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fxus61 kaly 250807 
afdaly

Area forecast discussion
National Weather Service Albany New York
407 am EDT Sat Mar 25 2017

Synopsis...
showers will continue through the today as a frontal boundary
sags southward through the region. Some partial clearing is
possible this evening as cooler air filters into the region,
but mixed precipitation is possible Sunday as the frontal
boundary lifts back northward as a warm front. Any snow or ice
accumulations are expected to be light, but untreated surfaces
could become slippery where freezing rain develops. Chances for
rain increase as a wave of low pressure passes to the west of
the region Sunday into Monday. There there is some uncertainty
as to whether or not Tuesday remains rainy, but we should
finally see some clearing by Wednesday. However, another
approaching low pressure system could bring more precipitation
by the end of the week.

&&

Near term /through tonight/...
as of 400 am EDT...regional radar reveals east-west oriented
bands of precipitation tracking across the northern 2/3rds of
the County Warning Area (cwa) as a cold front slowly progresses
southward. Impressive baroclinic zone across upstate New York
this morning as per the rap/hrrr, this zone will slip south of
i90 toward noon where we will shift our high chance and likely pops
from north to south. In addition, as the colder air slips under
the moisture across the north, some of the precipitation may end
with a wintry mixture as h850 temperatures dip below 0c just
north of the capital district. Then through the afternoon,
equally impressive dry air advection as large surface high north
of the Canadian border extends its influence further south.
Could see the sunset along and north of i90. As far as
temperatures are concerned for this afternoon, very challenging
depending on cloud coverage as the NAM MOS is a few degrees
cooler than the mav. With a northerly flow evolving we will
favor the cooler side of the guidance envelop.

Tonight the frontal zone, more likely the mid-frontal zone as
the surface cold front is expected to be well south of the
region this evening, will keep clouds and the threat for light
showers into portions of the Catskills, Mid-Hudson valley and northwest
CT. Otherwise, 1035mb surface high slides across the St
Lawrence Valley further extending its influence across the County Warning Area.
Temperatures tonight under partly cloudy to mostly clear skies
north of the above mentioned areas will likely dip down into the
teens and 20s with some lower 30s for the immediate capital
district and mid 30s where clouds are more prevalent. As storm
upstream begins to approach the lower Great Lakes overnight,
this will return the cold front as a warm front. Isentropic
analysis is rather diffuse with wind magnitudes on the 290k
surface rather weak. So any precipitation that does occur with
the warm front approaching will likely be light. Again,
depending on those tricky thermal profiles, a period of light
snow, sleet and freezing rain are all possible north of the Mid-
Hudson valley and into the terrain. Due to the aforementioned
light amounts expected, we will continue to highlight in the
severe weather potential statement.

&&

Short term /Sunday through Sunday night/...
Sunday into Sunday night, the NCEP model suite and international
guidance differ a bit with respect to timing of the warm frontal
passage and the expected period of tranquil weather late Sunday
into Sunday evening. The operational GFS appears to be the
fastest with the mid level dry slot while the NAM/European model (ecmwf) are in
closer agreement with a slower timing which was followed in this
forecast package this morning.

As the warm front lifts northward, a wintry mixture will
overspread the entire region with a transition to mainly light
rain for the region. The challenge remains with boundary layer
temperatures and valley locations where near or sub-freezing
temperatures may linger for a longer period of sleet/freezing
rain. We envision portions of the region will have winter
weather advisories with future updates as confidence that
portions of the terrain may experience some ice accumulation.
However, continued warm advection through the afternoon and late
March sunshine should aid with warming the boundary layer above
freezing by days end to minimize any additional glazing. Highs
Sunday generally into the 30s with some lower 40s for the Mid-
Hudson valley and southern Litchfield County.

Sunday night...a brief lull in the pcpn is possible Sunday
evening, and temps may actually fall below freezing especially
for locations north of the capital region/Mohawk Valley. The
low-level flow will be east to northeast with the sfc high still
downstream over New Brunswick. The low-level ageostrophic winds
are hinting at cold air being dammed into place early on again,
especially for the eastern Adirondacks, portions of the Lake
George and northern Saratoga region and southern VT, as well as
the northern Berkshires. Some freezing rain is possible again
Sunday night into Monday morning. Ice accretions may range from
a few hundredths to a quarter of an inch /though a lot could
change with these amounts depending on temperatures/. Much of
the rest of the region will have a cold rain, as the isentropic
lift increases as the sfc wave and associated h500 upper level
short-wave trough pushes east northeast from the eastern Great
Lakes region into the St Lawrence River valley/northern New York
toward sunrise.

