618
FXUS61 KALY 162307
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
707 PM EDT Wed Jul 16 2025

.SYNOPSIS...
Dangerous heat and humidity today into tomorrow with a warm
front tracking northward tonight into early tomorrow resulting
in scattered showers and thunderstorms. After a dry break late
morning into early afternoon, a cold front will lead to additional
scattered showers and storms tomorrow afternoon into the evening
with a marginal risk for severe weather. Then, we turn cooler
and less humid Friday into Saturday.

&&

.DISCUSSION...
Key Messages:

 - Dangerous heat and humidity today with heat index values
   ranging from 95 to 100 throughout portions of the Hudson and
   Mohawk River Valleys, eastern Windham County VT and northwest
   Connecticut, where a Heat Advisory is now in effect.
   Expecting low 100s heat index values in the immediate Hudson
   Valley.

 - Additional Heat Advisories will likely be needed for tomorrow
   with heat index values again reaching the mid/upper 90s.
   Probabilistic guidance shows 40 - 70% chance that high
   temperatures in the Hudson Valley will exceed 90 degrees.

 - Scattered to areas of showers/thunderstorms tonight with a
   second round of isolated to scattered showers and
   thunderstorms tomorrow afternoon. There is a Marginal Risk
   for severe thunderstorms tonight and again on Thursday with
   damaging winds the primary hazard.

Hot and humid weather continues for a second day this afternoon
with upper 80s and low 90s prevalent throughout much of eastern
NY and western New England. Given dew points in the upper 60s to
low 70s, the heat index or "feel-like" temperatures are in the
mid 90s to low 100s per NYS mesonet and ASOS sites in valley
areas, corroborating our heat advisories. While it remains dry
this afternoon, a dew point boundary positioned to our south in
PA/NJ will lift northward providing sufficient forcing for
increased coverage of showers and storms in the mid-Atlantic. As
the boundary lifts into western/central NY this evening along
with an upper level shortwave trough, both low and mid-level
forcing for ascent should be sufficient enough to result
initially isolated showers/storms mainly west of the Hudson
River. There is stronger agreement among the CAMs that the
shower/storm coverage increases as we approach Midnight in the
northern/eastern Catskills, western Mohawk Valley, and
western/southern Adirondacks with a second wave of
showers/storms in the pre-dawn hours into early Thursday
morning. Forecast soundings show ML CAPE values greater than
1000 J/kg ahead of the boundary with deep layer shear values
20-25kts so some storm clusters may develop, especially west of
the Hudson River. The Storm Prediction Center maintains its
marginal risk for severe weather for areas just west of the
Hudson River with damaging winds and downpours (PWATs surge
back towards 2" after 06 UTC tonight) the primary hazards.

After early morning convection winds down by 15 UTC, we should have
a break of dry weather through 18 UTC with guidance showing
early clouds giving way to breaks of sun as the low-level cap
erodes. With us entering into the warm/moist sector and dew
points in the low 70s, the increased insolation should easily
enhance our SB and ML CAPE values with values the HREF showing
>80% chance for SB CAPE values exceeding 1000 J/kg and even
30-40% chance of exceeding 2000 J/kg. With such a warm
environment, EL values over 30-35kft will likely lead to a
"tall-skinny" CAPE signature instead of the traditional "fat"
CAPE typically seen in severe weather soundings. This in
addition to mid-level lapse rates only steepening to 5.5-6C/km
could limit updraft strength. Even still, a conveyor belt of
stronger westerlies 30-40kts will slide into the Northeast by
the afternoon ahead of the parent shortwave trough tracking
across southern Ontario. This will enhance deep layer shear
values with 0-6km shear vectors reaching 30-35kts which will be
oriented more perpendicular to a pre-frontal trough (and
potential remnant MCV) pushing eastward through the Saint
Lawrence River Valley into eastern NY by 18 - 21 UTC tomorrow.
Forecast soundings also show veering shear profile with
southerly sfc winds becoming westerly in the mid and upper
levels. In fact, the 12 UTC HREF shows 30-50% chance of 4-hr max
updrafts exceeding 20 m/s in the western/southern Adirondacks,
the western/central Mohawk Valley and Upper Hudson Valley 20 -
02 UTC suggesting the potential for at least isolated severe
weather coverage. While the instability and shear are favorable
for storms to grow upscale and grow into semi-discrete or storm
clusters, it is a rather conditional threat as it will depend on
how quickly morning clouds and the cap can break which will
determine how much convection can initiate. The conditional
nature of this set-up lines up with the marginal risk from the
Storm Prediction Center with most CAMs showing limited storm
coverage. Damaging winds will be the primary hazard from any
severe storm. We will continue to closely monitor the severe
potential and how CAMs trend as machine learning guidance from
CSU also shows 15 - 30% chance for severe wind tomorrow
afternoon. The SPC probabilistic guidance does include a 2%
tornado risk mainly across our northern zones into the North
Country where helicity values are 100 - 150m2/s2.

