903
FXUS61 KALY 220841
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
441 AM EDT Thu May 22 2025

.SYNOPSIS...
Unseasonably cool today with light showers in eastern NY but
steadier rain in western New England as a coastal low tracks off
shore. Light wet snow accumulations expected late this
afternoon into tonight mainly for elevations 1500 feet and
higher in southern VT. Cool and cloudy with additional scattered
light showers on Friday and Saturday before temperatures
finally trend warmer Sunday into Monday albeit a few light
showers still not ruled out.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Message:

- Rainfall amounts have trended lower mainly in eastern NY for
  today as morning showers turn quite light and more
  intermittent for the afternoon. Steadier rain still expected
  in western New England where total rainfall amounts of 1 to
  1.50 inches still expected.

- Light wet snow accumulations likely in southern Vermont for
  elevations 1500 feet and higher late this afternoon into
  tonight with snow accumulation ranging from coatings up to 1
  inch. There is even a 20 to 40% chance for snow amounts to
  exceed 2 inches above 2000 feet.

Discussion:

Latest water vapor imagery shows our coastal low
beginning to develop off the coast of New Jersey in response to
a compact shortwave rotating around the main parent trough
resulting in increased CVA and forcing for ascent. Further north
over eastern NY and western New England, a band of more
organized showers tracks northward early this morning given
enhanced warm air advection in the low and mid-levels ahead of
the coastal low. After this band of steadier rain exits by mid-
morning, showers will turn lighter and more intermittent as we
remain north and west of the developing coastal low and well
east of the parent trough over the Great Lakes. While weak warm
air advection and plenty of moisture in the low levels will
maintain overcast skies and drizzle/patchy light showers,
organized steady rain should remain generally to our south/east
for much of the day. Easterly flow upsloping the terrain will
support steadier light showers along the east slopes of the
southern Green, Berkshires, and the northern/eastern Catskills.
Otherwise, we remain in the cool conveyor belt ahead of the
coastal low and daytime temperatures will struggle to rise out
of the 40s to only around 50 in valley areas. Needless to say,
this is unseasonably cool for late May and we likely will
challenge record low maximum temperatures for May 22. See our
climate section for details. Given the expectation for rather
light showers/patchy drizzle for most of the area, we trended
QPF amounts downwards except in western New England were more of
the effect of the coastal low will be felt.

By late this afternoon into this evening, our developing
coastal low undergoes cyclogenesis as the aforementioned
compact shortwave aloft takes on negative tilt resulting in
strong CVA while the low`s positioning in the equatorward exit
region of a 110-1220kt cyclonic curved jet streak provides
notable upper level divergence. The coastal low therefore
deepens to ~995hPa as it tracks northward towards Cape Cod and
the 40W/70N benchmark. While the coastal low will be quite
compact with much of its precipitation shield focused in New
England, bands of steadier rain look to extend into our western
New England zones. In fact, strong deformation within its NW
quadrant likely results in a pivoting band (as discussed in our
previous forecast discussion) with CAMs and sources of higher
resolution guidance pointing to this band pivoting across parts
of southern VT. With such a cool air mass in place and low dew
points around freezing within the southern Greens, as
precipitation turns moderate in intensity late this P.M (21 - 00
UTC), forecast soundings show wet-bulb cooling processes
resulting in a deep isothermal layer in the low to mid-30s which
should support a changeover to wet snow. Wet-bulb zero heights
drop to around 1500ft by around 00 UTC with moderate
precipitation continuing through 03 - 06 UTC before the low
lifts north/eastward into the Gulf of Maine. During this window,
steady enough snow looks to fall in the southern Greens to
result in snow accumulations from coating to 1 inch with
probabilistic guidance showing 20-40% for up to 2 inches in
elevations above to 2000ft. While generally low snow amounts
are expected, this is rather unusual for late May and anyone
planning to be on the road this evening in the southern Green
should allow extra travel time and be prepared for a period of
moderate wet snow.

After 06 UTC, the steady precipitation turns into scattered
light rain showers. Widespread clouds and lingering light
spotty showers will limit the diurnal temperature change
overnight with many remaining in the 40s. Total rainfall amounts
expected to range from the 0.25 to 0.75" with up to 1 - 1.50" in
the mid-Hudson Valley, eastern Catskills, and western New
England. Still not expected any flooding impacts.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...

Cool, cloudy, and unseasonably cool conditions continue into
Friday and Saturday and the start of the Memorial Day Holiday
weekend. The parent trough over the Great Lakes gradually shifts
eastward and absorbs the secondary low, maintaining moist
cyclonic flow overhead. With the cool pool aloft and daytime
heating in play, scattered areas of showers will be around most
Friday. As an inverted trough develops on the back side of the
weakening parent low and swings through the region late Friday
P.M into Friday night, a more organized area of showers look to
develop. We therefore trended POPs upwards to 50-70% chance
range by 00 - 06 UTC Friday for much of the area.

