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fxus61 kaly 231744 
afdaly

Area forecast discussion
National Weather Service Albany New York
144 PM EDT Thu Mar 23 2017

Synopsis...
temperatures will gradually moderate this afternoon with
high pressure in control, before unsettled conditions arrive for
tomorrow into the upcoming weekend, with the potential for a variety
of precipitation types. Initially, the warm front tomorrow will
bring a light wintry mix transitioning to rain by the mid to late
afternoon.

&&

Near term /through tonight/...
as of 120 PM EDT...a 1038 hpa sfc anticyclone continues to
build in over upstate New York and the mid Atlantic region this
afternoon. The strong subsidence from the Arctic high will
continue to yield sunny/mostly sunny conditions late this
afternoon based on the visible satellite picture. The 12z kaly
sounding is very dry and cold with a precipitable water value of 0.05". Mixing
to h925 will yield some lighter northwest winds today at 5-15 mph
across the region with a few gusts in the 20-25 mph range over
the higher terrain of western New England. Expect afternoon highs
to be in the mid to upper 30s in the lower elevations or
valleys with 20s to a few lower 30s over the hills and
mountains. Some cirrus will start to approach from the south and
west towards sunset. The latest guidance continues to shows
colder air remaining in place in the late morning into the early
afternoon with mixed pcpn impacting the region. Winter weather
advisories will likely be needed for portions of the region with
the next update.

For tonight, patchy high/mid level clouds should stream across the
region through midnight, but with at least occasional breaks, along
with nearly calm winds and a very dry low level air mass remaining
in place, have sided a bit colder than guidance with temps expected
to drop into the teens to lower 20s for most areas before or around
midnight, with temps then rising after midnight as clouds thicken
and a light south winds develops. Some light snow may approach
western areas prior to or right around 12z/Fri, so chance pops are
indicated for areas mainly west of the Hudson River. With warm
advective regimes, despite initial low level dry air, precipitation
often arrives a bit faster than models suggest, so will have to
watch near-term trends in case timing of snow onset needs to be
adjusted with subsequent forecasts.

&&

Short term /Friday through Sunday night/...
a very complex forecast including a wide variety of
precipitation types are in the forecast during the short term
period. The positioning of some of the key features resembles
some of the ice storm characteristics which were studied in a
recent cstar project on ice storms in the northeastern United
States. The complexity of the forecast requires speaking in
general terms as positioning of frontal boundaries relative to
the large ridge of high pressure to the north hold the key to
the forecast. Much of the extended forecast period will have
precipitation.

Starting on Friday morning a warm front will be lifting
northward from the Ohio Valley as a cold front starts to drop
south of James Bay. The forecast area will be under a warm
advection pattern with precipitation developing and moving
across the region during the morning hours in the form of snow
and sleet based on partial thickness values. The precipitation
will likely change to rain during the afternoon across most of
the area as the warm front lifts north toward the Canadian
border. Highs on Friday will be in the upper 30s to mid 40s. Any
snow and sleet accumulation should generally be less than an
inch except an inch or two across the Mohawk Valley, southern
Adirondacks, Lake George Saratoga region, southern Vermont and
the northern Berkshires.

For Friday night the frontal boundaries will converge near the
Canadian border and then slide southward with a cold front
draped across the southern half of the forecast area late Friday
night. High pressure southwest of James Bay will start to move
southeast allowing for colder air to start to drop southward
from Canada. Lows Friday night will generally be in the 30s with
most of the light precipitation in the form of rain.

Saturday through Monday...much of the precipitation types will
be diurnally driven with mainly rain during the daytime hours
and mainly freezing rain during the overnight hours into early
morning hours as indicated by partial thickness values and
BUFKIT model soundings. The frontal boundary is expected to drop
southward into the middle Atlantic region on Sunday as a wave of
low pressure over the Midwest tracks northeast reaching the
eastern Great Lakes by Monday morning. The best chances for
freezing rain appear to be between around midnight and 10 am
both Sunday and Monday. While it is still too early to pinpoint
ice accretion there is certainly the possibility of a tenth to a
third of an inch of ice accretion totals across a good portion
of the forecast area. Fortunately it does not look like
temperatures will be below freezing during the afternoons which
will allow what freezing rain which accretes to melt in most
areas. Highs on Saturday are expected to be in the upper 30s to
mid 50s with highs on Sunday in the mid 30s to lower 40s and
highs on Monday in the upper 30s to upper 40s. Lows Saturday
night will be in the upper teens to mid 30s with lows Sunday
night in the mid 20s to mid 30s.

