Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 170003

Area Forecast Discussion
National Weather Service Albany NY
803 PM EDT Wed Aug 16 2017

Fair and dry weather will prevail through Thursday as high
pressure builds into the region with seasonable temperatures
and comfortable humidity levels. More humid conditions and wet
weather will return late Thursday night into Friday night as a
low pressure system approaches and moves across the region
bringing showers along with chances for thunderstorms to the


High pressure will continue to build into the region at all
levels of the atmosphere overnight. It will be cooler and much
drier than last night expecting lows to drop into the mid 40s
to mid 50s with dew points down into the lower 40s to lower 50s.
Lingering clouds will dissipate this evening. Some patchy fog
is possible overnight as winds becoming calm with clear skies.

The high will gradually push eastward throughout the day
Thursday, allowing for plentiful sunshine and temperatures in
the mid 70s to lower 80s. Cirrus clouds are expected to stream
in during the afternoon and especially late in the day.


Clouds begin increasing Thursday night as the next storm system
approaches from the Great Lakes. A developing southerly wind
will allow moisture, and higher dewpoints, to return to the
region. Rain chances will also increase from the south and west
as a warm frontal boundary moves closer to the region. With the
increasing clouds/precip chances, temperatures will be fairly
mild, only falling into the upper 50s/lower 60s.

Rain, with potential thunderstorms, are expected on
Friday/Friday night as the warm front lifts across the area and
the cold front approaches from the west. Although the best upper
level dynamics will remain north/west of the area, enough
forcing will be in place, as the surface cold front will be
crossing during the late evening into the overnight hours. The
latest NAM suggests that instability doesn`t increase until
closer to 21Z/Fri-00Z/Sat with the cold frontal passage. Models
indicate that the cold frontal passage is later than in previous
runs and this timing will ultimately determine how much
instability will be available for thunderstorms to develop. At
this point, do not think thunderstorms will be widespread but
did include slight chance thunder throughout the evening and
overnight periods. The main issue may be heavy rainfall, as PWAT
values will be around 2 inches and any shower/storm may produce
very heavy rainfall within a short period of time. The latest
GEFS shows that the PWATS are 2 to 3 standard deviations above
normal. There should be enough flow to keep things moving, so
flash flooding probably won`t be a concern, but urban/low
lying/poor drainage flooding is certainly possible.

The storm`s cold front should be crossing at sometime late Friday
evening into Friday night, as POPs should lower and skies
should begin to clear throughout the day Saturday. Lows look to
fall into the 60s.


Gradually improving conditions Saturday into Saturday night as
occluded system moves off to our east. Expecting lingering showers
Saturday as upper level short wave trough associated with system
swings through during the day. Any threat for thunder should be
limited to mainly east of the Hudson River Valley. The GFS is a bit
more amplified and slower with upper trough than the ECMWF.

Guidance is in general agreement the upper flow becomes flat/nearly
zonal as we head into next week with ridging building in. Looking at
fair and dry weather for Saturday night through Monday night.

Unsettled weather will return as we head into mid week as a trough
develops over the Great Lakes region and Northeast Tuesday with an
upper low expected to form over eastern Canada Wednesday. Showers
and thunderstorms are expected Tuesday with the development of a
prefrontal trough and ahead of the system`s cold front Wednesday.

Saturday will be warm and muggy with dew points expected to mainly
in the 60s with seasonable readings and less humid conditions for
Sunday. Above normal temperatures are expected Monday and more so
Tuesday ahead of the approaching cold front along with rising dew
points. Looking at highs around 10 degrees above normal Tuesday in
the 80s. After a muggy, warm night temperatures Wednesday are
expected to be cool to normal.


High pressure will continue to build into the region at all
levels of the atmosphere overnight. Some patchy fog is possible
at KGFL and KPSF overnight as winds becoming calm with clear
skies; have MVFR conditions for these sites late at night. Any
fog should burn off quickly after sunrise.

Lingering clouds will dissipate this evening with clear skies
overnight. Cirrus clouds are expected to stream in Thursday
during the afternoon and especially late in the day.

Winds diminish this evening becoming light/variable to calm.
A light south to southwest flow will develop Thursday morning
and persist through the day.


Thursday Night: Moderate Operational Impact. Chance of SHRA.
Friday: Moderate Operational Impact. Likely SHRA...TSRA.
Friday Night: Moderate Operational Impact. Likely SHRA...TSRA.
Saturday: Moderate Operational Impact. Chance of SHRA.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.


Dry weather is expected tonight and tomorrow, before a
widespread wetting rainfall looks to occur for Friday. Dew
formation is expected tonight with some patchy fog as well.

RH values will fall to the 35 to 50 percent tomorrow afternoon,
but remain in the 65 to 85 percent range on Friday. RH values
are expected to recover to 80 to 100 percent both tonight and
Thursday night. NW winds will be 5 to 10 mph for the remainder
of the evening before becoming light and variable overnight and
into Thursday.


Dry weather is expected tonight and tomorrow, but a frontal
system will bring some showers and thunderstorms to the region
between Thursday night and late Friday night. With dewpoints
reaching into the upper 60s to lower 70s and PWATs reaching
around 2 inches, the chance for the heaviest rainfall be on
Friday afternoon and evening. Although flash flooding is not
anticipated due to stronger winds aloft (which should keep heavy
rainfall moving quickly), showers/thunderstorms will be capable
of producing heavy downpours within a short period of time,
which may lead to minor flooding of poor drainage, urban and low
lying areas. Main stem rivers may seem some minor rises, but no
river flooding is expected with this rainfall. Although a
lingering shower or two cannot be ruled out for Saturday, drier
weather should return on Sunday.

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.


Technicians will continue to work on the KENX radar Thursday and
hope to have the radar back in service in the afternoon.




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