297
FXUS61 KALY 121840
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
240 PM EDT Mon Aug 12 2024

.SYNOPSIS...
An upper level trough will bring scattered showers and isolated
thunderstorms this afternoon under partly to mostly cloudy
skies and breezy winds. High pressure building eastward will
give us a pleasant and dry Tuesday before scattered showers and
thunderstorms increase in coverage Wednesday afternoon and
Thursday afternoon. Otherwise, cooler temperatures today
gradually trend warmer through the afternoon.

&&

.NEAR TERM /THROUGH TONIGHT/...
.As of 130 PM EDT...A blanket of stratus clouds has progressed
south and east across eastern NY and western New England this
afternoon along the leading edge of the cold pool associated
with our incoming positively tilted upper level trough clearly
evident over Lake Ontario/Erie into western NY on GOES16 water
vapor. Temperatures are struggling to warm out of the 70s thus
far given the mostly cloudy skies and gusty winds reaching up to
20-25kts that have developed as lapse rates steepen beneath the
incoming cold pool (500 hPa isotherms -16C to -18C). Partial
breaks of sun at times will helps temperatures warm a few
degrees but temperatures will likely cool once clouds return.
Thus, high temperatures today will be cooler than recent days
thanks to the clouds and gusty winds only reaching into the in
the low to mid 70s in the valley with mid to upper 60s in the
higher terrain.

While cloud coverage will limit the amount of available
instability, the steepening lapse rates beneath the cold pool
has aided in isolated to widely scattered showers and isolated
thunderstorms develop. Latest regional radar shows shower
activity greatest over the southern Adirondacks and western
Mohawk Valley closest to the cold pool. As the cool pool shifts
eastward through the afternoon into eastern NY and western New
England, expect shower coverage to increase. With wet-bulb zero
heights remaining rather low around 8 - 8.5kft, any low-topped
storms that can develop can produce brief lightning strikes and
perhaps even some small hail. However, this will be contingent
upon storms growing upscale and this should be limited at best
given latest CAM guidance. Showers/storms, cloud coverage and
gusty winds will diminish with the loss of daytime heating
towards sunset.

Large scale subsidence building behind the trough will aid in clearing
skies and decreasing winds this evening supporting ideal
radiational cooling. With dew points remaining in the mid to
upper 50s, fog will likely develop towards the pre-dawn hours,
especially in areas where rain occurs during the day. Included
fog in the latest forecast update. Temperatures will turn chilly
as northerly winds in the wake of the trough axis supports cool
air advection. Overnight lows should reach into the mid to
upper 50s with upper 40s in the southern Adirondacks and
southern Greens.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Surface high pressure centered in the Midwest gradually building
eastward and broad trough centered over eastern Quebec maintaining
north to northwest flow aloft will keep eastern NY and western
New England dry and mostly sunny on Tuesday. After a cool and
sunny start to the day, some diurnally driven clouds will
develop once we reach the convective temperatures, especially in
the higher terrain areas. Highs will likely warm a few degrees
higher than Monday thanks to the increased insolation with highs
rising into the mid to upper 70s with around 80 in the valley
areas. Cooler in the higher terrain with highs in the upper 60s
to low 70s. Dew points should remain comfortable in the upper
50s thanks to the northwest flow aloft.

Another cool night expected Tuesday night thanks to ideal radiational
cooling as the sfc high from the Midwest builds eastward. Temperatures
should be similar to Monday night but may not be quite as
chilly. Overnight lows still expected to fall into the upper 50s
to around 60 so another great night to open up the windows.
Fog once again expected, especially in valley areas, as
temperatures cool towards the respective dew points.

