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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KOKX 161948
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
348 PM EDT Mon Jul 16 2018

.SYNOPSIS...
High pressure remains offshore tonight. A cold front will approach
from the west on Tuesday and move through late in the day into
Tuesday night. High pressure will build across the region Wednesday
through Thursday, then remain over the region through Friday. The
high will then move offshore on Saturday with low pressure and
its associated warm front approaching for Saturday night into
Sunday. The weakening warm front will then linger near the
region into Monday.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Any showers and storms this evening will be isolated to scattered in
nature and primarily inland where sea breezes have not reached.
Still can`t rule out additional showers and storms overnight for
roughly the same areas as weak shortwave energy passes through with
sufficient MUCAPES in place. It`ll be a muggy night with lows in the
70s.

There is a moderate risk of rip currents for the ocean beaches
into this evening.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
A cold front approaches and is expected to pass through the tri-state
 area mostly during the late afternoon to evening hours. This
will bring showers and thunderstorms to the area. SBCAPEs could
range 1500-2500 J/KG, coinciding with unidirectional 0-2 KM
shear of 20-30 kt. Strong wind gusts with TSTMs are possible
along with a marginal potential for severe gusts. The main
limiting factor for severe weather appears to be the high
moisture content limiting the potential for steep lapse rates.

Another threat with these showers and storms will be flash flooding.
Very high moisture content will be in place with PWATs around 2.25,
a warm cloud layer depth of 13-14 KFT, and a theta-e ridge shifting
through. Best chances for heavy rainfall will be in the afternoon
and evening hours when shortwaves and a llj pass through and tap
into this deep moisture. Limiting the chances of flash flooding will
 be the forward speed of the cells as the upper flow will not
be aligned with surface cold front, which will also limit the
chances of storm cell training. Although models signal higher
rain totals over the eastern half of the area, flash flood
guidance and antecedent dry conditions don`t support flash
flooding there. Any flash flooding would more likely be
localized. After collaboration with the surrounding office, have
decided to hold off on any flash flood watches. Given the dry
pattern we`ve been in and the convective nature of the rainfall,
have doubts with some of the guidance that show widespread 1.50
- 2.50 inch accumulations. Will go with the lower side of
guidance for total rainfall.

The remaining concern will be heat indices and the need for heat
advisories. 850mb temps are expected to be similar to today`s
however there should be more cloud cover tomorrow in addition to
rain-cooled air. Expecting highs in the mid-upper 80s for the
locations currently under a heat advisory. Dewpoints should
however be higher than today`s. Forecast dewpoints at the top of
the mixed layer are progged to be 15-16C and a S-SW wind flow
will prevail, so surface dewpoints are not expected to drop much
until after the cold front moves through. Expecting dewpoints
in the mid 70s, leading to heat indices in the mid 90s for areas
within the advisory. This is the only area that`s expected to
have 2 consecutive days of 95+ heat indices, so the advisory
will not be expanded in area at this time.

There is a moderate risk of rip currents for the ocean beaches
Tuesday into Tuesday evening.


&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
An Upper level trough will linger across eastern portions of the
region through Wednesday.  Have trimmed back any slight chance POPs
just a touch from previous forecast, as low level cold and dry
advection as depicted by most modeling should keep precip chances
near a minimum, even for eastern sections.  Upper level ridging will
then build Wednesday night through early Friday.  Dry conditions
with comfortable humidity levels are expected during this timeframe.

An upper level trough will then approach out of the Upper Midwest
and Southern Canada into the weekend.  With high pressure slipping
off the east coast early in the weekend, a humid southerly flow will
return to the region. With upper and mid level forcing precip
chances will increase through the weekend, and peak by Sunday with a
warm front just south and southwest of the region along with
greatest height falls just NW of the region. The upper level system
is then progged to weaken and fill to some degree on Monday. Forcing
should still be sufficient to carry chance POPs across the region.
Global ensemble mean 500 mb height forecasts still indicate some
mean troughing over the eastern CONUS through early next week which
would indicate at a minimum diurnal driven convective chances.
Ensemble viewer indicates PWs running about 1.5 to 2 standard
deviations above normal late in the weekend into early next week as
actual PW values should be approaching 1.75 inches during this time.
Too early to get into details, but there may be some localized
pockets of heavier rainfall during this timeframe with broad deep
southerly flow established.


