NYC Office Forecast Discussion

080
FXUS61 KOKX 232108
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
508 PM EDT Thu May 23 2019

.SYNOPSIS...
A warm front moves across the region late this afternoon into
this evening, followed later tonight by a cold front. The cold
front will move southeast of Long Island overnight. High
pressure gradually builds in from the north and west Friday and
Friday night. High pressure slides south of Long Island Saturday
with a weak cold front bringing showers Saturday night into
early Sunday. High pressure returns for Memorial Day followed by
a warm front Tuesday.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
First round of convection is now largely over the ocean waters,
with rain across Long Island and Connecticut. Clouds are
clearing again in its wake, allowing for additional diurnal
heating, though the window for increased surface-based heating
is limited as it`s now late in the day. It`s likely that more
favorable conditions will exist farther west of the forecast
area.

Regardless, water vapor imagery shows the next vorticity maximum
moving into central New York and Pennsylvania. Convection
associated with this secondary wave has largely been shallow
thus far, and surface convergence appears to be limited where
the cu field is increasing, as flow as become more westerly. As
the cold front moves through later in the evening, surface
convergence will increase, and may allow for more additional,
deeper convective initiation/development in response to the
forcing for ascent. Mid-level lapse rates upstream remain in the
6.5-7.0 C/km range, which combined with the increasing deep
layer shear should be supportive of a few stronger updrafts and
possibly hail. By the time the convection reaches the forecast
area, it`s likely that the loss of diurnal heating and the low
level warm advection will strengthen the existing inversion,
based around 850 mb, limiting a more widespread threat for
damaging winds, as storms will largely be elevated. The greatest
potential for any surface- based storms will be across the
lower Hudson Valley into northeastern NJ, though this
instability will be waning given the time of day. As such, the
primary threats into the late evening will be hail and heavy
downpours if any storm can be sustained.

After that, overnight, expecting rapidly decreasing POPs with
the cold front moving south of Long Island with surface flow
becoming more westerly.

Lows tonight are a narrow range from upper 50s to lower 60s
(consensus with greater weight for ECS) considering the
abundant clouds expected and increasing winds late tonight into
early Friday.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Ridging aloft will increase the subsidence so expecting dry
conditions Friday and Friday night along with minimal clouds.

At the surface, parent low pressure moves from near Maine out
into the northern Atlantic. Steep enough pressure gradient to
make for a breezy day across the region Friday with wind gusts
in the 30 to 35 mph range.

Backing of winds from low to mid levels in forecast soundings
shows cold air advection. Highs forecast on Friday mainly in the
lower 70s, relatively warmer at the coastline with the
downslope NW flow.

For Friday night, more of a spread for low temperatures, upper
40s to upper 50s. Winds decrease and without much clouds,
expecting more radiational cooling.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
High pressure builds from the Great Lakes Friday night before
sliding offshore late Saturday. This will lead to dry weather
and mild temperatures through Saturday. Lows Friday night will
be in the 50s.

With the high just to the south on Saturday high temperatures
will rise into the 70s, with cooler temperatures along the
coast. Southerly flow will advect in higher dew points, but in
general will be a nice afternoon with some increasing clouds
later in the day.

A weak cold front will approach Saturday night into Sunday.
This could bring a period of showers into early Sunday before
the front pushes offshore by Sunday afternoon.

Heights then rise behind the shortwave that drives the front
east with a ridge building behind for Memorial Day. That ridge
then becomes quite anomalous with a significant warming trend
likely into mid-week.

An approaching warm front may bring showers Tuesday followed by
dry weather Wednesday and another system on Thursday.

&&

.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
A warm frontal passes this evening and will quickly be followed
by a cold frontal passage tonight.

First round of showers/thunderstorms has passed east of the city
terminals and has begun to weaken as it continues east. There
will be a lull in activity for the next few hours with a chance
of a redeveloping showers and storms this evening. Questionable
timing and coverage however and its possible they may be more
scattered. Any showers/storms this evening will be capable of
producing brief MVFR/IFR. Brief wind shifts to the W-NW may
occur with any storm, but will prevail out of the S-SW.

Otherwise, winds will be from the S-SW this evening with some
gusts to near 20kt. Winds become more W after midnight and then
eventually NW towards Friday morning. Winds on Friday will gust
to near 30kt for most TAF sites.

 ...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: Showers and thunderstorm coverage this
evening questionable and its entirely possible no direct impacts
occur.

KLGA TAF Comments: Showers and thunderstorm coverage this
evening questionable and its entirely possible no direct impacts
occur.

KEWR TAF Comments: Showers and thunderstorm coverage this
evening questionable and its entirely possible no direct impacts
occur.

KTEB TAF Comments: Showers and thunderstorm coverage this
evening questionable and its entirely possible no direct impacts
occur.

KHPN TAF Comments: Showers and thunderstorm coverage this
evening questionable and its entirely possible no direct impacts
occur.

KISP TAF Comments: Showers and thunderstorm coverage this
evening questionable and its entirely possible no direct impacts
occur.

.OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY...
.Friday afternoon and Friday night...VFR. NW gusts around 30kt
during the day.
.Saturday...Mostly VFR, except chance of MVFR or lower in
showers/thunderstorms late day and evening.
.Sunday...Mostly VFR. Slight chance shra/MVFR.
.Monday...A chance of shra and MVFR.
.Tuesday...Mainly VFR.

&&

.MARINE...
Some thunderstorms could produce brief gale force gusts on the
waters into this evening, mainly for waters surrounding Western
Long Island.

Ocean seas increase to 5 ft tonight with wind gusts of 25 kt
across the ocean. SCA will remain for the ocean waters through
tonight. Non-ocean waters are forecast to stay below SCA through
tonight. For Friday though, efficient vertical mixing on the NW
flow will allow for widespread SCA gusts 25-30 kt for all
waters. The SCA gusts could linger into early Friday evening.
Ocean seas forecast stays near 5 ft Friday and below 5 ft Friday
night.

Waters will remain below SCA conditions as high pressure moves
offshore Saturday and a weak front passes through Sunday.

&&

.HYDROLOGY...
Showers and thunderstorms through the late evening may produce
quick heavy downpours. Around a quarter to four tenths of an
inch of rain is forecast. Locally higher amounts are possible.
Local minor urban and poor drainage flooding will be possible
with any series of heavy showers and thunderstorms.

No hydrologic impacts expected Friday through next week.

&&

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

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 6 AM to 8 PM EDT Friday for ANZ330-
     335-338-340-345.
     Small Craft Advisory until 8 PM EDT Friday for ANZ350-353-355.

&&

$$
SYNOPSIS...CB/JM
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...CB
AVIATION...BC/DS
MARINE...CB/JM
HYDROLOGY...CB/JM
EQUIPMENT...

NWS OKX Office Area Forecast Discussion