Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 202131
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
431 PM EST Sat Jan 20 2018

.SYNOPSIS...
Above normal temperatures will continue this weekend
into early next week. A low pressure system may bring some light
mixed precipitation to the area late Sunday night into Monday
morning with mainly rain then expected into Tuesday. However, the
threat for mixed precipitation will linger across portions of the
western and southern Adirondacks and southern Vermont through Monday
night. A colder, seasonable airmass will be ushered back into the
region behind the storm.

&&

.NEAR TERM /THROUGH SUNDAY/...
As of 300 PM EST...A mainly dry forecast is expected during the
near term period as a cold front will become stationary along
the U.S. Canadian border tonight and Sunday. Temperatures will
average above normal with lows tonight in the mid 20s to lower
30s and highs on Sunday in the mid 30s to mid 40s. There will be
some stratus clouds around tonight into at least Sunday morning
with the greatest cloud cover across northern areas.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
Quasi-stationary boundary either along or north of I90 will
persist Sunday night as low pressure upstream takes shape.
Meanwhile, Canadian high near James Bay is expected to build
further and extend its influence across New England overnight
into Monday. As the aforementioned low pressure takes shape
across the Plains States, downstream increasing moist transport
along with isentropic lift commences overnight into Monday
morning. This will at at the minimum increase and thicken/lower
the clouds and introduce the chance for light wintry mixture to
evolve. The challenge will be the temperature profile along with
low level ageostrophic flow from the north. Profiles suggest a
period of light snow, sleet and freezing rain developing from
southwest to northeast into Monday morning. QPF values appear to
be rather light so perhaps an advisory would be needed with
future updates.

Increasing low level jet and warm advection should continue
through the daylight hours Monday as a gradual transition to
mainly rain/drizzle should occur. Temperatures should moderate
well into the 30s for most locations with near 40F for portions
of the mid-Hudson Valley and Litchfield County.

The main rainfall event is expected along and ahead of the cold
front Monday night into Tuesday morning as a nearly vertically
stacked low tracks across the Great Lakes and begins to fill.
Rather impressive low level jet, with +3 standard deviations
above normal southerly component magnitudes along with PWATs
around 2 standard deviations above normal. So a period of
moderate rain is expected and could be briefly heavy if
convective elements were to develop. Showalter values on the
global models remain toward the positive side with mesoscale
models near to slightly below zero. For now, we will leave the
mention of thunder out of the forecast but continue to watch
trends.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Following the potent disturbance from Tuesday, we should enter in a
fairly quiet pattern to finish out the work week. We start off the
period on Wednesday which will feature a reinforcing shot of cold
air advection as a secondary cold front moves through the region
early in the day. While 850mb isotherms fall to -15-17C due to the
cold air advection, this will manifest into seasonable high
temperatures in the low to mid 30s. A decent pressure gradient
behind the departing low should lead to rather breezy winds as well
which should make it feel even cooler. Other than cooler
temperatures, strong westerly winds could also lead to lake effect
snow. Given the set-up, the highest probability of snow was put in
the Adirondacks and western Mohawk Valley with chance POPs and
decreased POPs down to slight chance down into the Greater Capital
District and southern Vermont. By sunset on Wednesday the subsidence
inversion should start to descend and westerly winds should shift
northwest due to the incoming high. Thus, decreased POPs heading
into Wednesday night. Moisture trapped under the inversion overnight
should keeping at least partly cloudy skies in place. This combined
with still somewhat breezy winds should prevent low temperatures
from becoming too cold, only falling into the teens.

By Thursday, the Canadian high pressure takes control of the region
and we should see mostly sunny skies with cooler high temperatures,
only reaching into the mid - upper 20s. Mostly clear skies overnight
under this chilly air mass and low dew points near zero should lead
to colder low temperatures falling into the single digits and low
teens (below zero readings in the Adirondacks possible).

High pressure shifts into eastern New England on Friday and a
moisture starved warm front crosses the area late in the day. Behind
the front, strong southwesterly flow sets up with warm air advection
leading to increased cloud coverage for Saturday and much milder air
reaching into the 40s. The warm air advection may also lead some
scattered showers in the Adirondacks of Herkimer and Hamilton.
Depending on exact timing, cold air at the surface may be stubborn
to exit and with the incoming mild air aloft, we could see wintry
mix. The newest forecast update reflects this threat.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
VFR conditions expected to continue today with dry air in the
low levels. A low pressure system will track well north of the
area today with just some areas of mid and high clouds ahead of
it. In the wake of this system, cold air advection is expected
to result in the expansion of stratus tonight. Expect cloud
bases to be at borderline VFR/MVFR levels, except at KPOU where
the stratus isn`t expected to reach.

Surface winds will be gusty this afternoon as the wind
direction veers from southwesterly and then westerly behind a
cold front this afternoon. Gusts of around 20 kts are possible
this afternoon, possibly closer to 30 kts at KALB/KPSF.
Gustiness will diminish this evening with west-northwest winds
around 5 to 10 kt tonight into Sunday morning.

Outlook...

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

&&

.HYDROLOGY...
Ongoing flooding due to ice jams will continue to be addressed
with areal flood warnings, as some lingering issues continue due
to existing ice jams which have become frozen in place.

Temperatures will run about 10 degrees above normal this
weekend into early next week. However, temperatures are forecast
to fall below freezing at night which will slow or stop any
melt. Monday night temperatures are not expected to drop below
freezing across most of the local area but are expected to be in
the 30s. Tuesday will be the warmest day in this forecast period with
highs in the upper 30s to upper 40s with a colder seasonable
airmass returning Tuesday night.

A storm develops and tracks across the Great Lakes through the
early week, initially the precipitation will be light Monday
and start out as a mix with a change to rain across much of the
area during the daylight hours. Monday night rain is expected
except across the western and southern Adirondacks and southern
Vermont where more mixed precipitation is expected before a
changeover to rain occurs on Tuesday. The bulk of the rain is
expected late Monday night and Tuesday morning. QPF from the
various models are now averaging over 1 inch.

The rain is expected to cause renewed river rises, which may
move and dislodge ice and possibly cause some flooding near ice
jams.

Our latest Winter/Spring Flood Potential Outlook (ESFALY) was
issued Friday evening.

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

&&

$$
SYNOPSIS...11
NEAR TERM...11
SHORT TERM...BGM
LONG TERM...Thompson/Speciale
AVIATION...11/Thompson
HYDROLOGY...IAA/BGM

www.weather.gov/albany



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