Area Forecast Discussion
Issued by NWS Albany, NY

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS61 KALY 070846
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
446 AM EDT Fri May 7 2021

.SYNOPSIS...
High pressure will move north and east of eastern New
York and New England today with increasing clouds ahead of the next
low pressure system.  Showers will gradually overspread the region
tonight.  The complex low pressure system will keep the threat of
showers going on the first half of the weekend.  High pressure will
briefly build in Saturday night into most of Mothers Day with fair
weather and some sunshine.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Frost Advisory in effect to 8 AM EDT for northern Saratoga,
southeast Warren and Washington Counties...

As of 417 AM EDT...High pressure is near eastern NY and New
England this morning. The cirrus clouds have thinned over most
of the forecast area with a batch south and east of the Capital
Region, and another batch over central NY extending into the
western Adirondacks. Mostly clear skies and light to calm winds
have allowed radiational cooling for temps to fall into the 30s
to lower 40s with some upper 20s over the southern Dacks with
Indian Lake 27F this hour on the NYS mesonet. It is also 31
degrees at Edinburgh, 35F at KGFL and 33F at Whitehall, so the
frost advisory looks good for the Lake George northern Saratoga
Region, where the growing season began on May 1st. Some patchy
frost is possible further south into the Capital District/Mid
Hudson Valley.

Most of the day will end up dry with the sfc anticyclone
retreating to the north and east. Mid and high clouds will
gradually increase from the south and west ahead of a short-wave
trough lifting northeast from the Ohio Valley. Another piece of
short-wave energy will dive into the trough from the Great
Lakes Region tonight. We brought a slight to low chance of
showers in for locations primarily west of Lake George and the
Hudson River Valley in the mid to late pm. The better QG lift
and moisture advection remains west of the ALY forecast area
based on the majority of the guidance.

Some sunshine this morning into the early afternoon should allow
temps to rise abruptly after the chilly start. Expect highs
close to a blend of the GFS/MET/EC MOS guidance with maxes in
the 60-65F range in the valley areas, and 50s over the hills and
mtns.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
Tonight...Convoluted and chaotic mid and upper level pattern
with an amplifying trough over the Northeast. A coastal low
forms and slips southeast of New England. Another cyclone forms
over PA and western NY with good low to mid level FGEN and
differential cyclone vorticity advection with the upstream piece
of short-wave energy digging in over the eastern Great Lakes
Region and northeast. Shower gradually spread eastward across
the region. The falling heights and steepening mid level lapse
rates will promote the formation of some wet snow flakes over
the western Adirondacks and the northern and eastern Catskills.
The best synoptic forcing looks like it will be over central NY.
Lows fall back into the upper 30s to lower 40s in the lower
elevations and 30s over the higher terrain.

Saturday...A combination of the cyclonic vorticity advection
with the mid and upper level trough and an inverted sfc trough
with the departing coastal low moving towards Nova Scotia will
bring scattered to numerous showers to the region. The showers
should decrease with the loss of the diurnal heating in the late
afternoon. Highs will be cool for May with 40s to around 50F
across the higher terrain, and lower to mid 50s in the lower
elevations. If the showers become cellular with some heating,
then some graupel or small hail may be possible due to the -25C
to -27C H500 cold pool aloft.

Saturday night...The isolated to scattered showers should
dwindle and shrivel up with the loss of the daytime heating and
better upper level dynamics moving away. The skies will become
partly cloudy with chilly temps in the 30s to around 40F in a
few spots.

Sunday/Mothers Day...Weak low and mid level ridging settles over
the region briefly. Some sunshine should start the day, but then
mid and high clouds will increase from the south and west in the
afternoon ahead of low pressure moving towards the Ohio Valley.
The warm front to the system will drift north/northeast with
increasing isentropic lift. Some showers or light rain may
reach the eastern Catskills, and the mid Hudson Valley late in
the day. We leaned towards the 00Z ECMWF/NAM/CMC timing over the
speedy 00Z GFS. Highs will still run cooler than normal by 5 or
so degrees with upper 50s to lower 60s in the lower elevations
and 50s with a few upper 40s over the mtns.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Cooler than normal temperatures persist for the upcoming long term
period as a closed low positioned in southeast Canada influences our
weather pattern through the middle of next week. Temperatures during
this period should average 5-10 degrees below normal each day with
the largest departure likely with respect to high temperatures. In
fact, the Climate Prediction Center has outlined most of eastern NY
and western New England in 50 - 70% confidence of featuring below
normal temperatures between May 12 - 16.

The period starts off Sunday night with a weak shortwave from the
Central Plains rounding the base of the broader closed low in place
over Ontario. The weak shortwave originates from the Pacific and a
low develops on the leeward side of the Rockies during the first
half of the weekend. As the shortwave interacts with the broader low
to the north, the surface low intensifies with enhanced
southwesterly winds feeding Gulf moisture into it. Meanwhile, high
pressure in place over the Northeast will introduce a dry air
mass to the region. Therefore, the precipitation shield advancing
northward from the mid-Atlantic into the Northeast on Sunday
could erode away or remain light over southern zones until
closer to 00 UTC Monday. The GFS is much more aggressive/faster
with precipitation arrival but this is likely an outlier as the
GFS tends to underestimate the effects of dry air ahead of
advancing lows. The NAM and ECWMF are generally on the same page
showing a similar pace for precipitation intruding into the
mid-Hudson Valley and eastern Catskills late P.M or early
evening on Mother`s Day. The CMC shows an even slower onset
arrival time with precipitation still well south/west in Central
PA by 00 UTC Mon. We sided with the ECWMF and NAM solutions
since the dry air to the north does not seemly overly robust and
introduce likely POPs into areas south of I-90 by 00 - 06 UTC
Monday which is when the best mid-level FGEN, moisture and
cyclonic vorticity advection overlap. We then place widespread
likely POPs outside of the southern Adirondacks after 06 UTC
Monday.

