303
FXUS61 KALY 201101
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
701 AM EDT Thu Jun 20 2024

.SYNOPSIS...
Our stretch of hot and humid weather continues today with
scattered areas of showers and thunderstorms this afternoon.
Some storms may become strong producing damaging winds gusts,
heavy downpours, and frequent lightning. We remain very warm and
humid Friday through the weekend but not quite as hot as
previous days. Areas of showers and thunderstorms redevelop
each afternoon with potential for more widespread rain and
stronger storms on Sunday as a cold front approaches.

&&

.NEAR TERM /THROUGH TONIGHT/...
**Heat Advisories remain in effect for all of eastern New York
 and western New England through 8 PM today. The Heat Advisory
 continues for the mid- Hudson Valley and southern Litchfield
 County through 8 PM Friday.**

Today will be our final day of our widespread dangerous heat
and humidity. We are starting the day quite muggy and warm once
again with record high minimum temperatures set yesterday at a
few climate sites. Regional radar shows a decaying MCS in
southern Canada but it should pass well to our north with a few
weak showers in central and western NY. Most of the morning
should be dry but latest CAMs suggest shower and storms start
developing by 16-17 UTC as our sfc trough approaches.

Previous discussion...Otherwise, expecting a third day of hot
and humid weather today as our large anticyclone with central
heights around 597dam gradually pushes southward into the mid-
Atlantic. With slightly faster zonal flow around the periphery
of the ridge sliding south into more of eastern NY and western
New England, we will be in a more favorable corridor that will
likely support afternoon shower and thunderstorms. Our
environment of 850hPa isotherms around 18-19C, mixing up to
around 800-850hPa, isolated storm coverage and a thicker cirrus
canopy the past few days has resulted in mainly low to mid 90s
highs and upper 80s in the higher terrain. Similar conditions
are expected today except with higher shower and storm coverage
so continue to show low to mid 90s for highs in the valley areas
with mid to upper 80s in the high terrain. We limited mid-90s
to the mid- Hudson Valley where shower/storm coverage should be
less. Combination of temperatures in the 80s/90s and high dew
points in the low 70s will once again support dangerous heat
index values reaching 95 - 100F. Technically we have lower heat
index values in the southern Adirondacks and southern Greens but
given this is the third day of hot/humid weather and that most
of these areas do not have air conditioning, we maintained heat
advisory headlines.

A sfc trough tracking southward towards our region midday into
the afternoon will provide a focus for afternoon shower and
thunderstorm development. In addition, embedded shortwaves
within the zonal flow aloft will also enhance forcing for
ascent. The hot/humid environment will easily support moderate
to high instability values ranging 1.5 - 2.5k J/kg so once
convective initiation begins, updrafts will likely quickly
strengthen. Taller storms will present damaging wind concerns
as DCAPE values reach >500J/kg. Given weak shear with 0-6km
shear values only around 20kt, storms should mainly be pulse-
type but can grow into storm clusters from outflow
boundaries/cold pools. High equilibrium levels >35kft will also
present high NCAPE and hail cape values which local research
shows supports frequent lightning as well. High PWATs around 2"
and high freezing levels >10kft means we will see efficient warm
rain processes and storms producing heavy downpours. Weak
steering flow aloft can result in some localized poor drainage
flooding, especially if storms persist over a given area.
Guidance and CAMs focus convection mainly around I-90 northward
where the best "ridge roller" environment should set-up so
placed likely POPs here and trended POPs to just chance in the
mid- Hudson Valley and NW CT. SPC maintained its "slight risk"
today with damaging winds the primary hazard. While the storm
coverage is not as widespread as we typically see with slight
risk type of days, the high instability will allow updrafts that
develop to quickly grow towards severe limits and with
increased forcing for ascent in place today, storm coverage
should be greater than we have seen in previous days.

