Albany Office Forecast Discussion

000
FXUS61 KALY 180013
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
713 PM EST Thu Jan 17 2019

.SYNOPSIS...
Clouds will increase this evening with light snow arriving
after midnight, producing minor accumulations by daybreak. Snow
will taper off quickly Friday morning, allowing for milder
temperatures by afternoon. After a brief break, a storm system
will impact the region Saturday afternoon through Sunday, which
will produce heavy snow accumulation for much of the region,
along with a wintry mix for southern areas. Cold and windy
conditions will follow this storm for Sunday night into the
start of next week.

&&

.NEAR TERM /THROUGH FRIDAY/...
Forecast is on track only some minor adjustments were made.
Clouds will thickening and lower this evening as a weak
disturbance approaches. It`s a subtle upper level disturbance
which will be pass within the mainly zonal flow aloft. Its
associated weak surface low over the Ohio Valley will move
towards the eastern Great Lakes tonight, while another low
develops near the mid-Atlantic coast by Friday morning. Some
warm advection looks to be occurring overnight, which will allow
precip to develop.

Surface dewpoints are very dry across the region. It will take
a little while for the column to moisten up, but some light
snowfall looks likely after midnight tonight, moving from south
to north across the area. With the limited moisture and rather
weak forcing in place, snowfall amounts will be fairly minor,
although snow ratios should be fairly decent considering the
cold air mass in place and rather low dendritic growth zone.

For most of the region, about a coating to an inch of snow
looks to accumulate by daybreak Friday. A few spots within the
Mohawk Valley or foothills of the southern Adirondacks may
locally see around 2 or 3 inches or so, as there has been a
persistent signal in hi- res guidance (including the latest 3km
HRRR/NAM) of a little enhancement in that area. Widespread snow
looks to be tapering off in the morning Friday, as the best
forcing shifts away. However, there may be a little additional
upslope/lake enhanced snowfall across the higher terrain (esp
the western Adirondacks) with an additional coating to half inch
for those areas through the day.

Clouds may finally break for some sun by afternoon, especially
for valley areas. Temps look to be fairly steady in the teens
and 20s this evening into tonight, but will rise into the mid
20s to mid 30s for Friday afternoon.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
     Major Winter Storm Expected Saturday into Sunday. Winter
Storm Watch remains in effect for the whole area...

Models, including deterministic and ensemble guidance, are in
fairly good agreement regarding the track and evolution of a
high impact winter storm for Saturday into Sunday.

Dry and cold weather is expected Friday night into Saturday
morning. However, active weather will be quickly heading our
way. A strong southern stream storm ejecting out of the Rockies
Friday night will head across the Plains and towards the Ohio
Valley on Saturday. This storm will have plenty of moisture
associated with it, with a connection right into the Gulf of
Mexico. Meanwhile, a secondary low will develop across the mid-
Atlantic on Saturday evening and lift northeast towards the New
England coast for Sunday. At the same time, northern stream
energy will be diving into the Northeast for Sat night into
Sunday, allowing the secondary low to rapidly develop. In
addition, there will be an impressive jet streak of nearly 185
kts over southern Quebec as well. Strong frontogenesis is
expected to develop across our area on Saturday night into
Sunday morning, which will be allowing for precip to be locally
heavy at times.

The initial warm advection well ahead of the storm will allow
for a band of light snow to start spreading into our area from
the west during the mid to late afternoon on Saturday. This
first light batch of snow may be mainly located across the
northern half of the area. By evening, steady, widespread
snowfall looks to move across the entire region and rapidly pick
up in intensity. Snowfall rates look to reach around an inch
per hour, with locally higher rates within some mesoscale
banding expected to be developing and lifting northward through
the region during the overnight hours.

By late in the overnight (after 07z-08z), a warm nose aloft
between 700-850 hpa will be moving towards the area. Although
most of the region should remain below freezing, warming within
this layer will reach up to +3 C across the eastern Catskills,
Mid Hudson Valley, southern Taconics, southern Berkshires and NW
CT. This will allow for a changeover to sleet for late night
hours. There is still some uncertainty in just how far north
this sleet will get, but model guidance is now pretty much in
agreement that areas from Albany on north and west will remain
all snow. Some freezing rain may also occur across NW CT towards
daybreak Sunday, although it won`t change to plain rain, as the
strong northerly flow at low-levels will keep cold air locked
in place from about the surface through 925 hpa.

On Sunday morning, any mixed precip will change back to all
snow, as the developing coastal low allows colder air to rush
back into the region aloft. Additional heavy snowfall is
expected on Sunday morning, as strong deformation banding sets
up, especially for the Mohawk Valley/Capital Region and into the
Saratoga Region and southern VT. Snowfall rates of 1 to 3 inches
per hour is expected at times on Sunday morning as well.

