Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 210600

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

A warm front will lift northward through the area tonight. This
will lead to fair and milder weather on Tuesday as temperatures
warm to above normal ahead of an approaching cold front. This
cold front will bring the chance for additional precipitation
overnight Tuesday into Wednesday morning.


As of 1245 AM EST, have mainly clear skies across area as
ridging dominates at the surface and aloft.Some high level
cirrus will stream across at times. Warmer air advects in
overnight. Temperatures will be fairly steady for the
overnight hours. As surface ridge axis shifts eastward and
off the coast a southerly flow will develop.


Digging upstream short wave approaches the western Great Lakes
through the day Tuesday. This in turn will allow for downstream
ridging to commence along with the southwest flow regime. A good
deal of November sunshine is in the forecast as just how high
temperatures will get and just how much of those wind magnitudes
mix down to the surface. A downsloping component should aid with
milder temperatures for valley locations as we will shade
closer to the warmer side of the guidance envelope. Along with
the warmer temperatures, BUFKIT momentum transfer for those
higher wind magnitudes suggest we tap into the 20-30KT range
during the day. So a relatively mild and breezy day appears to
be unfolding for Tuesday for entire region.

The aforementioned upstream trough amplifies further with
strengthening baroclinicity and frontogenesis is the result
Tuesday night. In addition, strengthening upper level jet and
diffluence across the southeast CONUS brings about a developing
surface wave tracking along or just east of the coastline. While
NCEP Model Suite and international guidance differ with this
track of this coastal wave, consensus was a bit east to limit
its direct impact to the region. But the cold front will impact
most of the region overnight with the chance of precipitation
increasing from northwest to southeast. As per thermal profiles,
seems initially a mainly wet start to the onset of
precipitation, then as colder air quickly advects in from the
west, a transition to rain/snow to just snow is expected mainly
west of the Hudson toward sunrise Wednesday.

This front is quite progressive and its timing would exit our
eastern zones by mid-morning Wednesday. Then brisk westerly
winds within cold advection will be the main story through the
remainder of the daylight hours. There might be some minor lake
response but profiles suggest subsidence layer is rather quick
to lower at this time so minimal to no lake effect impacts

Clearing skies and light winds expected toward sunset Wednesday
which should last into the nighttime period as yet another ridge
axis at all levels tracks across the region. Should be rather
chilly with mainly lower half of the 20s expected.


This will be a period of relatively dry conditions with just one
system of any real consequence.  Thanksgiving evening meals will
begin with partly cloudy and seasonably cool conditions, and
temperatures dipping below freezing everywhere well before midnight.
A cold front will barely make it into our region, and could produce
a period of light snow showers or flurries in the Adirondacks.

Low pressure racing eastward across southern Canada will bring most
of our region a quick hit of showers on Saturday.  Timing will
decide if it will be more snow or rain, overall, but since it looks
like more of a daytime event, from the Capital Region on south, we
can expect any snowy start to quickly mix over to rain.  Even most
areas in the Adirondacks and Greens will likely see more liquid, and
no accumulating snow.

The cold front with this system, expected to come through in double-
barrel form, will bring us colder than normal air, with high
temperatures by Friday ranging from only the lower and mid 20s in
the the upper 30s in the Mid-Hudson Valley.  A trof
of low pressure stays well north of New York State and weakens early
next week as high pressure begins to build in from the deep south.

High temperatures will peak on Saturday, with the readings in the
mid 30s to upper 40s range.  Lows peak at just below freezing Friday
night, with similar values Saturday night, but lows will range from
only around 10 degrees to the mid 20s Sunday night.


Clouds have shifted north of the terminals as upper level
heights rise and a warmer airmass advects into the region. This
will ensure VFR conditions throughout the TAF period. Aside from
a few high clouds, mainly clear skies are expected to prevail.

Winds tonight will be nearly calm to southerly at around 8 kt or
less. Marginal conditions for low-level wind shear, but LLWS was
added to the TAF sites into mid-morning except for KALB where
southerly flow will be strongest. With diurnal mixing, winds
may get a bit gusty Tuesday late morning into the afternoon,
with gusts of 20-30 kt possible, strongest at KALB. Winds will
diminish Tuesday evening.


Tuesday Night: Moderate Operational Impact. Chance of SHRA.
Wednesday: Low Operational Impact. Breezy Slight Chance of SHRA.
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...SHSN.


Light snow and lake effect snow showers will dissipate this
evening as a warm front lifts northward tonight. In its wake, looking
at fair and milder weather for Tuesday as temperatures warm to
above normal ahead of an approaching cold front. This cold front
will bring the chance for additional precipitation overnight
Tuesday into Wednesday morning.


No hydrologic problems are expected this week. Lake effect
snows will shift northward to the western and southern
Adirondacks and weaken this evening. Otherwise isolated to
scattered showers are expected across the remainder of the
region with drier conditions overnight. 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. QPF amounts are expected to be light with less
than a quarter of an inch. Fair weather returns for Thanksgiving
with unsettled weather expected this 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.




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