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425
FXUS61 KALY 261727
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
127 PM EDT Wed Jun 26 2024

.SYNOPSIS...
Mostly sunny, warm, and slightly breezy conditions expected
today. A period of moderate to heavy rain and embedded
thunderstorms overspread the region this evening along an
incoming cold front. Storms south of Interstate 90 will be
capable of producing gusty winds and heavy downpours that may
result in localized flooding. Cooler and even breezier
conditions arrive for Thursday as high pressure builds into the
Northeast.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
.UPDATE...The Storm Prediction Center has expanded the Slight
Risk (level 2 of 5) north/east to include the E. Catskills, mid
Hudson Valley, Taconics, S. Berkshire and Litchfield Hills for
this evening. Latest CAMs depicting a developing solid
cluster/line of storms tracking east across the southern part of
the area between around 8-11 PM. This is also where the best
overlap of instability/shear looks to be. There will be a sharp
northern gradient to the severe storms threat, with none
expected north of I-90. Main change with this update was to
expand mention of gusty winds/heavy rainfall farther north
through Greene, Columbia and Berkshire Counties.

.PREV DISCUSSION[1042]...A diffuse front approaching from the
west has resulted in a mix of sunshine and clouds across central
parts of the area including the Capital District. Winds remain
S-SW ahead of the front, and will shift to the west and increase
to 10-15 mph with some higher gusts this afternoon. 3km NAM
indicating an isolated shower/T-storm along the front this
afternoon, so added 20% PoP for areas south/east of Albany.
Other CAMs are dry, but isolated convection cannot be ruled out
along the boundary with some instability present (MLCAPE
~500-1000 J/Kg). Otherwise, it will become mostly sunny and very
warm with highs well into the 80s with some lower 90s in parts
of the mid Hudson Valley.

Early clouds give way to mainly sunny skies as zonal flow
strengthens aloft in response to an incoming potent shortwave
that will amplify as it swings into the Great Lakes. A boundary
settles just south of I-90 this afternoon with dew points north
of this boundary across the Greater Capital District, southern
VT, Upper Hudson Valley, and SW Adirondacks actually only rising
into the upper 50s to low 60s as a pocket of dry air in the
mid-levels tracks overhead and supports deep boundary layer
mixing. Not only will the deep mixing result in temperatures
warming into the mid to upper 80s but westerly winds should also
turn a bit breezy with gusts reaching up to 20kts at times.
South of this boundary temperatures will be a bit warmer
reaching into the low to mid 90s and higher dew points in the
low to mid 60s will make it feel even warmer. A few pockets of
heat index values reaching 95 degrees likely in the mid-Hudson
Valley but not enough coverage to warrant a heat advisory.

Clouds increase late this afternoon from southwest to northeast
as sfc winds back to the south and warm air and moisture
advection increase ahead of an approaching cold front. Guidance
remains in good agreement that the majority of the incoming
rain and possible thunderstorms hold off until after 21 UTC but
given the strong dynamics, forcing for ascent, and moisture
fetch, rain may arrive a few hours earlier than high res
guidance suggests so we still introduce likely POPs for the mid-
Hudson Valley, the eastern Catskills, and Litchfield County by
21 - 00 UTC.

We continue to closely monitor this evening from 00 - 06 UTC
Thursday for a period of potentially more impactful weather
mainly south of I-90, including periods of moderate to heavy
rain and damaging winds gusts from strong to severe
thunderstorms. The aforementioned potent shortwave from the
Ohio Valley and Great Lakes will continue amplifying, even
taking on a neutral to slightly negative tilt, with increasingly
stronger height falls occurring downstream. The Northeast will
be positioned in the favorable equatorward entrance region on
the anti-cyclonic side of 300hPa jet reaching 100 - 110kts. This
will support increasing upper level divergence and the
development of a sfc low along the incoming cold front as it
tracks through west/central NY this evening. The front will
feature a tight thermal and moisture gradient with a notable
wind core in the 850 - 700hPa layer immediately ahead of the
front reaching 40 - 50kts advecting a rich plume of PWATs
nearing 2" into the mid-Hudson Valley and southern New England.

While this event will occur in the evening and past peak
heating, dew points in the 60s in this region should
contribute to sufficient instability to support thunderstorm
activity with SB CAPE values ranging 500 - 1500J/kg. Such a
strong moisture fetch, low-level convergence along the
boundary/theta-e gradient, and forcing for ascent including mid-
level FGEN in an environment with high freezing heights ~13kft
will easily support very efficient warm rain processes and
potential for high rainfall rates. Along the leading edge of the
incoming cold front, a period of high rainfall rates is looking
likely for areas mainly south of I-90 as an area of moderate to
heavy rain and embedded thunderstorms overspreads the region.
In fact, HREF probabilistic guidance shows a swatch of 15 - 30%
for 3-hourly rainfall amounts >2" and 70 - 80% probabilities for
>1" in 3 hours across Ulster, Dutchess, Litchfield, southern
Columbia/Berkshire County from 00 - 03 UTC Thurs. Fast mid-
level winds means the heavy rain should be progressive so high
rainfall rates should only last for a few hours this evening but
could still result in a quick 1-2" of rain resulting in some
poor drainage or urban flooding. Isolated flash flooding cannot
be ruled out and WPC maintains its marginal risk for excessive
rainfall noting this event is on the higher end of its marginal
risk category.

