Area Forecast Discussion
Issued by NWS Albany, NY

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109
FXUS61 KALY 162044
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
344 PM EST Tue Jan 16 2018

.SYNOPSIS...
A developing coastal low pressure system will emerge off the
Delmarva this evening and track northeast to near Cape Cod
Wednesday morning. This system is expected to bring a moderate
to heavy snowfall to much of the region tonight into Wednesday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 330 PM EST...A sharp positively tilted trough over the
central part of the CONUS will continue to dig southward as it
progresses eastward this evening and into tonight. Ahead of this
feature, a weak surface wave of low pressure is moving across
the eastern Great Lakes towards the area. Persistent s-sw flow
ahead of these features have been allowing for a period of warm
air advection, which has brought some patchy light snowfall
through the day. This snowfall has been very light and has been
most persistent across upslope areas of the higher terrain, with
most of the area seeing a light accumulation of a coating to an
inch or two.

During this evening, snowfall will start to become more widespread
and steadier in coverage/intensity, as a weak wave of low pressure
develops off the mid-Atlantic coastline.  As this wave slowly lifts
northeast, an inverted coastal trough will allow the snowfall to
pick up in intensity for later tonight, especially for areas
south/east of Albany.  The heaviest snowfall looks to be for after
midnight, especially for southern/eastern parts of the region.

With the approaching upper level trough and a strong jet-streak
nearby, Northeast CSTAR research would suggest the potential
for a quasi-stationary mesoscale band of snowfall on the
northwestern side of this developing low pressure area.
Mesoscale models, including the 3km HRRR and NAM do suggest some
heavier snowfall amounts extending from the Poconos northeast
across the Catskills, mid Hudson Valley and into NW
CT/Berkshires.

Considering this, will upgrade eastern Ulster/Dutchess counties into
the existing Winter Storm Warning (which is in effect for the
Taconics/western New England) with expected totals around 6-10
inches in this area. Elsewhere, additional snowfall will
generally be 3 to 6 inches, with some locally higher amounts.

The morning commute will probably be fairly difficult across much of
the area on Wednesday morning due to the snow covered roadways and
low visibility. As the low pressure lifts up towards eastern New
England, snowfall will start to taper off from west to east during
the day on Wednesday. Snowfall should be done in the Capital Region
and mid-Hudson Valley by the mid to late morning and should be
ending in western New England by the late morning or early afternoon
hours. Winds will switch to the northwest behind the storm, but
shouldn`t be too strong since the surface low is fairly weak, so
blowing/drifting doesn`t look like a concern with this event.  Temps
on Wednesday will generally be in the 20s, with a few spots in the
mid-Hudson Valley and NW CT reaching the low 30s. Clouds should be
breaking for some sun on Wednesday afternoon from west to east as
well.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
A ridge of high pressure will build in Wednesday night
providing mainly dry conditions. However, due to well aligned
westerly flow and borderline conditional lake induced
instability, there will be some lake effect snow showers across
the western Adirondacks. Any accumulations should be light, with
shallow inversion heights of only around 850 mb are expected.
Temperatures will be near normal, with lows in the single digits
and teens.

Similar conditions should prevail on Thursday, with a flat
ridge in place and a westerly flow continuing. Again, some light
lake effect snow showers may affect the western Adirondacks,
but dry conditions should prevail elsewhere. Snow showers may be
a bit more enhanced with greater coverage Thursday night across
the western/southern Adirondacks, as a fast-moving short wave
trough is expected to move through. Still, only minor
accumulations are forecast with mainly dry conditions elsewhere.
Temperatures will remain near normal during this time. Highs on
Thursday will be in the upper teens to lower 30s with lows
Thursday night in the mid teens to lower 20s.

On Friday, any lingering lake effect should end during the
morning with dry conditions expected Friday afternoon. Highs on
Friday will be in the mid 20s to mid 30s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
This period will mark a turn toward much above normal
temperatures...with highs mainly in the 30s and 40s each day, and
lows stating out mostly around 20 degrees Friday night, with mostly
upper 20s and lower 30s by Sunday and Monday nights.  With mid-
January being Albany`s coldest time of the year, on average, lows
there are normally in the mid teens, with highs around 30 degrees.

High pressure centered over the deep south will build up into the
mid-Atlantic region.  An east-west frontal boundary will stay just
north of our zones as low pressure over the center of the contiguous
U.S. develops and tracks across the Great Lakes and into southern
Quebec through Monday night, displacing the high pressure and
bringing a good chance of rain showers throughout the area as early
as Sunday night, which could start as snow.  By midday Monday, all
areas outside of the high peaks of the Adirondacks will likely
experience pure rain shower activity ahead of a cold front which
will move quickly east across our zones Monday night.  It will be
overcast with low instability.  Only a modest decline in
temperatures will be experienced behind the front...to as low as
near normal.

&&

.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
As a weak storm approaches from the Great Lakes, light snow has
been intermittent across the region so far today, which has
allowed for variable flying conditions. Periods of light
snowfall have dropped visibility to 2 to 5 miles at times,
otherwise, it has been P6SM. Ceilings generally have been 3000
to 5000 ft for most sites, although lower ceilings have been
occurring at KPSF due to the interaction of the southwest flow
with the higher terrain. Winds will be calm or very light from a
southerly direction through the remainder of the day. Will
continue to allow TEMPOs through this afternoon for IFR
conditions, but it will probably be VFR/MVFR for much of the
time.

By this evening, snowfall will become steadier and more
widespread, allowing for IFR conditions to become predominate
after 22z-00z, as a coastal storm starts to take shape. All
sites will see snowfall through the overnight hours, with the
heaviest snowfall after midnight through about sunrise, allowing
for visibility as low as 3/4SM (especially at KPOU/KPSF). Winds
will continue to be fairly light and variable overnight,
eventually become westerly towards sunrise.

Snowfall will be tapering off by the mid-morning hours, allowing
for visibility to improve. However, some lingering clouds could
still allow for MVFR cigs through the late morning hours. Winds
will switch to the northwest and increase to around 5-10 kts.

Outlook...

Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: No Operational Impact. NO SIG WX.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.

&&

.HYDROLOGY...
Ongoing flooding due to ice jams will continue to be addressed
with areal flood warnings. There could still be some lingering
issues as any existing ice jams may tend to become frozen in
place due to the continued cold temperatures expected over the
next few days. Warmer weather is not expected until the weekend.

In terms of precipitation, a moderate snowfall is expected for
much of the area from today into Wednesday, with heavy snowfall
from the mid Hudson Valley and Taconics eastward across western
New England.

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 3 PM EST Wednesday for CTZ001-013.
NY...Winter Weather Advisory until 3 PM EST Wednesday for NYZ032-
     033-038>043-047>053-058>060-063-082>084.
     Winter Storm Warning until 3 PM EST Wednesday for NYZ054-061-
     064>066.
MA...Winter Storm Warning until 3 PM EST Wednesday for MAZ001-025.
VT...Winter Storm Warning until 3 PM EST Wednesday for VTZ013>015.

&&

$$
SYNOPSIS...11/JPV
NEAR TERM...Frugis
SHORT TERM...11/JPV
LONG TERM...ELH
AVIATION...Frugis
HYDROLOGY...11/JPV



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