Guilderland, New York Weather Forecast Discussion

261
FXUS61 KALY 231040
AFDALY
AREA FORECAST DISCUSSION
National Weather Service Albany NY
640 AM EDT Tue Sep 23 2025
.SYNOPSIS...
Some much-needed rain and a few rumbles of thunder are expected
for most areas today. More isolated showers are expected
Wednesday, then another batch of widespread rain is likely
Thursday. Temperatures will generally tend to run slightly above
normal through the weekend, but may drop to more seasonable
levels early next week.
&&
.DISCUSSION...
Key Messages:
- Beneficial rain expected today, with additional rain on
   Thursday.
- Greatest rainfall accumulations will likely occur Wednesday
   night through Thursday night, where probabilities for at
   least 1" remain around 30-60% across the region.
Discussion:
As of 2:45 AM EDT...A 1018 mb sfc high is currently located to
our south, off the Mid-Atlantic coast, while a 1010 mb sfc low
is tracking through the northern Great Lakes. This sfc low is
associated with an upper shortwave embedded within a larger-
scale trough. Ahead of this feature, scattered showers can be
seen on upstream radar over western NY and PA. These showers
should gradually spread eastwards into our western zones through
the remainder of the overnight period, although most areas are
dry at the current time. Ahead of the showers, we are seeing
some mid and high clouds increasing across the region, with some
low stratus developing as well between now and daybreak. With a
more humid airmass, temperatures are running on the warm side,
with most areas in the mid 50s to low 60s. Some patchy fog can`t
be ruled out in the more sheltered areas, but fog will remain
more isolated than the previous few nights.
Today into tonight...The upper shortwave tracks over our region,
although the parent trough axis remains off to our west. While
the attendant cold front associated with the low currently
tracking through the Great Lakes will track through our region
this afternoon and evening, we will be in the warm sector for
most of the day. CIRA ALPW satellite imagery shows increasing
low and mid-level moisture at this time, and PWATs should
continue to rise to 1.5-1.75" today, which is around 2 standard
deviations above normal for late September. The overlap of
moisture and forcing will allow for scattered to numerous
showers to develop through the day today. Areas south and east
of the Capital District will likely stay dry through the
morning, but will end up seeing the greatest coverage of
showers as we head into the afternoon and evening. With pockets
of up to around 500 J/kg of SBCAPE per the HREF mean, we would
not be surprised to see a few rumbles of thunder this afternoon
as well, mainly south of I-90. Showers diminish in coverage this
evening and overnight from northwest to southeast as the cold
front tracks through our region. While most areas desperately
need the rain, qpf amounts generally look to remain in the 0.25
to 0.5" range (with locally higher totals where any embedded
convective elements occur), which will not make an appreciable
dent in the current rainfall deficits. Temperatures today will
range from the upper 60s in the ADKs to around 80 near the I-84
corridor. Lows tonight will be on the warm side again, ranging
from mid 50s in the high terrain to low 60s in the valleys.
Wednesday...A 1024 mb sfc high building into southern Canada
will help push the cold front to the south of our region, where
it will stall near or south of the I-84 corridor. This will help to
shunt the deeper moisture off to our south. However, our
proximity to the front combined with diffluent flow aloft will
allow for the development of isolated to scattered showers again
during the afternoon, and possibly a rumble of thunder. Any
areas that see a shower could pick up a quick couple tenths of
an inch of qpf, but coverage of showers will be less than on
Tuesday. Highs Wednesday will range from upper 60s in the
terrain to upper 70s for valley areas.
