Thomaston, Connecticut Weather Forecast Discussion

155
FXUS61 KALY 230104
AFDALY
AREA FORECAST DISCUSSION
National Weather Service Albany NY
904 PM EDT Mon Sep 22 2025
.UPDATE...
Have increased winds within the Hudson River Valley, where
south/southeast winds have been gusting up to 20-25 mph at
times. Otherwise, initial area of showers across central NY has
eroded, however additional scattered showers are developing
across western NY and should track into portions of the SW
Adirondacks later this evening.
&&
.SYNOPSIS...
Showers will develop for areas north and west of Albany
overnight. Periods of much needed rain showers will then be
prevalent throughout the week as an unsettled pattern remains in
place with temperatures looking to remain generally above
normal for late September.
&&
.DISCUSSION...
Key Messages:
- Beneficial rain to come this week through multiple rounds of
   showers and isolated thunderstorms.
- Greatest rainfall accumulations will likely be attributed to
   the period spanning Wednesday night through Thursday night
   where probabilities for at least 1" have increased to 40-70%
   across the region.
Discussion:
Pleasant conditions persist regionwide as anticyclonic flow is
maintained about the southwest periphery of the surface high now
well off to our northeast and beneath the back side of the ridge
crest aloft. However, evidence of the anticipated changing
conditions is beginning to become apparent upstream as local
radars indicate isolated to scattered showers along and ahead of
a weak warm front just entering our northern zones. This
feature, along with the introduction of cyclonic flow as an
upper-level trough inches eastward from the Upper Midwest, will
ensure light showers spread into areas mainly north and west of
Albany tonight into tomorrow morning. For most, this will be the
first observation of precipitation in many days, so any rain is
welcome. However, with marginal forcing, accumulations won`t
exceed a few hundredths to about 0.4" or so which certainly
won`t do much to put a dent in the current deficit. Lows tonight
will be more mild in comparison to recent days given a greater
extend of cloud cover, so expect values primarily in the 50s.
Showers become a bit more widespread tomorrow in response to a
shortwave pulsing through the region within the mean flow of the
leading edge of the upper trough, whose axis will remain well to
our west. Marginal instability and increased dewpoints across
much of the region could lead to a few rumbles of thunder with
subsequent moderate downpours, but no severe storms are
anticipated. Showers will continue into tomorrow night as
forcing for ascent is reinforced by the northwest to southeast
progression of a cold front through the region. However, most of
the rain will become confined to areas within, south, and east
of the Capital District as subsidence from a southward building
high from the James Bay disturbs vertical ascent to the north.
Though, that said, the boundary will begin to slow as it makes
progress farther south, so the better low-level convergence will
also aid in the achievement of higher rainfall amounts in these
areas. Once again, the additional rainfall tomorrow into early
Wednesday morning, while not significant as it pertains to
reducing our deficit, will be a beneficial 0.25" to 0.5" with
isolated amounts reaching 0.75" to almost 1". The greatest
amounts will be found in areas where rainfall rates are higher
due to convective downpours as well as in areas that have
repeated showers. Highs tomorrow will be in the mid/upper 60s to
low 80s with lows in the mid 50s to low 60s. Wednesday should
be largely dry as the boundary settles just to our south and the
aforementioned high to our north expands south and eastward,
though a few isolated showers cannot be ruled out. Highs will
generally be in the mid/upper 60s to upper 70s.
Attention then shifts to Wednesday night through Thursday night
with our best chance for widespread, appreciable rainfall over
the next seven days. Though there continues to be some level of
uncertainty pertaining to the evolution of the responsible
system, confidence is increasing in at least some areas
receiving at least 1" of rainfall according to the latest 13z
run of the NBM.
