978
FXUS61 KALY 130529
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
129 AM EDT Tue Aug 13 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 /UNTIL 6 AM THIS MORNING/...
Skies are mainly clear across eastern New York and western New
England this morning outside of some low stratus across some of
the higher peaks of the SW Adirondacks, Eastern Catskills,
Southern Greens, and Berkshires. As such, temperatures have
succumb to the effects of ample radiational cooling, currently
ranging primarily from the upper 40s to 50s with pockets of low
60s in the Hudson Valley.

SPC Mesoanalysis shows the axis of the upper shortwave displaced
to the east of the region just off the New England Coast,
yielding northwest flow for our area on its back side. Advection
of cool, dry air will therefore continue throughout the night
tonight such that temperatures will fall to a low point of upper
40s to mid/upper 50s with pockets of mid 40s possible in the
Southwest Adirondacks should cloud cover remain minimum. And,
with surface high pressure building in from the west providing
plenty of subsidence, conditions will remain dry.

Few changes were necessary with this update as the forecast is
in good shape. Minor adjustments were made to temperatures and
sky cover, but outside of that, the forecast remains on track.
See the previous discussion below for additional details.

PREVIOUS DISCUSSION:
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 /6 AM THIS MORNING 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/...
Our upper level trough centered in the Canadian Maritime
persists into Thursday and closes off/deepens slightly to
570-575dm as it absorbs a mid-level impulse. A subtle backdoor
cold front sinks south and westward through northern New England
towards eastern NY as mid-level lapse rates steepen in response
the incoming cool pool aloft. Steeper lapse rates combined with
dew points rising into the low to mid 60s will help promote
increased surface based instability compared to the previous few
days. As the weak backdoor front progresses south and westward
into western New England, it should help focus shower and
thunderstorm activity and coverage should be higher compared to
Wednesday. Thus, we show widespread chance POPs for Thursday
afternoon with the highest POPs in the Upper Hudson Valley,
northern Taconics, southern VT and northern Berkshire County
which will be closest to the low-level forcing and cool pool
aloft. Even still, not expecting severe weather as deep layer
shear remain minimum. With northerly flow through much of the
column, showers and storms should once again travel from north
to south. Otherwise, daytime high temperatures should reach into
the upper 70s to low 80s with dew points slightly muggier but
still not oppressive thanks the northerly flow.

Showers/storms diminish with the loss of daytime heating as the
upper level closed low in the Canadian Maritimes exits and
shortwave ridging/subsidence builds into the Northeast. Friday
is looking like the nicest day of the weekend as shortwave
ridging remains in control as surface high pressure builds off
the East Coast, promoting a southwesterly return flow and mostly
sunny skies. Temperatures should turn more summer-like rising
into the mid-80s and humidity levels turning more uncomfortable.

Conditions turn more unsettled for the weekend as a disturbance
in the Central CONUS matures and closes off as it slowly
progresses eastward. Its occluded boundary shifts north and
eastward into the region on Saturday with increased warm air
and moisture advection supporting uncomfortable humidity levels
and increased chances for showers and thunderstorms as the
boundary and potentially its triple point tracks into the
Northeast. Should the triple point reach our area, we could see
an area of more organized rain and thunderstorms but it is still
far out in time to nail down the specifics. For now, we trend
POPs upwards through the day Saturday with widespread chance
POPs for Saturday afternoon.

The closed low slowly tracks through the Great Lakes with good
model consensus that it will remain upstream of us even by
Sunday. This would keep us within the southwesterly return flow
and maintain uncomfortable humidity levels through Sunday.
Depending on where the parent cyclone tracks, we either will
have a continued chance for showers and thunderstorms,
especially during the afternoon hours, into Sunday or, if the
cyclone escapes northward into Ontario, we could trend drier.
Given ongoing uncertainty and the fact that the cyclone should
still be nearby with the Northeast still in the southwesterly
return flow, we maintained widespread chance POPs for Sunday
with seasonable temperatures yet high humidity levels.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...


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...Gant/Speciale
SHORT TERM...Speciale
LONG TERM...Speciale
AVIATION...JPV