Area Forecast Discussion
Issued by NWS Albany, NY

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000
FXUS61 KALY 121432
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
932 AM EST Tue Dec 12 2017

.SYNOPSIS...
Low pressure will bring a wintry mix of precipitation to
the area today, with moderate to heavy snow accumulation across the
northern part of the forecast area. As the storm intensifies this
evening, an arctic front will cross the area changing any mixed
precipitation back to all snow. Wednesday will be cold and blustery
with snow showers and biting wind chills, as lake effect snow
develops downwind of the Great Lakes.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 932 AM EST...South of the Mohawk Valley, there appears to
be a back edge to the heavier precipitation just west of the
Albany Forecast Area. Across the southern Adirondacks, Lake
George Saratoga area and southern Vermont, there is more of an
east-west oriented band of heavy snow. From Albany southward,
looking for a gradual end to the heavier snow from west to east
this morning. High res models indicate snow may linger into the
afternoon in the Berkshires. For the mid-Hudson Valley,
precipitation still expected to transition to some drizzle by
afternoon. temperature now above freezing at many Hudson Valley
locations south of Albany.

We are watching the arctic front passage this evening as models
show it will cross the region during the evening rush hour. it
is expected to bring a brief snow squall and a flash freeze
to the Capital District which could make for a rough evening
commute. Otherwise, forecast pretty much on track. Did add a
couple of inches to the snow forecast in the southern
Adirondacks and lake George saratoga areas based on snowfall
reports this morning. We have seen some 6+ inch reports there
already.

Prev Disc...While overall little changes to ongoing forecast,
bands of snow along the strong warm advection and isentropic
lift was well underway across the region. Rapid cooling of the
cloud tops per the IR satellite imagery and DPVA per the
approach of the strong wave seen in the H2O vapor loop. Hence
the bands of snow that will impact the morning commute as
confidence of warmer air will move into the the Capital Region
and point to the southeast as combination of dry slot and
boundary layer moderation is expected. Per the LAV/LAMP
guidance, seems Hudson Valley temperatures should moderate into
the mid and some upper 30s toward Noon as surface low deepens
across upstate NY. Favorable upslope conditions into the Dacks
and southern Greens warrant the continuation of the current
headlines and higher terrain of the Catskills into the Berks and
northwest hills of CT where advisories look good (although
limited potential for freezing rain per the BUFKIT profiles from
CAN). There will likely be a period of minimal precipitation
developing from west to east later this afternoon as surface low
tracks across upstate NY into New England.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Strong cold advection is expected this evening as upslope
blocked flow should result in additional snow showers into the
higher terrain tonight. Meanwhile, the surface cyclone tracks
into far northern Maine on Wednesday, it is forecast to deepen
considerably to a possible sub-975 mb low during the afternoon.
With a strengthening pressure gradient and favorable mixing
developing based on cold advection regime, it will become quite windy.
The W-NW flow direction and forecast soundings indicating
mixing heights close to 850 mb appear favorable for at least
advisory level wind gusts. Will continue the mention the
potential for strong winds in the HWO. Upslope snow showers will
continue into Wednesday, then will tend to decrease during the
afternoon as the center of the upper low tracks into northern
Maine. However, lake effect snow will develop downwind of Lake
Ontario as H850 temperatures fall close to -20C. Flow
trajectory forecast to be around 295-300 degrees, which would
favor the western Mohawk valley for at least some light to
perhaps moderate accumulations. It will be quite chilly as the
wind chill temperatures will drop back to the single digits
across most of the region with below zero values into the Dacks.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
We start the period with a upper disturbance quickly diving out
of Canada and swinging through the Mid-Atlantic region
Wednesday night. Surface winds will be brisk overnight, and
combined with fresh snowpack and a cold air mass, temperatures
will fall into the teens but near zero degrees in the
Adirondacks. Some lake effect snow may be possible downwind of
Lake Ontario as winds generally remain out of the west. The
upper disturbance should pass well south of New York early
Thursday morning with potentially a few showers making it into
the southern reaches of the forecast area.

High pressure briefly builds into the region Thursday night into
Friday with continued below normal temperatures, in the upper teens
to mid 20s for highs.