Besides the heavy rain potential, the storms along the leading
edge of the cold front may grow upscale as the reach the
moisture rich environment where sfc - 6km shear values ranging
40-45kts can help storms organize into cluster or even bowing
segments. Damaging winds is the primary hazard from any severe
storms and SPC maintains its "slight risk" (level 2 of 5) for
severe weather in Dutchess, Ulster, and southern Greene County.

Since the period for high rainfall rates and potential severe
weather is mainly along the leading edge of the incoming cold
front during the evening hours, the window for any flooding or
damaging winds is rather short-lived and should end by 03 - 06
UTC. After this time, a period of stratiform rain will likely
follow after Midnight with temperatures cooling into the mid 50
to low 60s as drier air advects eastward and rain winds down
shortly before sunrise from west to east. Total rainfall amounts
range 0.50 to 2 inches with highest amounts in the mid- Hudson
Valley and Litchfield County.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Cooler and tranquil weather follows for Thursday into Friday
thanks to subsidence building across the Northeast in the wake
of the departing shortwave. Some lingering clouds and morning
showers Thursday, especially in the high terrain areas, will
diminish by midday into the afternoon as the upper level trough
axis shifts eastward. A tight sfc pressure gradient develops
over the Northeast between an incoming high to our west and
departing sfc low and results in gusty winds reaching up to
25kts. The strongest winds likely occur down the Mohawk Valley,
Capital District into Berkshire County. Otherwise, cool air
advection may support some lake effect rain showers that spill
into the western Adirondacks but the valley should remain dry
as skies give way to increasing sun through the afternoon.
Daytime highs should reach into the mid to upper 70s with low
80s in the mid-Hudson valley. Cooler in the mid to upper 60s in
the southern Adirondacks and southern VT.

Expect chilly temperatures Thursday night as skies remain clear
and winds turning calm supports ideal radiational cooling. Overnight
lows drop into the low 50s in the valley with mid to upper 40s
in the hill towns and high terrain. The higher peaks of the
southern Adirondacks may even approach 40.

High pressure builds over the Northeast for Friday giving us a
beautiful and seasonably cool day. Expect abundant sunshine and
temperatures warming into the mid to upper 70s with rather low
dew points by late June standard. Luckily winds will be much
lighter. Clouds return Friday night which will keep temperatures
milder with lows only in the mid 50s to low 60s. Chances for
showers approach out western zones late Friday night but the
higher probabilities hold off until daytime Saturday ahead of
our next disturbance.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Unsettled conditions return for the weekend, as an upper level
trough and surface low approach from the Great Lakes region. A warm
front associated with this system looks to bring showers and
thunderstorms Saturday into Saturday night, with scattered
showers/thunderstorms possible Sunday as the system`s cold front
tracks through the region. Locally heavy rainfall is possible
Saturday-Saturday night as 00Z/26 GEFs suggest PWAT`s increase to
1.5-2 inches (+2 to +3 SD).

A trailing upper level disturbance could bring isolated
showers/thunderstorms to portions of the region Monday, with fair
weather returning by Tuesday.

Slightly below normal temperatures are expected Saturday and again
Monday with highs mainly in the mid 70s to around 80. Seasonable
warmth is expected Sunday and Tuesday, with highs mainly in the
upper 70s to lower/mid 80s. Overnight lows will be warm Saturday
night, mainly in the 60s to lower 70s, then cooling into the 50s to
lower 60s for Sunday/Monday night, with some 40s possible across
higher elevations.

&&

.AVIATION /17Z WEDNESDAY THROUGH SUNDAY/...
Through 12Z/Thu...mainly VFR conditions are expected through
at least mid afternoon, although there could be borderline MVFR
Cigs for a brief time between 13Z-16Z/Wed at KALB and KPSF.

Later this afternoon, scattered showers/thunderstorms may
develop at KPOU, with more widespread showers and thunderstorms
expected after 00Z/Thu at KALB, KPOU and KPSF as a wave of low
pressure tracks just south of the region. Occasional MVFR/IFR
Vsbys/Cigs will be possible within any heavier showers/thunderstorms
this evening. The best chance of thunderstorms will be at KPOU
and KPSF between 01Z-05Z/Thu, lower chances of thunderstorms
at KALB during this time.

After the initial showers/thunderstorms, a period of steady
light to moderate rain is possible before ending from NW to SE
between 06Z-10Z/Thu. However, low stratus clouds may develop in
the wake of the rainfall, which could lead to MVFR/IFR Cigs and
MVFR Vsbys. Should any clearing develop, patchy ground fog could
quickly form.

South to southwest winds 5-10 KT with a few gusts of 15-20 KT
through mid morning will then shift into the west by late
morning at similar speeds/gusts. West to northwest winds will
decrease to less than 5 KT toward and after sunset, although may
become southeast at KPOU around 5 KT. Winds will be mainly
light/variable overnight.

Winds will be stronger, and variable in direction near and within
any thunderstorms.

Outlook...

Thursday Night: No Operational Impact. NO SIG WX.
Friday: No Operational Impact. NO SIG WX.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: High Operational Impact. Likely SHRA...TSRA.
Saturday Night: High Operational Impact. Definite SHRA...TSRA.
Sunday: Moderate Operational Impact. Breezy. Scattered SHRA...TSRA.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.

&&

$$

SYNOPSIS...Speciale
NEAR TERM...JPV/Speciale
SHORT TERM...Speciale
LONG TERM...KL
AVIATION...KL