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Area forecast discussion 
National Weather Service Albany New York
1259 am EST Thursday Dec 18 2014

Synopsis...
the combination of low pressure strengthening off the northern New
England coast...and an upper level disturbance passing through
overnight...will keep skies mostly cloudy along with some rain and
snow showers. Snow showers will be most frequent across the southern
Adirondacks and southern Vermont. Thursday will be blustery...
although some breaks in the clouds will be possible south of the
capital region. Slightly colder air will seep into the region from
the north for Thursday night and Friday.

&&

Near term /until 6 am this morning/...
radar echoes have increased across the local area as a short wave
trough heads toward Delaware-Maryland-Virginia. Probability of precipitation were increased and expanded with
previous update. Forecast is on track so only some minor adjustments
have been made. Have light mix of snow and rain here at the
office with 37 degrees.

Westerly winds will increase overnight as the area of low pressure
off the northern New England coast deepens and become vertically
stacked as it heads northward. Some gusts possibly reaching 25-30
miles per hour by daybreak...especially in favorable channeled west/east
valleys...such as the Mohawk River valley...as well as in the
Berkshires.

The combination of clouds...and increasing wind should prevent
temperatures from falling as low as the mav MOS suggests...and in some
areas...it is possible that temperatures may only drop to near or even
slightly above freezing...especially within the immediate Mohawk River
valley/capital region and upper Hudson River valley. Have
therefore went with...or above the slightly warmer met MOS for
overnight mins.

&&

Short term /6 am this morning through Friday night/...
Thursday...aforementioned second shortwave impulse should move
generally east of the region in the morning. However...some
lingering upslope snow showers will likely persist across portions
of the SW Adirondacks...southern Vermont...and western Massachusetts. Additional
accums of an inch or two could occur within the more persistent
areas of snow showers. Elsewhere...the main story for Thursday should
be gusty winds...which may gust up to 35 miles per hour or slightly
higher...especially in portions of the Mohawk Valley/capital region and
Berkshires. Although most areas near and north of Interstate 90
should remain mostly cloudy to overcast...some breaks of sun will
be more likely to the south...with skies possibly becoming mostly
sunny at times across portions of the middle Hudson
Valley...Litchfield Colorado CT...and possibly extreme southeast Vermont. In these
areas...temperatures could warm into the 40s. Elsewhere...expect mainly
30s in valleys...and upper 20s/lower 30s across higher elevations.

Thursday nt-Friday nt...a surface trough is expected to gradually settle
southward late Thursday nt into Friday...with a slightly colder...shallow
air mass in its wake. As the trough passes...it could allow for a
brief resurgence in snow showers/flurries...mainly across higher
elevations late Thursday nt. As winds shift more into the northwest to north in
the wake of the trough...any lake enhanced snow showers should
shift into the central New York state...perhaps occasionally grazing the
Catskills. Elsewhere...the potential for clearing skies will
increase in at least valley areas during Friday...with mainly
clear skies anticipated for Friday nt. Temperature Thursday nt should fall into
the 20s in most areas...with some teens possible across the
southern Adirondacks. Friday should be chilly...with maximum temperatures mainly
reaching the Lower/Middle 30s in valley areas...except near 40 across
the middle Hudson Valley and southern Litchfield Colorado CT...with mainly
20s to lower 30s expected across higher elevations. Friday nt should
be colder...with most min temperatures falling into the Lower/Middle 20s in
valleys...and teens across higher terrain.

&&

Long term /Saturday through Wednesday/...
Saturday still looks dry with seasonably chilly temperatures. After
that...it looks as if we will be dealing with a mainly weak southern
stream disturbance...but then a potentially much stronger "phased"
system as head to Christmas evening.

The only day that we might see any some sunshine would be
Saturday...otherwise plenty of clouds will persist. Either way look
for highs from the upper 20s northwest to look to middle 30s south.

