Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 081535
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1035 AM EST Thu Dec 8 2016

.SYNOPSIS...
A series of cold fronts cross the area Thursday through Friday.
High pressure builds through Saturday. Low pressure and associated
front impacts the area later Sunday and Monday. High pressure
returns Tuesday. Another front approaches Wednesday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Forecast remains on track with little change to database. Forecast
was updated to reflect latest observations.

Any lingering fog over southern CT should quickly burn off.

An upper level trough approaches today. Upper Jet and associated
thick mid/high clouds noted this morning. Multiple shortwaves
will move across or near the area as they rotate around the base
of an upper trough through the near and short term periods. The
first of the shortwaves will pass near the region today.

The first of the shortwave moves through dry, however it will provide
the region with a shot of cold air, and winds will increase and
gust out of the northwest by late afternoon. Temperatures today
will climb into the 40s, however, expect falling temperatures
through the mid to late afternoon north and west of NYC. Used a
MAV/MET/ECS blend for temperatures, which looked fairly
reasonable.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
Another shortwave moves across the region Thursday night into
Friday, providing yet another shot of cold air.

In addition, there should be enough moistening of the low and mid
levels early Friday morning to warrant a slight chance of snow
showers. The best chances of any precipitation will remain north and
west of NYC, however by mid to late morning, snow showers will be
possible across the entire CWA. little to no accumulations are
expected with these snow showers.

Low temperatures Thursday night will fall into 20s and lower 30s.
A gusty northwest flow 20-30 mph will allow wind chills to reach
the teens and lower 20s around sunrise Friday morning.

High temperatures on Friday will only reach the middle and upper
30s, but will feel like 20s, as the gusty northwest flow continues.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Uncertainty due to differences in details this time frame in a
progressive flow through the weekend, then a more amplified
pattern mid week next week.

Chilly air settles in from Canada through much of this time period,
and timing of individual systems remains a challenge.

Generally expect dry weather Friday night and Saturday as initial
shortwave departs, and surface high pressure builds to the south.

Next impulse and surface boundary approaches from the west Sunday
with potential for WAA precip (likely snow) developing later Sunday
and Sunday night. On Monday, track and strength of low pressure is
unclear, but frontal boundary looks to remain south of the area.
Will maintain likely PoP for this timeframe since models agree on
precip, if not overall pattern details. P-type will be tricky
late Sunday night and Monday, with some mix or changeover likely
as warmer air advects northward.

This upper shortwave races east by Tuesday, along with low pressure
and front, although 00Z ECMWF shows lingering Norlun type trough
nearby or just east of the area early Tuesday between inland
weakening low and offshore low.

More vigorous upper trough begins to take shape, tracking across the
upper mid west and pivoting across the Great Lakes region by mid
week. Latest GFS and ECMWF runs differ on depth of this trough, and
sfc features. This leads to overall lower confidence in forecast
day 7.

Temperatures should remain at or just below normal through much of
this period. Brief warmups could occur in WAA ahead of each
shortwave/low pressure in return flow.

&&

.AVIATION /16Z THURSDAY THROUGH MONDAY/...
A cold frontal passage occurs late today. High pressure over the
Plains then slowly builds towards the area on Friday.

VFR through the TAF period.

Westerly flow today veers slightly to the west northwest behind the
frontal passage this afternoon. Gusty winds will develop this
afternoon, before relaxing somewhat overnight. Winds and gusts
will increase after sunrise tomorrow.

     NY Metro Enhanced Aviation Weather Support...

Detailed information, including hourly TAF wind component forecasts,
can be found at: http:/www.weather.gov/zny/n90

KJFK TAF Comments: Start time of the gusts may be off +/- 1-2
hours from forecast. Wind direction will stay left of 310 magnetic
through this evening.

KLGA TAF Comments: Start time of the gusts may be off +/- 1-2
hours from forecast. Wind direction will stay left of 310 magnetic
through this evening.

KEWR TAF Comments: Start time of the gusts may be off +/- 1-2
hours from forecast. Wind direction will stay left of 310 magnetic
through this evening.

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

KTEB TAF Comments: Start time of the gusts may be off +/- 1-2
hours from forecast.

KHPN TAF Comments: Start time of the gusts may be off +/- 1-2
hours from forecast.

KISP TAF Comments: Start time of the gusts may be off +/- 1-2
hours from forecast.

.OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
.Friday...Ceiling around 3000 ft possible at times. Flurries or snow
showers possible. Northwest winds 20-30 kt.
.Saturday...Most likely VFR with light northwest flow.
.Sunday and Monday...Chance of MVFR or lower depending on the
position of a warm front. Mixed precipitation or snow possible,
especially inland.

&&

.MARINE...
Sub-SCA conditions are expected on the area waters this morning.
This afternoon...the pressure gradient tightens and remains tight
over all the waters through Friday. As a result expect gusts to
25-30 kt over the area waters. The gusts should start a few hours
earlier on the ocean waters than the non-ocean waters, however for
simplicity, have started the SCA everywhere at 18Z today.
Gusts to 35 kt are possible on the ocean tonight and possibly
Friday, however will hold off on any gale warning, thinking that
these gusts would be more occasional than frequent.

Gusty W-NW flow Friday night will diminish as the center of high
pressure builds. Sub SCA conditions are anticipated through the
weekend as the high settles to the south and a frontal boundary
approaches from the west. Low pressure and the associated front
approach and impact the waters Monday. SCA conditions are possible
Monday, particularly across the ocean waters.

Wave/sea forecasts are based on latest NWPS, with WaveWatch
followed toward the end of the forecast. Seas subside as the
winds diminish Friday night and through the weekend.

&&

.HYDROLOGY...
A widespread 1/2 inch or more of liquid equivalent precipitation
is possible from Sunday night through Monday.

&&

.EQUIPMENT...
The New York City transmitter, KWO35, is off the air. Time for a
return to service is unknown.

Central Park (NYC) observations are currently unavailable.
Technicians are troubleshooting.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EST Saturday for ANZ330-335-
     338-340-345-350-353-355.

&&

$$
SYNOPSIS...BC/PW
NEAR TERM...BC/Goodman/PW
SHORT TERM...BC
LONG TERM...PW
AVIATION...CB/JMC/DS
MARINE...BC/Goodman/PW
HYDROLOGY...BC/PW
EQUIPMENT...



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