A progressive clipper-type low will progress through the region on
Friday into Saturday with the possibility of phasing with a coastal
low traversing up the Eastern Seaboard. This low may provide a quick
shot of snow over the entire region with very light accumulations.
Brief lake-effect snow may develop over the western Adirondacks
Saturday night into Sunday morning due to westerly low-level flow
taking advantage of the long fetch/moisture of Lake Ontario.

There is the potential for yet another low pressure system to
approach and move through area from the Great Lakes region Sunday
into Monday. There is potential for some light snow accumulations.
However, there is variability among the global model solutions at
this time so kept pops in the slight chance to chance category for
now.

High temperatures should return to normal over the weekend with
highs in the upper 20s to mid 30s. Lows will remain chilly, in the
upper single digits to near 20 degrees.&&

.AVIATION /09Z TUESDAY THROUGH SATURDAY/...
VFR conditions this morning will deteriorate to IFR as snow
continues to move into the region, continuing through the
morning hours. There are hints of the deep moisture exiting
during the afternoon, which would end the steadier snow and
possibly change to a mix of light rain sprinkles and/or drizzle
and/or flurries.

So, snow will begin at KGFL, KALB and KPSF between now and 09Z
this morning as conditions drop to IFR. At KPOU, it should
start as a mix around daybreak, around 11Z, with mainly MVFR
conditions. Once the mix begins at KALB, KGFL and KPSF around
15Z-17Z, conditions should be predominantly MVFR. The
intermittent mix should continue through most of the afternoon
as a cold front tracks through.

Light north to west winds tonight will become east to southeast
at less than 10 Kt by daybreak, continuing through the morning.
Winds become south at 10 Kt or less early in the afternoon,
then west by sunset Tuesday with the frontal passage. Stronger
winds are expected behind the front near the end of the TAF
period.

Outlook...

Tuesday Night: Moderate Operational Impact. Chance of SHSN.
Wednesday: Moderate Operational Impact. Windy Chance of SHSN.
Wednesday Night: Moderate Operational Impact. Breezy Chance of SHSN.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: Low Operational Impact. Slight Chance of SHSN.
Friday Night: Low Operational Impact. Slight Chance of SHSN.
Saturday: No Operational Impact. NO SIG WX.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
Periods of snow will continue through the morning hours across
all TAF sites, with the exception of KPOU where mostly rain is
expected. A dry slot will work its way into the region mid-
morning which should help taper the precipitation and warm
temperatures enough for the snow to become a rain/snow mix. This
may help improve conditions from IFR to MVFR for a period of
time. Conditions may once again drop to IFR this evening as
more snow associated with the cold front moves through the area.


South to southeast winds at 5 to 10 kts will continue through
the day before becoming northwesterly behind the cold frontal
passage. Winds will then become gusty at 20 to 30 mph towards
the end of the TAF period.

Outlook...

Wednesday Night: Low Operational Impact. Breezy 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:  Slight Chance of SN.
Saturday: Low Operational Impact. Slight Chance of SN.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: Low Operational Impact. Slight Chance of SN.

&&

.HYDROLOGY...
No hydrologic problems are expected during the next week.

Cold weather with periods of snow and snow showers are forecast
much of the time. Some rain will mix with snow from around the
Hudson Valley south and east, but any rainfall amounts will be
light and not have any impacts on river levels.

Ice will form and thicken on area lakes and rivers and some
river gauges may start to show erroneous readings due to ice by
the end of the week.

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 Weather Advisory until 1 PM EST this afternoon for
     CTZ001.
NY...Winter Weather Advisory until 7 PM EST this evening for NYZ038-
     039-041-058-063-082-084.
     Winter Storm Warning until 7 AM EST Wednesday for NYZ032-033-
     042-043-083.
MA...Winter Weather Advisory until 7 PM EST this evening for MAZ001-
     025.
VT...Winter Weather Advisory until 7 PM EST this evening for VTZ013-
     015.
     Winter Storm Warning until 7 AM EST Wednesday for VTZ014.

&&

$$
SYNOPSIS...SND
NEAR TERM...SND/BGM
SHORT TERM...BGM
LONG TERM...Cebulko/JVM
AVIATION...NAS/JVM
HYDROLOGY...BGM/JPV



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