National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KALY 052245
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
545 PM EST Thu Dec 5 2019

.SYNOPSIS...
Snow showers early this evening will diminish tonight. Then, an
Alberta Clipper will bring a widespread light snow event during
the daytime tomorrow with some impacts to the evening commute
expected. High pressure returns for the weekend leading to dry
and cooler conditions.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 4PM, bands of light snow showers and flurries are moving
across the eastern Catskills, Schoharie County, the southern
Berkshires and Litchfield County, CT. Some flakes are also being
observed in the Hudson Valley but they are not accumulating.
Temperatures are generally in the upper 20s in the eastern
Catskills and Schoharie County and with additional snow showers
upstream in Central NY, we added some minor snow accumulations
to these higher terrain areas through 00z Friday. Otherwise,
snow showers should diminish in coverage tonight as subsidence
builds aloft.

Partial clearing tonight combined with a deep snow pack should
help temperatures cool down into the upper teens to low 20s.
Clouds increase in coverage from west to east after 06z tonight
ahead of our approaching Alberta Clipper.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
A potent shortwave progresses towards Lake Erie and Lake
Ontario by 12z Friday with warm air advection increasing over
New York as the surface low`s warm front advances into the
region. Isentropic lift intensifies quickly over eastern NY
after 12z which should allow snow to overspread the region from
west to east by mid-late morning Friday. An area of enhanced
850-700mb FGEN looks to develop midday into the early afternoon
hours along and north of I-90 and the latest HREF guidance shows
increased probabilities for greater than one inch per hour
snowfall rates for the Mohawk/Schoharie Valley into the Upper
Hudson Valley and southern VT and the northern Berkshires.
BUFKIT sounding from GFL also shows good lift through the
dendritic snow growth zone during this period suggesting the
potential for moderate to heavy snowfall rates. The BUFKIT
sounding from ALB shows the the dendritic snow growth zone
higher up in the atmosphere and may be higher than the layer
with the best lift. Areas south of I-90 should see snow at the
onset of the event Friday morning but snow should mix with rain
towards midday/early PM as the warm nose impinges up the Hudson
Valley and into NW CT. Some areas could even turn dry.

While initial snow ratios for areas along and north of I-90 should
be high (15-17:1) leading to a lighter/fluffy snow at the start
of the event, snow rates could decrease (11-13:1) heading into
the afternoon as warm air increases aloft. Surface temperatures
during the event should struggle to warm given the fact that
snow begins in the morning and wet-bulbing diabatic cooling
processes should limit the diurnal spread. Generally expecting
highs along and north of I-90 to only reach into the upper 20s
to near 32. However, areas south of I-90 which get into the
warm sector should rise into the mid-30s.

The best warm air advection exits western New England by mid-
afternoon which should end the chances for moderate/heavy
snowfall rates. The cold front associated with our Alberta
Clipper quickly pushes through the region towards sunset with
snow ending from west to east early evening. Winds could also
turn breezy with gusts 15-20mph in the wake of the front.
Impacts to the evening commute are possible from this event
especially in areas where roads and/or sidewalks are untreated.

Total snowfall amounts expected to range 1 to 3 inches with up
to 4-5 inches possible in southern Vermont, northern Berkshires
and northern Taconics. We have issued a Winter Weather Advisory
for these areas. Heading south of I-90, we could see a tight
gradient set-up south of Capital District as snow totals
decrease quickly where the warm nose impinges into the ALY CWA.
Generally expecting snow amounts south of I-90 to range from
coatings up to an inch. Higher amounts of 1 to 2 inches in the
eastern Catskills and southern Berkshire County.

After some scattered lake enhanced snow shower activity Friday
evening, expecting gradual clearing and drying Friday night as
high pressure builds into the Northeast. Dry and cooler weather
returns Saturday and Saturday night. High temperatures Saturday
in the upper 20s to low 30s with overnight lows turning much
colder. Clear skies and a deep snow pack should facilitate
radiational cooling with lows falling into the single digits and
teens.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Mild temperatures and rain early next week.

