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100
FXUS61 KALY 200806
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
406 AM EDT Tue May 20 2025

.SYNOPSIS...
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Another mostly cloudy and cool day is expected across eastern
New York and western New England today. Rain will then begin to
overspread the region from south to north Wednesday into
Wednesday night as a low pressure system approaches. Periods of
rain will continue on Thursday transitioning to scattered rain
showers Friday into the upcoming weekend with continued cool
conditions.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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Despite an upper level low, east of Maine, departing farther
out into the Atlantic, we will remain under the influence of
moist, cyclonic flow and an upper level trough pattern today.
925-850 hPa RH values remain high through this afternoon (80 to
95 percent) which will likely result in continued mostly cloudy
conditions. 850 hPa temperatures similar to Monday (+1 to +4C)
will keep high temperatures around 10 degrees below normal, only
in the 50s to mid-60s. Similar to Monday, portions of the
Adirondacks and southern Greens may not get out of the 40s.
Onshore flow from the Atlantic could result in a few light rain
showers or sprinkles across portions of western New England
during the afternoon hours; otherwise, all areas will remain dry
once again. The pressure gradient will relax slightly as the
upper low departs, so it will not be as breezy as Monday, but
some gusts of 20 to 25 mph could still occur.

Generally cloudy conditions will continue tonight as easterly
onshore flow increases. In addition, clouds associated with a
low pressure system approaching from the Ohio Valley will also
increase. Most areas will remain dry but some onshore light rain
showers or sprinkles are possible in some spots. Rain
associated with the approaching system will near southern areas
toward daybreak but much of this will hold off until the daytime
hours Wednesday. Lows fall back into the 40s for most with some
upper 30s across the Adirondacks and southern Greens.
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&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
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A complex double-barrel low pressure system will bring a
widespread rainfall to the region during the short term period.
An initial upper level shortwave and surface low pressure system
will trek across the Ohio Valley on Wednesday. Increasing
moisture advection and forcing for ascent will result in periods
of rain overspreading the region from south to north throughout
the day. The northward advancement of precipitation may be slow
as it will encounter increasing mid-level dry air from a high
pressure system to the north and east across Atlantic Canada. By
Wednesday night, an upper level low attempts to develop near
the lower Great Lakes as the shortwave undergoes a negative tilt
as it nears the mid- Atlantic coast. Continued upper level
forcing for ascent and increasing divergent flow will maintain
periods of rain through Wednesday night. As dynamic wet-bulb
processes take shape, some of the highest peaks of the
Adirondacks and southern Greens (especially above 3000 feet)
could see some snowflakes mix in but no accumulation is
expected. Highs Wednesday will be mainly in the 50s to near 60
with lows Wednesday night falling back into the mid-30s to
mid-40s.

On Thursday, the upper level shortwave continues to increase its
negative tilt near the Atlantic coast and results in the
gradual development of a coastal low (developing similar
characteristics to that of a wintertime/early spring
nor`easter) which will then track northeastward off the coast.
Over time, this coastal low will become the primary, stronger
low as the inland low near the lower Great Lakes weakens.
Periods of rain will continue on Thursday with the steadiest
rainfall developing mainly near or east of the Hudson Valley by
Thursday night once the coastal low takes over. How much rain
occurs during this period remains a bit uncertain but a general
0.50 to 1.00 inches of rain is expected with the higher amounts
across southern areas. The long duration and non-convective
nature of this event should limit hydrological concerns. The
clouds and rain will lead to a chilly day on Thursday with
highs only in the 40s to lower 50s. Daily record low maximum
temperatures will be challenged at Albany, Glens Falls and
Poughkeepsie. Lows once again fall back into the upper 30s to
mid-40s Thursday night.
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&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
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Cloudy and unseasonably cool weather continues for the first
half of the upcoming Memorial Day weekend as our occluded
coastal low from Thursday exits into the Canadian Maritime and
its upper level low becomes absorbed by the parent trough slowly
rotating eastward out of the Great Lakes. With the broad parent
trough and its associated cold pool persisting overhead Friday
into Saturday with deformation processes also at play on Friday,
each day will feature diurnally driven isolated to scattered
showers. The highest probability for showers (50 - 60% chance)
remain over the southern Adirondacks, northern/eastern
Catskills, Taconics, and southern Greens due to upslope flow
enhancements. Despite chance to even likely POPs in the
forecast, probabilistic guidance continues to support overall
low QPF amounts with mainly 25% or less for rainfall amounts to
exceed 0.10" each day. Given the isolated to scattered shower
character, we used coverage wording
(isolated/scattered/numerous) instead of probabilistic (slight
chance/chance/likely) to describe the shower potential both
days. We hope this helps communicate that we are not expecting
washouts and that there will likely be periods of dry time.
Otherwise, unseasonably cool temperatures persist under cloudy
skies with daytime highs 10 to 15 degrees below normal for late
May standards. Cloudy skies at night will limit the diurnal
temperature change overnight and thus prevent frost.

While some gradual improvements are expected for the second half
of the holiday weekend, latest ensemble cluster guidance
continues to suggest that broad troughing continues or, at best,
zonal flow develops Sun - Mon. Monday features higher potential
for more dry time. Should troughing continue with limited sun,
temperatures will likely remain cooler than normal. However, if
we finally see breaks of that strong May sun, tempertures will
likely rise closer to normal (upper 60s to low 70s). Still
moderate uncertainty on the cloud coverage at this lead time but
probabilistic guidance favors a warming trend with temperatures
inching closer to normal as we close the weekend. We also
limited POPs to just slight chance and chance (highest POPs in
the higher terrain areas) given uncertainty on the exact timing
and placement of shortwaves within the potential broad troughing
pattern.
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&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
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Through 06z Wednesday...Low end VFR conditions persist at
ALB/POU/GFL through 00 - 03 UTC while MVFR cigs continue at PSF
as our upper level low continues to slowly exit into the
Canadian Maritime. The wind direction becomes more northerly and
eventually northeasterly towards the end of the TAF period
resulting in more of an onshore flow and advecting marine
moisture inland. This will result in MVFR cigs returning to POU
with potentially near IFR cigs ensuing at PSF. Some patchy mist
cannot be ruled out as well at PSF but not enough confidence to
include at this time. Northwest to northerly flow around 5-10
kts with gusts near 15 kts through sunrise become breezy once
again by 14-16 UTC with sustained winds reaching 8-12 kts and
gusts up to 20kts. Winds continue shifting north to
northeasterly late this afternoon into this evening but trend
weaker, sustained 5-8kts.

Outlook...

Wednesday Night: High Operational Impact. Pds RA.
Thursday: High Operational Impact. Pds RA.
Thursday Night: High Operational Impact. Likely SHRA...RA.
Friday: Moderate Operational Impact. Scattered SHRA.
Friday Night: Moderate Operational Impact. Numerous SHRA.
Saturday: Moderate Operational Impact. Scattered SHRA.
Saturday Night: Low Operational Impact. Isolated SHRA.
Sunday: Low Operational Impact. Isolated SHRA.
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&&

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

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

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

&&

$$

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