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fxus61 kaly 231158 

Area forecast discussion
National Weather Service Albany New York
658 am EST Thu Nov 23 2017

mainly dry and continued chilly weather is expected today into
tonight, with light snow showers possible over the Adirondacks.
Temperatures will moderate on Friday, before an approaching cold
front returns the chance for some showers on Saturday. It will
turn colder again on Sunday with some lake effect snow showers.


Near term /through tonight/...
as of 600 am, infrared satellite imagery shows stratus finally having
eroded...well, almost, as there are some lingering patches in
portions of the Mohawk Valley, capital district, and Berkshires.
High pressure continues to nose into the region. Expect the
gradual clearing trend to continue into the morning hours,
although it will be tempered by high clouds approaching from the
west ahead of loosely defined shortwave energy.

Today, mainly dry and seasonably cool weather is expected.
Sunshine will be interrupted by periods of mid and high
cloudiness as the aforementioned shortwave energy passes, and
perhaps lingering lower stratus. In the wake of the shortwave,
the low/midlevel flow will align out of the west-southwest to
support a period of lake effect snow showers over portions of
the western Adirondacks this evening into tonight. Based on NAM
forecast soundings at gtb/rme, inversion heights briefly get
respectable around 3 km agl, but instability is marginal with
surface to 850 mb Delta ts around 17c and falling through the
night as warm advection takes place. As such, expect only
minimal accumulation. May even see patchy light freezing
drizzle late tonight as moisture profiles suggest that we lose
cloud ice. Low temps tonight mainly in the 20s will be near to
below normal roughly along and south of I-90, and perhaps a bit
above normal north of there where a light to moderate
southwesterly breeze may keep temps elevated.


Short term /Friday through Saturday night/...
850 mb warm air advection will continue Friday into Friday night
ahead of a deep low pressure system crossing from northern
Ontario into northern Quebec. Warm advection will be more muted
at the surface, but a light to increasingly moderate southerly
breeze with time along with the expectation of a good deal of
sunshine should allow high temps to be several degrees warmer
than Thanksgiving day, back up toward normal values mainly in
the 40s. Low temps Friday night are tricky. Skies are expected
to be mostly clear overnight, so the driving factor for low
temps will be the winds. Pressure gradient supports the
continuation of a southerly breeze in many spots, especially
over higher terrain and in north/south valleys, leading to mild
temps. However, sheltered spots could decouple, allowing temps
to drop toward the dewpoint in the 20s. 2m model temps are much
warmer than MOS. Sided with the warmer 2m temps for northern
portions of the forecast area, and cooler MOS for southern
portions where winds are likely to be lighter. Forecast reflects
relatively uniform lows in the upper 20s and lower 30s, but in
actuality there will likely be sharp local gradients in the low

Saturday, the aforementioned low will drag its cold front across
the forecast area. Model depictions of this system have weakened
over the last several days. It appears the front will be
somewhat washed out and out of phase with the best midlevel
forcing/sharpest shortwave trough. Model quantitative precipitation forecast fields reflect this
with a weakening band of showers Saturday morning along the
front. As a result, have mainly chance pops for the forecast
area. P-type should be mainly liquid during the daylight hours,
with some snow mixing in over the Adirondacks. High temps near
to a bit above normal ahead of the front.

Gradual cold air advection will support a lake response Saturday
night as the midlevel trough swings into the area. H850 temps
forecast to fall to near -8c over the lake by 12z Sunday. Light
accumulations in the forecast over the Mohawk Valley/Adirondacks
since the cold air advection looks to be gradual. Lows settling
back into the mid-20s to mid-30s.


Long term /Sunday through Wednesday/...
the extended forecast will feature a moderating trend of
temperatures into the middle of next week.

