Albany Office Forecast Discussion

000
FXUS61 KALY 150215
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
1015 PM EDT Tue Jul 14 2020

.SYNOPSIS...
An upper level low pressure system will move eastward off the New
England coast tonight, bringing an end to the showers and
thunderstorms. Mainly dry conditions are then expected from
Wednesday into Thursday morning, as a ridge of high pressure builds
in. Just an isolated shower is possible over the higher terrain of
western New England. Chances for showers and thunderstorms will
increase again Thursday into Thursday night, as a frontal system
approaches from the west.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 1010 pm, drier air working in on the west side of the
upper low, combined with the atmosphere having stabilized in the
wake of earlier convective activity, has resulted in a
significant downturn in the cloud cover and rainfall across the
area. Lower clouds are gradually approaching form the north and
east, and some evidence on the GOES-16 fog product that patchy
fog is beginning in favored spots. Going forecast captures this
well.

Previous discussion...

Skies will become partly cloudy across most of the area late
this evening into the overnight. Some lower cloud cover may
develop across the higher terrain to the west/east of the Hudson
Valley, and patchy fog could develop especially where decent
rainfall occurred today. Lows will range from the lower/mid 50s
in the mountains to lower 60s in the Hudson Valley.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
Upper level ridging will build in from the west on Wednesday,
with an seasonable air mass in place. This will result in mainly
dry conditions and near normal temperatures. An isolated shower
or two cannot be ruled out over the higher terrain of western
New England, as the flow will be slightly cyclonic just ahead of
the building ridge into the afternoon. Instability looks to be
scant for a change, so no mention of any thunder.

Tranquil conditions in store for Wednesday night, as the upper
ridge axis moves overhead. High pressure will be centered near
northern Maine, which will result in a light southeast flow
developing. Some low level stratus clouds may develop for areas
mainly south of Albany with this flow regime. Low temps will be
warmer if cloud cover increases quicker.

Dry conditions are expected to last through Thursday morning,
as the upper ridge axis start to shift eastward into New
England. There are some timing differences among the guidance,
but an upper level short wave along with the approach of a warm
front will result in increasing chances of showers and
thunderstorms from west to east during the afternoon and
evening. GFS/ECMWF faster than the NAM with the timing of this
system moving in, so will mention likely pops for areas west of
the Hudson Valley Thursday evening. Forecast instability looks
to be rather limited so threat for severe storms appears to be
low at this time. That could change based on eventual
timing/strength of the short wave and moisture return ahead of
the system. Temps look to be near normal again.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Anomalously high 500 mb heights are forecast to encompass much
of the eastern CONUS during most of the long term. 500 mb
heights in the upper 580s and 850 mb temps in the 15-20C range
over the local area lead to above normal temperatures in the
forecast, with potential for dangerously hot conditions at
times. The exact degree of warming will be subject to the
coverage and timing of showers and thunderstorms. The center of
the midlevel ridge will be located well to the south, with
respectable 500 mb flow, within which disturbances could set off
convective episodes. At this time, convection seems most likely
Friday and Monday. Friday may be closer to normal temperature-
wise if deterministic model timing is right with a shortwave
trough which could provide clouds, showers and thunderstorms for
a good portion of the day. Saturday and Sunday look to be the
best bet for hot temperatures and high dewpoints due to height
rises in the wake of Friday`s system. Evidence in the guidance
that height falls resume Monday/Tuesday leads to chance PoPs
returning to the forecast, but temperatures still have the
potential to be very warm.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
Showers and thunderstorms have ended across the terminals for
this evening as a drier airmass works into the region. Some
patches of midlevel clouds remain here and there. With
dewpoints remaining fairly elevated in the mid-60s, this raises
the potential for fog overnight, although it is not clear-cut.
Mitigating factors include a light northerly flow persisting
down the Hudson Valley, and the fact that the terminals largely
avoided rainfall today. Another wild card is potential for MVFR
stratus to wrap into the area from the northeast (potential is
highest at KPSF). For now, will introduce MVFR cigs/vsby
generally after 06Z for KGFL/KPSF and after 09Z for KALB/KPOU.
The stratus may linger for a while through Wednesday morning at
KPSF, but should mix out over the remaining terminals within two
or three hours after sunrise. VFR conditions expected to prevail
for Wednesday afternoon with scattered to broken cumulus.

Light northerly winds early in the TAF period will become light
and variable tonight into Wednesday.

Outlook...

Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: Low Operational Impact. Slight Chance of SHRA...TSRA.
Thursday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Friday: Moderate Operational Impact. Chance of SHRA...TSRA.
Friday Night: Low Operational Impact. Slight Chance of SHRA...TSRA.
Saturday: Low Operational Impact. Slight Chance of SHRA...TSRA.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: Moderate Operational Impact. Slight Chance of SHRA...TSRA.

&&

.FIRE WEATHER...
An upper level low pressure system will move eastward off the
New England coast tonight, bringing an end to the showers and
thunderstorms. Mainly dry conditions are then expected from
Wednesday into Thursday morning, as a ridge of high pressure
builds in. Just an isolated shower is possible over the higher
terrain of western New England. Chances for showers and
thunderstorms will increase again Thursday into Thursday night,
as a frontal system approaches from the west.

Relative humidity values will increase to between 90 and 100
percent tonight, decreasing to around 45 to 60 percent Wednesday
afternoon. RH values will increase to between 85 and 100
percent Wednesday night.

Winds will northerly less than 5 mph tonight, becoming variable
less than 5 mph on Wednesday. Winds will be southeast around 5
mph Wednesday night.

&&

.HYDROLOGY...
Isolated to scattered showers and thunderstorms will continue
into early this evening. Localized rainfall amounts have
exceeded an inch in some spots, but most locations that receive
rainfall look to pick up around a quarter to a half inch.
Brief/locally heavy rainfall could cause minor flooding in poor
drainage, urban and low lying areas, but flash flooding is not
expected. Some minor rises are possible along a few rivers, but
overall river levels will remain steady into Thursday.

Dry conditions are expected Wednesday into Thursday morning.
The next chance of showers and thunderstorms arrives Thursday
afternoon into Friday, as a frontal system approaches and moves
across the region. Some locally heavy rainfall may be possible
depending on available moisture/instability.

Hot, humid, and dry weather is expected during the upcoming
weekend.

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...JPV
NEAR TERM...Thompson/JPV
SHORT TERM...JPV
LONG TERM...Thompson
AVIATION...Thompson
FIRE WEATHER...JPV
HYDROLOGY...JPV

NWS ALY Office Area Forecast Discussion