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551
FXUS61 KALY 281419
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
1019 AM EDT Fri Jun 28 2024

.SYNOPSIS...
After a chilly start to our Friday, high pressure will give us
a sunny and comfortable end to the work week. Winds turn gusty
for Saturday with areas of rain tracking slowly from northwest
to southeast through the day. Rain turns moderate to potentially
heavy at times Saturday night with additional rain and
thunderstorms for Sunday as a cold front pushes through the
region.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 1019 AM EDT...Surface high pressure (around 1021 mb) is
centered right over eastern Upstate New York. The visible
satellite imagery shows sunny skies over the area, with just
some thin cirrus clouds in a few spots. The 12z KALY sounding
shows plenty of dry air in place, with PWAT value of 0.40". In
addition, a strong inversion around 800 hpa will help prevent
many clouds from developing today, so will continue to expect
sunny skies through much of the day.

After a cool start, temps have been rising thorugh the 60s.
Highs will be in the mid to upper 70s for many areas (upper 60s
to low 70s in the high terrain), which is about five degrees
below normal for late June. Dewpoints will be very low for late
June with values only in the 40s, so it will be very
comfortable. Winds will be much lighter than yesterday with the
high pressure nearby.

Cirrus clouds spill overtop the ridge late this afternoon into
this evening with skies becoming cloudy overnight as the upper
level ridge axis shifts to our east, allowing warm air and
moisture advection to increase. The increasing sky coverage
will keep temperatures milder than Thurs night with overnight
lows only dropping into the mid to upper 50s with low 60s in the
valley. Coolest temperatures likely in western New England
where the thicker clouds will be delayed.
-- End Changed Discussion --

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
Broad troughing develops over the Great Lakes on Saturday with
an amplifying shortwave tracking across the Upper Great Plains
while a 595dm Bermuda high sits just off the East Coast. This
set-up will result in a conveyor belt of strong southwest winds
directed into the Northeast with a sfc warm front tracking
northward through the mid-Atlantic. Guidance is in good
agreement keeping this boundary mainly to our south through most
of Saturday with gusty south to southeast sfc winds ahead of the
front reaching up to 25kts (strongest in the Hudson Valley).
Otherwise, mainly cloudy skies keep temperatures in the mid to
upper 70s with around 80 in valley. The conveyor belt of strong
southwesterly winds (including a corridor of 45-50kts in the
850 - 700hPa layer) will advect a moisture rich air mass from
the Gulf of Mexico into the Northeast with dew points soaring
into the mid to upper 60s and PWATs 2 - 2.25". Per the NAEFS,
such high PWATs rank 2.5 standard deviations above normal and
even reaches the 99th percentile of the model`s PWAT forecast.
The combination of high moisture content and strong kinematics
also supports impressive moisture transport ahead of the broad
upstream trough with a rather large breath of integrated water
vapor transport approaching 2 - 3 standard deviation above
normal.

The broad positively tilted upstream troughing will support
areas of showers advancing into our southern Adirondacks/Mohawk
Valley Saturday morning. Enough subsidence looks to remain for
areas along and east of the Hudson River that Saturday morning
remains mainly dry outside of some isolated showers. Southwesterly
flow deep through the column will slow the eastward progression
of rain showers until Saturday afternoon for areas east of the
Hudson. Western New England will remain drier for much of
Saturday with showers reaching this area late P.M or early
evening.

Overall instability Saturday based on forecast soundings is
quite limited thanks to cloud coverage and warm temperatures
aloft impeding steep lapse rates. Despite this, the high
moisture content and strong deep layer shear (0-6km shear values
40 - 45kts) means we cannot discount some strong to possible
severe thunderstorms developing, especially along the leading
edge of the incoming rain. SPC maintains its marginal risk for
severe weather on Saturday through much of eastern NY but leaves
out western New England given even less of a chance for
sufficient instability further east.

Showers become more organized and expand in coverage Saturday
evening with areas of moderate to heavy rain developing as the
aforementioned amplified shortwave trough progresses into
southern Ontario, resulting in stronger height falls over the
Northeast. The increased forcing for ascent including a broad
anti-cyclonically curved jet aloft within such a moisture laden
environment (freezing heights nearing 15kft) will easily
support efficient warm rainfall processes. In addition, elevated
instability advances eastward Saturday night into our area
which will support embedded thunderstorm activity and potential
for higher rainfall rates. With an impressive belt of 40-45kt
southwest flow both at 850hPa and within the 850-300hPa layer,
there are increasing signs that heavy rain will train/repeatedly
impact some areas, enhancing chances for flooding. Embedded
convection will also increase rainfall rates. To add insult to
injury, southwest flow typically upslopes the south facing
slopes of the southern Adirondacks and parts of the Mohawk
Valley, exasperating rainfall rates. Given theses factors, we
and BTV collaborated with WPC and a slight risk was introduced
in the Day 2 excessive rainfall for the southern Adirondacks and
western Mohawk Valley with a marginal for the rest of eastern
NY and western New England.

