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Area forecast discussion 
National Weather Service Albany New York
1232 PM EST Wednesday Nov 26 2014

Synopsis...
a coastal low tracking northward off the East Coast will
bring a widespread snowfall to the area that will significantly
impact Holiday travel today into tonight. Heavy snowfall is expected
across western New England and much of eastern New York...with the
heaviest snow occurring this afternoon into the evening. The snow is
expected to gradually taper off late tonight...with some lingering
snow showers across the area for Thanksgiving day.

&&

Near term /through Thursday/...
..Winter Storm Warning expanded to include northern Fulton...And
northern Warren counties...except for Herkimer and Hamilton
counties...the entire area is in a warning now.

..Winter Weather Advisory continues for Herkimer and Hamilton
counties until 7 am EST...

Winter has arrived on Thanksgiving evening...with the first big
coastal Nor'easter for the 2014-15 season!

As of 1203 PM EST...the snow shield has overspread the entire aly
forecast area...except for the northern reaches of Herkimer and Hamilton
counties. Impressive mesoscale multi-bands have set up over eastern
New York and New England with snow rates coming in a 1-2 inch/hour clip
over the Berkshires and south of the capital region. Feel
confident a single mesoscale band may form based on the cstar
research with sunya over the past decade. A potent multi-band may
form in the late afternoon with snow rates revving up to 3 inches
or so an hour. NAM cross-sections of fgen/epv/Omega/rh/snow growth
zone indicate potential for this single band evolution. Tremendous
qg Omega has set up in the h700-500 layer on the north/NE side of the
deepening and intensifying cyclone. Msas pressure falls are close
to 5-6 hpa/3 hours north/NE of the surface wave located just southeast of the
Delaware-Maryland-Virginia at 1600 UTC. Expecting this storm to track inside the
40n/70w benchmark...just east of Montauk...and Nantucket this
evening.

Capital region northward into the Saratoga region could get into
the Sweet spot with close to double digits snowfall amounts. Have
kept 8-16 inch range now. Feel confident with the staff to upgrade
northern Fulton and northern Warren to warnings for 6-10 inches of snowfall
based on a slight northwest jog of the three quarter inch quantitative precipitation forecast line with
the NAM/GFS. Expect periods of MDT-heavy snow to continue through
the afternoon. Also...less mix is expected in the middle Hudson
Valley/northwest CT with 8-14 inches now forecasted.

Temperatures have reached there maximum values in the middle to u30s...and will
continue to fall intoe h20s to l30s.

Winds will increase from the north to northeast this
afternoon...especially within the Hudson River valley due to
channeling of winds...as well as across the Catskills...and
southern Taconics/Berkshires/Litchfield Hills. In these
areas...gusts of up to 25 miles per hour are expected. Luckily...the snow
should be relatively wet in consistency through much of the
day...so blowing/drifting of snow is not expected to be too bad
through the daylight hours.

For tonight...bands of snow...moderate to heavy...will persist
through around 10 PM. The snow is expected to gradually taper in
intensity from southwest to northeast between 10 PM and 2
am...although it could linger a bit longer in portions of the
capital region...southern Vermont and Berkshires...partially in
response to some Mohawk/Hudson convergence. North winds will
remain a bit gusty...again mainly 10-20 miles per hour with some higher gusts
up to 25 miles per hour possible. The snow should become a bit drier in
consistency before tapering off tonight...some some
blowing/drifting of snow may develop. Min temperatures should fall into
the middle/upper 20s...except for some lower 20s across portions of
the Adirondacks and higher terrain of the Catskills and western
New England.

For Thursday...snow showers may still be lingering in the
morning...with additional minor accums possible. Snow showers
should decrease in areal coverage later in the morning and early
afternoon...before possibly increasing again late in the day with
the approach of an upper level trough. Maximum temperatures should reach the
Lower/Middle 30s in valleys...and upper 20s across higher elevations.

&&

Short term /Thursday night through Friday/...
while the coastal low will be far enough removed from the
region...cyclonic flow and one more additional short wave is
forecast to pass through the region Thursday night. Therefore...we
will keep probability of precipitation in the chance-scattered category with those higher probability of precipitation into
the terrain. As the column will be below freezing...precipitation type
will be snow showers/flurries with only light additional amounts of
accumulation expected.

