Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 201738
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
138 PM EDT Fri Oct 20 2017

.SYNOPSIS...
An area of high pressure will build in from near the Mid
Atlantic States this afternoon into tonight for the upcoming
weekend, resulting in continued dry weather and above normal
temperatures. Unsettled weather returns late Monday into the
midweek.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 109 PM EDT, Strong subsidence in the wake of a dry cold
front east of New England, and a sfc anticyclone building in
from the Piedmont Region and the Mid Atlantic States has yielded
sunny skies. The visible satellite picture is clear and there
are very little changes to make to the ongoing forecast with a
tweak upward for a few lower 70s over the mid-Hudson Valley. The
12Z KALY sounding shows the strong subsidence inversion with
weak/modest cold advection and the strong northwest flow
throughout the troposphere aiding in some downsloping. North to
northwest winds of 10 to 15 mph with some gusts to 25 mph or so
due to decent mixing will continue this afternoon before
subsiding quickly. Highs will be in the mid 60s to around 70F in
the valleys. Upper 50s to lower 60s will be common over the
mountains.

Some of the previous near terms...

Winds have become breezy out of the north-
northwest this morning behind the dry frontal passage last night
with temperatures currently sitting in the 50s to near 60
degrees. This will allow for a sunny and dry day today, which
remains on par with our current forecast. Further details
regarding the forecast are below.

There are indications that a boundary layer thermal gradient
sets up right in the middle of our forecast area, implying high
temperatures in northern areas could be considerably cooler
than in southern areas. Differences in guidance as to where that
gradient sets up result in some uncertainty but generally highs
in the 60s today with a few lower 70s southern areas and around
60 southern Adirondacks.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
High pressure controls the weather through the period and builds
east. Warm advection is expected to begin Saturday and continue
Sunday but with the upper ridge and low level ridge axes so
close to our region, winds should be quite light and it should
be quite dry through a deep layer.

Some thin high clouds will begin to filter into the region
Sunday and Sunday night well ahead of the developing system to
our west. How much warming we see Saturday and Sunday will
depend on how much the boundary layer warms and how much mixing
we can get with potentially such light south winds.

Highs Saturday around 70 to lower 70s but some mid 60s southern
areas. Highs Sunday in the lower to mid 70s. Nighttime lows look
to be on the cooler side of guidance with the clear sky, near
calm winds and such a dry atmosphere.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Large scale amplification of the upper pattern across North America
will continue through this period, resulting in an increasingly
active pattern featuring more rain chances, and a trend toward
cooler temperatures for the local area.

Models seem to have come into slightly better agreement regarding
timing of initial PV anomaly along the Gulf Coast/Lower MS Valley
region tracking north and deamplifying ahead of digging trough from
northern Plains region, with height falls spreading across the
northeast Tuesday-Wednesday. This suggests that chances for rain
should increase, perhaps as early as late Monday or Monday night
across southern/western areas, with the potential for a more
widespread, soaking rainfall Tuesday-Tuesday night. Ample low level
flow from the Gulf of Mexico and Atlantic Ocean, combined with the
slow approach of the upper level trough suggest some locally heavy
rainfall could occur.

Model uncertainty increases for Wednesday-Thursday, as the 00Z/20
ECMWF suggests a formidable upper level impulse closes off and
tracks north/northeast from Delmarva Thursday, with an attendant
surface low developing and tracking north/northwest into New
England. This would bring another bout of widespread rain to much of
the region, especially for areas near and east of the Hudson River.
The 00Z/20 GFS, GEFs, and GEM remain much more progressive with
little indication of such a feature. For now, will keep chance PoPs
for Wed night-Thu, but no higher at this time.

As for temperatures, still remaining well above normal for Mon-Mon
nt, with highs reaching 70-75 in valleys, and 65-70 across higher
terrain, and overnight lows mainly in the 50s, although some areas
may actually hold near or above 60 if clouds/wind persist. Still
mild Tuesday-Tuesday night, with highs 65-70 in valleys, 60-65
across higher elevations, and lows Tuesday night ranging from the
mid 40s across northwest areas, to the lower/mid 50s south and east.
Cooling becomes more evident Wednesday, with highs mainly in the 50s
and 60s, with highs Thursday only in the 50s, although some areas
may only remain in the 40s if steady rain occurs. Overnight lows Wed
nt/Thu am mainly in the upper 30s to mid 40s.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
High pressure will continue to build into the area today and
tonight, resulting in clear skies and continued VFR conditions.

North-northwest winds will continue to be gusty this afternoon,
at around 15 to 20 kts, before lessening this evening. Winds
will become light and variable at less than 5 kts tonight into
tomorrow.

Outlook...

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

&&

.FIRE WEATHER...
Northwest to north wind gusts will approach 25 mph this
afternoon...

An area of high pressure will build in from the south and west
today into the upcoming weekend, resulting in continued dry and
mild conditions.

RH values will fall to between 30 and 45 percent this afternoon
and Saturday afternoon. Nighttime RH values will range between
75 and 100 percent.

Northwest winds at 15 mph or less this morning will become north
to northwest at 15 mph midday and gusts could approach 25 mph
midday through this afternoon. Winds diminish to variable at
less than 15 mph tonight them become west to south at less than
15 mph Saturday.

&&

.HYDROLOGY...
No precipitation is expected through at least the weekend
thanks to persistent high pressure, with river/stream flows
remaining at normal to below normal seasonal levels.

The next chance of rainfall arrives early next week, as a
widespread rainfall is possible associated with a slow-moving
frontal system. It is much too early for specific details, but
some heavy rain may occur in the Tuesday to Wednesday time
frame.

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...NAS/Wasula
NEAR TERM...NAS/JVM/Wasula
SHORT TERM...NAS
LONG TERM...KL
AVIATION...KL/JVM
FIRE WEATHER...NAS
HYDROLOGY...NAS



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