Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 172340
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
640 PM EST Sun Dec 17 2017

.SYNOPSIS...
Above normal temperatures for Tuesday otherwise seasonable cold
this week. Some light snow is expected overnight into Monday
morning which may lead to some slippery travel for the morning
commute. The weather will be unsettled into Tuesday evening with
chances for showers especially across the higher terrain.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 640 PM EST...IR satellite imagery shows plenty of
thickening clouds across the region thanks to an approaching
warm front and associated weak shortwave and strong jet streak
aloft. Despite these clouds, its still rather cold this evening,
with many spots having already fallen into the teens to low 20s.

As the warm front approaches and shortwave slides by to the
south, some light snow is expected late in the overnight into
Monday morning. Guidance has been consistent the fact the QPF
should be very light however differs with the placement of it.
With recent cold weather the snow will stick to untreated
surfaces and result in some slippery conditions for the morning
commute.

Although there is lower confidence in the exact coverage of
snowfall, many locations should see some snow by late tonight.
Guidance does indicate there may be a loss of ice in the clouds
leading to the threat for freezing drizzle early Monday morning,
however it appears this should occur to our south so its not
mentioned in the forecast, as our precip will likely have ended
by that point. Based off hi-res and ensemble guidance, snowfall
amounts appear to be about a half inch for much of the area,
although the high terrain of southern VT/western Massachusetts
and the Adirondacks could see an inch or two.

Overnight lows are forecast to be mainly in the teens with lower
20s in the mid Hudson Valley into northwestern Connecticut and
readings of 5 to 10 degrees in portions of the western and
southern Adirondacks.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
The weather will be unsettled into mid week as short waves move
through the fast zonal flow on the periphery of the upper low
over Hudson`s Bay.

The approaching warm front is not expected to lift our north
until Monday night into Tuesday as short wave approaches. Any
light snow is expected to transition to showers with the better
chances being across the higher terrain. Temperatures will
moderate to seasonal levels with southwest flow and it will be
warm enough for some rain showers mainly below 1500 feet.

Temperatures won`t drop much Monday night as the warm front lift
northward and temperatures rise to above normal levels Tuesday
with highs in the mid 30s to mid 40s; about 10 degrees above
normal. As a result rain showers will be possible even across
the higher terrain during the day. Chances for showers will
linger into Tuesday night as a cold front moves through with a
transition back to snow as colder filters in. In the wake of the
cold front the flow will become favorable for lake effect and
upslope snows by late Tuesday night and for Wednesday morning.

QPF amounts are expected to light with only light accumulations
of snow when its cold enough.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Although the extended period will begin with cold temperatures, the
pattern will start to favor warmer temperatures across our area by
the weekend, with an increased threat of some southern stream
moisture into the region as well.

As an upper level trough departs, the flow aloft will be fairly
zonal for Wednesday night into Thursday. It will be dry, although
chilly, as high pressure over southern Canada slides by to the north
of the area. Lows on Wed night will be in the single digits and
teens with highs on Thursday in the mid 20s to mid 30s for most
areas (although some teens to low 20s are possible for the highest
elevations).  Sky cover will generally be partly to mostly clear.

The next system will be approaching our region from the Plains and
Midwest for the end of the week.  This system will be tracking well
west of the region across the Great Lakes, which will allow a south
to southwest flow to advect milder and more moist air into the
region aloft. Initially, some colder air will be trapped within the
valleys (especially the tight valleys of the Adirondacks and
southern VT). As a result, light precipitation may begin as early as
Thursday night or early Friday in the form of snow, but will start
to change over to sleet/freezing rain before going over to just
rain.  This changeover will occur quickly in southern and larger
valley areas, but may take until late Friday night to Saturday for
those northern areas. The steadiest precipitation looks to occur for
late Friday night into Saturday morning.   A light accumulation of
snow/ice is expected for northern and high terrain areas with little
to no snow/ice expected to accumulate in larger valley areas
(including the Capital Region). Temps will be in the 30s for Friday
and most areas will see temps holding steady or rising through the
night and reaching into the 40s ahead of the front on Saturday.

The storm`s cold front should cross for Saturday afternoon, with
colder air working back into the region for the rest of the weekend.
Any lingering precip may changeover to snow before ending, although
this will probably just be for the high terrain areas.  Lows on Sat
night will be in the teens and 20s with highs on Sunday in the 30s
with mainly dry conditions.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Flying conditions are currently VFR, although mid level clouds
continue to steadily lower and thicken ahead of an approaching
warm front.

Ceilings will gradually lower down to close to MVFR levels for
after midnight or so as a southerly flow aloft continues to
allow for the column to moisten and some stratus to move into
the area. In addition, a band of light snow will spread across
the region for the late night hours as well (after 06z-08z).
Although there still is a question about the exact coverage of
this snowfall, flying conditions will be at least MVFR for all
sites within this on and off snowfall, with brief periods of IFR
conditions possible as well through daybreak.

Snow should end from south to north by 12z-13z. Cannot totally
rule out a lingering sprinkle or flurry through the morning
hours, but this won`t have any impact on visibility.  However,
flying conditions look to generally be high-end MVFR for the
remainder of the day as ceilings remain around 2-3 kft for all
sites.

Winds will be calm tonight and be southerly during the day on
Monday around 5 kts.

Outlook...

Monday Night: Low Operational Impact. Slight Chance of SHRA...SHSN.
Tuesday: Low Operational Impact. Slight Chance of SHRA.
Tuesday Night: Moderate Operational Impact. Chance of SHRA...SHSN.
Wednesday: Moderate Operational Impact. Chance of SHSN.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: Low Operational Impact. Slight Chance of RA...SN.

&&

.HYDROLOGY...
No hydrologic problems are expected this week. Ice will
continue to form on areas lakes and streams.

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...IAA
NEAR TERM...IAA/Frugis
SHORT TERM...IAA
LONG TERM...Frugis
AVIATION...Frugis
HYDROLOGY...IAA


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