Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
350 PM EST Wednesday Dec 17 2014
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
passing rain and snow showers...most frequent across the southern
Adirondacks and southern Vermont. Thursday will be
blustery with lingering snow showers across higher
elevations...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...despite
the possibility for some breaks in the clouds to develop.
Near term /until 6 am Thursday morning/...
as of 4 PM EST...the occluded front has passed east and north of
the region. However...two shortwaves...one currently located
across the central New York state/PA border...and another over the southern
Great Lakes...will continue translating eastward overnight. The
first one will allow showers to persist through this
evening...especially across higher elevations of the eastern
Catskills...Taconics...and Berkshires. Some light rain showers
or drizzle will occasionally reach the valley areas as well
through early tonight. Cloud tops are relatively shallow...with
cloud top temperatures generally in the -5 to -8 c range or slightly
warmer. So...at least for now...there appears to be minimal ice
crystals in the clouds...with just perhaps some snow grains across
the higher elevations over the next 3 hours.
Later this evening...the first impulse will pass east of the
region...with the next one poised upstream. The combination of
enhanced low level moisture from the nearby lakes...and additional
middle level moisture rotating southeast to south from north of the
Great Lakes should allow for some seeder feeder processes...in
addition to overall cooling middle level temperatures...to allow for a
transition to mainly snow showers across higher terrain...with
rain showers or drizzle gradually mixing with...and possibly
changing to snow or snow grains in some valley areas after
midnight. Again...overall cloud top temperatures may not be quite cold
enough for dendritic snow crystals...so snow consistency may be
somewhat grainy in nature...and not conducive for significant
accums. At this time...it appears that 1-3 inches will be possible
across higher elevations across the southwest Adirondacks...as
well as across higher...west facing elevations across southern Vermont.
Some locally higher amts could occur for elevations above 1800 feet.
Also...portions of the Berkshires could get 1-2 inches late
tonight...with perhaps slightly higher amts for elevations above
1800 feet in eastern Berkshire Colorado.
It appears that low level directional wind shear will prevent true
single banded lake effect snow to occur...but still expect a
combination of synoptic...and orographic effects to produce the
overnight snow in higher elevations.
Winds will increase from the west to northwest overnight...with
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
Short term /6 am Thursday 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
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 /21z Wednesday through Monday/...
an upper level disturbance will continue to plague the sites
through the evening peak...with very slow improving trend to MVFR
kgfl/kpsf/kalb expected. This will be due to slightly drier air
advecting in the from the west...and a breeze also picking up from
the west 5-10kts through this evening.
Ceilings at kpou look to reach into the VFR threshold tonight but will
likely remain MVFR or even low MVFR (extra fuel required) at kpsf.
By Thursday...the wind will 10-15kts with gusts 20-25 kts (highest
at kpsf and kalb). The wind should help scour clouds out a
little...but still expect ceilings...reaching barely into the VFR range
(except holding at high MVFR at kpsf) after about 13z Thursday.
Showers could impact the tafs mainly early this afternoon...so we
assigned a vcsh at all the tafs except kpou where the threat was
lowest. Showers could help reduce visibilities very briefly down to
LIFR at kalb/kpsf/ and kgfl.
Thursday night: no operational impact. No sig weather.
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.
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
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