NWS Forecast Discussion - New York City Area

Forecast Discussion for OKX NWS Office
FXUS61 KOKX 241130

Area Forecast Discussion
National Weather Service New York NY
730 AM EDT Wed Apr 24 2019

High pressure builds in today and lasts into Thursday. A warm
front approaches Thursday night, then low pressure and cold
front pass Friday. Another weak low passes Sunday, followed by
another frontal system Tuesday. High pressure briefly builds
between each passing system.


The forecast is mostly on track with minor updates made to some
of the hourly elements.

Ridging at the surface and aloft today brings us a sunny day.
Cold air advection will help with breezy/gusty conditions, but
high temperatures will still end up above normal - even at
south-facing coasts as WNW winds should be strong enough to
prevent a sea breeze from moving in. Went closer to the warmer
guidance for high temperatures based on forecast temperatures
near the top of the mixed layer along with good mixing on the
downsloping flow.


Mostly clear skies and light winds tonight will result in good
radiational cooling conditions across outlying areas, where lows
could dip to into the upper 30s in some spots. Elsewhere,
temperatures drop into the 40s, except around 50 in the city.

Clouds increase during Thursday ahead of a warm front. Models
have trended earlier with the threat of showers ahead of the
front, so have gone with low chances of showers for most spots
by the end of the afternoon. Instability is lacking, so no
mention of thunder. High temperatures expected to be within a
couple degrees of normal.


Some differences are noted in amount of phasing between northern
stream and southern stream shortwaves Thursday night into Friday.
However, there does appear to be better agreement in global models
when compared to previous runs.

Warm frontal precip may impact the area early in the evening, with
perhaps a break in the rain for the remainder of the night Thursday
night. Then as trough approaches, deepening moisture and stronger
lift will allow for increasing coverage of showers Friday. Warm
front remains close to the coast, and sfc low likely develops around
the triple point of the warm front, occluded front extending north
to parent low, and cold front extending south. This triple point low
passes nearby late Friday, deepening as it moves northeast. This
scenario looks closer to previous ECMWF run. For Friday, expect
showers to prevail, with a rumble of thunder possible due to weak
elevated instability above the low level inversion.

The showers taper off Friday night as drier air gets ushered in
behind the deepening low and cold front. Gusty winds and dry
conditions can be expected into Saturday.

These dry weather conditions will persist between the departing
trough, and fast moving downstream shortwave. GFS is advertising a
stronger upper shortwave, and deeper sfc low reflection for Sunday
as this moves through compared to Canadian and ECMWF. Best chance
for showers will be Sunday, then dry conditions move back in behind
this system. Downstream trough approaches, and upper flow will
become nearly parallel with cold front that passes Sunday. As such,
more rain could move back in as air lifts over this front by
Monday night or Tuesday.

Overall, chances for rain followed by brief breaks in the rain is
expected during this time frame.

There will be minor fluctuations in temperatures, but in general,
temperatures should remain within a few degrees of climo through the


High pressure builds in from the west today, and over the
terminals tonight.


W winds 10-15kt become gusty this morning with gusts 20-25kt.
Gusts diminish and end 23Z to 00Z, and winds become NW to N
less than 10 kt. Winds will be around 310 magnetic, especially
this afternoon. At the outlying terminals winds become light and
variable tonight.

 ...NY Metro Enhanced Aviation Weather Support...

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

KJFK TAF Comments: No unscheduled amendments expected.

The afternoon KJFK haze potential forecast is GREEN, which implies
slant range visibility P6SM outside of cloud.

KLGA TAF Comments: No unscheduled amendments expected.

The afternoon KLGA haze potential forecast is GREEN, which implies
slant range visibility P6SM outside of cloud.

KEWR TAF Comments: No unscheduled amendments expected.

The afternoon KEWR haze potential forecast is GREEN, which implies
slant range visibility P6SM outside of cloud.

KTEB TAF Comments: No unscheduled amendments expected.

KHPN TAF Comments: No unscheduled amendments expected.

KISP TAF Comments: No unscheduled amendments expected.

.Thursday...VFR. A chance of showers late in the afternoon.
.Thursday night-Friday...A chance of showers Thursday night,
showers Friday with isolated thunder. MVFR conditions likely,
with IFR possible by Friday afternoon.
.Saturday...VFR. W to NW gusts to 25 kt.
.Sunday...A chance of showers with MVFR conditions.


Winds will be somewhat gusty behind a cold front and high
pressure building in today. There could be occasional gusts up
to 25 kt primarily on the ocean and nearshore waters, but sub-
SCA conds are expected to prevail. Winds then subside tonight
with a weaker pressure gradient, then become southerly on
Thursday, but still only at around 10 kt.

Winds back to the SE ahead of a warm front Thursday night, then
eventually shift to the SW as it passes, then W behind a cold front
Friday night and Saturday. Wind speeds increase Friday night into
Saturday, and SCA conditions are possible. Winds diminish Saturday
night as high pressure briefly builds. Another low and frontal
system are forecast to approach from the west Sunday, and winds
increase as they back to the S/SW. These winds then shift once again
to the W as the front passes Sunday night.

Seas will slowly build from late Thursday night through Saturday as
the low and front first approach, then pass. These seas should
subside briefly Saturday night before building once again ahead of
the next low and front.


Next chance for significant rain of at least a half inch, to
possibly over an inch in spots, will occur late Thursday night and
Friday. Other than possible nuisance urban/poor drainage flooding,
do not foresee hydrologic impacts at this time.


NYC NOAA Weather Radio Station KWO35 (162.55 MHz) remains off
the air.





NWS OKX Office Area Forecast Discussion