Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
639 PM EST Monday Dec 9 2013
an area of low pressure will move off the middle Atlantic coast Tuesday
and will pass well south of Long Island. Snow associated with this
low will spread far enough northward to impact areas to the south
and east of the capital district...mainly from middle morning into the
early afternoon. In addition...conditions will become favorable for
lake effect snows to impact portions of the Adirondacks Tuesday
night through Wednesday night. Also...it will turn colder across the
Near term /through Tuesday/...
as of 639 PM EST...our region remains in broad SW flow...with an
upper level trough axis centered over the Great Plains...and
strong ridging off the southeastern US coast. Although precipitation has
generally ended across our area...lingering low level moisture is
still allowing for plenty of clouds. With a developing westerly
breeze overnight...some of these lower clouds will break up...but
with enough middle level moisture still in place...skies will still
remain mostly cloudy.
Our region will see decent cold advection overnight...with 850 hpa
temperatures dropping to -14 over the Adirondacks by late tonight. This
will allow some lake effect snow showers to develop...and with the
expected west-SW flow...it will impact the far northwestern
Adirondacks...mainly to the north of Old Forge...with some light
snow shower activity. Elsewhere...it will be dry overnight...with
temperatures mainly in the 20s.
A wave of low pressure will track along a stalled frontal boundary
moving off the middle Atlantic coast Tuesday as northern stream energy
interacts with southern stream energy. The models and ensemble
guidance show little spread and pass the surface low about 230 miles
south of Montauk Point early Tuesday afternoon. The models are also
in agreement showing middle level frontogenetic forcing occurring just
to the south of our forecast area across the New York metropolitan
area and Long Island along with upper level divergence in the
right entrance region of a strong 180+ knot jet. Expecting a
light accumulation of snow...1 to 3 inches...to the south and east
of the capital district with the snow occurring mainly from middle
morning into the early afternoon. Maximum temperatures will range from the
low 20s over the Adirondacks to the low 30s in the Hudson Valley.
Short term /Tuesday night through Thursday/...
a lake effect snow watch has been issued for northern Herkimer and
Hamilton counties for Tuesday evening through late Wednesday night.
Conditions will become favorable for lake effect snows. An intense
lake effect snow band will develop east of Lake Ontario Tuesday
night. Based on local research on inland extent of lake effect...the
band should extend well inland since will have a multiple lake
connection and the Lake Ontario waters are still relatively. Based
on glerl the surface water temperature is 48 degrees fahrenheit
and 850 mb temperatures are forecast to drop to around -15 degrees
celsius. So lake effect snows will pick up in intensity Tuesday
night into Wednesday morning as the colder air continues to advect
into the region across the lakes.
The region will remain under the longwave trough with energy moving
through it. The longwave pattern will amplify allowing cold air
to surge in and it will get cold. This will also change the low
level flow resulting in a southward shift the lake effect snow as
we head into Thursday thus the ending time of the watch. Lows Wednesday
night are anticipated to drop to -5 to 15 degrees. Wind chill
values will approach advisory criteria...-20 degrees...across the
western advisory so continue mention in our hazardous weather outlook.
Long term /Thursday night through Monday/...
the extended period looks to begin with Arctic high pressure
situated well to the south of our forecast area. This will keep most
of the region dry but cold. However...the door is still open for
some additional lake effect snow...mainly across our Adirondacks and
Mohawk Valley...with a few bands possibly even working into the
capital region and into western New England through early Friday. By
this time...the subsidence inversion should be lowering and
therefore the snowbands will likely not be as robust as earlier in
the week. Lake effect snow will likely wind down by Friday night.
The high pressure moves offshore Friday. Before any real moderation
can ensue...another weak low pressure is forecast by the models to
track up the eastern Seaboard. The track is still up for grabs. The
GFS tracks the low the furthest inland near the I-95 corridor and
is the warmest solution. The Canadian forecast model tracks the low
further south and east and implied that most of our region would get
light if any snow. The 12z European model appeared to be a
compromise with the track and thermal profile...just to the south of
the Interstate 95...with enough warm air in the upper levels for a
wintry mix south.
We took a mean of all three models including ptypes...calling it a
chance of sleet and snow south and mostly snow from Albany
northward. This possible snow or wintry mix would be for Saturday
into Saturday night...ending on Sunday.
Behind the storm...more cold air will be ushered in as low pressure
winds up to east of the Canadian Maritimes...and another brisk
northwesterly flow ensues. There could be another round of lake
effect by early next week.
Temperatures through the period will average below normal.
Highs generally in the teens and middle 20s north...lower 20s to middle
30s south. Lows will range from around zero to the single numbers
north...single numbers to teens south.
Aviation /00z Tuesday through Saturday/...
lingering low level moisture is still allowing for IFR ceilings at
kgfl/kpou/kpsf. With a developing westerly wind at 5-10 kts...these
low clouds should break up over the next few hours...allowing for
VFR conditions to returns to the valley taf sites...with high end
MVFR ceilings at kpsf.
A storm passing to the south may brush kpou and perhaps kpsf with
some light snow late Tuesday morning into early Tuesday afternoon. This
could allow for a brief period of IFR visibilities/ceilings at kpou...and
perhaps MVFR visibility/ceilings at kpsf. Otherwise...it remain VFR and dry
for kalb/kgfl...with broken-overcast ceilings at 3500-4500 feet through the day
on Tuesday. Winds will continue to be out of the west around 10 kts.
Tuesday night: no operational impact. No sig weather.
Wednesday-Thu: moderate operational impact. Breezy. Chance of shsn.
Fri: no operational impact. No sig weather.
Friday night: low operational impact. Slight chance of shsn.
Sat: moderate operational impact. Chance of snow.
no Hydro related concerns are expected this week. The precipitation
that occurs will be in the form of 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.
New York...Lake effect snow watch from Tuesday evening through late
Wednesday night for nyz032-033.