Area Forecast Discussion
Issued by NWS Albany, NY

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000
FXUS61 KALY 250259
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
959 PM EST Sat Feb 24 2018

.SYNOPSIS...
Precipitation will overspread the area late tonight and continue
most of Sunday as a low pressure system approaches and moves
across the region. A wintry mix including snow, sleet and
freezing rain is expected in many areas before transitioning to
plain rain Sunday morning. High pressure will build in for
early next week returning fair weather to the area along with
above normal temperatures.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Winter weather advisory goes into effect at 1 am for all but the
Hudson Valley from the Poughkeepsie area up into the Capital
District.

As of 959 PM EST...High pressure is anchored just north of the
region over Quebec, allowing for a northerly flow of cold and
dry air into the region. Any lingering showers with a decaying
cold front have dissipated over the mid-Hudson Valley. Despite a
veil of mid and high level clouds, temps have been cooling
thanks to the northerly flow, with temps mainly ranging from the
upper 20s to mid 30s across the area (although a few spots in
the mid-Hudson Valley that recently have showers are in the
upper 30s).

With an approaching warm front, strong warm air advection will
occur after midnight, result in overrunning precipitation
quickly overspreading the area from south to north. Surface
temperatures will continue to cool a few more degrees due to
wet-bulbing, but then should hold steady or start to slowly rise
towards late tonight.

It will initially be cold enough for snow in many areas however
with warmer air moving in aloft the chances for sleet and
freezing rain will increase toward sunrise. Based off the 00z
NAM soundings, that warm nose is fairly high and with a deep
sub-freezing cold layer beneath there, there could be several
hour period of just sleet for northern areas.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
The low pressure system will occlude as it approaches so the
local area will not get into the mild airmass. However, it will
become warm enough aloft and at the surface for a transition to
plain rain across the entire forecast area. It will take longest
for this to occur across the southern Adirondacks, Lake George
Saratoga region, the Berkshire and southern Vermont but its
expected by noontime. Generally less than a 1/2 inch of snow/sleet
accumulations are expected with 1-2 inches across the Lake
George Saratoga region and portions of southern Vermont. Up to a
couple tenths of ice accretion are possible where the freezing
rain lasts the longest across portions of the southern Adirondacks,
Lake George Saratoga region, the Berkshire and southern Vermont.
Otherwise it will be wet, cold and dreary with temperatures
only rising into the mid 30s to about 40 degrees.

Easterly flow ahead of the system will become brisk and gusty
early Sunday with gusts up into the 30s at times especially in
areas where the flow is enhanced by the terrain. This could lead
to some power outages in areas where there is an accretion of
ice on the trees.

In the wake of the system, high pressure builds in returning
fair weather to the area. Clouds will decrease and temperatures
will drop into the mid 20s to lower 30s Sunday night. Ridging
will begin to build in aloft on Monday and with sunshine
temperatures are forecast to warm into mainly the the 40s with
30s across the western Adirondacks and lower 50s in the mid
Hudson Valley. With light winds and clear skies expecting lows
mainly in the 20s Monday night.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
The period will begin with above normal temperatures and dry/mostly
clear conditions on Tuesday and Wednesday with high pressure
overhead. The end of the week is shaping up to be wet as a deep low
pressure system approaches from the west.

Tuesday and Wednesday...Strong high pressure centered over the Mid
Atlantic states and stretching northward will provide warm Southwest
flow and dry conditions for the entire region. Some isolated light
rain showers could sneak into the Adirondacks late on Wednesday.
Highs will be in the upper 30s/low 40s North of the Capital Region
and mid 40s/mid 50s over the mid-Hudson Valley. Lows will be in the
upper 20s to mid 30s.

Thursday and Friday...Multiple pieces of shortwave energy will
approach from the Southwest late Thursday through Friday.
Deterministic and ensemble guidance suggests a deep surface low
approaching from the Southwest with redevelopment over New
Jersey/Long Island early Friday. There is a wide range of
precipitation totals suggested by ensemble forecast plumes, while
the latest deterministic runs of the ECMWF/GFS suggest higher
amounts in the 1-3 inch (total liquid) range. Precipitation types
are still in question with the best chance for snow located in the
higher elevations, with the valleys possibly starting as rain and
transitioning to snow. The key player with this system is the
blocking upper level high south of Greenland, which if it
retrogrades, could allow for a closed mid/upper tropospheric low to
develop, and could allow any surface low to remain slow moving.
Although, too strong of a block could shunt the storm farther south
and east of the region and limit any impacts.

&&

.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Aside from a few light rain showers near KPOU over the next hour
or so, dry weather is expected this evening into the first part
of the overnight with bkn-ovc mid/high level clouds in place.
Aside from some MVFR at KPOU through 01z, it looks VFR through
at least midnight for all sites, with a light northerly flow in
place.

Late tonight, strong warm advection will lead to precip moving
into the region from the south. KPOU will see rain as early as
06Z, KPSF could see a wintry mix by 08z, and a mix of
sleet/rain arriving at KALB by 09z. KGFL may start as snow or
sleet by 10z. After a brief hour or two of MVFR conditions,
conditions should go over to IFR/LIFR for all sites, with low
visibility and low ceilings around 800-1000 feet and these
conditions look to continue through all of Sunday morning.
Any mixed precip should quickly change to all rain at KALB by
13z, although KGFL/KPSF will continue to see FZRA/PL through 15z
or 16z. Winds will eventually switch to the E-SE for all sites
during the morning and may become gusty during the morning at
KPSF. Precip in the form of light rain showers will start to
taper off during the afternoon on Sunday, but flying conditions
will only improve to MVFR at ceilings remain low. Winds will
eventually switch to the northwest behind the storm by late in
the day Sunday, but should only be 5-10 kts.

Outlook...

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

&&

.HYDROLOGY...
Ice jams remain in place in multiple locations on the Mohawk
River from about Lock 9 through the Twin Bridges and on the
upper Hudson River in the Town of Thurman in central Warren
County. Looking at the USGS Lock 8 web cam ice has moved out of
this area. Also the USGS Stockade web cam showed water moving
through a channel along the shore.

Widespread precipitation will overspread the area late tonight
and continue most of Sunday as a low pressure system approaches
and moves across the region. A wintry mix of precipitation
including snow, sleet and freezing rain is expected in many
areas before transitioning to plain rain by mid Sunday. At this
time QPF amounts of around 3/4 of an inch to an inch. Temperatures
dropping back into the upper 20s to mid 30s tonight will limit
snowmelt. Runoff would result in some river rises and could
cause movement of ice jams. If confidence for flooding increases
then a flood watch and/or hydrologic advisory will need to be
issued.

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...Winter Weather Advisory from 1 AM to 1 PM EST Sunday for
     CTZ001-013.
NY...Winter Weather Advisory from 1 AM to 1 PM EST Sunday for
     NYZ032-033-038>043-047-048-051-054-058-061-063-066-
     082>084.
MA...Winter Weather Advisory from 1 AM to 1 PM EST Sunday for
     MAZ001-025.
VT...Winter Weather Advisory from 1 AM to 1 PM EST Sunday for
     VTZ013>015.

&&

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


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