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Area forecast discussion 
National Weather Service Albany New York
1000 am 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 the Lake George/Saratoga
region...and eastern/central Mohawk Valley region...

As of 945 am EST...previous forecast on track with most areas south
and southeast of Albany already snowing. Snow should break out
across the entire capital district by 1100 am...and areas to the
north and northwest around noon or early this afternoon. Have not
made any changes to snow amounts with this update.

Low pressure is currently developing just off the South Carolina
coast...with the best pressure falls suggesting it will track
north/northeast toward eastern North Carolina...most likely west
of Cape Hatteras.

Latest numerical guidance...including the latest rap/hrrr...as
well as the 00z/26 NAM...GFS and European model (ecmwf)...suggest that the surface low
tracks a bit further west than previous cycles had suggested. In
response...models have also trended slightly farther north and west with
the heavier quantitative precipitation forecast...and also with milder air aloft. Therefore...some
changes were made to our recent forecast...which are as follows...

Change 1...have adjusted snowfall upward by at least 2-5 inches
for the capital region...eastern Mohawk Valley...and Lake
George/Saratoga region. This has required the expansion of the
winter storm warnings into the Saratoga/Lake George region and
central/eastern Mohawk Valley. Generally 8-10 inches are expected
for the areas immediately north and west of the capital region...and
generally 10-14 inches within the immediate capital region.

Change 2...with the storm track expected to be slightly further
west...warmer middle level air is expected to reach portions of northwest
CT...and possibly into the middle Hudson Valley and extreme southern
Berkshires. Thus...in these areas...have lowered snowfall
totals...with mainly 6-8 inches expected...lowest in southern
Litchfield County...where some sleet is now expected to mix in due
to the warming aloft.

Change 3...have included mention of some rain this morning at the
time the precipitation starts...due to the relatively warm
boundary layer currently in place...mainly for areas from Albany
and areas to the S and east.

Otherwise...still expect precipitation to develop from south to
north between daybreak and 9 am across the southeast Catskills...middle
Hudson Valley...northwest CT and southern Berkshires...between 9 am and
noon further north across the capital region...Lake George/Saratoga
region...Schoharie valley...Berkshires...and Mohawk Valley...and
between noon and 2 PM across the western Adirondacks.

Again...the precipitation could initially begin as plain rain...or a
rain/snow mix for areas mainly south and east of Albany within an
hour or two of the onset of precipitation...before wet bulb
cooling allows for precipitation to change to mainly snow.

The potential for heavy snow will increase from south to north
this afternoon. Snowfall rates of 1 to 2 inches per hour will
become likely from south to north this afternoon...with some
possibility of even greater snowfall rates of between 2 and 3
inches per hour...especially from the greater capital region and points
just S and east...into the Taconics...Berkshires...and northern
Litchfield Colorado...where the strongest middle level frontogenesis is
suggested to be.

Temperatures may initially rise a bit before precipitation
develops...into the middle/upper 30s...before falling back through
the middle and eventually lower 30s for this afternoon.

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.

Regarding storm total snowfall amts...it appears that a stripe of
10-14 inches can be expected from the eastern Catskills...capital
region...central/southern Taconics...Berkshires and southern Vermont.
Slightly lower amts...of 6-10 inches are expected across the middle
Hudson Valley and northwest CT...where some initial snowfall may be lost
due to warmer temperatures...and due to the possibility of some
sleet mixing in this evening. Further north and west...6-10 inches are
expected across the Lake George/Saratoga region and
central/eastern Mohawk Valley...with mainly 2-6 inches across the
far western Mohawk Valley and across the western Adirondacks.

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 /12z Wednesday through Sunday/...
a developing Nor'easter will bring a widespread snowfall to the
area that will significantly impact Holiday travel today into
tonight.

Snow has been slow to develop this morning...as there is a dry
layer in the lower atmosphere that is taking time to saturate. So
pushed back timing of snow beginning from south to north between 12z
and 16z. Temperatures are warm enough for rain to mix in for a few
hours at kpou at the onset before changing to all snow. Precipitation type
will be all snow for the kalb/kpsf/kgfl terminals. Conditions will
initially be VFR/MVFR...quickly deteriorating to IFR by late this
morning.

Snow will increase in intensity by early to middle afternoon...with
conditions deteriorating to LIFR. Snow will start to lighten in
intensity after 01z-02z Thursday...with light snow persisting
into early Thursday morning with continued IFR conditions. Snow
should taper off around or shortly before sunrise Thursday...with
conditions improving to MVFR and eventually VFR.

Winds will be northerly and increase to around 8-12 kts by early
this afternoon...shifting to the northwest this evening and
overnight.

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 nyz058>061-
063>066.
Winter Storm Warning until 7 am EST Thursday for nyz039>041-
043-047>054-083-084.
Winter Weather Advisory until 7 am EST Thursday for nyz032-033-
038-042-082.
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...gjm/kl
short term...bgm
long term...bgm
aviation...jpv
hydrology...iaa/kl

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