By Sunday...we will be dealing with an easterly flow from high
pressure anchored in extreme eastern Canada...as well as some sort
of weak wave developing well south in the jetstream. Also...there
might be an even weaker wave in the northern branch of the jetstream
that might interact with the southern one to develop some sort of
inverted trough late Sunday into Monday. This feature...combined
with an easterly flow...could trigger enough lift to produce what
looks to be nuisance type precipitation...mountain snow and a valley
rain/snow mix Sunday into Monday. Again...this is not going to be a
big storm but it could produce some slippery roads...especially
Sunday night and higher elevations. The timing of this possible
event is still uncertain so for now we have included slight chances
Saturday night...and low chances Sunday into Sunday night and slight
chances
Monday.

Highs Sunday will generally be in the 30s...above freezing in the
valleys. Lows Sunday night will be around 30 in most places. Highs
Monday again in the 30s.

By late Monday...the European and GFS forecast models are
forecasting a much stronger trough associated with the northern
branch to dig in the nation/S middle section. This trough is forecast
to interact with southern stream energy to produce what could be a
powerful storm as we head into late Tuesday and Wednesday.

The track of this storm looks to be along or near the Appalachian
Mountains...well to the west of the Hudson Valley. It would impact
our region mainly on Christmas evening. A storm with this track would
likely bring mostly rain...perhaps a little wintry mix on the front
side. As it moves up to our northwest...it would pull air in cold
enough to perhaps switch leftover rain showers into snow showers by
Christmas evening night.

This storm might bring some strong wind to the higher terrain
Wednesday...as it looks similar to the setup of the great
appalachian storm of 1950 as well as the "cleveland bomb" of 1978.
Heavy rain might trigger some Hydro issues as we still have a bit of
snow to melt in the mountains.

Being nearly a week away a lot of the synoptic setup could
change...but this storm definitely bears watching.

Highs on Wednesday look to be mainly in the 40s...dropping to below
freezing by late Christmas evening night.

&&

Aviation /06z Thursday through Monday/...
an upper level trough is situated directly over upstate New York. This is
allowing for some precipitation to break out across the region for
the overnight hours. With chilly temperatures aloft...this looks to fall
mainly as snow showers...although some rain may mix in initially as
the surface temperatures may be slightly above freezing at first. Based on
current radar trends...the sites most likely to be impacted with
snow showers over the next few hours will be kpsf/kalb...although
kgfl/kpou may still see a snow shower around as well.

Flying conditions will generally be VFR/MVFR outside of snow shower
activity. Within snow showers...flying conditions look to lower to
low end MVFR or IFR...especially for kalb/kpsf...where a tempo for IFR
conditions within snow will be put until 10z.

Towards daybreak...the upper level trough will start to move
eastward towards New England...which should allow for mainly dry
conditions at the taf sites during Thursday and into Thursday
evening. There will still be a lot of clouds around....with broken-overcast
ceilings at 3500-5000 feet. Some MVFR clouds may make a return for
Thursday night.

Westerly winds will be around 5-10 kts overnight. During daytime
mixing on Thursday...W-NW winds will be around 10-15 kts with a few
higher gusts...especially for kalb/kpsf. Winds will diminish somewhat for
Thursday night.

Outlook...

Friday: no operational impact. No sig weather.
Friday night: no operational impact. No sig weather.
Saturday: no operational impact. No sig weather.
Saturday night: moderate operational impact. Chance of shsn.
Sunday: moderate operational impact. Chance of shsn.
Sunday night: moderate operational impact. Chance of shsn.
Monday: moderate operational impact. Chance of rain showers...shsn.

&&

Hydrology...
no hydrologic concerns through the remainder of the week.

Additional light rain or snow showers will continue into tonight.
Basin average precipitation amounts will be light...generally less than a
quarter of an inch. Only very minor rises are expected on rivers
and streams...with most river flows expected to remain fairly
steady.

Some additional light mountain snow showers are possible Thursday
into Friday...but these very be fairly limited and won't have any
impact on area waterways. Temperatures look to be a little colder
for thurs/Fri...which will limit the amount of snow melt that
occurs. Mainly dry weather is expected for the weekend...with just
a low chance for some light snow.

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. 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...none.
Massachusetts...none.
Vermont...none.

&&

$$
Synopsis...kl/gjm
near term...iaa/kl/gjm
short term...kl
long term...hwjiv
aviation...frugis
hydrology...kl

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