549
FXUS61 KALY 212353
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
753 PM EDT Fri Jun 21 2024

.SYNOPSIS...
Warm and humid conditions will continue across the area this
weekend, with shower and storm chances each day. Strong to
severe storms will be possible on Sunday as a cold front moves
through the area, with quieter conditions expected early next
week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
UPDATE...As of 745 PM EDT, initial area of showers/thunderstorms
now south of the region, however additional scattered
showers/isolated thunderstorms have redeveloped across portions
of the Mohawk Valley/Schoharie County, as well as across the
upper Hudson Valley into southern VT. Still can not rule out an
isolated strong wind gust with some of the taller storms over
the next 1-2 hour, which would be more likely across higher
terrain areas of the Helderbergs into the eastern Catskills.

Latest SPC Mesonanalysis suggests greatest instability (SB CAPES
1000-1500 J/kg) for areas west of the Hudson River and south of
I-90, and this is where the best chance for additional isolated
thunderstorms should be over the next 1-2 hours.

Showers/thunderstorms should decrease in areal coverage
toward/after midnight, with areas of fog then developing,
particularly in areas where heavy rainfall occurred today.

[PREVIOUS DISCUSSION 338 PM EDT]...

Regional observations to include the NYS Mesonet showing a
backdoor cold front draped just south of the Mohawk River early
this afternoon, with latest radar trends showing widespread
shwr and storm coverage both north and south of this boundary.
Activity has really picked up in the last hour or so, with some
support being provided by a weak impulse noted on upper-level
water vapor imagery and SPC Mesoanalysis data. With high PWAT
values (>90% of normal for today`s date), efficient rainfall
production and isolated flooding will be possible with any
storms that linger of an area for a period of time. That said,
storms so far have shown enough east-southeast movement to limit
residence time for now, however trends will have to be
monitored as the afternoon hours progress. WPC did upgrade
southern portions of our forecast area into the SLGT risk
category for excessive rainfall, which seems reasonable given
the high PWAT values currently in place. In terms of severe
potential, overall threat remains marginal this afternoon as
best deep-layered shear remains across northern NY and southern
Canada, with better instability located further south along
the I-90 corridor and points south. That said, steep low-level
lapse rates along with heavy precip loading may result in a few
isolated strong wind gusts with collapsing storms.

Convective coverage should begin to decrease later this evening
with loss of daytime heating. As this occurs, upper ridge
responsible for the excessive heat these past few days will
begin to deamplify with time. Have maintained mention of early
morning fog for valley locations early Saturday morning, however
uncertainty exist due to possible increased cloud as compared
to this morning. Lows tonight should range from the lower to
middle 60s across the southern Dacks, to low 70s further south
across the mid Hudson Valley.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
**Heat Advisory for the mid-Hudson Valley and Litchfield County,
 CT through 8PM Sunday.**

Very similar conditions expected across the area on Saturday as
aforementioned backdoor front remains hung up across our area.
As a result, another day of late morning shwrs and storms is
expected, with activity becoming more widespread during peak
heating in the afternoon. Overall severe threat again looks
marginal as best deep layered shear remains displaced to the
north and displaced from the main instability axis which again
will be positioned along the Mohawk Valley and points south.
SPC has our area in another marginal risk for Saturday, with
isolated strong wind gusts again being the biggest concern.
Another warm day is expected for the mid Hudson Valley and
Litchfield County, CT as these locations will remain south of
the backdoor front. Have expanded the heat advisory further east
to eastern Dutchess and Litchfield Counties in collaboration
with adjacent offices.

Diurnal shwr/storm activity will begin to come to an end early
Saturday evening with loss of daytime heating. Attention then
begins to turn to Sunday, as large-scale upper wave begins
digging into the western and central Great Lakes, before sliding
into our region and gradually taking on a more neutral to
slightly negative tilt with time. As this occurs, much if not
all our forecast area will quickly move back into the warm
sector with increasing southwesterly low-level flow. Model MSLP
field suggest there could be a pre-frontal trough that leads to
an initial round of convection late Sunday morning and early
afternoon, with another round possible later in the day as main
cold front approaches from the west.

As of right now, deep layered shear of 30-40 kts appears likely
as the main upper trough approaches from the west with time.
Shear magnitudes will likely be a bit better than what we`re
seeing both today and Saturday, however the biggest caveat
appears to be just how unstable the atmosphere becomes later in
the day behind the early round of convection. That said,
kinematics and large-scale forcing will definitely be present,
and Sunday into early Sunday night definitely warrants continued
focus.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Main upper trough will slide through the region on Monday in a
post-frontal airmass with instability shwrs/iso storms possible
across the area. This will finally result in cooler temps for
the start of next week with highs on Monday expected to warm
into the upper 70s to lower 80s down south. Weak upper ridging
will lead to dry conditions across the area on Tuesday before
next upper trough approaches from the west on Wednesday. Shwrs
and storms look to move back into the area Wednesday afternoon
with activity possibly lasting through Thursday morning. This
looks to be followed by the arrival of high pressure Thursday
night with drier weather expected through the early weekend.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Through 00z Sunday...scattered showers/isolated thunderstorms
will be possible through around 04Z/Sat, with most remaining
west of the TAF sites.

Areas of low clouds and some fog will develop later this evening
and persist through daybreak Saturday. Mainly MVFR Cigs/Vsbys
are expected, however there is a possibility for localized
IFR/LIFR conditions, especially at KGFL.

Low clouds/fog should lift between 12Z-14Z/Sat. Scattered
showers and thunderstorms will then develop Saturday afternoon,
with localized MVFR/brief IFR Vsbys/Cigs possible.

Winds will be light/variable overnight through Saturday morning,
then should trend into the southeast to south at 4-8 KT Saturday
afternoon.

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

Outlook...

Saturday Night: Moderate Operational Impact. Scattered SHRA...TSRA.
Sunday: High Operational Impact. Breezy. Definite SHRA...TSRA.
Sunday Night: Moderate Operational Impact. Numerous SHRA...TSRA.
Monday: Moderate Operational Impact. Chance of SHRA...TSRA.
Monday Night: Low Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: Moderate Operational Impact. Chance of SHRA...TSRA.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT Sunday for CTZ001-013.
NY...Heat Advisory until 8 PM EDT Sunday for NYZ064>066.
MA...None.
VT...None.

&&

$$

SYNOPSIS...Gitro
NEAR TERM...Gitro/KL/NAS
SHORT TERM...Gitro
LONG TERM...Gitro
AVIATION...KL