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FXUS61 KALY 210452
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
1252 AM EDT Fri Jul 21 2017

.SYNOPSIS...
High pressure will build eastward from the Great Lakes Friday into
Saturday with dry conditions and slightly above normal temperatures.
The next chance of rain arrives Saturday night into Sunday, as a
frontal boundary approaches from the west.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
As of 1250 AM EDT, with mainly clear skies and light/calm winds
in place, temperatures across portions of the Adirondacks have
dropped into the lower/mid 50s according to latest NY Mesonet
obs. Based on this, have lowered overnight forecast min
temperatures in these areas by another 2-4 degrees from current
levels, with upper 40s to lower/mid 50s expected. In these
areas, patchy dense fog will be likely, especially in close
proximity to lakes/streams.

Elsewhere, a band of low clouds is noted on latest 11-3.9 IR
satellite imagery across the Catskills, and extending into
portions of the far western Mohawk Valley, and areas south and
east of the immediate Capital Region, as well as across portions
of the mid Hudson Valley. These low clouds are likely due to
residual moisture/cold pool and low level inversion induced from
earlier convective complex. These clouds are expanding east, and
expect to continue extending into Berkshires through daybreak.
So, partly to mostly cloudy skies for the remainder of the night
for many areas south of I-90. Outside the relatively chilly
Adirondacks, expect most low temperatures to reach the upper 50s
to mid/upper 60s, warmest closer to the I-84 corridor.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/...
Tranquil, but warm conditions expected Friday as a ridge of
surface high pressure extends east from the Great Lakes.
Westerly flow will lead to continued above normal temperatures
in the 85-90 range for valley locations, although humidity
levels should be lower than Thursday and a persistent 10-15 mph
breeze will be make it feel more comfortable. High pressure will
move overhead Friday night with continued dry conditions and
seasonable temperatures.

Models have come into somewhat better agreement, especially
indicating dry conditions persisting through Saturday, delaying
the approach of a frontal boundary from the Great Lakes and Ohio
Valley region. Even the previously faster NAM has delayed onset
of showers until just after dark Saturday. So, it appears we
will have two consecutive dry days Friday and Saturday. Will
mention warmer temperatures for Saturday as well compared to
previous forecasts due to delayed onset of showers and more
sunshine during the first half of the day.

Chances for showers will increase Saturday night, as the
boundary approaches from the west. However, models differ with
the placement of this feature, which will have implications for
where more persistent showers eventually set up. Will mention
chance pops for now across the entire area, with time to fine-
tune as guidance comes into better focus with the position of
the boundary over the next day or so.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
An unsettled pattern is expected for the long term with many
uncertainties in play.

We start off with a 1010mb Canadian high situation over the
Northeast and a system in the southern Great Lakes advancing
eastward. Each model suite for the past few days has
consistently shown its associated warm front edging close to the
southern tier of our CWA in the Saturday night - Sunday time
frame. However, the main forecast challenge here is just how far
north its thermal gradient extends which will impact two
things...which of our areas receives precipitation and how much.
To matters even more challenging, guidance continues to
indicate a weak shortwave riding along the stalled boundary
during this time, bringing the potential for a period of rain to
those areas near the boundary. At this time, most of the
guidance continues to show the warm front stalling near Long
Island/NYC/coastal CT meaning our far southern tier counties
have the highest probabilities of receiving precipitation. Thus,
have reflected that in the latest update giving high chance
POPS to Ulster/Dutchess/Litchfield counties. It is important to
note that in these situations, if the front stalls a few miles
north or south of where guidance indicates, that can have large
impacts on which area see precip and how much.

After the weak shortwave exits sometime Sunday, we could see a
dry break before our attention turns to a stronger positively
trough over the Great Lakes which is expected to swing into the
Northeast for Sunday night/Monday. This system looks to bring an
increasing threat for precipitation during the Sunday
night/Monday period with the previously discussed warm front
still south of our CWA. Given that our 1010mb high should still
be wedged over New England/eastern NY, the precip associated
with the incoming system may struggle to reach our CWA initially
thanks to mid level dry air and subsidence. Eventually, as the
trough becomes neutrally tilted and enters the Northeast, more
widespread precipitation is expected from west to east but again
uncertain on exactly when precip begins during the Sunday
night/Monday period.

Unsettled conditions linger into Tuesday as the neutrally
titled trough is slow to exit with continued threat for showers.
For now, left chance POPS for the entire CWA. Guidance suggests
that the system cuts off at 700mb with a trowal developing as
the system gradually moves through NY and western New England.
There is an associated cool pool aloft so included slight chance
thunder as well for Tuesday. Temperature wise, we should end up
below normal with highs only in the 70s. Could see the
Adirondacks struggling to rise out of the 60s and have reflected
that in the newest update.

Once the low exits Tues night/Wed, heights rise and we should
see high pressure lead to drier and slightly warmer weather mid
- week. Another shortwave arrives for the end of the extended
and have increased to slight chance POPS for Thursday/Friday.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
Mainly VFR conditions are expected at the TAF sites through the
end of the TAF period ending at 06Z Saturday. The exception will
be some late night fog during the remainder of the overnight
period at KGFL and KPSF which will result in some IFR
conditions. Once any fog burns off this morning skies will be
expect mainly some high cirrus clouds with perhaps some cumulus
hanging around at KPSF during the morning hours.

Calm to light and variable winds during the overnight period
will give way to west to northwest winds of 6-10 kts today.
Winds will then become light and variable once again tonight.

Outlook...

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

&&

.FIRE WEATHER...
Showers and thunderstorms will move across portions of the area
this evening, especially south and east of Albany. Then high
pressure will build eastward from the Great Lakes Friday into
Saturday with dry conditions and slightly above normal
temperatures. The next chance of rain arrives Saturday night
into Sunday, as a frontal boundary approaches from the west.

Relative humidity values will increase to around 90 to 100
percent tonight, dropping to minimum values of 40 to 55 percent
on Friday. RH will increase to between 90 and 100 percent again
Friday night.

Winds tonight will be westerly around 5 mph or less. Winds on
Friday will become west-northwest and increase to 10 to 15 mph.
Westerly winds will continue Friday night around 5 to 10 mph.

&&

.HYDROLOGY...
Some showers and thunderstorms will move across parts of the
area this evening, especially south of Albany, as an upper level
disturbance moves through the region. Storms are expected to
move relatively quickly, so no flooding is anticipated at this
time, although brief downpours could result in ponding of water
on roads and poor drainage locations.

Dry weather will return Friday through Saturday with high
pressure building in. Then, another bout of wet weather with
additional showers and few thunderstorms expected from Sunday
through early next week.

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...KL/BGM/JPV
SHORT TERM...JPV
LONG TERM...Speciale
AVIATION...11
FIRE WEATHER...JPV
HYDROLOGY...JPV
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