&&

Long term /Monday through Friday/...
at the start of the extended period, an upper level shortwave trough
will be moving from the eastern Great Lakes on Monday morning
towards northern New England for Monday night. Along with this upper
level feature will be a weak surface wave of low pressure that
tracks across the area from west to east. All 00z operational
guidance (gfs, ggem and ecmwf) along with all 00z gefs members
suggest that a period of steady rainfall occurs across the area for
Monday morning into at least the early afternoon hours. Will go
with categorical pops across the majority of the area for Monday. A
few spots across western New England and in the central Adirondacks
may start out on early Monday morning with temps just at or below
freezing, so a brief period of freezing rain is possible for a few
hours in some sheltered mountain valleys, allowing for a light
accretion of ice. Otherwise, southerly flow (both at the surface and
aloft) will allow temps to warm up on Monday, with highs reaching
into the 40s. Some rain or drizzle may linger into Monday night,
although many spots may see a break at some point. Temps will fall
into the 30s with persistent cloudy and damp conditions in place.

The forecast is a little more uncertain for Tuesday, as the GFS
suggest yet another wave of low pressure moves across the area as a
cold front heads towards the area. Meanwhile, the other models are
a little more quiet for during the day Tuesday, but do have some
additional showers associated with the cold front for late Tuesday
into Tuesday night. As colder air works into the area, some rain
showers may change to snow showers over the high terrain of the
Adirondacks or southern greens for Tuesday night, but any
accumulation will be fairly limited, as quantitative precipitation forecast should be fairly
minimal. Despite plenty of clouds, temperatures look to reach into
the upper 40s to mid 50s ahead of the cold front on Tuesday, but
will fall into the 30s for Tuesday night.

Mainly quiet weather is expected for Wednesday, although the
departing upper level trough could still allow for a few additional
rain or snow showers over the high terrain. Otherwise, clouds will
finally break for some sunshine on Wednesday with temperatures once
again reaching in the mid 40s to mid 50s.

With surface high pressure located near the area, it will continue
to be dry for Wednesday night into Thursday with a partly to mostly
clear sky. Lows will be in the upper 20s to mid 30s on Wed night and
highs on Thursday will reach the 40s to low 50s.

Another storm system will be possible for Friday into Saturday,
although the models are all over the place regarding the track and
timing of this system. For now, will go with chc pops for rain or
snow depending on diurnally-driven sfc temps, with temps close
to seasonal normals.

&&

Aviation /06z Saturday through Wednesday/...
a cold front will start to push southward across the region
overnight into early Saturday morning. Winds will shift to the
north behind the front and conditions will deteriorate to
mainly MVFR with occasional IFR during this time, especially at
kpsf/kgfl and perhaps into kalb. Kpou remains south of the
frontal boundary overnight for mainly VFR conditions. Scattered
light showers will be possible in vicinity of the cold front,
so will mention vcsh in tafs north of kpou. Conditions expected
to remain MVFR through Saturday, with a colder northerly flow
and drying aloft beneath a developing subsidence inversion
keeping low clouds in place through around 00z Sunday.

Light and variable winds will quickly shifting to the north
behind the cold front overnight at speeds 10 kts or less.

Outlook...

Sunday night: high operational impact. Likely rain.
Monday: high operational impact. Definite rain.
Monday night: moderate operational impact. Chance of rain.
Tuesday: moderate operational impact. Chance of rain.
Tuesday night: moderate operational impact. Chance of rain showers.
Wednesday: no operational impact. No sig weather.
Wednesday night: no operational impact. No sig weather.
Thursday: no operational impact. No sig weather.

&&

Fire weather...
the snow pack remains in place across much of eastern New York
and western New England. The weather pattern will remain
unsettled this weekend into early next week with occasional
rain and wintry mixed precipitation. A warm front will move
southward as a cold front today with high pressure trying to
build in late, but the boundary and a wave of low pressure
brings additional rounds of precipitation Sunday into early next
week.

&&

Hydrology...
an unsettled weather pattern will impact the Hydro service area
the next several days.

There is a potential for several rounds of precipitation into
early next week. Initially, the precipitation will be light with
a frontal boundary moving southward through today as high
pressure builds in from eastern Canada. Most of the
precipitation will fall in the form of light rain and snow
initially with total quantitative precipitation forecast a few hundredths to a few tenths of an
inch.

Tonight into Sunday, the front will lift back northward from PA
and the mid Atlantic region bringing a mixture of snow, sleet,
freezing rain, and rain to the region. The front stalls over
central New York into eastern PA and Long Island for mix precipitation
to occur again Sunday night into early Monday. A wave of low
pressure approaches from the eastern Great Lakes region with the
warm front moving through finally with periods of rainfall. The
rainfall looks the heaviest late Sunday night into Monday.

Temperatures look to be warm enough during the afternoon hours
each day that most of the precipitation should fall in the form
of rain before changing over to a wintry mix at night on the
weekend into early next week. While there is still some
uncertainty with precipitation types and amounts, there is the
potential for between three quarters of an inch of rain to up
to an inch and a half tonight through Monday.

The latest mmefs forecast indicates a few locations going into
action stage by early next week, but confidence is not high for
potential of any flooding 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...bgm/mem
near term...bgm
short term...bgm
long term...frugis

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