Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 282037
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
437 PM EDT Tue Mar 28 2017

.SYNOPSIS...
Rain showers will continue into this evening before
tapering off tonight. In the wake of the rainfall, dry weather will
return for Wednesday and Thursday with temperatures close to normal
under clearing skies. Another storm system with rain and snow will
impact the region Thursday night into Friday night.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
As of 330 PM EDT, widespread coverage of rain for areas near and
south/east of the I-90/I-88 corridors. Pockets of moderate to heavy
rain currently ongoing across portions of the far SE Catskills, mid
Hudson Valley and NW CT, where some embedded convective elements are
occurring.

Through sunset, expect periods of rain to continue for most areas
from the eastern Mohawk Valley and points south and east into the
mid Hudson Valley, NW CT and adjacent western New England. A few
additional pockets of moderate/heavy rain will likely continue, esp
from the SE Catskills into the southern Berkshires.

Farther N and W, lighter showers or sprinkles currently ongoing
across portions of the upper Hudson Valley, with steadier light rain
across southern VT. This rain should gradually taper off from NW to
SE through sunset.

After sunset, the main shield of rain should continue eroding from
NW to SE, although it may take until midnight or shortly thereafter
across far SE areas. Also, some lingering spotty showers or drizzle
may redevelop behind the main rain shield across portions of the
Capital Region and eastern Catskills, as the main upper level
shortwave approaches from the Great Lakes, in combination with the
surface front settling southward.

Clouds should remain fairly abundant overnight, so despite
developing low level cold advection, have kept min temps above
blended MOS, with mainly 30s expected by daybreak for most areas,
except for some upper 20s across portions of the western Adirondacks.

On Wednesday, models suggest quite a bit of low level moisture may
initially become trapped beneath subsidence inversion through the
morning, leading to areas of clouds, before deeper mixing allows dry
air aloft to eventually become entrained into the lower levels of
the atmosphere. So, mostly cloudy through the morning for most
areas, followed by gradual clearing, first in valleys, last for
higher terrain. There could even be isolated sprinkles/flurries or
patchy drizzle in the morning as mixing first develops.

Afternoon highs should reach the 30s across higher elevations, and
40s for most lower elevations, although some 50s will be possible
across portions of the mid Hudson Valley where more sunshine and
downsloping should prevail.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
Wednesday night into Thursday, northwesterly upper-level flow
will be over the northeastern US. Good subsidence will be
working into the local area, reflected in a ridge of high
pressure building in. This will promote tranquil weather and
mainly clear skies with temperatures around seasonal normals.
As the high is not directly overhead Wednesday night, a weak
pressure gradient will be maintained which may prevent temps
from tumbling further.

Thursday night into Friday night, the focus will be on the upper
low that is currently over the Desert Southwest as it tracks
eastward into the mid-Atlantic. Though this wave is expected to
pass well to our south, there will also be some northern-stream
energy tracking roughly along the same longitude and potentially
phasing with the southern stream offshore. The attendant
composite low-level circulation associated with these upper
waves is expected to form across the Upper Midwest/Western Great
Lakes with a solid low-level jet along its eastern flank.
Moisture transport and isentropic lift from the LLJ, in tandem
with some contribution from the equatorward entrance region of
the aforementioned upper jet, will allow precipitation to spread
into the local area Thursday night into early Friday. Good
confidence on this scenario, so likely/categorical PoPs are in
place Thursday night into early Friday night. Thermal profiles
and resultant P-type carry lower certainty. Fairly good
confidence in precip beginning as snow Thursday night due to
cool boundary layer and midlevel wet bulb temps well below zero.
After sunrise Friday, continued positive midlevel warm advection
and diurnal boundary layer warming from the late March sun will
be battling against cooling due to upward motion and evaporative
effects to edge the rain/snow line northward and toward higher
elevations. For now, areas north of I-90 and above 1000` are
favored for accumulating snowfall continuing into Friday. Will
hone in on the details as we get closer, but for now the message
is that a plowable snowfall is possible even into the valleys
but especially across higher elevations. Will likely need high
rates to allow snow to stick on the roads after sunrise Friday,
but that is a possibility in the favored locations.

More uncertainty Friday night with potential coastal development
potentially prolonging the precip especially east of the Hudson
Valley. 12Z ECMWF/GFS are on opposite sides of the envelope,
with the ECMWF being the stronger/further north solution. For
now, will trend PoPs down from west to east during the latter
part of the night and continue to monitor.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
The period starts out at the tail end of the system which will be
affecting us on Friday.  Dry conditions can be expected through
Monday before a complex system from the west brings rain showers
across the region. The Adirondacks and Greens may flirt with a
mixture of rain and snow.

Temperatures will start out several degrees below normal but will
climb to near normal by the end of the period.  Normal highs in very
early April in Albany are in the 50 to 55 degree range, with lows
right around freezing.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
A wave of low pressure passing south of the region this
afternoon will bring some areas of light to moderate rain and
drizzle, although steadiest rain may remain south and east of
KGFL. Expect MVFR/IFR conditions, mainly for CIGS but could also
drop into these ranges for VSBY within pockets of moderate rain.

The rain should taper off from NW to WE between roughly 23Z
Tue-03Z/Wed. With abundant low level moisture remaining in
place, areas of BR/FG could develop before winds increase later
this evening. This potential appears greatest at KPSF and KPOU.
CIGS should remain MVFR/IFR through at least daybreak, and it
may linger longer, perhaps through 15Z/Wed, esp at KPSF before
drier air builds in.

Light/variable winds may briefly trend into the south to
southeast this afternoon at 5-10 KT, before shifting into the
north later tonight at 5-10 KT. North to northwest winds will
increase slightly to 8-12 KT Wednesday morning, with some gusts
of 20 KT possible.

Outlook...

Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: Moderate Operational Impact. Chance of SN.
Friday: High Operational Impact. Definite RA...SN.
Friday Night: High Operational Impact. Likely SHRA...SLEET.
Saturday: Low Operational Impact. Slight Chance of SHRA.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.


&&

.FIRE WEATHER...
Much of eastern New York and western New England continues to
have snow on the ground. Some of the valley areas have bare
patches, but the mountains have a deep snow pack. High pressure
will build in for the mid-week into Thursday with cooler and
drier weather. Some wind gusts could reach around 25 mph on
Wednesday, although RH values will remain elevated. Rain and
snow are expected again across the region Thursday night into
Friday night.

&&

.HYDROLOGY...
Rain showers will taper off later this evening. This rainfall,
along with the expected snowmelt, will cause some within bank
rises on rivers and streams. However, this rain and snowmelt is
not likely to produce any concern for flooding at this time.
Current forecasts have a few points getting to close or up to
the alert or action stage, but no flooding is forecast at this
time.

Flows will recede Tuesday night through the mid-week with a
cooler and drier air mas building in. Temps are expected to go
below freezing Wed night and Thu night with a normal diurnal
melting of the snowpack in spots.

Some additional precipitation in the form of rain and snow is
expected for Thursday night into Friday night with another
storm system. The area has the potential to see moderate
amounts of precipitation, resulting in river rises. However, the
airmass will be cool, and current MMEFS forecasts keep the
forecast sites below flood stage.

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.
NY...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...Thompson
NEAR TERM...KL
SHORT TERM...Thompson
LONG TERM...ELH
AVIATION...KL
FIRE WEATHER...Frugis/Thompson
HYDROLOGY...Frugis/Thompson



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