Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 140052

Area Forecast Discussion
National Weather Service New York NY
852 PM EDT Tue Mar 13 2018

The Nor-easter well east of Long Island will track towards Nova
Scotia late tonight. An upper level low moves overhead on
Wednesday. A series of troughs of low pressure pass through the
region from Wednesday night through Thursday night. High
pressure then gradually builds down from south central Canada
through early next week. A coastal low near the mid-Atlantic
coast begins to impact the area on Tuesday.


The intense low pressure center is well east of Long Island and
Cape Cod, eventually tracking into Nova Scotia overnight.

Some light snow is still possible across SE CT and the Twin
Forks of Long Island early this evening, but no accumulation is
expected. This activity is expected to diminish by mid to late
evening as mid level PVA exits northeast of the region along
with the relatively higher 700mb deformation. Otherwise,
expecting dry conditions tonight.

Temperatures dropping below freezing will result in any
snowmelt freezing, creating icy areas on untreated surfaces.
Special weather statement already out regarding this. Lows
expected to range from the low 20s to low 30s late overnight
into very early Wednesday.


Temps will be slow to rise in the morning as well, so the icing
issue will continue into Wednesday. By the afternoon,
temperatures will be above freezing for most locations and with
westerly winds increasing and deeper vertical mixing,
temperatures will reach highs in the upper 30s to lower 40s on

However, precipitation will return to the forecast. The upper
low swings over the region on Wednesday resulting in
destabilization and showering pcpn. At this time, not expecting
any accumulation with temps above freezing. Speaking of temps,
have cut down from MOS due to higher albedo and below
climatological values.

Breezy conditions are also expected with gusts of 30 to perhaps
35 mph in the afternoon.


A cutoff low tracks from eastern New England Wednesday night,
then into the Canadian Maritime Provinces on Thursday. This low
then meanders about there through Friday night. Other than some
lingering snow showers Wednesday evening as the upper low lifts
to the northeast, around 30kt of WNW-NW boundary layer flow will
should keep things dry during this time frame. Temperatures
should be below normal Wednesday night-Friday night as well.

The region will be under NW-WNW flow aloft Saturday-Monday, and
with no shortwaves of note progged to be embedded in this flow,
it should be dry. Temperatures will continue to be below normal
during this time frame.

Models then differ in the handling of a cutoff low over the
Central Plains, and associated downstream ridging. The CMC is
the most aggressive in opening up the cutoff and developing a
coastal low which brings precipitation in Tuesday. The GFS is
much faster than the other models in opening the cutoff, so has
weaker downstream ridging, and hence has a more suppressed low
track. The ECMWF is similar to the CMC, but about 12 hours
slower (also about 12 hours slower than the 00Z ECMWF). Noting
the continuity in theme between the CMC/12z and 00z ECMWF
believe the GFS is a southern outlier with this system. Noting a
general slowing trend with this system in the guidance, have
kept Monday night dry, then increase pops to chance during the
day on Tuesday. For now have mainly snow across the interior and
a rain/snow mix near the coast. However, would not be surprised
if this storm ultimately ends up producing snow over the entire
CWA. Still quite a bit of time to sort this storm out, including
recognizing the possibility this storm might end up more on
Wednesday than on Tuesday.


Strong low pressure near Nova Scotia will lift into the Canadian
Maritimes tonight and remain there through Wed. A trough of low
pressure moves through late Wed.

VFR has return to all terminals except KGON where MVFR still
prevails with -SN. VFR is expected to return here by 02z or so
and remain at all terminals through Wed. There is a low chc of a
few snow showers as a trough of low pressure approaches and
moves through late Wed aftn/early Wed eve which could result in
a temporary drop to IFR.

Westerly flow continues through Thu. Gusts may be more ocnl
outside of NYC terminals overnight and may even cease
completely in the city as well aft 08z, but they will return
after sunrise Wed. Then, expect a burst of higher winds behind
the trough with gusts around 30kt possible for a few hours
before diminishing.

     NY Metro Enhanced Aviation Weather Support...

Detailed information, including hourly TAF wind component forecasts,
can be found at: http:/

KJFK TAF Comments: Gusts may diminish a few hours earlier than
forecast this eve. Directions to remain left of 310 magnetic on

KLGA TAF Comments: Gusts may diminish a few hours earlier than
forecast this eve. Directions to remain left of 310 magnetic on

KEWR TAF Comments: Gusts may diminish a few hours earlier than
forecast this eve. Directions to remain left of 310 magnetic on

KTEB TAF Comments: Gusts may diminish a few hours earlier than
forecast this eve. Directions to remain left of 310 magnetic on

KHPN TAF Comments: Gusts may diminish a few hours earlier than
forecast this eve.

KISP TAF Comments: Gusts may diminish a few hours earlier than
forecast this eve.

.Wed night...Low chc of IFR in -SHSN early. W wind gusts
25-35KT during the evening.
.Thu...VFR with W wind gusts 20-25KT.
.Fri...VFR with NW gusts 25-30KT.
.Sat...VFR with NW gusts around 20-25KT.
.Sun...VFR with NW gusts around 20-25KT.


The very strong Nor-Easter will keep the region under a moderate
pressure gradient the next few days resulting in Small Craft to
Minimal Gales. Gales across ocean east of Fire Island Inlet and
SCA level gusts across other waters for tonight into Wednesday.

Winds ramp up again in the afternoon with deeper vertical mixing.

Gale gusts are likely on all waters Wednesday night and probably
will continue into Thursday on the coastal ocean waters, Eastern
Sound and the Bays of Long Island, with Small Craft Advisory
(SCA) conditions likely on the W Sound and NY Harbor. SCA
conditions are then probable on all waters Thursday night-Friday
night and quite possibly into Saturday on the coastal ocean
waters east of Fire Island Inlet and Eastern Long Island Sound.
The pressure gradient then relaxes for the remainder of the
weekend, with winds up to around at most 15 kt, strongest over
the coastal ocean waters.


No significant hydrologic impacts are anticipated the next 7
days. Snow melt should be gradual with yet another storm
possible on Tuesday.


NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the
air for an extended period of time.


MARINE...Small Craft Advisory until 6 PM EDT Wednesday for ANZ330-335-
     Gale Warning until 2 PM EDT Wednesday for ANZ350-353.


LONG TERM...Maloit
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