Wednesday night through Thursday night...Confidence continues to
increase in another round of widespread rainfall during this
time period. An upper disturbance tracking out of the Rockies
will phase with the upper trough axis to our west Wednesday
afternoon and night, and then the whole system will track
eastwards and evolve into an open wave aloft Thursday into
Thursday night. At the surface, an area of low pressure looks to
track to our west, through the eastern Great Lakes. This system
will help to lift our stalled frontal boundary back north as a
warm front on Thursday. Once in the warm sector, deep southerly
flow and a strengthening LLJ will aid in moisture transport into
our region, with PWATs potentially approaching 2", which is +2
to +3 standard deviations above normal. We should see more
isolated to scattered showers begin to develop Wednesday night
with low-level warm advection/isentropic lift, but strengthening
upper forcing overlapping with the deep moisture will allow for
more widespread rain on Thursday.
There remains some subtle differences in the exact evolution
and track of the upper low and sfc cyclone, which will impact
rainfall totals. Nevertheless, latest NBM guidance continues to
show around a 60-70% chance for >1" of QPF across the Mid Hudson
Valley and western CT/MA, with a 30-50% chance for >1" of QPF
along and north of I-90. Locally higher amounts will be possible
with any convection, and in the S/SE favored upslope areas.
Will continue to reiterate that this rainfall will be very
beneficial and we are not at all concerned about any hydro
issues given ongoing dry conditions. Lows both nights remain on
the warm side, similar to those from the previous few nights.
Thursday will be slightly cooler with widespread rain and
clouds, so many areas will see highs in the 60s.
Friday...There remains some uncertainty in coverage of showers
Friday, as the system`s cold front will be pushing off to our
east during the day Friday. However, troughing aloft and the
right entrance of the upper jet nearby may allow for some
lingering showers, although we should see more drying by Friday
night. Slightly above normal temperatures continue Friday and
Friday night
Saturday through Monday...Flow aloft becomes zonal behind the
cold front Saturday, but an upper shortwave and associated sfc
cold front may give us a glancing blow as they track through
southern Canada Saturday night or Sunday. We are not expecting
much in the way of showers with these features, so while NBM
guidance continues to show slight chances for precip we are
thinking that most of the weekend should remain dry with. High
pressure then builds overhead Sunday into Monday, with continued
dry conditions. Saturday will see temperatures in the 70s for
most areas, but temperatures should trend downwards slightly for
Sunday into early next week. Overnight lows will be mainly in
the 40s to 50s each night. The CPC is leaning towards above
normal temperatures and below normal precip for days 8-14.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
VFR conditions begin the TAF cycle for KALB/KPOU/KPSF ahead of an
upper level disturbance and cold front. KGFL has high MVFR cigs with
some showers approaching from the west.  Mid and high clouds will
thicken and lower between 12Z-16Z/Tue. MVFR conditions will be
common in the showers from KALB/KGFL northward prior to noon. Better
chances for showers and even a few thunderstorms ahead of the cold
front and a sfc wave will occurs in the afternoon/early evening.
PROB30 groups were maintained for KPOU for thunderstorms 21Z/Tue to
03Z/Wed for MVFR/IFR conditions. Have stayed with MVFR conditions
for showers/rain for KGFL/KALB/KPSF between 18Z/Tue to 00Z/Wed.  Low
MVFR/IFR cigs will develop in the wake of the cold front after
00Z/WED with some light rain or patchy drizzle at all the TAF sites.
Widespread low MVFR/IFR vsbys/cigs are possible shortly before or
after 06Z/WED at all the TAF sites in the deeper moisture in the
wake of the boundary and wave.
The winds will be south/southwest generally less than 10 KT during
the late morning through the afternoon. Expect light/variable
direction winds to calm tonight. Winds may be stronger and variable
in direction in/near thunderstorms.
Outlook...
Wednesday Night: Moderate Operational Impact. Likely SHRA.
Thursday: High Operational Impact. Likely SHRA...TSRA.
Thursday Night: High Operational Impact. Likely SHRA...TSRA.
Friday: Moderate Operational Impact. Chance of SHRA...TSRA.
Friday Night: Low Operational Impact. Slight Chance of SHRA.
Saturday: Low Operational Impact. NO SIG WX.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Main
DISCUSSION...Main
AVIATION...Wasula

NWS ALY Office Area Forecast Discussion