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afdaly

Area forecast discussion
National Weather Service Albany New York
426 PM EST Mon Nov 11 2019

Synopsis...
a low pressure system will bring heavy snow to the southern
Adirondacks through tonight. Elsewhere, a spotty light wintry
mix will turn to snow late tonight into Tuesday morning, with
light accumulations that could impact the morning commute. It
will turn sharply colder and blustery Tuesday into midweek with
potential record cold temperatures.

&&

Near term /until 6 am Tuesday morning/...
..a Winter Weather Advisory has been issued for the
helderbergs, eastern Mohawk Valley, greater capital region and
the northern Taconics from midnight to 10 am Tuesday....

Winter Storm Warning for the southern Adirondacks of
Hamilton...northern Herkimer and northern Warren counties is in
effect until noon Tuesday.

Winter Weather Advisory is in effect until noon Tuesday for
southern Herkimer, Fulton, Washington, Montgomery, Schoharie,
northern Saratoga, southern Warren counties in eastern New York
and Bennington and western Windham counties in southern Vermont.

As of 425 PM EST...a cold front has become stationary near the
I-84 corridor late this afternoon, as relatively shallow cold
air has oozed down the Hudson River valley to between Hudson
and Poughkeepsie. To the east, the cold air reached about the
Mass Pike. A really strong thermal gradient has set up over the
forecast area with mid 20s over the Adirondacks, and 50s over
the southern Taconics and CT. Do not do a double take, the
calendar does read November 11th!

This strong baroclinic zone is just the beginning of changeable
weather with record breaking cold on the way. The frontal
boundary is acting like a warm front with over running moisture
riding over the top with snow and possibly some sleet breaking
out over the west-central Mohawk Valley/southern Adirondacks and
the upper Hudson Valley, and The Glens Falls/Lake George region.
South of these regions, there is little or no pcpn occurring. A
sfc wave is approaching from the Ohio Valley and western PA. This
sfc cyclone is riding the eastern flank of a positively tilted
h500 longwave trough over the eastern Continental U.S..

The isentropic lift continues to increase over the northwest
portion of the forecast area in the evening hours on the 290k
sfcs. The sfc wave will move over southern New York and likely passes
just south and east of the capital region and Berkshires
according to the 12z NAM/CMC/GFS/ECMWF. The warm air at h850
surges up the Hudson Valley tonight which enhances the warm nose
for a possible transition for sleet and freezing rain between
midnight and 3 am north of the capital region, and between 3 am
and 6 am south. We placed our highest confidence in the NAM
thermal profiles. The 3-km NAM shows more of a threat for sleet
and freezing rain for Albany and the capital region for a brief
period than the 3-km hrrr. The icy mix will likely be brief and
this is not a traditional set-up for a light mix with the warm
air surging north, and then the cold air gushing south towards
sunrise. The commute could be challenging tomorrow morning due
to a trace to a few hundredths of "flat ice" we have expanded
the advisory to the capital district, helderbergs of Albany co.,
And the northern Taconics.

Meanwhile, further north and west the snow/sleet should pile up
with some locations in the southern and western Adirondacks
getting close to a foot. We are expected 2 to 6 inches for
portions of the Lake George region and the western Mohawk
Valley with a glaze of ice.

Max temps will likely be in the early morning hours before the
surge of cold advection comes in between 3 am and 6 am. Lows
will be in the 20s to lower to mid 30s, but temps will be
falling especially north and west of the I-90 corridor.

&&

Short term /6 am Tuesday morning through Wednesday night/...
tomorrow...old man winter makes a guest appearance in the middle
of astronomical fall. An intrusion of Arctic airs occurs across
the region with all the mix pcpn quickly transitioning to snow
between 6-9 am. The 850-700 hpa fgen intensifies tucked in the
northwest quadrant and deformatio zone of the sfc cyclone
moving across eastern New England. A quick 1-3 inches of snow
could occur over the northern and central Taconics including the
Rensselaer plateau. In the immediate Hudson River valley and
the capital region around a half an inch to maybe 2 inches. The
Berkshires and southern greens could get a quickly 1-3". The
ice threat looks less over the Berkshires, but we will monitor
if an upgrade is needed later to an advisory. The 12z hrefs
shows the pcpn ending quickly before noon. The west to northwest
winds will kick up rapidly at 10-20 mph with some gusts 25-35
mph. It will be very cold with temps steady and then falling
into the teens and 20s. All the untreated surfaces will become
slick with the strong cold advection. H850 temps fall to -13 to
-19c by the early evening.

Tuesday night...a quick transition to lake effect multi-bands
with northwest aloft will occur. Locations impacted will be the
eastern Catskills, western Mohawk Valley, and Schoharie valley.
Coating to an inch or so of snow is possible. Otherwise, it will
be cold and blustery. Temps will be close to record cold
levels. Please see the climate section below. The h850 temp
anomaly from this gyre of cold air is -2 to -4 stdevs below
normal according to the naefs and gefs. Wind chills could
approach advisory levels in the southern Adirondacks at 20
degrees below zero...something we deal with in
January...usually. Lows will be frigid in the single digits and
teens with below zero readings over the southern Adirondacks and
southern greens possible. Wind chills will be in the single
digits to 10 below zero in many areas.

Wed-Wed night...the winds gradually subside as high pressure
builds in with a very cold day. We could have record low maxes
with highs in the 20s with a few lower 30s near kpou, and
teens over the mountains. Some clouds increase Wed night, and it
will be cold again, but it will be less windy. A short-wave
trough will be approaching from southeast Canada and the Great
Lakes region. Lows will still be in the single digits and teens,
but again less windy.

