546
FXUS61 KALY 131845
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
245 PM EDT Tue Aug 13 2024

.SYNOPSIS...
Beautiful weather today with seasonable temperatures before
chances for isolated to scattered showers and thunderstorms
increase tomorrow and Thursday, especially in the higher
terrain, thanks to a disturbance in the Canadian Maritimes.
Humidity levels turn more uncomfortable Friday into the weekend
as a disturbance from the Great Lakes slowly pushes eastward.
Chances for showers and thunderstorms increase Saturday and
Sunday as the occluded boundary approaches.

&&

.NEAR TERM /THROUGH TONIGHT/...
Beautiful August day continues across the Northeast as a 1020hPa
anticyclone centered over the Great Lakes builds eastward. Morning
sun will continue to mix with some fair weather cumulus clouds
as areas reach their respective convective temperature. 12 UTC
ALY sounding shows low PWATs under 1 inch once again thanks to
northerly flow through the column as we remain on the east side
of the incoming high. Thus, humidity levels will once again be
low/comfortable today. Forecast soundings support deep boundary
layer mixing extending up to and even above 5kft this afternoon
and with 850hPa isotherms ranging from +11C to +13C, high
temperatures this afternoon should easily reach the mid to upper
70s with even around 80 in the valley.

Cumulus clouds dissipate late this afternoon once we cool below
the convective temperature. Sfc high pressure building eastward
will support ideal radiational cooling tonight thanks to clear
skies, light winds, and low humidity. Another great night to
open up the windows as temperatures cool into the mid to upper
50s across eastern NY and western New England with even mid to
upper 40s in the southern Adirondacks, southern Greens, and
higher peaks of the eastern Catskills.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...

An upper level disturbance from the Canadian Maritimes will
shift into the Gulf of Maine Wednesday into Thursday as a subtle
backdoor front gradually progresses south and westward through
northern New England. Meanwhile, upper level ridging from the
Great Lakes and sfc high pressure will be slowly building into
the Northeast. Such a synoptic set-up will maintain northwest
flow over the region and keep dew points comfortable in the
upper 50s to around 60 with temperatures trending a bit warmer
rising into upper 70s to low 80s but remaining seasonable.

As the cold pool from the disturbance in the Canadian Maritimes
shifts south and westward, lapse rates will steepen over much of
eastern NY and western New England both days ranging 5.5C/km to
6C/km. After morning fog burns off, morning insolation will
contribute to increased surface based instability but marginal
dew points will keep CAPE values in check only rising to 500 -
1000J/kg. Deep layer shear values will also be minimal both days
only reaching 15 - 25kts. Thus, expecting cumulus clouds to
develop once we reach the convective temperature mid to late
morning with isolated to scattered showers and thunderstorms
developing early to mid afternoon, initially in the southern
Adirondacks and southern Greens before northerly flow directs
showers/storms southward. Any shower/storm should be short-lived
but some areas could see more than one brief shower/storm,
especially in the Mohawk Valley and Upper Hudson Valley as
shower/storms track southward out of the Adirondacks. While
storms will likely not turn severe given weak shear/instability,
the cold pool aloft (500hPa isotherms cooling to -13C to -14C)
will keep wet- bulb zero heights near or slightly below 10kft so
any updrafts that can grow tall enough may be able to support
small hail.

Isolated to scattered showers/storms diminish once we loss peak
heating late afternoon into the evening with clouds clearing and
wind becoming light/variable. With dew points remaining near 60
and radiational cooling setting in, fog looks to develop both
nights, especially in valley areas and where rain falls during
the day.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
The period starts out on Fri with surface high pressure shifting
east off the New England coast, with an upper level ridge axis
forecast to be in place through the day. This should result in dry
conditions and near normal temperatures across our area.

The pattern then becomes unsettled during the upcoming weekend, as
an upper level trough approaching from the Great Lakes slowly moves
east across the region. Low level southerly flow will increase ahead
of the trough, which will transport anomalous moisture (PWAT
anomalies increase to +1 to +2 STDEV) northward. Along with forcing
from the upper trough, a frontal system/triple point at the surface
looks to gradually push eastward through Sun. So will mention 50-70%
PoPs Sat through Sun night, with the highest values during the
diurnally favored times for convection (afternoon/evening). Locally
heavy rainfall may occur, especially within any persistent
convective showers/T-storms. Temperatures look near normal for
highs, but above normal for lows due to mostly cloudy and humid
conditions at night.

The main upper level trough axis may still be over or even west of
our area on Mon, so will linger mention 30-60% PoPs. There will be
chances for thunder again during the afternoon/evening hours.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Flying conditions are currently VFR across the region with just some
diurnal cumulus and some passing thin high cirrus clouds.  Through
the rest of the day, flying conditions will be VFR with light north
to northwest winds.

Skies will clear out for tonight with very light or calm winds. This
could allow for some radiational fog to develop for the late night
hours at KGFL and KPSF, but the other sites should have a large
enough T/TD spread to prevent any fog from developing.

On Wednesday, any early morning fog or mist will dissipate shortly
after daybreak.  This will allow for another day of VFR conditions
with just few-sct clouds for the morning and early afternoon hours
around 4-6 kft.  North to northwest winds on Wednesday will be
around 5 kts for all sites.  A stray shower or t-storm cannot be
ruled out for the mid afternoon into early evening hours, mainly for
the northern sites.

Outlook...

Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: Moderate Operational Impact. Scattered SHRA...TSRA.
Thursday Night: No Operational Impact. Patchy FG.
Friday: No Operational Impact. NO SIG WX.
Friday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Saturday: Moderate Operational Impact. Likely SHRA...TSRA.
Saturday Night: Moderate Operational Impact. Likely SHRA...TSRA.
Sunday: High Operational Impact. Likely SHRA...TSRA.

&&

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

&&

$$

SYNOPSIS...Speciale
NEAR TERM...Speciale
SHORT TERM...Speciale
LONG TERM...JPV
AVIATION...Frugis