The more organized showers associated with the surface low gradually
exit Monday morning but given that the main trough axis hangs
back well to the west, we lingered chance and slight chance POPs
through 00 UTC Tuesday. Continued cloud coverage and leftover
showers should make for a cool Monday with highs struggling to
climb out of the 50s. The main trough axis presses southeastward
Monday night into Tuesday with the true cold front moving
through the region overnight. With much cooler air infiltrating
into the region behind the front, some showers in the higher
terrain of the southern Adirondacks could even mix with snow.
Overnight lows expected to fall into the mid 30s to low 40s.

The main trough axis swings through on Tuesday with northwest
flow/cold air advection ongoing most of the day. The 500mb cold pool
is quite chilly by May standards with all members of the global
guidance showing -30C or lower isotherms in place which ranks 2.5 -
3 standard deviations below normal. As the cold pool moves overhead
on Tuesday, scattered convectively driven showers look to develop,
especially during the afternoon peak heating hours and for
areas north/west of the Capital District. Overall, Tuesday will
be quite chilly and breezy with highs once again barely rising
toward 60.

The trough and associated cold pool exit Tuesday night with
continued breezy northwest flow lingering showers (even rain/snow
showers) in the upslope favored areas of the southern Greens and
southern Adirondacks. Even with overnight lows falling into the mid-
30s in some spots where the growing season already started north of
the Capital District, the breezy winds should prevent any frost
formation.

High pressure and drier weather returns Wednesday and Thursday with
seasonably cool temperatures on Wednesday turning milder on
Thursday. Since winds turn calmer Wednesday night as high pressure
moves overhead, this may present a better chance for frost concerns
but this is still too far out to mention in the Hazardous Weather
Outlook at this time.

&&

.AVIATION /09Z FRIDAY THROUGH TUESDAY/...
Mid and high clouds continue to gradually exit from the TAF
sites tonight with mainly clear skies expected from 09 UTC
through 16 UTC Friday. Then, mid-level clouds return and lower
with ceilings drop to 4-6kft. POU and PSF likely will experience
these reduce ceilings first before they advect northeastward to
ALB and GFL. In addition to lower ceilings, some scattered light
showers are also possible after 18 UTC tomorrow. POU and PSF
have the greater potential to observer some showers so included
SHRA here. Less confident for ALB and especially GFL to see
showers so only included VCSH. Most showers should diminish
towards 03 UTC but mid-level clouds should stick around through
the end of the TAF period.

Calm winds tonight become southeasterly tomorrow and remain
light with sustained winds near or less than 5kts through 18
UTC. Then southeasterly winds increase to 5-10kts after 18 UTC
for a period before turning light after sunset.

Outlook...

Saturday Night: Moderate Operational Impact. Chance of SHRA.
Sunday: Low Operational Impact. NO SIG WX.
Sunday Night: High Operational Impact. Likely SHRA.
Monday: Moderate Operational Impact. Chance of SHRA.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: Low Operational Impact. Breezy. Slight Chance of SHRA.

&&

.FIRE WEATHER...
High pressure will move north and east of eastern New
York and New England today with increasing clouds ahead of the next
low pressure system.  Showers will gradually overspread the region
tonight.  The complex low pressure system will keep the threat of
showers going on the first half of the weekend.  High pressure will
briefly build in Saturday night into most of Mothers Day with fair
weather and some sunshine.

The RH values will drop to 30 to 45 percent this afternoon,
then to 75 to 100 percent Saturday morning. The RH values will
lower to 40 to 65 percent with chances for showers Saturday
afternoon.

The winds will be southeast 10 mph or less today and variable in
direction at 10 mph or less tonight. The winds will become west
to northwest at 10 mph or less Saturday afternoon.

&&

.HYDROLOGY...
Flows will continue to lower after the persistent and beneficial
rainfall over the past week or so

The next chance of showers will be late this afternoon into
Saturday. Light to moderate amounts of rainfall are possible on
the order of a few hundredths to a quarter of an inch isolated
amounts of a quarter to half inch in the western Adirondacks,
Schoharie Valley, western Mohawk Valley and eastern Catskills.
Little or no impact is expected on the Albany HSA waterways.

Another chance of rain with light to moderate amounts arrives
late Sunday through Monday.

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...Frost Advisory until 8 AM EDT this morning for NYZ041-043-083-
     084.
MA...None.
VT...None.

&&

$$
SYNOPSIS...Wasula
NEAR TERM...Wasula
SHORT TERM...Wasula
LONG TERM...Speciale
AVIATION...Speciale
FIRE WEATHER...Wasula
HYDROLOGY...Wasula


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.