Albany, NY WFO Forecast Discussion

Forecast Discussion for ALY NWS Office
000
FXUS61 KALY 262025
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
425 PM EDT Sun Sep 26 2021

.SYNOPSIS...
A warm front will bring scattered showers late tonight through
Monday and milder temperatures on Monday with an isolated
rumble of thunder possible. A cold front will bring another
threat of showers Monday night into Tuesday morning with
clearing and seasonable temperatures later Tuesday behind the
front. Wednesday looks unsettled with below normal temperatures.

&&

.NEAR TERM /UNTIL 8 PM THIS EVENING/...
Diurnal clouds will slowly decrease later this afternoon as
sun`s heating weakens. A few light rain showers are possible
over the southern Adirondacks this afternoon. Mid level clouds
will again start to increase from west to east starting around
sunset as warm front starts to approach from the southwest. High
temperature will range from around 60 in the higher elevations
to around 70 in the valleys.

&&

.SHORT TERM /8 PM THIS EVENING THROUGH TUESDAY NIGHT/...
850mb warm advection increases tonight around ridge of high
pressure south of our area. 850mb temps rise from +4 to +7C this
evening to +9 to +13C by Monday morning. Lift associated with
warm advection is forecast to produce clouds and showers across
the northern half of the area from late tonight into Monday.
Showalter indices go negative from time to time so can`t rule
out an isolated rumble of thunder. Precipitation amounts look to
be light, generally a quarter inch or less. Lows tonight
generally in the 40s to around 50. With the mild 850 temps
Monday afternoon temps should be above normal from the Mohawk
Valley southward where breaks in the clouds should help temps
rise into the mid 70s in the valleys. Northern high terrain
areas look to be cooler with clouds and showers and highs in the
50s and 60s.

Monday night, low pressure develops along the front and high
pressure starts to push in from the upper Great lakes. The wave
of low pressure looks to bring another round of showers to
central and southern areas Tuesday night into Tuesday morning.
Once again, showalter indices go negative so thunder can not be
ruled out. With mostly cloudy skies Monday night low temps only
drop to the 50s with some upper 40s possible in southern
Adirondacks and higher terrain of southern vermont.

By later Tuesday, low pressure near Maine and high pressure over
Great Lakes combine to bring a northerly flow of cooler and
drier air to the area. Skies should gradually clear during the
afternoon. There will be a large range in high temperatures from
the 50s over the southern Adirondacks and hills of southern
vermont to the lower 70s across the far southern part of our
forecast area.

Tuesday night looks to be partly cloudy and cold. Some areas of
frost are possible where skies remain mostly clear as 850 temps
are generally between +1 an +5C. Lows forecast in the 30s and
40s.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
The main story for the long term period will be a closed low
that perpetuates over the Northeast from Wednesday through
potentially Friday as we remain on the east side of an omega
block. However, riding from the Central CONUS gradually pushes
eastward over the weekend, which should result in improving
conditions. Read on for details.

We start the long term on Wednesday with a closed ~550-555dm low
over northern New England and a highly amplified ~585-590dm ridge
over the Midwest. Blocked flow allows the closed low to persist
over the Northeast through the second half of the week as multiple
shortwaves rotate around the low. With 500hPa temperatures
nearing -20C to -25C, mid-level lapse rates steepen to 6C/km to
7C/km which should result in stratocumulus clouds, especially
during peak heating. In addition, the instability under the cold
pool should generate scattered showers, especially in the
higher terrain areas of the southern Adirondacks, Upper Hudson
Valley, southern VT and the Berkshires. The deterministic
guidance is in generally fair agreement that 850hPa
temperatures drop to +1C to +3C with even hints on the GFS and
CMC that northerly flow ushers sub-zero 850hPa air into the
southern Adirondacks. We therefore show some pockets of
rain/snow mix in the higher peaks of the southern Adirondacks
Wed night. Such chilly temperatures aloft will also support
seasonably cool temperatures at the surface Wed and especially
Thurs when daytime highs may struggle to rise out of the low
60s. According to climatology, high temperatures in late
September are in the mid 60s. Overnight lows will also turn
chilly and fall-like with lows in the low to mid 40s Wed and
Thurs night.

By Friday, our closed low finally starts to exit into the
Canadian Maritimes as strong ridging and surface high pressure
builds northeastward out of the Southeast U.S. Deterministic
guidance suggests that the ridging struggles to take control of
the Northeast for very long as our cut-off low may maintain
control just off shore from the Canadian Maritimes with
additional shortwaves within the active northern branch of the
jet stream sending more shortwaves our way which may act to flatten
out any riding. There are still many differences between the
ECWMF, CMC and GFS regarding how the synoptic pattern will
evolve over the weekend so we maintained a generally dry
forecast with seasonably daytime temperatures in the 60s and
overnight lows in the 40s.

&&

.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
A ridge of high pressure will build across the TAF sites this
afternoon and evening. A warm front and upper level disturbance will
then approach from the west tonight into Monday morning.

VFR conditions are expected through at least sunset, and possibly
through the end of the TAF period at KALB/KPSF and KPOU.

At KGFL, there could be a brief period of fog development between
roughly 03Z-08Z/Mon, which could lead to periods of MVFR/IFR Vsbys.

A mid level cloud deck should advance across the TAF sites between
09Z-12Z/Mon. A few sprinkles or showers may fall from this cloud
deck, especially between 13Z-17Z/Mon. Best chances for showers
(possibly briefly moderate in intensity) will be at KGFL, where a
PROB30 group has been indicated. There is a small possibility that
some thunder could occur at KGFL during this time as well, however
overall probability too low to include mention at this time.

West to northwest winds will increase to 8-14 KT this afternoon,
with some gusts of 20-25 KT possible, especially at KALB and KPSF.
Winds will decrease to less than 8 KT after sunset, and may become
calm at times overnight. Winds will then increase from the south to
southwest at 5-10 KT toward and especially after 18Z/Mon.

Outlook...

Monday Night: Moderate Operational Impact. Chance of SHRA.
Tuesday: Moderate Operational Impact. Chance of SHRA.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: Low Operational Impact. NO SIG WX.

&&

.FIRE WEATHER...
A warm front will bring scattered showers late tonight through
Monday and milder temperatures on Monday with an isolated
rumble of thunder possible. A cold front will bring a threat of
showers to southern areas Monday night into Tuesday morning
with clearing and seasonable temperatures behind the front.
Wednesday looks unsettled with below normal temperatures.

RH values will rise overnight to 80 to 100 percent. RH values
fall to 60 to 80 percent on Monday and recover to 80 to 100
percent again Tuesday morning. Winds will become light and
variable tonight before increasing to 10 to 20 mph from the
southwest on Monday.

&&

.HYDROLOGY...
Forecast precipitation during the next 7 days is one half inch
or less. River levels should slowly recede during the period so
no hydro issues are anticipated.

For details on specific area rivers and lakes, including observed
and forecast river stages and lake elevations, please visit the
Advanced Hydrologic Prediction Service /AHPS/ graphs on our
website.

&&

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

&&

$$
SYNOPSIS...SND
NEAR TERM...SND
SHORT TERM...SND
LONG TERM...Speciale
AVIATION...KL
FIRE WEATHER...SND
HYDROLOGY...Thompson

NWS ALY Office Area Forecast Discussion