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FXUS61 KALY 150223
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
1023 PM EDT Wed Apr 14 2021

.SYNOPSIS...
An upper level low across the Great Lakes will move
eastward overnight and bring scattered showers to the region. A
secondary area of low pressure will develop off the mid-Atlantic
coast on Thursday and lift northward into New England by Friday. A
soaking rainfall is expected on Thursday. As colder air returns
Thursday night, rain will change to snow or a rain snow mix.
Occasional rain and snow will continue on Friday before ending
Friday night.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
.UPDATE...
As of 1023 pm EDT...Clouds continue to thicken and lower ahead
of an upper level low, as a series of weak sfc troughs are
moving across the region. Some light isolated to scattered
showers are moving across the Saratoga/Lake George Region. This
rainfall is spotty and light.

The 00Z KALY is dry below 750 hPa with steep low-level lapse
rates. The PWAT is around 0.58". It will take a little time for
the lower atmosphere to moisten. The synoptic forcing increases
especially between 06Z-12Z ahead of the warm front for the
showers to become more numerous. We increased the PoPs gradually
to likely and categorical values towards daybreak. Lows will
fall back into the 40s with some upper 30s over the western
Dacks.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
A Winter Storm Watch remains in effect for Bennington, Windham
and Berkshire counties from Thursday evening to Friday night...

A late-season winter storm will affect the region on Thursday and
Friday with rain mixing with and changing to snow for most areas.

The upper-level low across the Great Lakes continues to slowly
progress eastward toward New York City and New England by Friday.
The upper-level low will take on a negative tilt on Thursday which
will induce surface cyclogenesis off the mid-Atlantic coast with
that low strengthening Thursday night into Friday as it progresses
northeastward across New England. An occluded front will slowly push
eastward across New York state as a sufficient plume of moisture
spreads across the region ahead of the boundary.

Continued upper-level divergence will lead to a quick increase in
rainfall coverage Thursday morning with a widespread, soaking
rainfall expected by midday. This will lead to a much cooler day due
to the clouds and rain with high temperatures mainly in the 40s
(except some upper-30s across the higher terrain of western New
England). As colder air slowly builds in aloft, temperatures will
start to fall during the afternoon, dropping into the mid-30s to mid-
40s by the late-afternoon hours.

As the colder air continues to build aloft, rain will begin to
mix with and change to snow, first across the higher elevations,
by late Thursday afternoon and Thursday evening. Most valley
locations will also see a mix or a changeover, but not until
Thursday night as dynamic cooling will occur slower here. Low
temperatures Thursday night will dip into the lower to mid-30s
across most areas with some upper 20s across the higher terrain.

Snow or a rain/snow mix will continue on Friday before gradually
tapering off Friday night as the low across New England slowly moves
farther away.

Regarding snowfall totals, the greatest amounts are expected across
the southern Greens and Berkshires (as the greatest QPF amounts are
expected in these areas once the changeover to snow occurs). Amounts
in excess of 6 inches are possible, especially for areas above 1500
feet with 2 to 6 inches possible below. We have continued the
Winter Storm Watch for these areas.

Outside of these areas, a general coating to two inches is possible
with a few higher amounts. There remains quite a bit of uncertainty
regarding how well the snow will accumulate, especially where
temperatures remain above freezing overnight. Accumulations will be
most favored across non-paved surfaces, though some slushy spots
cannot be ruled out on paved surfaces, especially if the snow falls
moderate to heavy at times. All in all, plan for slippery travel for
the Friday morning commute. Winter weather headlines may also be
needed in these areas in later updates, especially if confidence
on impacts during Friday morning increase.

High temperatures Friday will reach the mid-30s to mid-40s with lows
Friday night in the upper 20s to upper 30s.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Upper and surface low exits and some weak cold advection occurs as
split upper flow develops. Likely more clouds than sun Saturday
with highs in the lower to mid 50s and some upper 40s higher terrain.

