain below normal.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
As of 930 PM EST, some areas of patchy fog are still present
where there are breaks in cloud cover. However, thicker mid to
upper level clouds have begun moving in to the southern half of
the region, per latest IR imagery. These thicker clouds should
gradually move into the rest of the forecast area throughout the
overnight hours, likely eliminating any remaining fog potential.
Depending on how quickly skies become overcast will determine how
cool temperatures get tonight. In terms of the forecast grids,
only needed to freshen up the temps and sky cover to reflect most
recent obs.

The next piece of upper level energy will move into the region
after midnight. There could even be some flurries in some areas
toward daybreak due to the possibility of some seeder-feeder
processes with the thickening mid level cloud deck, and any lower
clouds beneath.

Meanwhile, across the far western Adirondacks, some snow showers
are expected to develop after midnight, possibly leading to some
accumulations of a coating up to an inch, mainly north of Rte 28.

Overnight lows should fall into the mid/upper 20s for most areas,
perhaps holding closer to 30 in some valley areas where clouds
thicken more quickly.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/...
Lake Effect Snow Warning for northern Herkimer/Hamilton
Counties remain in effect from 9 AM EST Thu to 7 AM EST Fri...

Thursday-Friday, main story will be colder air and developing lake
effect snowbands for the region. The initial frontal boundary
looks to pass through Thursday morning. Again, some flurries will
be possible from passing upper level dynamics. Then, scattered
snow showers/flurries will increase in areal coverage across the
region Thursday afternoon into Friday, with more pronounced lake
effect snowbands expected to impact northern Herkimer/northwest
Hamilton Cos Thursday afternoon and evening. It appears that this
period will feature the greatest threat for rapid accumulations in
these areas, before a surface trough pivots southeast and allows
the low level to veer more NW. Snowfall rates could reach at least
1-2 inches per hour within any more pronounced single band off
Lake Ontario. Any such bands is then expected to pivot southward
into central Herkimer and extreme west central Hamilton Cos later
Thursday evening, and then into southern Herkimer CO and the
western Mohawk Valley Friday morning.

Total accumulations of 8-14 inches are currently expected across
northern Herkimer CO, mainly north of Rte 28, with 6-10 inches
possible across extreme west central and northwest Hamilton CO
from Thursday into Friday morning.

For the southern Herkimer CO and NW Schoharie CO, current forecast
accumulations of 1-3 inches are expected Thursday night into
Friday. A Lake Effect Snow Advisory may be needed if confidence
builds further that greater amts may occur.

Elsewhere, upslope snowfall could lead to at least 1-3 inches
across portions of the Berkshires and southern Greens late
Thursday afternoon into Friday morning, although locally higher
amts will be possible.

In valley areas, scattered coatings to less than an inch could
occur Thursday afternoon through Friday, especially late Thursday
night/Friday morning as the trough passes through. Despite such
light amts, brief squalls can not be ruled out which can still
have highly localized but significant travel impacts.

Temperatures should reach the 30s to around 40 in valleys and
mainly 20s to lower 30s across higher terrain Thursday, then
mainly 30s for valleys and 20s for higher elevations Friday. By
Saturday, highs will mainly be in the 20s to lower 30s in valleys,
and teens to lower 20s across higher terrain.

Overnight lows will mainly be in the 20s for Thursday night, then
teens and lower 20s for Friday night, although some single digits
may occur across portions of the southern Adirondacks and
southern VT.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Transition period Saturday night ahead of the next system tracking
out of the central U.S.  Decent consensus in sources of guidance
and ensembles on the timing of the advance of clouds and the leading
edge of snow through the day Sunday.  So, chances for snow
increasing through the day Sunday with highs in the lower to mid 30s
but 20s higher elevations.

Quick shot of warm advection, low level southwesterly jet energy and
isentropic lift Sunday night and Monday. There are a few
disagreements as to how much we warm at the boundary layer during
peak warm advection, with the warmest guidance suggesting a mix of
rain and snow during the day Monday for much of our area.  This is
the first indication in any set of guidance of such warming, so
siding on the cooler side of guidance until better agreement in
sources of guidance and run to run consistency.

So, high chances to likely snow Monday with highs in the 30s,
perhaps near 40 southern areas and around 30 southern Adirondacks.
There could be light to moderate accumulations of snow where we see
all snow. Any steadier precipitation ends Monday morning, becoming
more rain/snow showers in the afternoon.

Strong cold front with tight boundary layer thermal gradient tracks
through some time in the Tuesday through Tuesday night time frame,
some uncertainties in the timing.  There could be a line of snow
showers with the front and then lake effect snow bands developing
behind the cold front in the strong cold advection off the lakes.
Highs Tuesday in the 30s but 20s higher elevations with scattered to
isolated snow showers, again, due to the forcing along the cold
front and the development of some lake effect snow shower activity.
Highs Wednesday in the 20s to lower 30s but upper teens to lower 20s
higher elevations.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
Weak high pressure ridge in from the south early this morning, but
a cold front will approach from the west with scattered snow
showers and brisk conditions.

Partly cloudy to mostly clear conditions with calm winds and a
moist boundary layer has allowed for mist and fog to form at the
terminals this morning. Conditions have lowered to LIFR to IFR
levels at KGFL/KALB/KPSF with MVFR conditions at KPOU. Mid level
clouds ahead of the next front are quickly approaching from the
south and west. These lower VSYBYS and CIGS will likely last the
next 3-4 hrs to 10Z...but conditions should improve to MVFR VSBYS
and VFR CIGS btwn 10Z-14Z with the dissipation of the mist and
fog.

VFR conditions should persist during most of the day with
scattered snow showers especially from the Capital Region
northwest. VCSH groups were used in the afternoon. CIGS will
generally be 3.5-5 kft AGL. The skies should clear at KPOU towards
23Z with BKN-OVC conditions lingering further north.

The winds will be light to calm early this morning. They will
increase from the south to southwest at 5-10 kts by the late
morning and veer to the west at 10-15 kts with some gusts close to
20-25 kts at KALB/KSPF during the afternoon with the frontal
passage.

Outlook...

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

&&

.HYDROLOGY...
Light precipitation amounts in the form of mainly snow occurred
last night into this morning with liquid equivalents of a tenth to
a quarter of an inch.

The active weather THU into FRI will be from lake effect snowfall
downwind of Lake Ontario. Precipitation will fall mainly as snow
through the weekend. Heavy lake effect snowfall is expected for
the western Adirondacks...and possible portions of the western
Mohawk Valley and Northern Catskills late in the week into the
early portion of the weekend.

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 from 9 AM this morning to 7 AM EST
     Friday for NYZ032-033.
MA...None.
VT...None.

&&

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



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