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Area Forecast Discussion (AFD)

Issued by Albany, NY (ALY)

                            
000
FXUS61 KALY 162148
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
448 PM EST Fri Nov 16 2018

.SYNOPSIS...
Areas of snow showers are moving across the Adirondacks 
down into parts of the Capital District this afternoon with lake 
effect snow showers possible for the higher terrain into tomorrow. 
Otherwise, temperatures remain below normal through the weekend with 
another threat for widespread light snow possible Sunday afternoon 
into Monday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
GOES16 water vapor this afternoon shows an shortwave moving
eastward across Lake Erie and southern Canada. This is the 
responsible lifting mechanism for the area of organized snow 
showers downstream over the Adirondacks into the Mohawk Valley
and Upper Hudson Valley. The southern fringe of these snow 
showers are even skirting parts of the Capital District.
Generally radar reflectivities are low ranging 15-25dbz with
the airports showing light snow and flurries although a few NYS
mesonet cameras show brief steadier bursts under the isolated 
bands. With surface temperatures in these areas remaining in the
low 30s, some light accumulations are possible and updated the
latest forecast to include coatings to less than half an inch of
new snow for most areas with up to an inch in the Adirondacks. 
The latest HRRR shows these snow showers exiting southern VT 
and the Albany CWA by around about 00z tonight. 

Zonal westerly flow continues tonight so some upslope snow 
showers are possible in the typical prone areas of the 
Adirondack but the air mass moving over the lakes is not 
terribly cold so not expecting much assistance from lake 
moisture. Some clearing is possible in the wake of the exiting 
shortwave in the mid- Hudson Valley and NW CT and with snow pack
on the ground, temperatures tonight should fall into the upper 
20s. Further north, flow off the lakes should keep moisture 
trapped underneath the inversion giving those areas mostly 
cloudy skies. Thus. there should not be much of a diurnal 
temperature change and low temperatures should only fall a few 
degrees into the low 30s. 

Winds could be a bit breezy this evening into tonight, mainly in
areas above 1000ft, as high pressure noses into the Northeast
behind our exiting coastal storm leading to a tightening
pressure gradients. Westerly winds could gust up to 20 - 30 knots.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
High pressure continues pushing into the Northeast with a 
weakening cold front dropping down from Canada. Continued 
westerly flow off the lakes should keep most areas mostly cloudy
but high temperatures should finally reach the low 40s in 
valley locations with mid - upper 30s in the hill towns/higher 
terrain.

The front weakens and even washes out as it drops into Upstate 
NY towards 00z Sunday so we are not expecting much in the way of
precipitation. However, there should be reinforced shot of cold
air advection behind it and with 850mb isotherms near
-10C to -13C moving over Lake Ontario where water temperatures
 are near +9C, there should be a strong enough temperature 
 difference that lake effect snow showers become possible. The 
 latest guidance shows potential for a single lake effect band 
 to develop overnight. We have coordinated our POPs, QPF and 
 snow amounts well with BUF and BGM to represent the potential 
 snow accumulations in the typical lake effect prone regions 
 where 1 - 2 inches look possible. 

Cold air advection overnight should allow temperatures 
to fall into the 20s for most areas in the Albany CWA so any 
snow melt that occurs during the day could refreeze into ice on
any untreated areas.

By Sunday, high pressure should take control of the area and end
the lake effect threat. Upstream, a broad longwave trough over 
southern Canada should deepen allowing westerly winds over 
eastern NY/western New England to back to the southwest. This 
should lead to weak isentropic lift and warm air advection and 
with the washed out front from Saturday night stalled over New 
England down into NYC, we could see the leftover baroclinic zone
strengthen. At 500mb we see a weak shortwave within the broad 
trough head into the northeast which could allow a weak wave of 
low pressure to develop along this stalled boundary. The latest 
ECMWF and GFS are in agreement with a broad area of light 
precipitation developing and spreading northeastward into the 
mid-Hudson Valley and western New England Sunday afternoon into
Sunday night. With temperatures in the mid-upper 30s and dew 
points in the 20s, wet bulbing processes could allow 
temperatures to drop to near freezing leading to a broad area 
of light snow. While moisture is not terrible high with QPF 
amounts generally around a tenth to less than two tenths of an 
inch, this set up could lead to a period of light snow with 
snow accumulations possible, especially as we head into the 
night time hours. We will continue to monitor this next snow 
potential in future updates.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Much of the long term will be dominated by a reinforcing broad upper 
level trough across the Great Lakes/northeast U.S., favoring below 
normal temperatures and generally dry conditions outside of some 
possible Lake Effect snow showers and any snow showers 
associated with individual upper level impulses/cold fronts 
passing through.