Showers and thunderstorms diminish in coverage this evening
with the loss of daytime heating but a few isolated showers and
storms likely linger overnight as the sfc trough stalls over
the region. Otherwise, continued cloud coverage will keep
temperatures warm and it will stay muggy, especially in areas
that experience rainfall, once again overnight with
temperatures only dropping into the upper 60s to low 70s. Fog
should develop shortly after sunset in areas that experience
rain given the moist environment.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
**Heat Advisories continue for the mid-Hudson Valley and
 southern Litchfield County through 8PM Friday**

We remain within the northern periphery of our broad ~595dm
anticyclone Friday into Saturday with the conveyor belt of
increasingly stronger zonal/westerly flow and thus stronger
shear developing over eastern NY and western New England each
day. For Friday, the sfc trough from Thursday likely lingers
just south of Interstate 90 with a cold front gradually
approaching from the International border. Areas south of the
sfc trough, mainly the mid-Hudson Valley and Litchfield County,
will remain in the very warm and humid air mass with
temperatures likely rising back into the low to mid 90s. Given
continued high humidity, heat index values in these southern
zones should exceed heat advisory criteria reaching 95 - 100F
for a fourth day and thus we have extended our heat advisory for
Dutchess, eastern Ulster and southern Litchfield County through
8 PM Friday. We considered added in northern Litchfield and
western Ulster but current thinking is heat index values will be
a few degrees shy of the 95F heat advisory criteria and thus
did not included these zones. The day shift and reevaluate and
expanded the advisory if needed. The rest of the region will
still very warm and humid but high temperatures should only
reach into the mid to upper 80s and although it still will be
quite humid, the lower temperatures will keep heat index values
under the 95F threshold.

Given the lingering sfc trough near or just south of I-90 and
the additional forcing from the incoming cold front pressing
southward, isolated to scattered showers and thunderstorms will
likely quickly initiate once we reach the diurnal peak heating
hours by late morning with storm coverage growing through much
of the afternoon. Sfc instability will remain sufficiently high
1 - 2k J/kg and stronger westerly flow aloft will contribute to
higher deep layer shear ranging 25 - 35kts. Damaging winds
again are the primary concern with pulse type storms developing
along the sfc trough capable of evolving into line or bowing
segments thanks to stronger shear values. SPC has expanded it
marginal risk for severe weather from the I-90 corridor
southward through the mid-Hudson Valley and Berkshire/Litchfield
County where the higher instability and sfc trough should
overlap. However, the cold front pushing southward from
northern NY later in the afternoon will serve as a secondary
focus for organized convection for areas north of I-90 and the
stronger shear will help compensate for the somewhat weaker
instability. Thus, strong to severe storms including line or
bowing segment capable of damaging winds are possible even for
areas north of I-90. Heavy downpours are possible from
thunderstorms throughout the region as well given PWATs hovering
around 2" and efficient warm processes still in place.

Showers and storms gradually weaken in coverage and strength
Friday night but with boundaries lingering overhead, we
maintained chance POPs overnight. Expect another muggy and warm
night thanks to the lingering showers/isolated storms with
overnight lows only dropping into the mid to upper 60s. Areas in
the southern Adirondacks and southern Greens should turn a
little cooler as winds shift to the north-northeast in the wake
of the cold front. Patchy fog will also likely develop where
daytime rain took place.

Our boundaries from Friday hang around into Saturday and as our
anticyclone builds further south in to the TN/MS Valley, the
"ring of fire" around its northern periphery remains over
eastern NY and western New England. While temperatures will not
be hot as previous days, it will still be summer-like with high
temperatures reaching into the low to mid 80s for much of the
area. Dew points will also remain high enough to make it feel
humid. Heat index values will luckily finally be below heat
advisory criteria which will be a welcomed relief. Our region
remaining in the "ring of fire" combined with the boundaries
lingering overhead will allow for renewed convection during the
peak heating hours once again. Overall instability will be
weaker and the sfc boundaries will be less pronounced but with
embedded shortwaves still tracking aloft within the fast
westerly flow, strong shear may still be able to support some
stronger storms. Guidance suggests the boundary starts to lift
back northward as a warm front later in the afternoon which
could be a more favorable time for more widespread shower and
thunderstorm activity. We thus placed likely POPs Saturday
afternoon.

