Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 250542
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
142 AM EDT Sat Mar 25 2017

.SYNOPSIS...
A warm front will initially become stationary over
upstate New York and New England tonight.  The front will sag back
southward as a cold front tomorrow morning into the afternoon with a
mixture of light rain and snow, as high pressure builds in from
James Bay.  The front will begin to lift back north as a warm front
Saturday night through the rest of the weekend with a wintry mix of
precipitation impacting portions eastern New York and western New
England.

&&

.NEAR TERM /THROUGH TODAY/...
As of 130 AM EDT...Cold front continues to sag southward as
evident by the wind direction contrast across the region from
north to south. Mid level frontal zone has become increasing
active mainly south of I90 where upstream lightning activity has
remain evident per the NLDN. Per the latest RAP/HRRR, seems we
will need to expand the coverage of rain/showers as these
upstream showers move across the region from west to east along
and south of I90. Otherwise, the secondary cold front near the
St Lawrence Valley was producing more stratiform precipitation
with a mix of rain and snow. As this drifts south, portions of
the Dacks and Lake George Saratoga Region will likely see a
mixture to snow overnight with light accumulations possible.

Prev Disc...The cold front will continue to gradually slide
south through the area Saturday, as high pressure and colder air
push southward into the region. Both of these features will
allow for continued light precipitation chances through Saturday
evening. Cannot rule out some pockets of light freezing rain or
drizzle in the higher elevations as temperatures drop just
below freezing. Elsewhere, temperatures should remain fairly
mild, in the mid 30s to lower 40s. Highs tomorrow will warm into
the upper 30s to upper 40s. These high temperatures may be
realized early in the day up north as the front slides south.

&&

.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
The short term portion of the forecast remains complicated based
on the tricky thermal profiles and the movement of a frontal
boundary late in the weekend into early next week. Precipitation
types may vary depending on the depth of cold air, and how
quickly above freezing air returns to the entire region
especially late Sunday into early Monday.

Saturday Night...There is increasing confidence that a large
Canadian anticyclone /around 1036 hPa/ will ridge
south/southeast from James Bay across New England and much of
northern and eastern NY Sat night. This ridge would push the
cold front well south of the region, that most of the overnight
period would remain dry. There was a good consensus from the
latest NAM/GFS/Canadian GGEM/ECMWF here. It does look like a
short-wave in the west/southwest flow and the front try to move
north/northeast between 09Z-12Z for from light pcpn to break out
especially south and west of the Capital Region. Using a Top-
down ptype method with the NAM/GFS thermal profiles blended,
some of this light over-running pcpn could be sleet, snow and
freezing rain, especially over the elevated surfaces. The better
thrust of isentropic lift looks like it will come on Sunday. We
were not confident about a late 3rd period advisory, especially
if most of this time frame ends of dry. Lows will be in the
lower to mid 30s from the Capital District south/southeast into
the Mid Hudson Valley and NW CT. Expect 20s outside of these
areas. Any ice accretions if they occur look light.

Sunday...A closed H500 low moves over the Midwest and lower
Great Lakes Region with the warm front hung up south and west of
the region. Over-running pcpn will continue...mainly light. The
greatest threat for mixed pcpn due to the cold air dammed in
place will be north and east of the Capital Region...and just to
the west. BUFKIT model soundings and critical partial
thicknesses indicate sleet and freezing rain will be possible as
the warm nose increases aloft in the H850-700 layer. Some snow
is possible early on over the southern Adirondacks/southern
Greens. Temps should still warm above freezing in the afternoon
/in late March this helps/ for a transition to rain. Snow/sleet
amounts will be a half an inch or less. Any ice accretions in
the few hundredths to a tenth of an inch range or so range,
which is close to WPC guidance. High temps will generally be in
the lower 40s in the valley areas, and mid to upper 30s over the
mountains.

Sunday night into Monday...A brief lull in the pcpn is possible
again 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 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/. 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 NY during the day. The synoptic
forcing is greatest during Monday morning into the early
afternoon portion of the day with good moisture advection.
Total QPF could be in the third of an inch to three quarters
inch range during the late morning into the afternoon Monday.
Temps should be on the rise during the late morning into the
afternoon for rain across the forecast area. We used a non-
diurnal trend for temps in collab with WFO BTV, and any mixed
pcpn headlines /Winter WX Advisory/ might be needed Sunday night
into early Monday. We will continue to mention in the HWO the
threat of mixed pcpn. Highs Monday will generally be in the mid
and upper 40s in the valley areas and over the hills with upper
30s to lower 40s across the mountains.

Monday night...The sfc wave and H500 short-wave trough swings
through with the rain tapering to isolated to scattered showers
overnight. Additional QPF looks light. It will remain dank and
cool with lows in the mid 30s to lower 40s.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
On Tuesday, an upper level impulse will track toward the region
from the southern Plains, bringing the chance for rain or a mix
of rain/snow in higher elevations into Wednesday morning. Once
this system lifts north and east of the region, there remains
significant uncertainty regarding the timing of yet another
southern stream impulse approaching. Latest 12Z/24 deterministic
models and ensembles suggest there could be a break from the
clouds and precip Wed into Thu, and will therefore lower pops
during this period, but with low confidence. Temps will remain
near normal, with highs Tue- Fri mainly in the mid 40s to low
50s. Overnight lows will mainly be in the low to mid 20s across
the high terrain and in the low 30s elsewhere Tue-Fri nights.

&&

.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...

Saturday Night: Moderate Operational Impact. Chance of RA...SN...FZRA...SLEET.
Sunday: Moderate Operational Impact. Chance of RA.
Sunday Night: High Operational Impact. Likely RA.
Monday: High Operational Impact. Definite SHRA...RA.
Monday Night: Moderate Operational Impact. Chance of SHRA.
Tuesday: Moderate Operational Impact. Chance of RA.
Tuesday Night: High Operational Impact. Likely RA.
Wednesday: No Operational Impact. NO SIG WX.

&&

.FIRE WEATHER...
The snow pack remains deep and in place across much of eastern
New York and western New England. The weather pattern will
remain unsettled this upcoming weekend into early next week with
occasional rain and wintry mixed precipitation. A warm front
will move southward as a cold front late tonight into tomorrow
with high pressure trying to build in, 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 tonight
into early next week. Initially, the precipitation will be light
with a frontal boundary moving southward tonight through
tomorrow as high pressure builds in. Most of the precipitation
will fall in the form of light rain and snow initially with
total QPF a few hundredths to a few tenths of an inch.

Saturday night 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 NY 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.
NY...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...Wasula
NEAR TERM...BGM/JPV/JVM/MEM
SHORT TERM...Wasula
LONG TERM...KL/JVM
AVIATION...BGM/JPV/MEM
FIRE WEATHER...Wasula
HYDROLOGY...11/Wasula

www.weather.gov/albany


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