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Area forecast discussion 
National Weather Service Albany New York
703 PM EST Sat Nov 22 2014

Synopsis...
high pressure off the eastern Seaboard will drift out to sea..with
an increasing southwest flow over the region. A warm air surge
aloft tonight will bring a wintry mix to the region...followed by
milder weather Sunday. Sunday night a stronger warm front will
push north with widespread rain. It will be followed by very mild
weather for November Monday. A cold front will pass through the
northeast Monday night...with a return to fair and seasonable
weather midweek.

&&

Near term /through Sunday/...
as of 630 PM EST...Winter Weather Advisory expanded to include the
capital district...helderbergs...nrn Taconics...northern
Berkshires...Washington City...and southern Vermont. Many reports of sleet
and spotty freezing rain coming on. This advisory will go to 5 am
Sunday...though parts may be dropped sooner. The better batch of
precipitation is over the Mohawk Valley...northern Catskills...and southern
dacks...but reports keep coming in eastward over the capital region
and Berkshires. Large surface T/dew point spreads continue with
sleet/-fzra/-ra being reported.

The Winter Weather Advisory also remains in effect until 5 am EST
Sunday for the Mohawk Valley...Schoharie valley...southern
Adirondacks...and the Lake George Saratoga region...

Previous discussion...
our region is under broad large scale lift this tonight...as a 120
knots jet streak is situated to our southwest...putting eastern New York
and western New England in the left front exit region. In
addition...a weak shortwave is embedded with the fast westerly
flow at 500 hpa.

With surface temperatures at or just below freezing across the western
Adirondacks...Mohawk and Schoharie valleys...and Lake George
Saratoga region...this precipitation may initially fall as a wintry mix.
Model soundings show warming aloft due to warm air advection within
the fast west-SW middle level flow aloft...but dry air the surface should
allow surface temperatures to wet bulb down a few degrees. This will allow for
a period of sleet/freezing rain through the evening hours...especially
within the sheltered and elevated valley locations. This is the
reason for the current advisory headline...whose start time was also
sped up to account for latest radar trends.

Elsewhere...surface temperatures will remain just above freezing /such as in
the capital region and middle Hudson Valley/ or precipitation coverage will be
too sparse to warrant an advisory. There still may be a few pockets
of freezing rain the Catskills...southern Vermont...taconcis and
Berkshires...and special weather statements may be needed to account
for this activity later this evening. The best chance of seeing
precipitation will be for areas north of Interstate 90...with more spotty
coverage the further south you go. Dry low levels will also cause a
lot of precipitation to dry up before reaching the surface for valley
locations...so high terrain areas look to have a better chance of
seeing precipitation as compared the valleys. Any precipitation looks to taper off
by late tonight...as the surface wave and associated jet streak slide
east of the region.

After temperatures fall this evening...they look to hold steady or even
slowly rise overnight. Mins this evening look to be in the low
30s...and most areas...even northern/high terrain areas...look to be
above freezing by around daybreak Sunday.

During the day on Sunday...mainly dry weather is expected. There
could be an early morning rain shower over the Adirondacks...
otherwise no precipitation is expected. It will remain fairly cloudy during
the morning hours...but there should be more breaks of sun as the
day GOES on thanks to building heights...especially in the afternoon. Warming
temperatures aloft and breaks of sun will allow for warmer temperatures than
recent days...with highs generally in the 40s for most
locations...with even a few readings near 50 in the middle Hudson
Valley.

&&

Short term /Sunday night through Tuesday night/...
the model suite (nam/GFS/Gem/ecmwf)is in good agreement during the
short term period. Sun nt large 500hpa trough in the Great Plains
triggers a major cyclogen event in the Great Lakes (i hear a 1972 Gordon
Lightfoot song). This intense storm lifts NE toward James
Bay...dragging a warm front and a period of steady rain through the region
sun nt...ending Monday morning. In its wake a 16 hpa SW surface wind
gradient is across fca...and very mild air is pumping NE into region.

Monday nt the systems trailing cold front and the 500hpa trough mv across
region. GFS brings this through around 00utc...with the others implying
a later to ovrnt frontal passage. Given the close to parallel nature of the
cold front to the 50hpa flow...forecast will go with the overnight
frontal passage...and rain showers with frontal passage. Given the dynamics...available moisture a
rumble or two of thunder cant be ruled out but cant exactly get
excited about mu cape of 200 j/kg at this time.

Afternoon Monday nt frontal passage...intense surface low races NE into qb..and fca is
mostly in the dry slot Tuesday as the last pieces of the 500hpa trough
pass across New York/new eng. Surface flow remains west-southwest much of the day. So
most of fca will see breezy fair return to seasonable temperatures. Lake
effect may begin into the west Adirondacks...with a better chance Tuesday
nt as the surface/h850 flow turns W-WNW.

&&

Long term /Wednesday through Saturday/...
there is quite a bit of spread and uncertainty in the extended
portion of the forecast...as coastal low may track close to the
coast Wednesday night through Thanksgiving. The mean upper level
trough keeps temperatures cold and below normal for the Holiday weekend
into early next week.