Showers and storms coverage weakens Saturday night as front
lifts north of the region. Just how far north the front reaches
remains uncertain and northern areas could still see
shower/storm activity should it not totally clear our area. Southerly
winds return in the wake of the boundary and guidance suggests
the warm sector that had finally left our region could make a
return. Temperatures remain warm in the mid to upper 60s and it
stay muggy.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Long term begins at 12z Sunday with a potent upper shortwave and
associated surface low located over the northern Great Lakes
region. The surface low deepens as these features track to the
eat/northeast Sunday. The system`s warm front will have lifted
north of our region by Sunday morning, placing our region in the
warm sector. As the pressure gradient strengthens, S/SW winds
increase and help to advect warm moist air into our region.
Exact highs are somewhat uncertain due to uncertainty in how
much cloud cover we see, but the current forecast is for highs
in the low 90s for portions of the Mid Hudson Valley with dew
upper 80s for the remainder of our valley locations with dew
points in the upper 60s and low 70s. Accordingly, heat indices
are currently forecast to reach low-end heat advisory criteria.
If forecast confidence in these heat index values increases over
the coming days, then additional heat advisories may be needed.


The system`s cold front will track through our region Sunday night
or Monday, and a pre-frontal trough will cross the region late
SUnday afternoon or evening ahead of the main cold front. With ample
instability and the LLJ and flow aloft both strengthening, there may
be enough overlap of instability and shear for some storms to be
strong to severe. Coverage and strength of storms will ultimately
depend on the timing of the pre-frontal trough relative to peak
heating. Best chance for strong to severe storms is on Sunday, but a
slower cold frontal passage may leave the window open for a few
stronger storms in western New England on Monday as well. Forecast
confidence on the timing of the cold front remains on the lower
side, but we should get a better idea over the next couple of days.

We see briefly cooler and drier weather Tuesday behind the front as
high pressure builds in from the southwest, but this high will
quickly slide to our east putting our region in a warmer S/SW flow
regime again for Wednesday. Then, Wednesday or Thursday, another
cold frontal passage may bring additional shower and thunderstorm
chances with cooler weather returning towards the end of the week.
However, the CPC still expected temperatures for days 8 to 14 to
average above normal with near normal precip for that same
timeframe.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
Through 12z Friday...Any lingering fog/mist burns off by 12z this
morning with just FEW to SCT mid and high clouds and prevailing VFR
conditions through at least noon today. This afternoon, showers and
storms are expected to develop. Have used tempo/prob30 groups to try
to hone in on the most likely time for showers/storms, but will
mention here that showers and storms are possible any time from
early afternoon through sunset this evening. If any storms move over
one of the terminals, then gusty winds and brief IFR vsby reductions
can be expected.

Showers and storms diminish tonight after sunset. Any areas that see
rain this afternoon/evening may see patchy fog overnight. Most
likely locations are GFL/PSF where fog has already been added to the
TAFs tonight. Will work to refine fog potential more with subsequent
TAF issuances.

Winds will be at 5-10 kt from the south/south west through most of
the day today, except will be more westerly at PSF. Winds diminish
to 5 kt or less after sunset tonight.

Outlook...

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

&&

.CLIMATE...
Record High Temperatures...

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...

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 this evening for CTZ001.
     Heat Advisory until 8 PM EDT Friday for CTZ013.
NY...Heat Advisory until 8 PM EDT this evening for NYZ032-033-
     038>043-047>054-058>061-063-082>084.
     Heat Advisory until 8 PM EDT Friday for NYZ064>066.
MA...Heat Advisory until 8 PM EDT this evening for MAZ001-025.
VT...Heat Advisory until 8 PM EDT this evening for VTZ013>015.

&&

$$

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