FXUS61 KOKX 141435

Area Forecast Discussion
National Weather Service New York NY
1035 AM EDT Tue Aug 14 2018

A slow moving low pressure system will be in the vicinity
today, then exit eastward tonight. Weak high pressure will then
slide across Wednesday into Thursday night. This will give way
to a frontal system and low pressure late Friday or Friday
night. Weak high pressure builds to the north this weekend and
into next week as a frontal boundary remains stalled just south
of the area.


Dry conditions for most of the forecast area to start off the
day. Nearby showers and isolated thunderstorms associated with
the mid-upper level low pressure continue to produce moderate to
heavy rainfall to our west. Sunshine this morning will increase
instability over the area. As the mid-upper level low slowly
moves eastward, it will provide lift for convective initiation
this afternoon along with possible left exit region of upper
jet. Shear and CAPE profiles are not exactly conducive to a
significant severe weather threat, but an isolated strong gust
or two cannot be ruled out.

PWATs lower than yesterday's levels with 12Z OKX RAOB
indicating 1.62 inches, which will still be high enough for
heavy rainfall. With upper low's forward/eastward motion faster
than the past couple of days, it should be a little harder for
storm cells to continually track over the same locations,
mitigating the flash flooding threat. Thinking is that the
better chances of training or slower moving cells will occur to
our north based on the expected track of the upper low and
what's been happening relative to its position. That said, it
won't take as much rain as usual to get some form of flooding
due to the amount of rain that has fallen recently. After
collaboration with the surrounding offices, will hold off on
issuing a flash flood watch at this time.

There is a moderate risk for rip current development today.


Showers and storms exit east tonight with the low aloft and a
surface trough shifting out of the tri-state area. Dry for the late
night hours, and dewpoints will be dropping into the 60s.

For Wednesday, partly to mostly sunny with high pressure ridging.
Forecast 850mb temps are 16-17C, and with a westerly flow, highs in
the upper 80s to low 90s across most spots. The westerly flow and
dewpoints aloft should help mix out surface dewpoints in the
afternoon, so have gone slightly below guidance. Heat indices should
therefore be just a degree or two higher than the actual
temperature. Spotty 95 degree heat index values could occur in the
city and immediate surrounding suburbs, but not enough coverage for
heat advisory consideration.


Aloft, ridge builds ahead of next shortwave Wednesday night through
Friday. The shortwave will result in lowering heights across the
northeast this weekend before ridge builds Monday.

At the sfc, high pressure builds Wednesday night-Thursday. An area
of low pressure then tracks across the Great Lakes region Thursday
night and Friday, passing to the north. A warm front lifts to the
north ahead of the low early Friday, followed by a cold front that
looks to pass Friday night or early Saturday per global model

The front slowly traverses across the area Saturday, and remains
stalled just south of the area Sat night-Monday as waves of low
pressure ride along it. In the meantime, weak high pressure builds
to the northwest.

As for sensible weather, dry conditions Wed night-Thursday will give
way to an increasing chance for showers/thunderstorms Friday and
into Friday night. With marginal instability in place, thunder
mention remains in the forecast, and cannot rule out heavy downpours
as PW values rise and exceed 2 inches as progged by global models.

In general, dry conditions are anticipated later Saturday through
Monday, with perhaps an isolated shower/thunderstorm through this

As for temps, Thursday will be a hot day with many locations
reaching or exceeding 90 degrees. Even coastal locations should
reach 90 with westerly flow expected.

This could result in heat indices in the middle 90s. On Friday,
temps will be warm to hot, but more cloud cover and southerly flow
ahead of the cold front should keep 90 degree temperature readings
confined to NYC metro, and metro NJ.


An upper level low will approach this afternoon and move across
the region tonight.

Variable conditions this morning with many airports MVFR or
less. Expect a gradual improvement to MVFR and then VFR
expected by late morning/early afternoon. A few terminals have
already become VFR, however can not rule out a short return to
MVFR cigs.

S-SW flow around 10 kt with a few gusts 15-18kt at the NYC
metros and KISP today.

As the upper low approaches, chances for thunderstorms with IFR
conditions and gusty/erratic winds should increase after 18Z-
20Z from the NYC metros north/west. Some of this activity could
make it to KBDR/KISP toward evening.

Winds become westerly tonight behind any storms, with VFR

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: Variability in cigs and vis likely thru 15z.

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

KLGA TAF Comments: Variability in cigs and vis likely thru 15z.

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

KEWR TAF Comments: Variability in cigs and vis likely thru 15z.

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

KTEB TAF Comments: Variability in cigs and vis likely thru 15z.

KHPN TAF Comments: Variability in cigs and vis likely thru 15z.

KISP TAF Comments: Variability in cigs and vis likely thru 15z.

.Wednesday-Thursday...Mainly VFR.
.Friday...MVFR or lower conds possible in late day/evening
showers/tstms from the NYC metros north/west.
.Saturday...Mainly VFR.


Winds and seas will remain below SCA levels today although any tstms
that develop could produce locally hazardous conditions. A brief
period of increasing southwesterly flow tonight into early Wednesday
could produce waves close to 5 ft, but will hold off on any SCA

Winds and seas remain relatively tranquil Wednesday night through
Thursday night as weak high pressure builds. Southerly winds
increase somewhat Friday into Friday night ahead of low pressure and
a cold front. At this time, expect winds to remain below 25 kt, and
seas to remain just below 5 ft over the ocean waters. Non ocean
waters remain safely below SCA thresholds.

On Saturday, winds lighten as they shift to the west behind the
front, and seas will subside.


Rainfall amounts through tonight should average below a half
inch, however locally up to an inch or two of rain is possible
in any heavier showers and/or thunderstorms. Any area that does
experience locally heavy rainfall, given wet antecedent
conditions, could experience localized flash flooding.

An approaching frontal system could produce showers/tstms with heavy
rain Friday afternoon and evening. Given PW increasing to over 2
inches and deep layer SW flow nearly parallel to the approaching
frontal boundary, there is potential for heavy rain with individual
cells and also training of cells, mainly from the NYC metro area


Astronomical tide levels will be very close today and again tonight.
As such, will issue a coastal flood statement for tidal locations
along southern Nassau, and southern Queens, along the south shore
back bays. This is based on what was observed with the earlier high
tide cycle.


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




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