Wednesday...most of the medium range guidance has an h500 upper
level trough east of the MS River Valley with a strong low-level
baroclinic zone along the middle Atlantic coast...or just off the East
Coast. The GFS has low pressure forming east of the Carolinas and
moving north/NE out to sea with some light over running snow/snow
showers perhaps impacting extreme eastern New York and western New England in the
afternoon/early evening. The can ggem is even further east with the
storm evolution and track. The 12z European model (ecmwf) is the furthest west of
the envelope of solutions...and it would be phasing some northern and southern
stream upper level energy for a Miller type-a storm track from near
the Carolinas Wednesday PM to just southeast of the Delaware-Maryland-Virginia region by 00z/Thu.
This type of storm track and evolution would be a big problem for
the Wednesday PM travel into Thanksgiving day. Over running precipitation would be
spreading well north and west of the ongoing cyclogenesis into much
of upstate New York. For now...we have chance probability of precipitation from the capital district
east...and slight chance to the north and west with some light snow or
a mix of light snow/rain to the south. It should be noted most the
gefs members and its mean are either east of the 12z operational GFS
or are in agreement with it. The wpc track is close to the GFS and
the gefs mean. We will continue a mention of the storm in the severe weather potential statement
at this time. Highs on Wednesday will range from the u30s to l40s in the
valleys and u20s over the hills and mountains

Wednesday night into Thanksgiving...the exact track of the coastal or
oceanic cyclone is the big issue here. The European model (ecmwf) would have a major
storm with the cyclone deepening to 989 hpa just S/southeast of NYC at
06z/27 to 983 hpa just NE of kbos by 12z/27. The h850 circulation
would close off over upstate New York and New England during the day with
persistent snowfall. Again...the GFS is further to the east and out
to the Atlantic with the storm with a 992 hpa surface cyclone near Nova
Scotia by 12z/27. Some light snow is definitely possible Wednesday night
into Thursday on the northwest side of the cyclone with the middle and upper level
deformation zone. Stay tuned on this storm system over the next few
days. Lows Wednesday night will be in the m20s to l30s...and highs on Thursday
will range from the l30s to l40s in most locations.

Thanksgiving night into Friday...a cold front and an upper level
trough moves across the region with a reinforcing shot of cold
air...and a chance of snow showers Thursday night. Cold and brisk
conditions will be likely on the busy shopping day on Friday...some
westerly upslope/lake effect snow showers and flurries will be
possible for the western dacks...and southern greens during the day. Lows
will be mainly in the 20s with some teens over the southern dacks...southern
greens...and the eastern Catskills. Highs on Friday will be below normal
in the 20s over the mountains...and u20s to mainly m30s in the valleys.

Friday night into Saturday...surface high pressure will try to ridge in
from the Tennessee Valley with the cold weather persisting...but a short-wave
in the west/northwest flow aloft may trigger more isolated-scattered upslope snow
showers and flurries mainly north and west of the capital
district. Below normal temperatures will continue on the Holiday weekend.

&&

Aviation /00z Sunday through Thursday/...
a weak thermal trough and an upper level disturbance will bring
some light mixed precipitation to eastern New York and western New England
overnight. High pressure will ridge back in from the south and
east tomorrow afternoon.

VFR conditions will lower to MVFR ceilings/visibilities in the mixed precipitation
of -ip/-fzra/-ra for kalb/kpsf/kgfl north and east. The ceilings may
briefly lower to high MVFR ceilings between 03z-08z/sun at kpou...but not
much precipitation is expected there. The best chance of a period of -fzrapl
is at kgfl and kpsf between 01z-08z/sun. The ceilings and visibilities will
lower to MVFR levels in the mixed precipitation. Kalb will have some -ra
around between 01z-05z with some MVFR ceilings visibilities.

Temperatures will climb well above freezing at kgfl/kpsf towards
daybreak...and expect all the taf sites to have VFR conditions
return in the late morning through the afternoon.

The winds will be from the south to southwest at 5-10 kts tonight
with some gusts in the 15-20 knots range at kalb and kpsf. Expect
southerly winds of 5-10 kts tomorrow in the late morning through
the afternoon.

Outlook...

Sunday night: high operational impact. Definite rain showers.
Monday: high operational impact. Likely rain showers...ra.
Monday night: moderate operational impact. Chance of rain showers.
Tuesday: no operational impact. No sig weather.
Tuesday night: no operational impact. No sig weather.
Wednesday: low operational impact. Slight chance of rain...sn.
Wednesday night: moderate operational impact. Chance of snow.
Thanksgiving day: low operational impact. Slight chance of
shra/shsn.

&&

Hydrology...
no significant hydrologic problems are expected over the next
several days.

A light wintry mix will impact the region...mainly for areas
north of Interstate 90...for late this afternoon into tonight.
Basin average liquid equivalent of precipitation will be a quarter of an
inch or less...which will have little effect on area rivers and
streams. Along with a milder air mass...a more widespread precipitation
event...this time in the form of liquid rainfall...will impact the
region Sunday night into Monday. Rainfall amounts will generally
be around a half inch or so...locally higher across the southeast
Catskills/middle Hudson Valley and northwest CT. This may allow for some
minor rises on rivers and streams...but no flooding is
anticipated. Behind this rain event...cooler and drier air will
move back into the region for much of the upcoming week.

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 5 am EST Sunday for nyz032-033-
038>043-047>054-082>084.
Massachusetts...Winter Weather Advisory until 5 am EST Sunday for maz001.
Vermont...Winter Weather Advisory until 5 am EST Sunday for vtz013>015.

&&

$$
Synopsis...Snyder
near term...frugis/wasula
short term...Snyder
long term...wasula
aviation...wasula
hydrology...frugis/kl

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