The upper-level trough over the Midwest will finally begin to
make some slow eastward progress Wednesday night, allowing
heights aloft to lower across the region. Meanwhile, an open
wave traversing the Central Plains will begin to phase with its
southern periphery, deepening the trough into a closed low aloft over
the Great Lakes. At the surface, an area of low pressure looks
to develop in the Ohio Valley, extending a warm front
horizontally to the east with a trailing cold front to the
southwest. Isentropic lift and cyclonic vorticity advection will
increase across the region aloft with increased convergence and
moisture transport in the low-levels, courtesy of the warm
frontal boundary; surface low; and increasing 850 mb LLJ, all
working together to enhance vertical ascent. Therefore, an area
of rain with some embedded locally moderate to heavy downpours
will overspread the region beginning Wednesday night, looking to
persist through Thursday night. Depending on the resulting
evolution of this system, showers could linger into Friday given
the presence of the cold frontal boundary that will not have
fully completed its passage through the region just yet.
However, this is where much of the uncertainty comes in, as the
details surrounding the timing of the departure of the system
lack consensus within the medium to long range guidance.
Therefore, maintained the NBM`s chance PoPs through Friday.
However, as the bulk of the rain will fall Thursday, additional
rainfall will not amount to much. When all is said and done, QPF
looks to widely range from just under 1" to isolated amounts of
1.5". The latest NBM probabilities have risen since the previous
forecast issuance, thereby increasing confidence in these
amounts. Now, regionwide probabilities for at least 0.5" span
~60-80% with probabilities for at least 1" ranging from ~40-70%.
As with prior messaging, the expectation for a lack of
hydrological concerns remains given the extensive rainfall
deficit that we are currently faced with. Low temperatures
Wednesday night will fall into the low 50s to low 60s with
highs Thursday only rising into the low/mid 60s to low 70s given
the rainy, cloudy conditions. Lows Thursday night will be
similar to those of Wednesday night before a warming to the
mid/upper 60s to upper 70s for highs Friday. Lows Friday will be
in the upper 40s to upper 50s.
For the most part, the upcoming weekend should be dry with flow
becoming more zonal in nature. A weak disturbance may just pass
us by to the north on Saturday night into Sunday which could
bring some additional light showers, specifically in the
Southwest Adirondacks, but this is uncertain at this time. Highs
Saturday and Sunday will be similar in the upper 60s to upper
70s with lows in the upper 40s to upper 50s Saturday night and
mid/upper 40s to low 50s Sunday night.
&&
.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
Although a few showers will be possible overnight, most should
remain north and west of the Terminals. Better chances for
showers develop at KGFL late Tuesday morning through mid
afternoon, and elsewhere during the afternoon hours. Some
embedded thunderstorms will be possible, with best chance mainly
south of KALB. Have therefore included a PROB30 at KPOU after
21Z/Tue. As for flight conditions, mainly VFR overnight, however
areas of MVFR Cigs are expected to develop between 08Z-12Z/Tue.
Areas of MVFR Cigs will remain possible through at least
Tuesday morning, with additional periods of MVFR/IFR Cigs/Vsbys
possible within any heavier showers.
South to southeast winds overnight generally decreasing to 5-10
KT, though may occasionally gust up to 20 KT at KALB through
03Z/Tue. South to southwest winds expected Tuesday at less than
10 KT. However, winds will be stronger and variable in direction
in/near thunderstorms.
Outlook...
Tuesday Night: High Operational Impact. Likely SHRA.
Wednesday: Moderate Operational Impact. Slight Chance of SHRA.
Wednesday Night: Moderate Operational Impact. Chance of SHRA.
Thursday: Moderate Operational Impact. Chance of SHRA.
Thursday Night: High Operational Impact. Likely SHRA...TSRA.
Friday: Moderate Operational Impact. Chance of SHRA...TSRA.
Friday Night: Moderate Operational Impact. Chance of SHRA.
Saturday: Moderate Operational Impact. Chance of SHRA.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
UPDATE...KL
SYNOPSIS...Gant/KL
DISCUSSION...Gant
AVIATION...KL

NWS ALY Office Area Forecast Discussion