413
FXUS61 KALY 190845
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
445 AM EDT Wed Jun 19 2024

.SYNOPSIS...
The dangerous combination of near-record heat and elevated
humidity continues through at least Thursday, especially at
lower elevations. Isolated to scattered afternoon thunderstorms
are possible through Thursday, with an approaching cold front
expected to bring more widespread shower and thunderstorm
activity on Friday. The first half of the weekend may bring a
modest respite from the oppressive heat, but temperatures will
still remain seasonably warm to hot into next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
**Heat Advisories are now in effect across all of eastern New
 York and western New England through 8 PM Thursday**

Following another mild and muggy night, oppressive heat and
humidity returns today, as the closed 500 hPa high continues to
build overhead, reaching its peak amplitude near 600 dam by
this evening. 850 hPa temperatures look to remain around 18-20C
today, while surface high pressure located southeast of Cape Cod
will yield southwesterly low-level flow locally, allowing modest
downsloping into the Hudson, Mohawk, and Connecticut Valleys to
aid in warming temperatures a few degrees beyond yesterday`s
highs. Afternoon highs will thus reach the 80s in high terrain
and low to mid 90s at lower elevations, with a few pockets of
upper 90s expected within the Capital District. Daily records
highs may be challenged at Albany and Poughkeepsie.

Continued surface dewpoints in the upper 60s to low 70s will
result in heat indices again reaching up to 95 degrees in the
high terrain of the southern Adirondacks, eastern Catskills, and
southern Greens, while valley locales see values from the mid
90s to low 100s. Mild and muggy conditions continue tonight, as
temperatures only fall to lows in the mid 60s to low 70s again,
providing little relief from the daytime heat. Heat Advisories
therefore remain in effect through tonight across all of eastern
New York and western New England for another day.

Elevated temperatures and humidity at the surface will result
in ample convective instability of around 1500-2000 J/kg, with
vorticity maxima traversing the apex of the ridge again allowing
for isolated to scattered initiation of thunderstorms. While
storms are expected to remain below severe thresholds today, any
taller convective cell will be capable of a brief heavy
downpour. Coverage of storms will quickly diminish through the
evening following the loss of diurnal heating.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
**Heat Advisories continue through 8 PM Thursday for all of
 eastern New York and western New England**

By Thursday, the ridge will begin to flatten while the closed
upper high slides to the southwest toward the Ohio Valley.
Temperatures will nonetheless remain at near-record levels for
another day, with afternoon highs again expected in the 80s in
high terrain and 90s at lower elevations. Persistent dewpoints
in the upper 60s to low 70s will yield similar heat indices to
Wednesday, up to 95 degrees in the high terrain of the southern
Adirondacks, eastern Catskills, and southern Greens, and mid 90s
to low 100s at lower elevations. Heat Advisories therefore
continue through 8 PM Thursday evening.

A weak surface trough will develop over the northeast between
persistent high pressure over the North Atlantic and a building
surface high over the Upper Great Lakes. This trough may serve
as a focus for afternoon convection, as the heat and humidity
again provides fuel in the form of ample instability. Despite
marginal shear, isolated to scattered severe thunderstorms
capable of damaging winds may therefore develop, with any taller
convective cell again additionally capable of a brief heavy
downpour. SPC has raised the convective outlook to a Slight Risk
across portions of the Northeast in response to this threat.

Mild and muggy conditions continue through Thursday night, as
low remain stubbornly lodged in the mid 60s to low 70s across
the region, again providing little relief from the daytime heat.
Upper heights will finally begin to trend downward Thursday
night into Friday, as an approaching cold front brings a brief
respite from the extreme heat to some. Afternoon highs will
reach the mid 70s to low 80s north of I-90 behind the front as
it sags across the region, with mid 80s to low 90s to the south.
Dewpoints in the low 70s ahead of the front may again yield heat
indices in excess of 95 degrees in portions of the Mid-Hudson
Valley, with extensions of Heat Advisories through Friday
possible pending increased confidence in heat indices.

The cold front will bring more widespread chances for rain
showers with embedded thunderstorms to much of eastern New York
and western New England. Locally heavy rainfall is possible,
especially south and east of Albany, with a Marginal Risk for
excessive rainfall resulting in isolated flash flooding for
locations south and east of Albany. Behind the frontal passage,
modestly cooler nighttime temperatures return, with lows
expected in the upper 50s to upper 60s across the region.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Our boundary from Friday stalls across eastern NY and western New
England on Saturday as upper level flow becomes more zonal in
response to the large area of high pressure becoming centered in the
TN/MS Valley. With the conveyor belt of faster westerly winds along
the periphery of the ridge becoming centered across the Northeast on
Saturday along with a sfc boundary stalled over the area, POPs
remain elevated at chance and trend to likely during the afternoon
peak heating hours. It still looks like temperatures will trend
lower on Saturday with high temperatures only reaching into the low
to mid 80s with mid to upper 70s in the higher terrain and hill
towns but dew points and thus humidity still remain a bit
uncomfortable. With the faster westerly flow in play, increased
shear and sufficient instability should aid in some more organized
thunderstorm activity but mild temperatures in the mid-levels should
keep lapse rates weak and thus limit overall severe weather
potential.