Latest QPF amounts range 1 to 2 inches for areas mainly north
and west of the Capital District with 0.50 - 1 for the rest of
eastern NY and western New England. But, locally higher amounts
are possible depending on where any areas of rain can train or
repeatedly impact.

Heavy rain exits into New England by the pre-dawn hours Saturday
night as the sfc boundary finally tracks eastward through our
area. While Sunday starts off dry, it will still be very humid
as dew points remain in the upper 60s to low 70s with a period
of morning sun generating instability. As the trough axis
associated with our incoming potent shortwave pushes west to
east through our area late Sun morning into the early afternoon,
the boundary will result in renewed scattered areas of rain and
thunderstorms. Since the boundary will not reach the mid-Hudson
Valley and western New England until Sunday afternoon, there
likely will be more time for the environment here to destabilized
within this highly sheared environment to support strong to
even severe thunderstorms. SPC introduced a slight risk for
severe weather for these areas with damaging winds the main
hazard from severe thunderstorms. There is a marginal risk for
severe weather across the rest of eastern NY into southern VT
but given the earlier arrival time of the trough axis, there is
more uncertainty on how much destabilization can occur. Areas
south/east of the Capital District have a higher chance to
destabilize enough than north/west.

Otherwise, it will turn quite warm on Sunday thanks to increased
sunshine with the air mass ahead of the trough axis featuring
850hPa isotherms +15C to +18C. Highs should reach into the mid
to upper 80s and with dew points still in the 60s, it will fee
closer to 90 in the Hudson Valley with near Heat Advisory
criteria (heat index ~95F) in the mid-Hudson Valley. Behind the
trough axis and renewed showers/storms, westerly winds turn
quite breezy/gusty as a large area of high pressure in the
Midwest builds eastward, tightening the sfc pressure gradient.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Cold front should move south/east of region Sunday evening with
perhaps some lingering showers/thunderstorms across the mid Hudson
Valley and NW CT. Upper level trough then slowly shifts across and
east of the region Monday, however lingering cold air aloft could
promote isolated showers across the southern Adirondacks, southern
VT and Berkshires, especially through early afternoon. Otherwise,
high pressure building in from the Great Lakes should bring
generally fair weather Monday night through Tuesday night. It may be
breezy Monday with a relatively tight low level pressure gradient
across the region.

High pressure then shifts off the eastern seaboard Wednesday, with a
cold front approaching from the west late Wednesday, and then
tracking across the region Wednesday night into Thursday. Some
showers/thunderstorms will be possible with this system late
Wednesday through Thursday, although exact timing details and areal
coverage remain uncertain.

Temperatures will initially be slightly below normal Sunday night
through Monday night, with lows in the 40s to lower 50s, and Monday
highs mainly in the 70s for valley areas 60s across higher terrain.
Near seasonable temperatures expected Tuesday with highs 80-85 in
valleys and 75-80 across higher terrain. Above normal temperatures
then expected Wednesday into Thursday, with highs 85-90 in valleys
and upper 70s/lower 80s across higher terrain areas. Increasing
humidity levels could allow heat indices to approach the mid 90s
within the mid Hudson Valley, especially on Thursday.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
Through 12Z/Sat...VFR conditions are expected through at least
08Z/Sat with just occasional patchy high/mid level clouds. Some
lower clouds and isolated showers may approach KGFL and KALB after
10Z/Sat with brief MVFR Vsbys/Cigs possible. MVFR Cigs may
also develop at KPOU toward 12Z/Sat.

North to northwest winds 4-8 KT this morning will become north to
northeast at 5-10 KT by mid morning, shifting into the east to
southeast at similar speeds this afternoon. Winds will become
light/variable around/shortly after sunset, however will remain
southeast to south and increase to 8-12 KT at KALB with some gusts
of 15-20 KT possible after 03Z/Sat.

Outlook...

Saturday Night: High Operational Impact. Breezy. Definite RA...TSRA.
Sunday: Moderate Operational Impact. Breezy. Likely SHRA...TSRA.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: Low Operational Impact. NO SIG WX.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: Low Operational Impact. Isolated SHRA...TSRA.

&&

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

&&

$$

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