Steady precip will start to taper off on Sunday afternoon,
although additional spotty light snowfall is still expected as
the large upper level low will be diving towards the area. With
the developing coastal low, northwest winds will start to pick
up Sunday afternoon, with gusts up to 30 mph allowing for
blowing and drifting of snowfall.

Total snowfall amounts will vary from around 8 inches in
southern areas where mixing will occur to nearly 20 inches in
Saratoga-Glens Falls area into southern VT. The Capital Region
should see around 12 to 18 inches of snowfall. This could be the
largest snow storm in Albany since the 14-15 March 2017
Blizzard when 17 inches fell. If sleet does get a little further
north than currently forecast, snow totals may be a little lower
in the Capital Region, but our 10th percentile totals are still
around 10 inches or so.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Bitterly cold with life-threatening winds chills expected in
wake of the winter storm...

Arctic air will plunge into the region Sunday night and have a grip
on the area into Tuesday morning. GEFS indicates 850 mb temperatures
1 to 2 standard deviation below normal Sunday night/Monday. Guidance
has 850 mb temperatures down to -20 to -24 degrees Celsius by
12Z/Monday. Blustery winds will accompany the arctic air creating
life-threatening wind chills Sunday night into Monday. Dangerous
wind chills readings are then expected into Tuesday morning. Wind
chill warnings or advisories may be needed.

Lows Sunday night and Monday night are forecast to be from around 20
degrees below zero to around zero degrees. Highs Monday are forecast
from around 5 degrees below zero to about 10 degrees. Temperatures
are expected to moderate as ridging shifts off to our east with
highs in the mid teens to mid 20s Tuesday. On Wednesday highs mainly
30s with southwest ahead of an approaching cold front.

The blustery winds Sunday night and Monday will cause blowing and
drifting of the snow. Snow showers are expected to linger across the
area Sunday night as the deepening storm moves away from the region.
Lake effect snows are also expected to develop in the northwest flow
in the wake of the system mainly across central New York with
chances into the Mohawk Valley, Schoharie and the eastern Catskills.
The lake effect will dissipate during the day Monday as ridging
builds in disrupting the favorable low level flow.

Fair weather is expected Monday night and Tuesday as ridging quickly
shifts across the region. A low pressure system is expected to move
across the region Wednesday bringing widespread chances for snow
to the area Tuesday night into Wednesday night.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Clouds will thickening and lower this evening as a weak
disturbance approaches. It`s a subtle upper level disturbance
which will be pass within the mainly zonal flow aloft. Its
associated weak surface low over the Ohio Valley will move
towards the eastern Great Lakes tonight, while another low
develops near the mid-Atlantic coast by Friday morning. We are
expecting some light warm advection snows to develop between
04-07Z across the area with IFR conditions quickly developing
due to visibilities. Light snow expected to taper off around
12Z/Friday with MVFR then persisting due to ceilings with an
improvement to VFR late in the TAF period. The only exception to
this is at KPSF were MVFR may persist longer.

A light southeast to south flow expected 6 knots or less with a
shift to the west late in the TAF period, remaining light.

Outlook...

Friday Night: No Operational Impact. NO SIG WX.
Saturday: Moderate Operational Impact. Likely SN.
Saturday Night: High Operational Impact. Definite SN.
Sunday: High Operational Impact. Breezy. Definite SN.
Sunday Night: Moderate Operational Impact. Breezy. Chance of SHSN.
Martin Luther King Jr Day: Low Operational Impact. Breezy.
Slight Chance of SHSN.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.

&&

.HYDROLOGY...
No hydrologically significant precipitation is expected until
the weekend. Temperatures will remain mainly below freezing,
favoring continued ice formation/expansion on area waterways.

A powerful winter storm is set to impact the region over the
weekend. The precipitation type is expected to be mainly snow,
with a wintry mix possible across the Catskills, mid Hudson
Valley, Taconics, Berkshires and NW CT. QPF over an inch is
expected, possibly up to two inches in some areas.

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 Watch from Saturday afternoon through Sunday
     evening for CTZ001-013.
NY...Winter Storm Watch from Saturday afternoon through Sunday
     evening for NYZ032-033-038>043-047>054-058>061-063>066-
     082>084.
MA...Winter Storm Watch from Saturday afternoon through Sunday
     evening for MAZ001-025.
VT...Winter Storm Watch from Saturday afternoon through Sunday
     evening for VTZ013>015.

&&

$$
SYNOPSIS...Frugis
NEAR TERM...IAA/Frugis
SHORT TERM...Frugis
LONG TERM...IAA
AVIATION...IAA
HYDROLOGY...Frugis/Thompson

NWS ALY Office Area Forecast Discussion