The forecast area will be under the influence of cyclonic flow in
the low to mid levels of the atmosphere to close the weekend, and as
we enter Monday. One short-wave trough will move downstream of the
region on Sunday with some lake effect and upslope snow showers
persisting from the capital region north and west. Light snow
accums are possible especially for the western Adirondacks, west-
central Mohawk Valley, and the northern and eastern Catskills of a
few tenths to an inch or so. It will be brisk and cold with highs
in the mid 20s to lower 30s over the higher terrain, and lower to
upper 30s in the valleys. High pressure will be attempting to ridge
in from the Ohio Valley Sunday night, but another mid-level short-
wave trough will dive across southern Quebec, northern New York from I-90
northward into New England with scattered snow showers and flurries
based on the latest 00z GFS/ECMWF/CMC/gefs mean. The short-wave will
be moisture starved with the best chance of some light accums once
again being the western Adirondacks and western Mohawk Valley. Lows
will be in the 20s with some teens over the Adirondack park and
southern greens. A lowering subsidence inversion will end the snow
showers across the western extreme of the forecast area on Monday.
Heights begin to rise aloft, as the sfc anticyclone builds in from
near the mid-Atlantic coast. Temps rise back into the upper 30s to
lower 40s in the valley areas with a few mid 40s in northwest CT and the
Mid-Hudson valley, and upper 20s to upper 30s over the mountains.

Monday night through Tuesday night...high pressure drifts offshore
with a warm front drifting north of the region Mon night. There is
not much moisture for this boundary to work with, as clouds will
increase and h850 temps rise about 1 to 2 Standard devs above normal
based on the latest gefs. After a chilly start to the day with lows
in the 20s, then expect high temps to be 10 to 15 degrees above
normal with upper 40s to lower 50s in the valleys, and 40s over the
higher terrain in the warm advection pattern on Tue. A cold front
will be approaching from the west Tue night. The latest GFS is
faster than the European model (ecmwf) with the front. We have gone with the slower
timing based on the superblend of the guidance and wpc. Increasing
clouds Tue night with maybe a shower over the western Adirondacks
late. Lows temps will be in the mid and upper 30s with a few lower
30s in the sheltered valleys.

Wednesday...the cold front moves through with limited low-level
moisture associated with it. A low chance of showers was kept in
the forecast north and west of the capital district with a slight
chance from the Tri Cities south and east. Highs will continue to
be above normal by 10-15 degrees for late Nov before the cold
advection kicks in later in the day in the wake of the frontal

Temps look to be above normal for the long term with pcpn likely
below normal.


Aviation /12z Thursday through Monday/...
high pressure will continue to ridge in from the Ohio Valley
and Pennsylvania this morning. The surface high will drift
eastward over the mid Atlantic region during the afternoon, as
some clouds will increase ahead of the next upper level
disturbance for tonight.

Moisture is finally eroding beneath an inversion over kalb/kpsf
based on the GOES-16 satellite imagery this morning. High MVFR
clouds continue at kpsf in the 2.4-3.0 kft above ground level range. The
clouds should dissipate between 12z-14z at both these sites due
to the subsidence with the high.

VFR conditions will continue during the late morning through the
afternoon with some mid and high clouds increasing ahead of the
next short-wave trough. Clouds bases will generally be broken in
the 10-15 kft above ground level range by 18z-22z. The clouds will continue to
thicken and lower into the overnight period especially from
kalb/kpsf before thinning after 06z/Fri.

The winds will be north to northwest 5-12 kts this morning with
a few gusts around 20 kts at kpsf. The winds will be from the
southwest to west at 10 kts during afternoon before becoming
light and variable in direction at 5 kts or less tonight.


Friday night: no operational impact. No sig weather.
Saturday: moderate operational impact. Chance of rain showers.
Saturday night: low operational impact. Slight chance of rain showers...shsn.
Sunday: low operational impact. Breezy slight chance of rain showers...shsn.
Sunday night: no operational impact. No sig weather.
Monday: no operational impact. No sig weather.


Fire weather...
mainly dry and chilly weather is expected today. Relative humidity values will
fall to 40 to 70 percent, with the highest values in northern
and high terrain areas. West-northwest winds at 5 to 10 mph
today. Friday will be a bit milder with a southerly breeze at
5 to 15 mph and relative humidity values bottoming out in the 45 to 65 percent
range. Scattered light showers are possible on Saturday, with
seasonable temperatures.


no hydrologic issues are anticipated through early next week.

Aside from a few passing light lake effect snow showers or
flurries over the Adirondacks this evening into tonight, mainly
dry weather is expected through Friday night. A passing cold
front may bring some light rain showers to the area on
Saturday, possibly mixed with snow over the Adirondacks. There
may be some additional lake-effect snow showers again for
western areas on Sunday, otherwise, mainly dry weather is
expected to end the weekend into early next week. This light
precipitation will have little to no impact on rivers and
streams. As a result, river and stream levels will generally
hold steady. Temperatures will be below normal today, returning
to seasonable values Friday and Saturday.

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...
New York...none.


near term...Thompson

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