Otherwise, it will be another hot and humid day with heat index
values again likely exceeding 95 degrees, necessitating heat
advisory in the Hudson and Mohawk Valley. If clouds linger
longer into the afternoon, temperatures could be a few degrees
lower but high dew points will still make it uncomfortably
humid. Most convection diminishes by Midnight with our rather
potent cold front and trough following in its wake overnight.
This will usher in a much cooler and less humid air mass and
even breezy northwest winds in the wake of the front. Breezy
winds including gusts up to 20kts linger into Friday morning
with a tight pressure gradient still overhead. Friday will be a
beautiful day with a noticeable drop in humidity and cooler
temperatures in the 70s/low 80s with winds decreasing through
the day as high pressure builds further east. Friday night will
be a good night to open up the windows as temperatures drop into
the 50s. Pleasant weather continues into Saturday. Sat night
into Sunday features our next chance for rain and embedded
storms as a warm front and sfc low track into the region but
there remains uncertainty on the overall track and timing of
these features. For now, we show widespread chance and likely
POPs Sat night into the day on Sunday.

Then, Canadian high pressure builds back overhead for early to
middle of next week ushering in cooler and comfortable humidity
values. Will continue to monitor the next potential period of
above normal temperatures and higher humidity for the middle to
end of next week.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Through 00z Friday...VFR conditions generally expected to
prevail through much of the 24 hour TAF period. The only
exceptions will be possible MVFR cigs associated with low
stratus clouds at KPOU/KPSF early Thursday morning, although
confidence is low so will just mention SCT clouds for now.
Also, widely scattered TSRA expected late tonight with a surface
trough passage and again Thursday afternoon with a cold front
passage. So will mention PROB30 for TSRA at all TAF sites for
both late tonight and Thursday afternoon. Winds will be
southerly less than 10 kt tonight, shifting to the south-
southwest Thursday morning and increasing to 10-12 kt with
occasional gusts near 20 kt.

Outlook...

Thursday Night: Low Operational Impact. Slight Chance of SHRA...TSRA.
Friday: No Operational Impact. NO SIG WX.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: Low Operational Impact. Slight Chance of SHRA.
Saturday Night: Moderate Operational Impact. Likely SHRA...TSRA.
Sunday: Moderate Operational Impact. Chance of SHRA...TSRA.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Air Quality Alert until 11 PM EDT this evening for CTZ001-013.
     Heat Advisory until 8 PM EDT this evening for CTZ001-013.
NY...Air Quality Alert until 11 PM EDT this evening for NYZ063>066.
     Heat Advisory until 8 PM EDT this evening for NYZ038-040-041-
     043-049-050-052-053-059-060-064>066-083-084.
MA...None.
VT...Heat Advisory until 8 PM EDT this evening for VTZ015.

&&

$$

SYNOPSIS...KL/Speciale
DISCUSSION...Speciale
AVIATION...JPV