One such upper level disturbance should be exiting southern New 
England Monday morning, with some rain/snow showers lingering across 
the mid Hudson Valley and NW CT. Another approaching disturbance and 
Lake moisture may bring snow showers to mainly the western 
Adirondacks later in the day. Otherwise, chilly with daytime highs 
in the mid 30s to lower 40s in valleys, and mid 20s to lower 30s 
across higher terrain.

The biggest uncertainty during the long term will be regarding a 
stronger disturbance which amplifies the upper level trough, with 
the 12Z/16 GFS favoring an earlier passage for Tuesday/Tuesday 
night, with an ensuing cold outbreak for Tuesday night-Wednesday, 
while the 12Z/16 ECMWF is about a day later, with the coldest air 
passing across the region Thanksgiving Day. Have sided with a blend 
at this time with the coldest temps Wednesday, with subfreezing 
highs regionwide, with teens/20s for higher terrain, and 20s/lower 
30s for valleys, and overnight lows mainly in the single digits and 
teens for Tuesday night/Wednesday morning, along with some wind. 
Slight rebound forecast for Thursday with highs mainly in the 20s 
and 30s, and overnight lows still in the teens for most areas. 
However, should the ECMWF prove correct, much colder max temps, 
mainly in the teens and 20s, would be possible Thursday.

Also, depending on the timing of the upper level shortwave and 
attendant cold frontal passage, snow showers will be possible, 
especially across the southern Adirondacks, with timing favoring 
mainly Tuesday night-Wednesday evening.

Slight moderation expected for Friday as heights gradually build, 
with highs mainly in the 30s to lower 40s, and overnight lows mainly 
in the 20s Friday morning.

&&

.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
Steady snowfall has ended across the region, as the storm system
tracks eastward from the Gulf of Maine. A few light snow showers
or flurries are still occurring near KALB, where an hour or so
of IFR conditions may occur. After around 19Z, mainly dry 
conditions expected at the terminals with MVFR cigs through the
afternoon into early evening. BKN-OVC cigs will persist, as a 
short wave trough moves across the area this evening. There 
could be a few flurries at KGFL/KALB so will mention VCSH. 

Improving conditions to VFR expected overnight, as the 
disturbance moves east of the region. Cigs will still be mainly
BKN, although lower level clouds should tend to scour out at 
KPOU by Saturday morning.

Outlook... 
Saturday: No Operational Impact. NO SIG WX. 
Sunday: Low Operational Impact. Slight Chance of SHSN. 
Sunday Night: Moderate Operational Impact. Chance of SHSN. 
Monday: Moderate Operational Impact. Chance of SHRA...SHSN. 
Monday Night: No Operational Impact. NO SIG WX. 
Tuesday: Low Operational Impact. NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.

&&

.FIRE WEATHER...
Areas of snow showers are moving across the Adirondacks 
down into parts of the Capital District this afternoon with lake 
effect snow showers possible for the higher terrain into tomorrow. 
Otherwise, temperatures remain below normal through the weekend with 
another threat for widespread light snow possible Sunday afternoon 
into Monday.

&&

.HYDROLOGY...
Mainly dry through early Sunday outside of lingering snow 
showers in the higher terrain. Another system has potential to 
bring some light snow to portions of the area Sunday afternoon 
into Sunday night.

&&

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

&&

$$
SYNOPSIS...Speciale
NEAR TERM...Speciale
SHORT TERM...Speciale
LONG TERM...KL
AVIATION...JPV
FIRE WEATHER...Speciale
HYDROLOGY...Speciale