We are expecting to end the weekend with fair weather and continued
below normal temperatures as ridging dominates at the surface and aloft.
Aloft the ridge is expected to crest over the region Sunday while at the
surface the high is expected to shift off the coast. A southerly flow
about the departing high will begin a moderation of our temperatures.
After a very cold night temperatures are expected to rebound
into the 30s with only 20s limited to mainly above 1500 feet.

Guidance continues to develop a low pressure system over the Southern
Plains from southern stream energy then and tracks it northeastward
across the Great Lakes region and Saint Lawrence Valley through
early next week with interaction with northern stream energy.
There are timing and strengthen differs however there is consistency
our region will be in the warm side of the system. At this
time, looking at temperatures warming above freezing on Monday
and remaining above freezing into Tuesday night until colder air
is ushered back in with the passage of the system`s cold front.

Based on the current forecast expecting precipitation to overspread the
region Monday morning with some now initially as it should be cold enough
then rain through Tuesday. 12Z GEFS guidance indicates 850 mb temperatures
of +1-2 SD, 850 mb winds +2-3 SD and PWATS +2-3 SD in the warm sector just
ahead the system`s cold front. Forecasting highs in the 40s Monday with
30s limited to across portions of the southern Adirondacks, lows in the
upper 30s to lower 40s Monday night and highs Tuesday lower 40s to
lower 50s. Expecting ripening of the deep snowpack due to the mild
temperatures and rainfall with at least some runoff and rises on
area waterways. However it is too early to determine if there will
be a flooding threat during this period.

Seasonable temperatures will be ushered back into the region Tuesday
night and Wednesday in the wake of the cold front, however a secondary
front is expected to cross the region ushering in even colder
air in. Highs Wednesday in the 20s and lower 30s with lows mainly
between 10 and 20 degrees with single digits above 1500 feet and
highs Thursday only in 20s with teens above 1500 feet. In addition
to the cold, low level flow is expected to become favorable of
lake effect snows across the Tug Hill Plateau into portions of
the western Adirondacks.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Upper level trough will remain over the region into early this
evening. Scattered lake enhanced snow showers are expected from
around KALB to KPSF later this afternoon into early evening.
Occasional/brief deterioration to MVFR/IFR conditions will be
possible within any snow showers. Best chance for IFR will be at
KPSF. Snow showers expected to remain far enough away from KPOU/KGFL
to omit mention in TAFs.

Snow showers will end by around 00Z, with VFR conditions prevailing
overnight. Mid level clouds will increase late tonight ahead of a
clipper type system approaching from the Great Lakes. This system
will bring widespread mainly light snow to the KALB/KPSF/KGFL
terminals starting late Friday morning. Steadier snow should set up
north of KPOU, so will only mention VCSH there. Vsbys will quickly
lower to IFR levels once snow commenced between 15Z-16Z.

Surface winds will be west-northwest around 10-20 kt, with gusts
around 25-30 kt at KALB/KPSF. Winds will become west-southwest
overnight, gradually decreasing to around 3-5 kt late. Winds will
become southerly around 4-6 kt Friday morning.


Outlook...

Friday Night: Low Operational Impact. Slight Chance of SHSN.
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 RA.
Monday: High Operational Impact. Likely RA.
Monday Night: High Operational Impact. Likely RA.
Tuesday: High Operational Impact. Likely RA.

&&

.HYDROLOGY...
Temperatures will remain below normal through Sunday, so little
melting and/or runoff is expected through the next several days. A
period of light snow is expected on Friday. This will allow the snow
pack to be maintained and for some ice to build on shallow
waterways, especially during the overnight hours.

Temperatures will likely rise to above normal values by Monday into
Tuesday, with periods of rain likely. This will likely lead to at
least some ripening and melting of the snowpack and runoff, although
it is too early to determine if there will be a flooding threat
during this period. Rises on area waterways are likely during this
timeframe.

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.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Winter Weather Advisory from 10 AM to 10 PM EST Friday for
     NYZ054.
MA...Winter Weather Advisory from 10 AM to 10 PM EST Friday for
     MAZ001.
VT...Winter Weather Advisory from 10 AM to 10 PM EST Friday for
     VTZ013.

&&

$$
SYNOPSIS...Speciale
NEAR TERM...Speciale
SHORT TERM...Speciale
LONG TERM...IAA
AVIATION...JPV
HYDROLOGY...Thompson