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310
FXUS61 KALY 070352
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
1052 PM EST Fri Dec 6 2019

.SYNOPSIS...
High pressure will build in overnight then will move eastward
across the region this weekend resulting in fair but cold
weather. Our next weather system moves into the Northeast early
in the work week bringing in milder temperatures and a
widespread rainfall.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Clipper system moves eastward out to sea overnight as high
pressure quickly builds in from the west. Please refer to our
Public Information Statement for total snowfall reports from
Friday`s snowfall. Thanks to those we have sent in reports. Much
appreciated and helps the forecast process.

Winds will become light overnight as surface high pressure
takes control. Any lingering upslope snow showers across the
higher terrain to the east of the Hudson River Valley are
expected to taper off. The northwesterly low level flow is
focusing the lake effect across central New York with low
chances for snow showers in the western Mohawk Valley and
Schoharie Valley.

With some clearing, cold air advection and the snow pack in
place expecting temperatures to bottom out in the teens and
lower 20s with single digits across the southern Adirondacks.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
Any lake effect effect snow should diminish by Saturday morning
as the subsidence inversion lowers. High pressure builds into
the Northeast on Saturday with breezy northwest flow continuing
to advect in a chilly air mass. Generally expecting mostly to
partly cloudy skies with clearing downstream of the higher
terrain possible due to downsloping. High temperatures should be
below normal due to breezy northwest winds and the chilly air
mass moving into the area. Expect high temperatures to reach
into the mid to upper 20s with near freezing the mid-Hudson
Valley.

Skies clear Saturday night as high pressure moves overhead and
radiational cooling allows temperatures to decrease quickly.
The deep snow pack and calming winds should lead to cold low
temperatures reaching into the single digits to low teens by
Sunday morning.

High pressure heads east into New England on Sunday with warm
air advection ensuing. Clouds should gradually increase through
the day with high temperatures warming into the low to mid 30s.
The stronger temperature and moisture advection holds off until
overnight as broad southwest flow intensifies ahead of our next
disturbance brewing the Mississippi Valley. Tempertures should
actually warm Sunday night but depending on the timing of the
thicker cloud coverage, initial overrunning precipitation may
fall as a wintry mix including potential for sleet. We
gradually increase POPs after 06z with chance POPs overspreading
the region from southwest to northeast towards 12z Sunday.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
In the long term, we are looking for a period of above normal
temperatures with rainfall Monday and Tuesday, followed by sharply
colder air and mainly dry conditions (aside from lake effect snow in
the usual snow belt) Wednesday into Friday.

For Monday into Tuesday, a deep trough will dig into the upper
Midwest and western Great Lakes, with a warm sector and increasing
low level jet forcing spreading into the Northeast corridor. The 850
mb V component increases to around 30 kt, which is +1 to +3 standard
deviations per the NAEFS (highest south and east of Albany). As a
result, precipitable water values look to increase to 0.75-1.00
inches Monday into Monday night, which are +2 to +3 standard
deviations, per the NAEFS. The poleward exit region of a strong
upper jet looks to become favorably placed over our region to
enhance lift Monday into Monday night, as well. These factors
support a high likelihood of precipitation Monday into Monday night.
There is a little bit more uncertainty for Tuesday, with the
GFS/GEFS being a little more progressive with the trough/cold front
compared with the ECMWF, which depicts a slower passage and wetter
solution for Tuesday. As a result, the QPF projections between the
two camps are different, with the GFS/GEFS Mean showing generally
0.50-1.50 inches, with the ECMWF more in the 1-3" range (highest
south/east of Albany). The combination of warm temperatures
generally in the 40s to lower 50s, dewpoints in the 40s, and
rainfall will lead to ripening of the snow pack and some melting and
runoff, although how much is still questionable.

Tuesday night into Wednesday night, sharp cold advection will occur
with 850 mb temps possibly falling to -15 to -20C. 12Z ECMWF run
shows the cold air cutting in while deeper moisture is still in
place Tuesday night, which could lead to some accumulating snow
before the precip ends. This is the first recent run to depict this
scenario, so we will continue to monitor this potential. Otherwise,
a drying trend will occur, aside from areas downwind of Lake
Ontario, where lake effect snow will be possible. High pressure is
likely to build in for Thursday and Friday, keeping temperatures
cold but with dry weather expected.

&&

.AVIATION /04Z SATURDAY THROUGH WEDNESDAY/...
Clipper system moves off to our east as high pressure quickly
builds in from the west tonight. Widespread steady snow has
ended however lingering upslope snow showers are possible
through the evening across the higher terrain to the east of the
Hudson River Valley. Lingering MVFR at will improve to VFR
shortly after midnight. Overall cloud cover decreases however
will be back on the increase as short wave trough moves over the
region with VFR ceilings expected. Cloud cover will decrease
once again with the passage of the short wave.

Winds became northwesterly and with the pressure rises a brief
period of gusty winds is occurring is some areas. Winds will
become light overnight as surface high pressure quickly builds
in and takes control. Westerly flow expected Saturday at 10
knots of less.

Outlook...

Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: Moderate Operational Impact. Chance of RA...SN.
Monday: High Operational Impact. Definite SHRA.
Monday Night: High Operational Impact. Definite SHRA.
Tuesday: High Operational Impact. Likely SHRA.
Tuesday Night: Moderate Operational Impact. Chance of SHRA...SHSN.
Wednesday: Low Operational Impact. Slight Chance of SHSN.

&&

.HYDROLOGY...
Temperatures will remain below normal through Sunday, so little
melting and/or runoff is expected through the weekend. 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. There is uncertainty with the
amount and placement of QPF, with some models indicating potential
for 0.50-1.50 inches, and others 1-3 inches. Either way, at least
some ripening and melting of the snowpack and runoff is expected,
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.

It will turn sharply colder from Wednesday through the end of the
week, which should put a stop to any melting/runoff, and allow river
levels to recede.

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...None.
MA...None.
VT...None.

&&

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