870
FXUS61 KALY 280848
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
448 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/...
We will start the day quite cool by late June standards with
much of eastern NY and western New England in the 40s to low 50s
thanks to ideal radiational cooling conditions overnight. We
checked June 28 record lows and ALB and POU look to be out of
reach but GFL will be close. Its record low is 40 degrees from
1970 and our forecast is for 43.

Large scale subsidence and sfc high pressure strengthening to
~1020hPa will build over the Northeast today giving us sunny
skies. The very dry air mass (PWATs around 0.50") will also
maintain low dew points in the 40s and thus very low humidity
once again. While winds today will be much lighter than
yesterday, northwest flow aloft will keep temperatures
seasonably cool with high temperatures only rising into the mid
to upper 70s (upper 60s in the southern Greens and southern
Adirondacks). This is about 5 degrees below normal as late June
high temperatures typically reach into the low 80s.

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 increases. 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.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...

Broad trough develops over the Great Lakes on Saturday with an
amplifying shortwave tracking across the Upper Great Plains
while a 595dm Bermuda high just off the East Coast. This set-up will
result in a strong southwest jet over the Northeast with a sfc
warm front tracking northward through the mid-Atlantic towards
our area. Guidance is in good agreement keeping this boundary
mainly to our south through most of Saturday with south to
southeast sfc winds and mainly cloudy skies keeping temperatures
in the mid to upper 70s with around 80 in valley areas. Despite
slightly below normal high temperatures, the conveyor belt of
strong southwesterly winds through much of the column (including
a corridor of 45-50kts in the 850 - 700hPa layer) will advect a
moisture rich air mass into the Northeast with dew points
soaring into the mid to upper 60s. This includes a plume of
PWATs 2"+ with origins from the Gulf of Mexico advancing from
west to east across eastern NY into western New England through
the day Saturday. 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 integrated
water vapor transport approaching 3 standard deviation above
normal.

With all this said, the broad positively tilted upstream
troughing and embedded shortwaves within the fast southwesterly
flow aloft will support areas of showers advancing into our
southern Adirondacks/Mohawk Valley Saturday morning. Enough
subsidence looks to remain in place for areas along and east of
the Hudson River that Saturday morning remains mainly dry yet
gusty (wind gusts up to 25kts) outside of some isolated
showers. Southwesterly flow deep through the column will slow
the eastward progression of rain showers until Saturday
afternoon when chances for showers eventually spill east of the
Hudson River. 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 completely 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 the delayed arrival of
any storms. Otherwise, some embedded thunderstorm activity
within the incoming rain showers is not ruled out but not
expecting widespread thunderstorms.

Areas of moderate to heavy rain tracks eastward across our area
Saturday night as the aforementioned potent/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 further. Given theses factors, we and BTV
collaborated with WPC to introduce a slight risk 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 quite humid
as dew points remain in the upper 60s to low 70s with a period
of morning sun. 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 enough time
for the environment 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 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 /07Z FRIDAY THROUGH TUESDAY/...
Through 06z/Sat...mainly VFR conditions are expected through the TAF
period with just occasional patchy high/mid level clouds. There is a
slight chance some patchy ground fog could briefly develop at KGFL
between 09Z-11Z/Fri, but overall chances seem quite low given the
dry air mass in place.

North to northwest winds should remain less than 5 KT through
daybreak, with north to northeast winds 5-10 KT developing shortly
after sunrise, shifting into the east to southeast at similar speeds
this afternoon. Winds will become light/variable around/shortly
after sunset.

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...Speciale
SHORT TERM...Speciale
LONG TERM...KL
AVIATION...KL