Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 111219
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
719 AM EST Mon Dec 11 2017

.SYNOPSIS...
High pressure builds briefly across the area today. Low
pressure will then pass across the Great Lakes tonight, while an
associated warm front lifts through the waters Tuesday morning,
followed by a strong trailing cold front in the afternoon. An
intensifying low pressure system will move into the Canadian
Maritimes Tuesday night into Wednesday night, with brief high
pressure building across the area in its wake. A weak Alberta
Clipper passes to the south on Thursday, followed by a low
pressure system passing off the coast late Friday into Friday
night. High pressure returns for the weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Updates this morning to include the potential for light snow
this morning, mainly across Connecticut and Long Island. Using
extrapolation for the short wave seen on WV this morning and the
back edge of the radar returns, any snow should be east of the
area by around 8 am.

Also updated to increase gusts this morning, as JFK has been
reporting an occasional gust to near 30 mph. Any gusts should
gradually diminish over the next few hours as high pressure
begins to briefly build across the area.

Skies will start off partly to mostly sunny, then clouds
increase through the afternoon. High temperatures today will top
out in the upper 30s to lower 40s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Low pressure moves across the Great Lakes tonight into Tuesday morning.
The associated warm front approaches the area from the south
late tonight into Tuesday with increasing chances of
precipitation, followed by a strong trailing cold front Tuesday
afternoon.

Warm advection ahead of the main portion of the storm will make
this a mixed precip event. Rain is forecast for the city,
adjacent suburbs and coastal section, although some snow can mix
in at first. Across inland areas, snow or a snow/rain mix
changes over to rain as Temperatures rise during the morning
hours on Tuesday. Snow accumulations expected to be 1 or 2
inches for the northern suburbs, with 2 to 3 inches expected
further north across Orange County. Less than an inch is
expected anywhere else where snow manages to accumulate.

Highs on Tuesday will be in the upper 30s to lower 40s inland
and mid to upper 40s along the coast, with even some 50 degree
readings for Long Island.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
A period of brisk weather is anticipated Tuesday night into Thursday
as an intensifying low pressure system moves towards the Canadian
Maritimes. With the tightening pressure gradient on the back side of
the low, strong cold advection combined with sustained winds around
20-30 mph and gusts above 40 mph will lead to wind chill values in
the single digits to teens on Wednesday, and largely the single
digits to near zero Wednesday night. Although some moderation will
occur on Thursday as flow backs to the WSW ahead of the next system,
temperatures will remain well below climatological normals, with
cold wind chill values in lingering breezy flow.

Overall, a blocking pattern with low pressure anchored over the East
Coast will continue a period of below normal temperatures and above
normal precipitation as a series of waves rotate around the broader
low. Chances of precipitation increase again into Friday as the
subtropical jet shifts northward, combining with polar energy and
leading to the development of a coastal low. The general track and
intensity of the low will need to be monitored, but expected at
least a slight chance of snow showers across the interior and
perhaps a rain/snow mix along the coast into Friday night. Gusty
flow and below normal temperatures will once again be possible as
the low departs, with a slow moderation occurring through the
weekend as high pressure builds across the area.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
A cold front will move across the area today.

Mainly VFR today. A few snow showers will be possible early this
morning, which may produce some brief MVFR cigs. The best chance of
any snow showers will be east of NYC and only last til 13z.
Cigs may drop to 3000ft. No runway accumulation expected,
although visibility could be briefly reduced to MVFR or lower.

Cigs fall to MVFR late in the TAF period, mainly after 09z Tuesday
as a warm front pushes north of the area and associated low
pressure system passes north of the area. precipitation starts
after 06z, mainly in the form of a mix of rain and snow for most
terminals, except KSWF, where precipitation should be all snow.
As warmer air works into the the coastal locations,
precipitation should quickly change over to all rain. Interior
locations should stay snow through at least 12z Tuesday.

Generally westerly winds today. There may be a few occasional gusts
early this morning, then gusts become more frequent during the
afternoon with speeds around 20 kt. Gusts will end after 23Z.
Tonight, winds become more southerly and remain less than 10 kt.

     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: Gusts this afternoon may be occasional.

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

KLGA TAF Comments: Gusts this afternoon may be occasional.

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

KEWR TAF Comments: Gusts this afternoon may be occasional.

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

KTEB TAF Comments: Gusts this afternoon may be occasional.

KHPN TAF Comments: Gusts this afternoon may be occasional.

KISP TAF Comments: Gusts this afternoon may be occasional.

.OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY...
.Tuesday...MVFR or lower possible with a wintry mix to rain at
northern terminals and rain at southern terminals. Conditions
improve to VFR Tuesday afternoon. SE-SW winds G15-25KT possible.
.Tuesday night-Wednesday...Mainly VFR, with a chance of MVFR in snow
showers. W-NW winds G20-35KT probable.
.Wednesday night-Thursday night...VFR. W-SW winds G15-25KT possible.
.Friday...MVFR possible with snow. W-NW winds G15-20KT possible.

&&

.MARINE...
Update this morning to extend the SCA on the eastern Long Island
Sound with ongoing gusts. As high pressure begins to build
across the area, gusts will gradually begin to diminish, with
seas slowly subsiding on the ocean waters later today. Winds and
seas then increase again on Tuesday, with SCA conditions
becoming likely on the area waters. By Tuesday night, gale-
force winds will be possible as an intensifying low pressure
system ejects into the Canadian Maritimes. Gusty flow and at
least SCA-level conditions will continue into Thursday before
gradually subsiding into Thursday night as flow weakens across
the area. Relatively tranquil conditions persist through Friday
before winds and seas increase into Friday night behind a
departing low pressure system.

&&

.HYDROLOGY...
No significant hydrologic impacts expected.

&&

.EQUIPMENT...
NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the
air for an extended period of time. See our headline news on
the web at: http:/weather.gov/nyc

The Riverhead NOAA Weather Radio Station WXM-80 (162.475 MHz)
is currently out of service. NWS technicians are working with
Verizon to restore service. An estimated time of return to
service is not currently known.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ350-
     353-355.
     Small Craft Advisory until 10 AM EST this morning for ANZ330-
     340.

&&

$$
SYNOPSIS...MD/Fig
NEAR TERM...MD/Fig
SHORT TERM...Fig
LONG TERM...MD
AVIATION...BC
MARINE...MD/Fig
HYDROLOGY...MD/Fig
EQUIPMENT...


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