Only slight improvements expected for Saturday as the parent
flow slowly exits into northern New England. While the core of
its cool pool shifts to our north/east, enough of it remains
nearby and with the upper deformation zone of the low overhead,
additional diurnally driven showers are expected. Northwest
cool air advection around the low will maintain a fetch of
moisture off Lake Ontario so the highest POPs were placed in the
western Adirondacks, northern/eastern Catskills and southern
Greens where upslope flow could enhance shower activity.
Elsewhere, shower coverage should be less numerous compared to
Friday and there should be periods of dry time. Otherwise, it
will be the third day in a row with unseasonably cool
temperatures struggling to rise out of the 50s (low 60s mid-
Hudson Valley) under mainly cloudy skies once again.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The unsettled pattern of late remains in place through much of the
extended forecast period. With the aforementioned closed, upper low
remaining within reach through at least Monday evening, eastern New
York and western New England will remain locked into cyclonic flow
about its southwestern periphery. Numerous shortwave perturbations
will rotate through the region about the slow, eastward-tracking low
through Monday evening, generating sufficient ascent to support
several rounds of scattered showers. Coverage remains a bit
uncertain at this time courtesy of discontinuities within the medium
to long-range guidance. However, with the cold pool aloft beginning
to weaken and much weaker forcing with the gradual departure of the
primary low, showers will be fairly light and contribute little in
the way of additional precipitation to what will have preceded in
the previous week. The scattered nature of showers also means that
the end of the Memorial Day weekend will not be complete wash outs,
so expect opportunities for outdoor activities.

Surface high pressure and shortwave ridging aloft build in Monday
night, reinforcing regionwide dry conditions into Tuesday. Most of
the region should remain dry through Tuesday afternoon before rain
chances increase once again Tuesday evening into Wednesday. However,
at this point, there is still quite a bit of uncertainty in the
conditions expected Tuesday night into Wednesday. General consensus
indicates a Southern Stream surface low developing in and around the
Southern Plains/Deep South, tracking eastward and off the coast of
the Carolinas/Mid-Atlantic Tuesday night/Wednesday morning whilst
another upper-level, closed low develops over the Great Lakes. A
secondary surface low also looks to develop along the Appalachians,
which, along with the upper closed low, looks at this time to be our
primary rain producer. However, the significant differences in the
depiction of the track and timing of the coastal low are what impact
this forecast the most at this point. Should this disturbance hug
the Atlantic Coast, rainfall could be enhanced especially south and
east of Albany. If it`s track is more easterly, our main
precipitation source will be the secondary surface and upper-level
closed low which would likely mean lower QPF.

Temperatures finally begin to moderate through Wednesday with
Sunday`s mid/upper 50s to mid 60s likely being the coolest highs of
the period. Values rise to the 60s and low 70s Monday with
widespread 60s expected Tuesday and Wednesday. Lows will primarily
be in the 40s and 50s.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
Through 06z Friday...MVFR to VFR conditions currently prevail across
all terminals with light rain showers scattered throughout eastern
New York and western New England. Throughout the 06z cycle, rounds
of rain will force mainly MVFR conditions through lowered ceiling
heights, though some improvements to VFR heights are anticipated in
between batches. As rain is anticipated to be relatively light in
terms of rates per hour, visibility will generally remain within the
VFR category, though some MVFR visibility could occur at KPSF where
some upslope enhancement could strengthen rainfall rates. There is
some uncertainty in timing and evolution of the rain bands that will
cause the less than ideal flying conditions, but included TEMPOs and
PROB30s where confidence is greatest in rain, and subsequent
category change, occurrence. Winds throughout the period will
generally prevail out of the northeast at speeds under 10 kt.
However, KPSF could see some sustained speeds at or just above 10 kt
with gusts up to around 20 kt due to the terminal`s proximity to the
coastal low that will be responsible for some of the rain incoming
this afternoon and tonight.

Outlook...

Friday Night: High Operational Impact. Numerous SHRA.
Saturday: Moderate Operational Impact. Scattered SHRA.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: Low Operational Impact. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Memorial Day: Low Operational Impact. Slight Chance of SHRA.
Monday Night: Low Operational Impact. NO SIG WX.
Tuesday: Moderate Operational Impact. Chance of SHRA.

&&

.CLIMATE...
Record low maximum temperatures for May 22:

Albany: 52F (2005)
Glens Falls: 52F (2005)
Poughkeepsie: 56F (2005, 2003)

&&

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

&&

$$

SYNOPSIS...Speciale
NEAR TERM...Speciale
SHORT TERM...Speciale
LONG TERM...Gant
AVIATION...Gant
CLIMATE...Rathbun