Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 211417
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
917 AM EST Tue Nov 21 2017

.SYNOPSIS...
Fair and mild today with temperatures rising into the upper 40s
to mid 50s ahead of an approaching cold front. The front will
sweep across the region late tonight into Wednesday bringing
some snow and rain showers to the area. A more seasonable air
mass will be ushered back in with mainly fair weather then
expected through Friday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 917 AM EST...Made some minor adjustments based on current
obs/trends. Otherwise, current forecast on track.

Mild, fair and breezy today ahead of an approaching cold front.

Ridge axis, upper and surface, shifts off the coast and deep
southwest flow develops advecting warmer air into the region.
Southerly flow will develop this morning and become breezy as
the gradient pressure tightens across the region between the
approaching cold front and departing ridge. South to southwest
winds increasing to 10 to 20 mph with gusts up to around 30 mph.
These winds and sunshine will help boost temperatures into the
upper 40s to mid 50s; around 10 degrees above normal.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
Fair weather for Thanksgiving.

Sharp northern stream short wave trough will approach tonight
and move overhead Wednesday as it shears out. In the meantime,
a piece of southern stream energy and its associated surface low
will remain well off the coast as it quickly heads northeastward
off the southeast coast.

Clouds will be in the increase in the evening with chances for
snow and rain showers increasing mainly after midnight as the
cold front moves into the region from the west and some moisture
is drawn into the region from the coastal low. Showers will
taper off in the afternoon lingering the longest across the
higher terrain. QPF amounts are expected to be light with about
a quarter of an inch across the western Adirondacks with lesser
amounts elsewhere. Light snowfall accumulations of 1-2 inches
are expected across the western Adirondacks with less than an
inch for areas generally above 1500 feet.

With the passage of the cold front a more seasonable air mass
will be ushered back in on brisk and gusty west-northwest winds.
Areas generally west of the Hudson River Valley will experience
little if any rise in temperatures Wednesday while east of the
valley temperatures will rise some before dropping off later in
the day.

Upper flow is expected to go briefly flat Wednesday night across
the region between short waves rotating about the upper low
over Hudson`s Bay. The next short wave trough will not be as
deep and will pass to our north across eastern Canada Thursday
night. While at the surface higher pressure builds in. The
result will be fair weather with below normal temperatures
Wednesday night and Thanksgiving Day. Chances for any snow
showers are expected to limited to portions of the western
Adirondacks Thanksgiving night with seasonable lows as winds
shift to the southwest.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Good model agreement that the progressive pattern continues into the
long term period with the mean Hudson Bay upper low remaining
dominant. Disturbances pinwheeling around the low have favored a
storm track along or north of the St. Lawrence Valley recently, at
it appears that will continue to be the case. Little evidence at
this time that any southern stream energy will phase with the
northern stream.

Friday appears to be a tranquil and seasonable day. Upper heights
will rise in conjunction with shortwave energy tracking across the
northern Great Lakes region. Attendant surface low looks to track
well north into northern Quebec, dragging its front across the
forecast area on Saturday. Midlevel forcing will augment the front
and result in shower potential, but it appears to be a low-QPF
scenario attm given lack of moisture source and progressive forcing.
Given the storm track, a p-type of rain is favored over most areas
Saturday, with a tendency to mix with snow with time later Saturday
into Saturday night, mainly at elevation. Additional shortwave
energy is forecast to carve out a deepening upper trough over the
greater Northeast Sunday and Monday. H850 temps progged to fall to -
10 to -15C, or possibly a bit lower as shown by the 00Z ECMWF, by
Sunday night. These values are 1 to 2 SD below normal. This will
allow for a lake response Sunday into Sunday night, with flow
trajectories veering from NW to NNW. Some synoptic forcing with the
reinforcing wave could carry some showers further inland than the
normal lake effect/upslope favored areas Sunday. It appears height
rises build in Monday, allowing lake effect to diminish.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
Aside from a few high clouds, mainly clear skies are expected
to prevail throughout the day. An approaching cold front will
allow clouds to increase and lower somewhat late tonight, but
VFR is expected to prevail throughout the TAF period.

Low-level wind shear is likely being seen at the terminals this
morning with nearly calm winds at the surface and west-southwest
winds around 35 kt at 2000 ft agl. With diurnal mixing, winds
may get a bit gusty late this morning into the afternoon, with
gusts of 20-30 kt possible, strongest at KALB. Winds will
diminish this evening, with low-level wind shear likely once
again at the terminals overnight.

Outlook...

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

&&

.FIRE WEATHER...
South to southwest winds 10 to 20 mph with gusts up to around
30 mph at times today with minimum relative humidity values
in the 30s this afternoon.

Fair and mild today ahead of an approaching cold front. The front
will sweep across the region late tonight into Wednesday bringing
some snow and rain showers to the area. A more seasonable air mass
will be ushered back in with mainly fair weather then expected
through Friday.

&&

.HYDROLOGY...
No hydrologic problems are expected this week.

Fair and milder weather today with some rain and snow showers
late tonight into Wednesday as a cold front crosses the region.
QPF amounts are expected to be light with about a quarter of an
inch across the western Adirondacks with lesser amounts elsewhere.

With the passage of the cold front a more seasonable air mass
will be ushered back in with mainly fair weather then expected
through Friday.

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...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...IAA
NEAR TERM...IAA/JPV
SHORT TERM...IAA
LONG TERM...Thompson
AVIATION...Thompson
FIRE WEATHER...IAA
HYDROLOGY...IAA



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