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fxus61 kaly 191443 
afdaly

Area forecast discussion
National Weather Service Albany New York
943 am EST Fri Jan 19 2018

Synopsis...
a warming trend is expected through Saturday with mainly
dry weather expected through the weekend. A low pressure system is
likely to bring periods of precipitation Monday and Tuesday, with
a variety of precipitation types possible.

&&

Near term /through tonight/...
as of 930 am, not much change to the forecast as clouds and
lingering light snow showers downwind of Lake Ontario continues.
Made modifications to the pop/wx per trends and matched
satellite images with forecast trends from the hrrr/hrrrx/rap13.



As of 645 am, upper level disturbance has shifted eastward,
with subsident northwest flow in its wake and warm advection at
850 mb. Areas of morning sunshine are expected to give way to
increasing clouds in the late morning to afternoon as moisture
remaining trapped beneath the inversion is mixed into low-level
stratus or stratocu. GOES-16 fog product already showing stratus
north of I-90 expanding southward. These clouds should continue
to be most prevalent along and north of I-90. Temps are
expected to be several degrees warmer compared with yesterday,
although this forecast kept temps below the warm mav MOS which
may be too optimistic with highs. Possibly a couple degrees
above normal values for highs.

Clouds decrease tonight, although they may be stubborn for the
higher elevations up north. It appears a modest pressure
gradient will be maintained thanks to a clipper passing well
north of the region, so low temps should be above seasonal
normals in the upper teens to mid-20s.

&&

Short term /Saturday through Sunday night/...
on Saturday, the aforementioned clipper will drag a cold front
across the region, though with little deep layer moisture and
upper-level support, expect it to be dry. Good mixing is
forecast behind the front, so expect temps to get a nice boost
before the weak cold air advection kicks in. Looking at temps
well above normal in the mid-30s to mid-40s, possibly a bit
higher if mixing is a bit deeper. The mixing will result in a
breezy day with westerly gusts of 30-40 mph possible over
favored westerly wind areas such as the Mohawk/Schoharie
valleys and capital district into the Berkshires as well as at
higher elevations. A diurnal increase in clouds is expected once
again, which could mute the rise in temperatures somewhat. Have
increased cloud cover from blended grids based on forecast
soundings indicating moisture remaining beneath the inversion.
Clouds should once again be most prevalent in northern areas,
though all areas should see a fair amount of sun as well.

Saturday night into Sunday night, the forecast area is expected
to be in a col between strong cyclogenesis occurring on the
plains and high pressure centered both northwest and southeast
of the region. Forecast soundings suggest low-level moisture
will increase over this time frame, so have worked an increase
in cloud cover into the forecast. This is somewhat of a low-
confidence scenario, however. Temps expected to remain on the
mild side of normal, but highs Sunday forecast to be a few
degrees cooler than Saturday. A couple light snow showers or
areas of drizzle/freezing drizzle are possible due to moist
upslope flow over the Adirondacks. Precipitation associated with
moisture advection ahead of the advancing system is mainly
expected to hold off until the long term period. Slight chance
to chance pops are in place late Sunday night in case the
moisture advection is a little faster than current solutions
indicate.

&&

Long term /Monday through Thursday/...
guidance remains consistent that a large vertical stacked storm
system will impact the region early next week. However, there
are differences in the exact timing, track and amplitude of the
system plus when there will be an interaction between northern
and southern stream energy. The weather prediction center has
recommended a blended model approach which was used for this
forecast. It still appears the system should occluded as it
moves across the region which will limit the degree of warming
which will occur.

As the system approaches guidance indicates the low level southerly
jet should be 2-3 Standard deviations above normal. Also, pwats
are forecast to climb up 2-3 Standard deviations above normal.
Quantitative precipitation forecast amounts now for Monday through Tuesday are forecast to be
1 to 1 1/3 inches across the local area with the bulk of that
occurring late Monday night into Tuesday afternoon.

Initially cold enough for snow however as warmer air works in a
changeover to mixed precipitation is expected before just plain
rain is expected to occur across most of the forecast area.
P-types issues will occur mainly across the northern portion of
the forecast particular in the upper Hudson Valley and across
southern Vermont. With the passage of the system colder, seasonable
air will be ushered back in with rain changing back to snow Tuesday
afternoon into the evening. In the wake of the system will have
cold cyclonic flow across the region with some lake effect and
upslope snows Tuesday night lingering into perhaps Wednesday night.

Temperatures are expected to be in the 30s Monday and Monday night
with areas mainly along and east of the Hudson River valley warming
into the 40s on Tuesday. Temperatures Tuesday night should drop
back into the upper teens to upper 20s. Despite near seasonable
temperatures for Wednesday brisk and gusty westerly winds will
make it feel colder. Lows Wednesday night are expected to fall
into the single digits to teens with seasonable readings for
Thursday.

&&

Aviation /15z Friday through Tuesday/...
forecast soundings suggest cloud fraction will increase during
the late morning and afternoon hours as cooling near the
inversion related to diurnal processes allows any morning
clearing to fill in. Stratus already in place at kgfl early this
morning, expanding southward. The question will be whether these
will be MVFR or low-VFR level. Current taf package leans toward
MVFR clouds returning in the late morning, except at kpou. It
appears that clearing may occur around 00z.

Winds tonight will be from the west at around 5 kt for the rest
of the night, increasing modestly to 5-10 kt with a gust or to
to 20 kt possible at kalb/kpsf in the afternoon.

Outlook...

Saturday: low operational impact. Breezy no sig weather.
Saturday night: no operational impact. No sig weather.
Sunday: no operational impact. No sig weather.
Sunday night: low operational impact. Slight chance of snow.
Monday: moderate operational impact. Chance of rain...sn.
Monday night: high operational impact. Likely rain.
Tuesday: high operational impact. Likely rain showers.

&&

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. A
gradual warming trend will occur into this weekend, although
the degree of warming is not expected to be as significant as
what occurred last week. We will monitor trends in temperatures
due to potential impacts on existing ice jams.

In terms of precipitation, no hydrologically significant
precipitation is expected through the weekend. A period of
mixed precipitation and/or rain is possible early next week,
although details on precipitation types and amounts are
uncertain at this time.

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.
New York...none.
Massachusetts...none.
Vermont...none.

&&

$$
Synopsis...Thompson
near term...bgm/Thompson

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