Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 250855

Area Forecast Discussion
National Weather Service New York NY
455 AM EDT Tue Oct 25 2016

High pressure slowly builds in from southern Canada through
Wednesday. The high moves east on Wednesday giving way to a
frontal system Thursday into early Friday. Another frontal system
impacts the area this weekend, followed by high pressure Monday.


The upper level trough will move east into the Canadian Maritimes
today with a shortwave going through the region around the base of
the trough.

Going into daybreak, high pressure centered in Ontario builds
slowly southeastward.

Stratocumulus clouds are moving into the region. Not a widespread
cloud cover, just broken coverage over certain parts of the
region. Gusts are mainly across immediate coastal sections and
over the water, where enough of a vertical temperature gradient
exists to allow for more mixing.

Strong high pressure remains centered in Ontario while continuing
to slowly build southeast closer to the region through the day. A
weakening low in the Canadian Maritimes in combination with the
strong high in ontario creates a steep pressure gradient. This
will allow for gusty northwest flow to continue today. The cold
air advection increases as well with a continuous northwest fetch.
850mb temperatures will lower several degrees compared to the
previous day so temperatures will be noticeably cooler. There will
be cold air advection aloft which should increase the coverage of
stratocumulus driven by diurnal instability. Models are even
showing some very light QPF extending into the far northwest and
southeast sections of the region, which is primarily evident in
strong cold air advection scenarios. However, aside from this
morning across Orange County NY where there is a slight chance of
precip, low levels will be too dry for precip elsewhere and later
on today.

Used ECS guidance for highs.


The center of the high tracks to southeast Ontario and continues to
build into the local region. There will be some slight ridging
aloft. The winds will become lighter in response to a weaker
pressure gradient. The cooler airmass will already be within the
region. The closer proximity of the high will result in more
subsidence and less clouds. The combination of factors will lead
to better efficiency of radiational cooling especially across the
interior. Freezing temperatures expected across much of the
interior where freeze warning is in effect.

Used MAV guidance for lows.

For Wednesday, the high pressure center moves east into Quebec
with a continued decrease in pressure gradient across the local
region. Winds will be lighter but will still be a little breezy
from diurnal heating and inherent mixing. The cold air advection
at 850mb decreases as the weather pattern shifts. Cyclonic flow
aloft lessens as the upper level low in the Canadian Maritimes
shifts east while across the local region, there will be some
slight ridging aloft. Model guidance in pretty good agreement with
a downward trend in temperatures Wednesday as highs will be a few
degrees cooler than the previous day.

Used a blend of MET/MAV/ECS guidance for highs Wednesday.


A shortwave moving across the Great Lakes region late Wednesday
night into Thursday morning, will slowly move east, passing
across the local area Thursday night.

At the surface, high pressure continues to slide east as a warm
front approaches from the west as low pressure tracks across the
Great Lakes and across PA/western NY.

Warm air advection rain move in late Wednesday night and through the
day Thursday. Enough cold air ahead of the WAA, and time of day
being early morning could result in some light snow briefly NW
zones. Some accumulations are possible across higher elevations
before a change to plain rain occurs.

Rain is expected through thursday night, before ending during the
day on Friday. There is a chance some lingering rain showers could
continue into the afternoon across the eastern half of the CWA.

High pressure builds to the south as another low moves across the
Great Lakes Region Saturday, passing to the north early Sunday.
Drier weather returns for the start of next week.

Temperatures through the long term will remain slightly below or
right around normal.


VFR as high pressure builds over the region.

NW flow with occasional gusts to 20kt possible from 11-14z. Gusts
becoming more frequent after 14z. Winds near 310 magnetic most of
the day. See comments below for details.

...NY Metro Enhanced Aviation Weather Support...

Detailed information...including hourly TAF wind component fcsts
can be found at:

KJFK TAF Comments: Winds probably prevail mostly south of 310
mag through 14z, but chance that winds continue to prevail at or
south of 310 mag through 15-16z. Winds could still be south of 310
mag at times thereafter.

KLGA TAF Comments: Winds probably prevail mostly south of 310
mag through 14z, but chance that winds continue to prevail at or
south of 310 mag through 15-16z. Winds could still be south of 310
mag at times thereafter.

KEWR TAF Comments: Chance that winds occasionally are north of 310
mag through 15-16z. Thereafter, equal chances of being north or south
of 310, but best guess is they will favor south of 310.

The afternoon KEWR haze potential forecast is green...which
implies slant range visibility 7SM or greater outside of cloud.

KTEB TAF Comments: Winds could be mostly 270-300 magnetic around 5
kt instead of light and variable before 12z.

KHPN TAF Comments: No tactical amendments scheduled and no
strategic amendments expected.

KISP TAF Comments: No unscheduled amendments expected.

.TUE NIGHT...VFR with diminishing NW winds.
.WED...VFR. NW-NNW G20KT possible near the coast.
.THU...MVFR conditions likely in rain. IFR conditions possible at
night. SE winds 10-20KT.
.FRI...VFR. W-NW winds G25-30KT.
.SAT...VFR. Chance of rain. SW winds G15-20KT.


SCA conditions once again on all waters today with the steep
pressure gradient between a weak low in the Canadian Maritimes
and a strong high in Ontario.

For tonight, the pressure gradient weakens so gusts will decrease
likewise. SCA conditions will keep up across the ocean while non-
ocean waters will subside below SCA during the evening after 00Z.

For Wednesday, the pressure gradient is weak enough to
keep conditions below SCA on all waters.

Sub-SCA conditions are expected Wednesday night through much of

SW flow increases to 15-20 kt Thursday night out ahead of a frontal
system which should push ocean seas up to 5-6 ft. As the low passes
by Friday, winds shift back around to the west/nw and increase
behind the departing low. These winds back yet again to the west/SW
ahead of next frontal system Saturday into Sunday.


Dry weather remains forecast through Wednesday.

Low pressure impacts the area Thursday and Thursday night. Forecast
QPF is expected to produce anywhere from 1/2 to 3/4 of an inch of
rainfall. Local amounts over an inch are possible. No hydrologic
impacts expected at this time.


CT...Freeze Warning from 2 AM to 9 AM EDT Wednesday for CTZ005>008.
NY...Freeze Warning from 2 AM to 9 AM EDT Wednesday for NYZ068>070.
NJ...Freeze Warning from 2 AM to 9 AM EDT Wednesday for NJZ002-004-
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ330-
     Small Craft Advisory until 6 AM EDT Wednesday for ANZ350-353-


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