Friday...the aforementioned short wave lifts across New England. In
its wake the combination of rising heights and surface pressures
will leave US under tranquil conditions and some improvement to the
sky cover. Most of the cloud cover will be across the higher
elevations...however...this will not help too much with temperatures
as h850 temperatures will average between -10c to -13c. Highs Friday
afternoon will likely range from the upper 20s to lower half of the
30s.

&&

Long term /Friday night through Tuesday/...
per the previous excellent long term discussion...long term period
of this forecast will remain unsettled with the combination of warm
air returning before a sharp cold front moves through on Monday.

Friday night through Sunday night...
through the Holiday weekend...global model trends favor a gradual
warm advection regime as low pressure develops along the Arctic
boundary situated along the U.S./Canadian border. This low is
forecast to track east then northeast across the Great Lakes region
this weekend. The downstream impacts will favor a rebound in the
thermal profiles...however...the issue will be a gradual moist
isentropic lift. This should keep a mostly cloudy forecast and the
slight chance to chance for light precipitation to develop across the
region. Precipitation types will vary due to the thermal column and
nocturnal processes to warrant a mixture of light rain and/or snow
showers across the region. We followed wpc guidance temperatures
which were a blend of the ECMWF-MOS/gmos.

Monday into Monday night...this will be the day of transition as
that sharp cold front/Arctic boundary is forecast to slide across
the region through the day. In fact...trends in the showalter index
are getting lower which will need to be monitored in future trends
with a slight chance for thunder. Regardless of convection...this
front will bring another change to the region with h850 temperatures
initially in the +6 to +8c range earlier in the day...to -10c to
-15c Monday night. Highs Monday will climb into the 40s for valley
locations and M-u30s for the terrain. Monday night lows...the
combination of strong cold advection and clearing skies thanks to
1040mb surface high quickly building into the region...temperatures
will likely drop back to the teens and middle 20s and with some
winds...wind chills will be lower.

Tuesday...consensus favors a large 1040mb surface high across
upstate New York with a very dry column of air. This should result in
good amount of early December sunshine and near seasonable
temperatures.

&&

Aviation /18z Wednesday through Monday/...
a developing Nor'easter will bring a widespread snowfall to the
area that will significantly impact Holiday travel today into
tonight.

Widespread snow and heavy snow will affect the kalb/kgfl/kpou/kpsf
taf sites for the rest of the afternoon and most of this evening
with IFR to vlifr conditions. Between 02z and 06z conditions will
slowly improve from southwest to northeast to MVFR cigs/vsbys...then
mainly VFR conditions are expected after 10z Thursday...with the
exception of kpsf where ceilings will likely remain MVFR through the end
of the taf period at 18z Thursday.

Winds will be northerly and increase to around 8-12 kts with some
gusts of 14 to 18kts this afternoon into the evening...then become
more northwesterly later tonight and decrease to less than 10 kts by
late tonight...and continue into Thursday.

Outlook...

Thursday night: low operational impact. Slight chance of shsn.
Friday: no operational impact. No sig weather.
Friday night: no operational impact. No sig weather.
Saturday: slight chance of shsn.
Saturday night: low operational impact. Slight chance of shsn.
Sunday: low operational impact. Slight chance of rain showers...shsn.

&&

Hydrology...
no significant hydrologic problems are expected through the
weekend.

Widespread snowfall as coastal low impacts region Wednesday and
Wednesday night. Warmer temperatures Sunday will be short lived
and will result some snow melt and ripening of snow pack. However
temperatures are expected to be in the middle 30s and colder Saturday
night and Sunday night so melt will stop.

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...Winter Storm Warning until 7 am EST Thursday for ctz001-013.
New York...Winter Storm Warning until 7 am EST Thursday for nyz039>043-
047>054-058>061-063>066-082>084.
Winter Weather Advisory until 7 am EST Thursday for nyz032-033-
038.
Massachusetts...Winter Storm Warning until 7 am EST Thursday for maz001-025.
Vermont...Winter Storm Warning until 7 am EST Thursday for vtz013>015.

&&

$$
Synopsis...iaa/kl
near term...kl/wasula
short term...bgm
long term...bgm
aviation...gjm
hydrology...iaa/kl

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