Split flow continues Sunday and Monday with weak warm advection
beginning and lingering mid and upper level moisture, producing
considerable cloudiness and perhaps an isolated shower Sunday
afternoon and Monday afternoon. Highs Sunday in the mid 50s to
around 60 with around 50 higher terrain. Highs Monday in the upper
50s to lower 60s with lower 50s higher terrain.

Stronger warm advection ahead of upper energy and an associated cold
front Tuesday. The upper energy and cold front exit Tuesday night
into Wednesday with some cooling behind the front. There is a good
consensus from sources of guidance/ensembles for the leading edge of
the boundary layer thermal gradient to be quite tight for some good
forcing. There is also a good consensus on the timing through our
region. So, scattered showers Tuesday afternoon and night with
lingering isolated showers into Wednesday.

Highs Tuesday in the lower to mid 60s with mid 50s to around 60
higher terrain. Highs Wednesday in the lower to mid 50s with upper
40s to around 50 higher terrain.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Weak high pressure will move eastward tonight, as an initial low
pressure system and a warm front will bring some light rain or
showers in the early to mid morning hours. A secondary low
pressure system will interact with the frontal boundary as it
moves northeast from near the Delmarva Region bringing periods
of rain in the afternoon with a transition to rain and some snow
Thursday night.

Clouds will continue to thicken and lower ahead of the frontal
boundary and the upper low approaching from the Great Lakes
Region. VFR conditions may last to 04Z-08Z/THU, but cloud bases
and vsbys may lower to MVFR levels with the initial surge of
rainfall. The rain shield will become steadier after 12Z/THU and
continue into the afternoon. Expect conditions to fall into
widespread MVFR conditions at all the TAF sites prior to noon.
Widespread low MVFR and IFR conditions will likely materialize
between 16Z-20Z/THU and continue into the evening.

The winds will be south to southwest at less than 10 KT early
this evening. They will become light and variable at 4 KT or
less after midnight. Expect east to southeast winds at 5-10 KT
in the late morning into the early pm. A shift to the north to
northeast may occur in the late afternoon with the secondary low
approaching.

Outlook...

Thursday Night: High Operational Impact. Definite RA...SN.
Friday: High Operational Impact. Definite RA...SN.
Friday Night: Moderate Operational Impact. Chance of SHRA.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: Low Operational Impact. Isolated SHRA.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: Low Operational Impact. Isolated SHRA.

&&

.FIRE WEATHER...
An upper-level low across the Great Lakes will push eastward
tonight and bring scattered showers to the region. A secondary
area of low pressure will develop off the mid-Atlantic coast on
Thursday and push northeastward into New England by Friday. A
soaking rainfall is expected on Thursday. As colder air returns
Thursday night, rain will change to snow or a rain snow mix.
Occasional rain and snow will continue on Friday before ending
Friday night.

RH values will be elevated at 75 to 100 percent through Thursday
night and lower to 60 to 80 percent on Friday.

Winds will be light and variable tonight, then be out of the
southeast at at 6-12 mph on Thursday. Wind will shift to the
north to northeast Thursday night and then north to northwest
Friday at 6-12 mph.

&&

.HYDROLOGY...
A much needed soaking rainfall, which will transition to snow
for many areas before ending, is forecast tonight into Friday
night. 1-2 inches of liquid equivalent precipitation is forecast
which will lead to rises on area rivers and streams. No
flooding is anticipated at this time although some smaller
creeks could approach bankfull.

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...Winter Storm Watch from Thursday evening through late Friday
night for MAZ001-025.
VT...Winter Storm Watch from Thursday evening through late Friday
night for VTZ013>015.

&&

$$
SYNOPSIS...Rathbun/Wasula
NEAR TERM...Rathbun/Wasula
SHORT TERM...Rathbun
LONG TERM...NAS
AVIATION...Wasula
FIRE WEATHER...Rathbun
HYDROLOGY...Rathbun
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