Area Forecast Discussion
Issued by NWS Upton, NY

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135
FXUS61 KOKX 060607
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
107 AM EST Tue Dec 6 2016

.SYNOPSIS...
As high pressure moves northeast across New England, low pressure moves
off the mid atlantic coast through early Wednesday. A series of cold
fronts will move southeast across the region through Friday followed
by cold canadian high pressure Saturday through Sunday. Low pressure
will approach Monday.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
High pressure will move east across the area tonight as NW winds
continue to decrease.

SCT-BKN overrunning cirrus clouds will advect east across the
region.

Changes were made to the overnight temperatures including the
overnight low temperatures. Where surface winds have decoupled
from the upper flow, temperatures have plummeted, especially
across the pine barrens of Long Island.

A Special Weather Statement remains in effect where wet snow fell
earlier today for the potential development of black ice, which
could impact the Tuesday morning commute. Low temps should be in
the 20s inland and central Suffolk County, and 30s NYC metro and
along the coast.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
After a sunny start, high clouds will increase in the late
morning and afternoon as the upper ridge axis slides across. As a
closed low over Eastern TX opens up into a mid level trough and moves
into the ridge, the associated sfc low pressure in the OH/TN
valleys should start to redevelop late in the afternoon along the
NC coast, and could bring a chance of rain to NYC metro and the
Lower Hudson Valley late in the afternoon. High temps will be in
the 40s.

There are some model timing and intensity differences with the
approaching system for Tue night. The NAM is faster and has a more
ideal juxtaposition of synoptic and mesoscale lift via the
approaching trough, the left entrance of an upper jet streak, and
mid level frontogenesis. This lift also leads to more dynamic
cooling aloft and greater potential for snow across the interior.
Meanwhile the GFS/ECMWF are slower, not quite as wet, and warmer,
with less potential for snow inland. The official forecast
straddles these two scenarios, with potential for a 1-2 inch
snowfall inland, a coating to an inch just inland of I-95 in CT
and I-287 in the lower Hudson Valley and interior NE NJ, and
little to no accumulation farther south where precip will be
mostly in the form of light rain.

Mid level moisture heads to the east by Wed morning, with any
lingering precip changing mostly over to rain. Some clearing
expected across the western half of the area. High temps will
once again be in the 40s per guidance blend.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
A closed upper low that is nearly stacked will remain across
southeastern Canada Wednesday night into Friday. Meanwhile a
shortwave will be rotating through the upper trough with a cold
frontal boundary and trough moving through the Mid Atlantic
Thursday. This cold front will bring a cold air mass into the
Northeast with temperatures running around 10 degrees below normal.
There is still some uncertainty as too how quickly the cold
airmass will reach the northeast before becoming modified.

The upper low opens and moves out late Friday and Friday night with
weak upper ridging. The upper flow become nearly zonal across the
continental United States Friday night and through the weekend.
With high pressure moving off the northeast coast Sunday a return
flow develops and warm advection sets up into Monday.

Friday night the next shortwave to affect the area will be
moving on shore of the Pacific northwest and quickly move across the
country. Cyclogenesis occurs across the central plains Sunday
into Sunday night with the low tracking through the Great Lakes.
Precipitation Sunday night may start as snow inland and transition
to rain Monday and will be dependent on how quickly the warmer
air moves into the area. If a warmer layer moves in aloft before
the low level cold air is scoured out there will be a chance for
some freezing rain Sunday night. With the uncertainty did not
include in the forecast at this time and leaned toward a warmer
solution.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
High pressure will move through this morning. Low pressure
approaches from the southwest late in the day, passing to the
south tonight.

VFR with few clouds through the morning. Increasing mid and high
clouds are expected during the afternoon. Stratus develops toward
00Z as rain approaches the NYC metro. The rain and MVFR conditions
sweep across the remainder of the area during the evening. Snow
expected to at least mix with the rain at KSWF. Local IFR possible.

.OUTLOOK FOR 06Z WEDNESDAY THROUGH SATURDAY...
.Late tonight...MVFR/IFR in light rain with light snow or a wintry
mix possible inland.
.Wednesday...MVFR in stratus, with improvement during the afternoon.
.Wednesday night-Thursday night...VFR.
.Friday-Friday night...VFR. NW winds 15-20 kt, gusts 25-30 kt.
.Saturday...VFR. NW winds 15 kt gusts 20-25 kt.

&&

.MARINE...
A Small Craft Advisory/SCA remains in effect for the ocean and
eastern Long Island Sound through tonight as high pressure builds
in and NW winds gust up to 25-30 kt, highest S of Montauk. Ocean
seas should also reach 5 ft S of Montauk, but remain less than 5
ft farther west due to limited offshore fetch.

Winds and seas will remain below SCA levels Wednesday night
through Thursday as low pressure remains to the north across
southeastern Canada. A cold front will move through Thursday and a
strong and gusty northwest flow will develops. Thursday night SCA
gusts develop on the ocean waters, and then during Friday winds
increase, with marginal gale force gusts possible on the ocean
waters, and SCA gusts on the remainder of the forecast waters.
Gale and SCA gusts continue into Friday night, then subside late
as high pressure begins to build to the west. Saturday morning
winds and seas are expected to be below SCA levels on all the
waters as high pressure continues to build.

&&

.HYDROLOGY...
No hydrologic impacts are anticipated the next 7 days.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EST early this morning for
     ANZ330-350-353-355.

&&

$$
SYNOPSIS...Goodman/MET
NEAR TERM...GC/Goodman
SHORT TERM...Goodman
LONG TERM...MET
AVIATION...PW
MARINE...GC/Goodman/MET
HYDROLOGY...Goodman/MET



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