Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 190245

Area Forecast Discussion
National Weather Service New York NY
945 PM EST Sun Nov 18 2018

High pressure will move east as a cold front approaches tonight.
The front will sag south on Monday as a wave of low pressure
develops and passes on Tuesday. An Arctic front will pass
Wednesday evening. Cold weather on Thanksgiving will gradually
warm through the weekend.


The fcst is on track. Upper trough digs southeastward,
approaching Great Lakes Region tonight. Deep SW upper steering
flow prevails ahead of this trough axis, which will run nearly
parallel to a weak cold front. The front will settle over the
area tonight.

Low chance for measurable precip will develop along this front
as upper jet aids in some weak development.

A light southerly flow will warm the boundary layer enough for
mainly light rain if any precip were to develop, except light
rain/snow mix or plain snow inland. Do not expect any
significant accumulations, less than inch across NW zones.

Temperatures fall a few degrees by evening, but light south flow
and clouds will result in nearly steady temperatures overnight.
Lows will range from the lower 30s inland to around 40 in NYC.


Upper trough pivots eastward in time, which will allow a wave of
low pressure to develop out ahead of it Monday near the Ohio
Valley and toward the mid Atlantic coast. Leaned toward a
GFS/ECMWF tracks per collab with WPC and surrounding offices,
with a low pressure passage just to our south Tuesday.

Generally dry conditions Monday, outside of any light precip in
the vicinity of the front, will give way to a higher chance of
measurable precip Monday night into Tuesday.

Analysis of various guidance suggests enough warm air for plain
rain, with a cooling of the column Tuesday as the low passes
just south. More QPF likely just north of the area where
baroclinic zone is expected and deeper lift is noted.

Would generally expect snow accumulations of 1 to 4 inches
across the interior zones, with very little near the coast as
colder air does not arrive before precip winds down late in the
day. Lack of cold air damming ahead of the low will also suggest
less snow attm.

Temps on Monday will be seasonably mild Monday. As winds turn
toward the north Monday night into Tuesday and precip cools the
column, cooler air is expected, with lows in the 30s to around
40 at night, and highs in the upper 30s to middle 40s Tuesday
before readings fall a few degrees during the afternoon.


Any residual light rain or snow will exit quickly Tue eve. Temps
mainly in the 20s with a cold airmass building in. Winds however
should keep the readings from completely bottoming out, especially
NYC and LI. If decoupling does occur, temps in the Pine barrens will
be several degrees cooler than fcst. Fair weather for most of Wed,
but the arctic front appears to reach the area by eve. The trend
with the fropa is slightly faster. The 12z NAM, although it does not
go beyond 00z Thu, has some sbcape abv 100. The GFS and ECMWF are
trending higher with pcpn coverage invof the front. As a result, sct
snow shwrs have been included in the fcst. Due to the instability,
some heavier shsn cannot be ruled out, capable of putting down at
least a coating where they occur. Pops were manually adjusted abv
the model consensus.

Very cold Thanksgiving mrng, with wind chills in the single digits
most areas. Some blw zero wind chills possible in the interior. The
high temp fcst is blw freezing for the entire cwa, with mainly teens
overnight. Please see the climate section for info on records.

A low-mid 1030s high drifts over the cwa on Fri. This will result in
sunny skies, light winds but cold temps. Highs generally in the 30s.
As the high drifts ewd, temps will modify thru the weekend. The
models have sped up with the arrival of a Pacific sys, so rain
chances have been included for late Sat, particularly the wrn half
of the cwa. Better rain chances Sat ngt and Sun. A little fzra has
been included for extreme interior portions Sat ngt. Everything
warms up abv freezing Sun and remains so thru Sun ngt according the
the GFS. Confidence is not high however as the ECMWF is a bit colder
and the overall pattern slightly different, with low pres taking
over off the coast.


High pressure will continue to work offshore this evening as a
weak warm front approaches from the southwest. The front will
briefly lift through late tonight into early Mon morning, then
pass back to the south as a cold front by afternoon.

Warm front sits south of Long Island attm, with more widespread
MVFR cigs then originally anticipated. Improvement to VFR
forecast overnight, but MVFR cigs could hang on longer if the
front remains to the south.

Mainly VFR for daytime Mon except at KSWF. Chances for precip
will be on the low side and have not been mentioned in the TAF
through 00Z Tue.

Light E winds tonight will shift SE overnight as the warm front
gets closer, then may briefly shift S-SW late tonight into
early Mon morning with the weak warm frontal passage, then W-NW
by late morning or afternoon as the front passes back to the
south as a cold front.

.Monday Night-Tuesday...MVFR or lower conditions possible in
rain or wintry mix. NW winds G15-20kt.
.Tuesday Night-Wednesday...Mainly VFR. Low chance MVFR. W-NW
winds G20-30kt.
.Wednesday Night-Thursday...VFR. NW winds G20-25kt.


High pressure will give way a weak cold front tonight and
Monday. Light winds and tranquil seas will be the result.
Winds shift around to the north gradually Monday night and
Tuesday as low pressure rides along the front and passes. Sub
SCA conditions persist.

Winds and seas will increase to sca lvls late Wed and Wed ngt with
the passage of an arctic front. There is a low prob for gales. Winds
and seas subside Thu aftn across all waters. Cond blw sca lvls on
Fri, then may ramp up again Sat, especially on the ocean, as low
pres approaches.


QPF amounts between 1/4" and 1/2" are expected through Tuesday,
with the bulk of this falling Monday night into Tuesday. No
hydrologic issues are expected through Friday. A sys will bring
pcpn to the region next weekend, but confidence in forecasting
hydrologic impacts is low attm.


Record low temperatures for Thu Nov 22:

Central Park.....13 (1880)
LaGuardia........21 (1987)
Kennedy..........20 (1987)
Newark...........19 (1987)
Bridgeport.......18 (1987)
Islip............20 (1987)

Record high minimum temperatures for Thu Nov 22:

Central Park.....23 (1880)
LaGuardia........31 (1972)
Kennedy..........34 (2008)*
Newark...........33 (1949)
Bridgeport.......30 (1972)
Islip............31 (2008)

Record low temperatures for Fri Nov 23:

Central Park.....14 (1880)
LaGuardia........23 (1972)
Kennedy..........25 (2008)*
Newark...........21 (1932)
Bridgeport.......16 (1972)
Islip............13 (1989)

*also occurred in previous years


NYC NOAA Weather Radio Station KWO35 (162.55 MHz) will remain off
the air for an extended period of time.




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