Our next potential for strong to possibly severe weather looks to be
Sunday into Sunday night as the aforementioned stalled boundary
lifts north as a warm front in response to an amplifying shortwave
trough in the Great Lakes. Southwesterly flow strengthen over the
Northeast ahead of the shortwave, ushering our unseasonably warm and
humid air mass back into the area. With 850hPa isotherms potentially
returning to +19C to +20C, more widespread 90s are possible and
given increased humidity, heat index values may approach dangerous
levels again and warrant heat advisory headlines to be reissued.
However, this is still a day 5 forecast and there remain
uncertainties with cloud coverage, boundary layer mixing, and timing
of precipitation which may limit just how hot temperatures become
but this will be monitored in the coming days.

The warm sector making a return would also provide plenty of
instability and with increasing height falls and a pre-frontal
trough expected ahead of the approaching shortwave, confidence is
increasing that stronger forcing will be in play to support
thunderstorm development for the afternoon into the evening.
Increased southwesterly winds would also increase deep layer shear
and support organized convection. While mild temperatures in the mid-
levels continue for much of Sunday, cooler air aloft spills eastward
into the evening hours. With stronger height falls also arriving, we
maintained likely POPs even into Sunday evening.

The sfc cold front pushes through the Northeast overnight Sunday but
continued southwest to westerly flow will keep us warm into Monday,
albeit not as warm and humid. The main shortwave trough pushes
eastward through the day and the incoming trough axis/wind shift
should provide additional forcing for ascent to support renewed
shower and thunderstorm activity, especially during the afternoon. A
northerly wind shift Monday night should help provide some relief
from the stretch of warm/muggy nights with temperatures trending
back towards normal by late June standards.

Large scale subsidence builds into the Northeast for Tuesday,
providing us a break for dry weather and increased sunshine.
Temperatures should remain slightly above normal as very warm air
remain in the Midwest/Central US and winds becoming westerly over
the Northeast should help redirect that air mass back into our
area.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions at ALB, PSF, and POU through 12 UTC while GFL will
continue to vary between IFR and MVFR visibility due to foggy
conditions after daytime rain yesterday and a muggy night. There
will be instances of LIFR visibility but given uncertainty on exact
duration of any LIFR visibility, we only show IFR visibility in the
TEMPO group. If longer periods of LIFR vis are expected, we will
make amendments.

Fog at GFL dissipates by 10-12 UTC with VFR conditions mainly
prevailing through the rest of the TAF period. The exception will be
during any periods of isolated to widely scattered afternoon
thunderstorms that develop. Highest chances for afternoon storms
(mainly developing by 17 - 19 UTC through sunset) look to be for GFL
which will be closer to the periphery of the broad upper level ridge
and thus closer to the "ridge roller" activity. ALB and PSF could
see some brief showers and storms as well but activity should be
more isolated. We therefore included PROB30 groups at GFL, PSF, and
ALB for the afternoon and show potential for MVFR visibility during
any storms. POU should experience stronger subsidence and therefore
storms are more unlikely.

Any storms should dissipate by sunset. However, where storms can
occur, fog may quickly develop towards or shortly after sunset given
such a humid air mass staying in place. Included MVFR vis at GFL by
00 UTC/20 with potential for IFR vis/cigs given higher potential for
this terminal to experience a storm but maintained VFR conditions
for ALB and PSF where storm coverage is more isolated and less
certain on exact placement. If storms occur at ALB and PSF, MVFR or
even brief IFR vis will be possible after 00 UTC/20.

Light and variable winds through 12 UTC except at ALB where
sustained southeasterly winds remain around 5-7kts. Then, south to
southwesterly winds become sustained 5-8kts at all terminal by 15 -
17 UTC. Brief strong wind gusts are possible during any
thunderstorms this afternoon (17 - 23 UTC), especially during any
stronger storms. Winds turn light and variable after 00 UTC/20.

Outlook...

Thursday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Friday: High Operational Impact. Likely SHRA...TSRA.
Friday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Saturday: Moderate Operational Impact. Chance of SHRA...TSRA.
Saturday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Sunday: High Operational Impact. Likely SHRA...TSRA.
Sunday Night: High Operational Impact. Likely SHRA...TSRA.
Monday: Moderate Operational Impact. Chance of SHRA...TSRA.

&&

.CLIMATE...
Record High Temperatures...

Wednesday, June 19:
Albany - 94 (1995)
Glens Falls - 97 (1995)
Poughkeepsie - 92 (1941, 1943, 1993, 2016)

Thursday, June 20:
Albany - 97 (1953)
Glens Falls - 97 (1923)
Poughkeepsie - 96 (2012)

Friday, June 21:
Albany - 97 (1938)
Glens Falls - 96 (2012)
Poughkeepsie - 97 (1949)

Record High Minimum Temperatures...

Wednesday, June 19:
Albany - 71 (1976)
Glens Falls - 67 (1905, 1949, 1976, 2017)
Poughkeepsie - 73 (1993)

Thursday, June 20:
Albany - 73 (1893)
Glens Falls - 68 (1964)
Poughkeepsie - 71 (1931)

Friday, June 21:
Albany - 72 (1923)
Glens Falls - 71 (1953)
Poughkeepsie - 73 (1931)

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT Thursday for CTZ001-013.
NY...Heat Advisory until 8 PM EDT Thursday for NYZ032-033-038>043-
     047>054-058>061-063>066-082>084.
MA...Heat Advisory until 8 PM EDT Thursday for MAZ001-025.
VT...Heat Advisory until 8 PM EDT Thursday for VTZ013>015.

&&

$$

SYNOPSIS...Picard
NEAR TERM...Picard
SHORT TERM...Picard
LONG TERM...Speciale
AVIATION...Speciale
CLIMATE...Picard/Rathbun