&&

Long term /Thursday through Monday/...
the period starts out on Thursday with dry and cold conditions in
place, although with high pressure moving eastward off the New
England coast, a developing southerly flow will allow for some
moderation. Still, we will be looking at high temperatures
around 10 degrees below normal for mid November ranging from
upper 20s to upper 30s across the region. A weak short wave
trough aloft will be moving through Thursday afternoon into
Thursday evening, however moisture will be very limited so will
only mention slight chance of snow showers for the northwest
Adirondacks and dry conditions persisting across most of the
area.

Temperatures expected to moderate further on Friday, as a west-
southwest flow develops ahead of an Arctic cold front
approaching from southeast Canada and the Great Lakes regions.
So we are forecasting only slightly below normal temperatures.
However, this cold front should move through Friday evening and
will usher in another anomalously cold air mass (-1 to -2 stdev
at 850 mb) Friday night through the upcoming weekend. Again we
are not expecting much precip with this front due to limited
moisture, although isolated to scattered rain/snow showers may
accompany the cold front passage for areas north and west of the
capital district.

Behind the cold front, high pressure will move eastward across
northern New England during the weekend. This will provide US
with below normal temperatures with dry conditions. The next
chance of precipitation looks to be Sunday night into Monday, as
some model guidance showing a potential storm system off the
southeast/mid Atlantic coast bringing some moisture northward
into our region during this time. Model differences in
timing/track of this system resulting in a low confidence
forecast, especially given any potential impacts would be 7 days
out. Temperatures do look to moderate due to upper level ridging
along the East Coast, but a east-NE surface flow could result in
low-level cold air remaining in place for the chance of some
frozen precipitation in some spots.

&&

Aviation /21z Monday through Saturday/...
tricky aviation forecast for this taf period as we assess impacts
from a low pressure system tracking just south of the terminals
and a strong cold front for late tonight/Tuesday morning.
Steady precipitation with this system will mainly be north of
the terminals until the cold front arrives. The edge of the
steadier precipitation will be near kgfl, resulting in periods
of light wintry precipitation. Some sleet and freezing rain may
mix in especially from 11/22z to 12/04z. Moisture wraps in
behind the cold front, causing a period of snow (with perhaps a
wintry mix at the onset) from around 08-15z.

At the other terminals, nothing more than a brief, spotty light shower
is expected until that frontal passage in the 08-10z timeframe.
The precip type of any light shower through 08z could produce a
snow/sleet mix at kalb/kpsf. Once the front moves through, a
period of steady snow (perhaps starting as a brief wintry mix)is
expected at kalb/kpsf through around 15z. At kpou, the temps
near the surface may be warm enough for a rain/snow mix.
Accumulations look to be rather light across the terminals,
generally looking at around an inch or less of snow/sleet, with
perhaps up to 3 inches at kgfl.

Ceiling heights are expected to mainly be in the VFR/MVFR category at
the start of the period, with some IFR becoming possible late
tonight, especially after the front passes. Vsby in the wake of
the front late tonight into Tuesday morning is also expected to
reach IFR in snow. Ceilings will rise late in the taf period
when the snow tapers off, with clouds mixing out as strong cold
advection occurs in the wake of the front.

Winds will generally be northerly at around 5-10kt through much of
tonight, becoming westerly in the wake of the frontal passage
at 10 to 15 kt with some gusts to 20 kt late tonight into
Tuesday morning.

Outlook...

Tuesday night: low operational impact. Breezy no sig weather.
Wednesday to saturday: no operational impact. No sig weather.

&&

Fire weather...
a low pressure system will bring heavy snow to the southern
Adirondacks through tonight. Elsewhere, a spotty light wintry
mix will turn to snow late tonight into Tuesday morning, with
light accumulations that could impact the morning commute. It
will turn sharply colder and blustery Tuesday into midweek with
potential record cold temperatures.

&&

Hydrology...
no widespread problems are expected on the main Stem rivers the
next several days.

No widespread problems are expected on the main Stem rivers the next
several days. A low pressure system will bring heavy
accumulating snow to the western Adirondacks through tonight.
Elsewhere, a light wintry mix will turn to light snow late
tonight into Tuesday morning. An unseasonably cold airmass will
arrive in the wake of this system, with temperatures remaining
below freezing throughout the region Tuesday into Thursday
morning. No hydrologically significant precipitation is expected
through the remainder of the week. This will allow some ice to
form on area waterways.

For details on specific area rivers and lakes, including latest
observed and forecast river stages and lake elevations, please
visit the advanced hydrologic prediction service /ahps/ graphs
on our website.

&&

Climate...
forecast temperatures may approach records on November 13 and
14. Here are the record low temperatures at eastern New York
climate sites...

Min 11/13 Max 11/13 min 11/14

Albany, New York 13 (1981) 31 (1911) 12 (1996)

Glens Falls, New York 13 (2001) 32 (1916) 5 (1905)

Poughkeepsie, New York 16 (2013) 35 (1986) 13 (1986)

&&

Aly watches/warnings/advisories...
CT...none.
New York...Winter Weather Advisory from midnight tonight to 10 am EST
Tuesday for nyz048>054.
Winter Weather Advisory until noon EST Tuesday for nyz038>041-
043-047-082>084.
Winter Storm Warning until noon EST Tuesday for nyz032-033-042.
Massachusetts...none.
Vermont...Winter Weather Advisory until noon EST Tuesday for vtz013-014.

&&

$$
Synopsis...Thompson/wasula
near term...wasula
short term...wasula

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