While the weak ~1020hPa sfc high builds further into the
Northeast on Wednesday, the upper level trough over eastern
Quebec looks to strengthen as its upper level cool pool shifts
south and westward through northern New England. Guidance
remains in good agreement that as the cool pool shifts south and
westward steepening mid-level lapse rates towards 5.5 - 6C/km
with northerly winds being maintained aloft, afternoon showers
and thunderstorms should develop, especially in the southern
Adirondacks and southern Greens. The northerly winds will help
advect showers and storms from north to south through the
afternoon. Overall instability is not overly impressive
generally under 1000 J/kg; however, the steepening lapse rates
and temperatures warming in the low to mid 80s in valley areas
can support updrafts growing upscale enough that they can
develop into isolated to scattered non-severe thunderstorms
during the afternoon.

Isolated to scattered showers and storms diminish with the loss
of daytime heating with clearing skies and cooling temperatures
into upper 50s to low 60s.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
The extended forecast period begins with high pressure building in
at the surface over NY and PA.  However, an upper level trough will
still be over the Canadian Maritimes and northern New England. Some
diurnally driven scattered showers and isolated thunderstorms will
be possible over most of the region, especially over the higher
terrain, as a weak impulse on the north/northwest side of the mid
and upper low rotates across the region. Max temps will be near
normal in the upper 70s to lower 80s in the lower elevations and
upper 60s to mid 70s over the higher terrain.  The
showers/thunderstorms will diminish Thu night with the loss of the
daytime heating with lows in the 50s to lower 60s.

The mid and upper level ridge axis and high pressure at surface will
be near or over NY and New England providing enough subsidence for
partly to mostly sunny skies and fair weather with dewpoints in the
mid 50s to mid 60s.  Max temps will be near to slightly above normal
with 70s to lower 80s.  Mid and high clouds increase Fri night with
a slight to very low chance of a shower or isolated thunderstorm
ahead of a warm front especially southwest of the Capital Region.

The weekend features a trend to more unsettled weather, as the warm
front attempts to move through on Saturday with low pressure moving
through the Great Lakes Region and a cold front from the Mid
Atlantic States. The timing of this system and the cold front varies
on the medium range deterministic guidance and ensembles.  The
blocking mid and upper level ridge near the East Coast slows down
the system. For now, we forecasted a chance of showers and a slight
chance of thunderstorms each day.  Temps look seasonable each day
for mid August with moderate humidity levels. The latest Day 8 to 14
Temp and Pcpn Outlook from CPC for Aug 19-25 forecasts above normal
temps and pcpn for eastern NY and western New England.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
Upper level trough is moving across the Northeast today, which is
allowing for some spotty rain showers.  Within showers, a brief
reduction down to MVFR conditions is possible for both visibility
and ceilings.  Otherwise, it will continue to remain VFR with bkn-
ovc cigs around 4-6 kft through the rest of the day.  West to
northwest winds will be 5 to 10 kts, although slightly higher
winds and some higher gusts are possible at KALB.

By evening, the threat for showers will decrease as the shortwave
moves away and the loss of daytime heating.  Clouds will also start
to dissipate, allowing for skies to clear out for tonight.  With the
clearing skies and lighter winds, some radiational fog may develop
for the late night hours.  This is most likely for KGFL and KPSF,
where IFR conditions are currently expected within fog after 05z.
Elsewhere, its unclear how much of an impact there will be with
fog/mist, but will mention MVFR mist for KPOU and MIFG towards
sunrise at KALB.

Any fog or mist should break up after sunrise, allowing for VFR
conditions to return for Tuesday morning.  VFR conditions are
expected through the day on Tuesday with just some few-sct diurnal
cumulus clouds, especially for the high terrain.  West to northwest
winds will be light around 5 kts for all sites through the day.

Outlook...

Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: Moderate Operational Impact. Scattered SHRA...TSRA.
Wednesday Night: Low Operational Impact. NO SIG WX.
Thursday: Low Operational Impact. Slight Chance of SHRA...TSRA.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: No Operational Impact. NO SIG WX.
Friday Night: Low Operational Impact. Slight Chance of SHRA.
Saturday: Moderate Operational Impact. Chance of SHRA...TSRA.

&&

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

&&

$$

SYNOPSIS...Gant/Speciale
NEAR TERM...Speciale
SHORT TERM...Speciale
LONG TERM...Wasula
AVIATION...Wasula