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fxus61 kaly 201415 
afdaly

Area forecast discussion
National Weather Service Albany New York
915 am EST Mon Nov 20 2017

Synopsis...
brisk conditions today with below normal temperatures and
continued lake effect snow. The lake effect snows will shift
northward to the western and southern Adirondacks this morning.
Otherwise isolated to scattered showers are expected elsewhere
much of the day. Lingering snow showers will taper off this
evening. Looking at fair and milder weather for Tuesday as
temperatures warm to above normal ahead of an approaching cold
front.

&&

Near term /until 6 PM this evening/...
as of 915 am EST...issued a Winter Weather Advisory for lake
effect snow for northern Herkimer and western Hamilton counties
today into this evening.

Latest hi-res guidance and radar trends indicate with backing
flow today, there will be multiple lake effect snow bands that
will migrate northward across the advisory area, with the
potential for 3-6 inches within the most persistent bands.
Multiple surges of moderate to briefly heavy snow bands will
lead to accumulating snow in this area.

Otherwise, eastward extent of lake effect plume this morning
still resulting in scattered snow showers across the Mohawk
Valley, capital district, Taconics and even some narrow bands
into parts of eastern Greene and Columbia counties. Have updated
pop/wx/snow grids to account for this activity this morning.
Snow showers are expected to lift northward out of the Mohawk
Valley to capital district corridor by early this afternoon as
the low level flow backs to more of a westerly trajectory.

As the upper trough exits and another short wave passes over
the region will have the threat for isolated to scattered snow
showers across much of the local area along with upslope snows
into the southern green, Taconics and Berkshires.

Below normal temperatures with highs in the upper 20s to lower
40s. Westerly winds will remain brisk as region is squeezed
between the departing system and advancing ridge. Gusts of 25
to 35 mph are expected.

Please refer to the our public information statement for
snowfall reports. We received our first measurable snow of the
season at the National Weather Service office with a half of an inch occurring around
midnight.

&&

Short term /6 PM this evening through Wednesday Night/...
Lake effect will shift farther to the north and will diminish
this evening as ridging builds in at the surface and aloft.
Skies will clear however with winds shifting to the south
expecting seasonable lows mainly in the 20s. Temperatures are
expected to start to begin to rise before sunrise.

Short waves rotating about a large upper low over hudson's Bay
will bring a quick moving system across the region Tuesday
night into Wednesday. Temperatures will warm to above normal
levels on Tuesday as ridging shifts eastward and a deep
southwesterly flow develops again of the approaching cold front.
Highs are expected to top out around 10 degrees above normal in
the mid 40s to mid 50s.

The cold front sweeps across the area late Tuesday night into
Wednesday morning as the main low passes well to our north. In
meantime, an area of low pressure associated with southern
stream energy is forecast to develop along the southeast coast
and track northeastward passing well southeast of Long Island.
The combination of these features will bring some rain and snow
showers to the area. The bulk of the precipitation associated
with the coastal low is expected to remain to our east. Quantitative precipitation forecast
amounts are expected to be light with less than a quarter of
inch.

A seasonable airmass will be ushered back into the region for
Wednesday and Wednesday night. The threat for showers is expected
to come to end by Wednesday afternoon with fair weather for
Wednesday night as high pressure builds in from the west at the
surface.

&&

Long term /Thursday through Sunday/...
medium-range deterministic models and gefs members in generally good
agreement on the large-scale pattern from Thanksgiving day through
the weekend. The pattern remains very progressive with the mean
Hudson Bay upper low remaining dominant and disturbances pinwheeling
around it. A tranquil and cool Thanksgiving day is expected as an
expansive surface high covering much of the southern and central US
noses into the northeast. At night, a weakening cold front will
track into northern portions of the forecast area. Best forcing will
remain well to the north, but a few/sct snow showers are possible
across the Adirondacks along the front and with a weak lake
contribution. The front washes out and southerly flow commences
Friday/Friday night in response to a low pressure system crossing
southern Canada. Could see temps rising in some spots Friday night.
The system's cold front crosses most of the region Saturday. This
front will be augmented by midlevel forcing as we transition back to
deep upper troughing, so chance to likely pops are in the forecast
with highest potential across northern zones. Based on the track of
the low, p-type of rain is favored for most locations, mixing with
snow over the Adirondacks/greens. Another chilly airmass then behind
the front for Sunday/Monday. Gefs mean h850 temps average around -
9c, but latest European model (ecmwf)/GFS drop these values down into the negative
teens. Lake effect snow should get cranking again across favored
areas Saturday night into Sunday.

&&

Aviation /14z Monday through Friday/...
VFR conditions will prevail through the taf period. However,
there are some lake effect snow showers to contend with this
morning. Activity is rather weak and disorganized attm over
kpsf and just south of kalb. Brief visibility reduction cannot
be ruled out at those terminals through mid-morning. Included
vcsh wording but will amend if it appears a heavier snow shower
will reduce visibility. The activity will tend to shift
northward north of kalb/kpsf and toward kgfl later in the
morning into the early afternoon.

This morning into the afternoon, westerly winds will become
gusty once again to 20-30 kt. Winds will diminish to 5-10 kt
this evening, backing to the southwest, becoming southerly at 5
kt or less overnight. Possibly could have some low-level wind
shear issues late tonight but confidence not high enough to
include in the tafs attm.

Outlook...

Tuesday night: moderate operational impact. Chance of rain showers.
Wednesday: moderate operational impact. Chance of rain showers.
Wednesday night: no operational impact. No sig weather.
Thanksgiving day: no operational impact. No sig weather.
Thursday night: no operational impact. No sig weather.
Friday: no operational impact. No sig weather.
Friday night: no operational impact. No sig weather.
Saturday: moderate operational impact. Chance of rain showers.

&&

Fire weather...
brisk conditions today with below normal temperatures and
continued lake effect snow. The focus for the lake effect will
shift from the western Mohawk and Schoharie valleys northward to
the western and southern Adirondacks this morning. Otherwise
isolated to scattered showers are expected elsewhere much of the
day. Lingering snow showers will taper off this evening.
Looking at fair and milder weather for Tuesday as temperatures
warm to above normal ahead of an approaching cold front.

&&

Hydrology...
no hydrologic problems are expected this week. Lake effect
snows will shift from the western Mohawk and Schoharie valleys
northward to the western and southern Adirondacks this morning.
Otherwise isolated to scattered showers are expected today with
lingering snow showers tapering off this evening. Fair and
milder weather for Tuesday with some rain and snow showers
expected late Tuesday night and Wednesday morning as a cold
front crosses the region and an area of low pressure passes well
south and east of Long Island. Quantitative precipitation forecast amounts are expected to be
light with less than a quarter of an inch. Fair weather returns
for Thanksgiving with unsettled weather expected 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.
New York...Winter Weather Advisory until 9 PM EST this evening for nyz032-
033.
Massachusetts...none.
Vermont...none.

&&

$$
Synopsis...iaa
near term...iaa/jpv

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