Albany, NY WFO Forecast Discussion

Forecast Discussion for ALY NWS Office
000
FXUS61 KALY 141054
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
554 AM EST Wed Nov 14 2018

.SYNOPSIS...
Unseasonably cold and blustery today with lake effect snow
showers diminishing in the afternoon. Tonight will be the
coldest night of the year for most areas under high pressure. An
approaching low pressure system will bring a wintry mix to the
area Thursday evening into early Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 425 am, moderate to heavy lake effect band was located
just south of the Thruway west of Albany, extending into
northern Berkshire County. This band is moving south and has the
potential to dump a quick half inch to an inch locally. SPS was
issued highlighting locally slippery conditions possible. CAMs
suggest this band will continue to progress southeast toward the
eastern Catskills and Mid Hudson Valley as we head toward 12Z,
with activity decreasing behind it. Some more snow showers are
possible again 15-18Z mainly for the western Mohawk/Schoharie
Valleys before quickly ending by 21Z as upper level height
rises occur and high pressure builds in. Outside of the lake
effect, partly to mostly sunny skies are expected today, but it
will be frigid with high temperatures not far off from average
lows for this time of year. 850 mb temps will be a very frigid
-12 to -16C, or 3 SD below normal per the NAEFS. It will be
 blustery as well as 925 mb winds of 25-30 kt should be in the
 middle of the mixing layer and represent frequent gusts. This
 will produce wind chills as low as the single digits for the
 southern Adirondacks/Greens and teens and low 20s elsewhere.

Tonight, high pressure crests over the region, presenting an
ideal radiational cooling opportunity as it appears cloud cover
from the approaching system won`t be fast enough to influence
temps. MOS guidance continues to advertise very cold temps with
record lows at Albany, Poughkeepsie, and Glens Falls. Meanwhile,
2m temps are considerably warmer. The magnitude of the cold may
be a bit overdone in areas without snow cover, so went with a
blend of the MOS guidance and Superblend, which still yields
lows near record territory. Below-zero temps appear likely in
the southern Adirondacks where there is snow cover.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
Upper low now spinning near the Arklatex will drift eastward and
possibly become an open wave Thursday into Friday as it moves up
the Ohio Valley and into southern New England. A pair of surface
lows are forecast to develop on either side of the southern
Appalachians, with the western low weakening and the eastern low
strengthening as it moves toward the NYC area by 12Z Friday.
Isentropic lift will strengthen Thursday afternoon into Thursday
night as warmer, moister air overruns the cold airmass in place
in the Northeast. Ascent will be enhanced by the equatorward
entrance region of a strong upper jet. As the upper low
approaches and the surface low strengthens, the lower level
temperature gradient will contract, supporting an area of
frontogenesis between roughly 09-18Z Friday. So widespread
wintry precipitation is likely from Thursday afternoon into
Friday morning, but the details are still a bit murky.

The precipitation is expected to start out as snow everywhere
with wetbulb temperatures below freezing throughout the column.
This should support a quick burst of accumulating snow spreading
from south to north over the entire forecast area between
around 18Z Thursday and 03Z Friday. This could result in some
issues for the Thursday evening commute, especially from the
Capital District south. After that, a warm nose aloft is
forecast to approach from the south and east, which should allow
precipitation to mix with sleet and freezing rain from south to
north through about 12Z. At this point, is appears likely that
the southern Adirondacks will remain mostly if not all snow from
this event as the warm nose does not reach the area. The
transition zone may feature p-type changes based on precip
intensity. There are also indications that a dry slot works in
from 03-12Z Friday, which would result in decreasing precip
intensity and perhaps a change to freezing drizzle as soundings
suggest ice nuclei are lost. This is depicted in the 00Z
NAM/GFS, while the latest ECMWF appears colder and would support
more in the way of snowfall. Between roughly 12 and 18Z, the a
good frontogenesis signature works its way from west to east
across the area, which may allow some areas to change back to
snow with precip intensity increasing. There is not great
agreement on this scenario, though. Boundary layer temps
increasing after 12Z south and east of Albany may allow for a
period of plain rain, although a return to wintry precip is
possible if rates are high enough in the potential Fgen band(s).

At this time, not enough confidence to go with any winter
headlines, as there is still high model spread with respect to
QPF and p-type. Current forecast message is for the potential
for 3-7" of snow/sleet and up to 0.10" ice, Thursday evening
into Friday morning except over the southern Adirondacks where
it will be more like 6-9" snow. Regardless of particular
accumulations, there is a high probability that the Friday
morning commute will be impacted just about everywhere in the
forecast area.

Temperatures should creep above freezing most areas below 1500
feet elevation after the precip ends Friday late morning into
the afternoon. Lake enhanced/upslope snow should continue after
18Z for the southern Adirondacks and perhaps the southern
Greens.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
The region will remain under a longwave trough through the
period as short waves rotate about the upper low over Hudson`s
Bay Canada as it drifts southward. There are difference amongst
the guidance regarding the timing and amplitude of the individuals
short waves which impacts the timing of their associated systems/
fronts across the region.

Overall looking at chances for mainly snow showers to the north
and west of the Capital District due to lake enhancement and cyclonic
flow Friday night through Saturday night. High pressure at the
surface is expected to quickly slide across the region Sunday however
another short wave/system will be on the approach. As this system
approaches and moves through will have a chances for mainly snow
showers across the area Sunday night and Monday. In wake of the
system, expecting more showers due to lake enhancement and
cyclonic flow for Monday night.

Below normal temperatures are expected with departures of by 5
to 10 degrees. An even colder airmass is expected to be ushered
Monday night and Tuesday with departures of 15 to 20 degrees
possible.


&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
A band of snow effect snow continue to drift southward across
the area. As of 545 am it extends from the Schoharie Valley
eastward across the Berkshires. MVFR with brief IFR conditions
are occurring within this band. The lake effect activity will
diminish today especially this afternoon as high pressure builds
in. Otherwise, VFR conditions are expected.

Brisk and gusty west-northwest winds through much of the day
with gusts approaching 30 knots. Winds are expected to quickly
diminish in the evening as the high takes control becoming light
and variable to calm overnight.

Outlook...

Thursday: No Operational Impact. NO SIG WX.
Thursday Night: High Operational Impact. Definite SN...SLEET...FZDZ.
Friday: High Operational Impact. Definite RA...SN...SLEET.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: Moderate Operational Impact. Chance of SHSN.
Monday: Moderate Operational Impact. Chance of SHRA...SHSN.

&&

.FIRE WEATHER...
Unseasonably cold weather through tonight with lake effect snow
diminishing. A system will bring widespread wintry
precipitation to the region Thursday afternoon into Friday.

&&

.HYDROLOGY...
Mainly dry weather is expected through tonight aside from some
lingering lake effect snow. A low pressure system will bring
widespread wintry precipitation to the region Thursday afternoon
into Friday. The precipitation may become rain or freezing rain
especially from the Capital District south Thursday night into
Friday morning. QPF ranges from around 0.60 to 1.30 inches, with
the heaviest amounts over the Mid Hudson Valley, Litchfield
County, and the Berkshires where rivers are already running
high. Flooding on the main stem rivers is not expected, but some
urban and poor drainage flooding cannot be ruled out due to the
saturated ground.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...Thompson
NEAR TERM...Thompson
SHORT TERM...Thompson
LONG TERM...IAA
AVIATION...IAA
FIRE WEATHER...Thompson
HYDROLOGY...Thompson

NWS ALY Office Area Forecast Discussion