&&

Long term /Monday through Wednesday/...
uncertainty regarding timing and strength of impulses ejecting out
of the Southern Plains remains through the long term portion of the
forecast, with southern stream systems tending to deamplify within
slightly confluent upper level flow across the northeast states and
southeast Canada.

Per latest long range discussion from wpc, followed close to model
ensembles, particularly the 00z/23 gefs, regarding timing of precip
with systems, with best chances appearing to be Tuesday/Tuesday
night, then decreasing Wednesday. Thermal profiles suggest that
initial lingering precip Mon night could be light rain/drizzle in
valley areas, with perhaps a mix of freezing rain/snow across
portions of the southern Adirondacks and southern Vermont. Generally
cloudy, cool and damp for Tuesday into at least early Wednesday,
with areas of light rain and drizzle Tuesday, possibly mixing with
or changing to snow for some areas Tuesday night/early Wed as colder
air aloft potentially seeps into the region. Some drying is possible
later Wednesday, depending on how quickly a second upper level
impulse departs, and whether northern stream upper level energy
reaches the region.

Temperatures should average below normal through the period, largely
skewed by chilly daytime highs only reaching the 30s to lower 40s,
with overnight lows ranging from the upper 20s/lower 30s across
higher terrain of the southern Adirondacks/southern VT, to mid/upper
30s elsewhere.

&&

Aviation /18z Thursday through Tuesday/...
high pressure will be over New York and New England this afternoon,
and then will drift offshore tonight. A warm front will approach
from the south and west tonight and will bring mixed
precipitation to the region late tomorrow morning into the
afternoon.

Clear skies will give way to increasing mid and high clouds by
the 06z/Fri. The clouds will continue to lower between 06z-12z
Friday with snow overspreading the region from the southwest to
northeast especially after 12z/Fri. Expect cigs and vsbys to
quickly lower to low MVFR/IFR levels between 12z-15z. Our
confidence was greater in terms of vsbys in the IFR range late
in the taf period. The snow will quickly transition to sleet and
freezing rain especially at kalb/kpsf north to kgfl between
15z-18z. Kpou may only have a light mix of rain and snow. Temps
should continue to climb above freezing in the afternoon.

The north to northwest winds of 5-12 kts this PM will quickly
become light to calm early this evening. The winds will increase
from the south at 5-10 kts towards daybreak Fri, except at kalb
where the winds could increase sooner at 5-10 kts around 10z.
The winds will increase to 8-13 kts by the late morning with
some gusts in the 20-25 kt range at kalb/kpsf.

Outlook...

Friday night: moderate operational impact. Chance of rain.
Saturday: moderate operational impact. Likely rain.
Saturday night: moderate operational impact. Chance of rain...fzra.
Sunday: high operational impact. Likely rain.
Sunday night: high operational impact. Likely rain...fzra.
Monday: high operational impact. Likely rain.

&&

Fire weather...
a deep snow pack remains in place across much of eastern New
York and western New England. Temperatures will gradually
moderate today, before unsettled conditions arrive for Friday
into the upcoming weekend, with the potential for a variety of
precipitation types.

&&

Hydrology...
no precipitation is expected through most of tonight, with
below normal temperatures expected. There is a potential for
several rounds of precipitation Friday into the upcoming week,
with a variety of precipitation types possible. Precipitation
amounts, types, and temperatures are uncertain at this time, but
it appears temperatures will warm Friday and Saturday before
returning to below normal values for the second half of the
weekend.

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...kl/wasula
near term...kl/wasula
short term...11

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