&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
     High Impact Day on Tuesday with Numerous Showers and
Thunderstorms in the Afternoon...

Offshore high pressure will gradually give way to an
approaching frontal system over the Ohio Valley.

Largely a VFR forecast outside of any isolated to widely
scattered convection through Tuesday morning, which should be
mainly north and west of the NYC terminals. A more widespread
convective event is forecast for Tuesday afternoon as a cold
front approaches the area.

Additionally, there could be a period if IFR/MVFR ceilings east
of the NYC terminals toward daybreak. The best chance for this
would be at KGON.

S winds 10-15 KT this afternoon, but a bit weaker across the
interior. Seabreeze likely as far north and west as KHPN. KTEB,
and KEWR this afternoon. Winds drop off a bit tonight with S-SW
10-15 G20kt on Tuesday.

     NY Metro Enhanced Aviation Weather Support...

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

KJFK TAF Comments: Low chance for a thunderstorm this afternoon.

KLGA TAF Comments: Low chance for a thunderstorm this afternoon.

KEWR TAF Comments: Timing of afternoon seabreeze could vary by
an hour of either side of 19Z. Low chance for a thunderstorm
this afternoon.

KTEB TAF Comments: Timing of afternoon seabreeze could vary by
an hour of either side of 21Z. Low chance for a thunderstorm this
afternoon.

KHPN TAF Comments: Low chance for a thunderstorm late this afternoon.

KISP TAF Comments: No unscheduled amendments expected.

.OUTLOOK FOR 18Z TUESDAY THROUGH FRIDAY...
.Tuesday Afternoon...Widespread showers/tstms likely with MVFR
or lower conditions. S winds G20KT into early evening.
.Wednesday-Saturday...VFR.

&&

.MARINE...
Sub-SCA conditions prevail tonight with light winds and seas
below 5 ft. Winds and seas then increase Tuesday ahead of a cold
front. SCA conds expected on the ocean waters by mid-morning and
lasting into Tuesday night.

Lingering S-SE swell component may result in SCA conditions due to
seas for eastern ocean waters during Wednesday afternoon and
evening. Otherwise, sub SCA conditions will persist through Friday
as high pressure builds across the coastal waters with a light
pressure gradient. High pressure will then move east and northeast
of the coastal waters on Saturday resulting in an increasing SE
swell component. This could result in small craft conditions due to
high seas for the ocean waters by Sunday.

&&

.HYDROLOGY...
Showers an thunderstorms will be capable of producing locally
heavy rain with the potential for primarily minor urban/ poor
drainage and small stream flooding. The best overall chances for
flooding will be Tuesday afternoon into evening. While not
likely to be widespread, localized flash flooding cannot be
ruled out. The convective nature of this event will produce a
wide range of total accumulated rainfall. Most spots probably
end up with around a half inch of rain with amounts ranging up
to 1.50 inches less common. Isolated amounts of 2 to 2.50 inches
are possible.

No hydrologic impacts are expected Wednesday through Monday.

&&

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

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Heat Advisory until 6 PM EDT Tuesday for NYZ072>075-176-178.
NJ...Heat Advisory until 6 PM EDT Tuesday for NJZ004-006-103>108.
MARINE...Small Craft Advisory from 8 AM Tuesday to midnight EDT Tuesday
     night for ANZ353-355.
     Small Craft Advisory from 8 AM Tuesday to 6 AM EDT Wednesday
     for ANZ350.

&&

$$

SYNOPSIS...JC/JE
NEAR TERM...JC
SHORT TERM...JC
LONG TERM...JE
AVIATION...DW
MARINE...JC/JE
HYDROLOGY...JC/JE
EQUIPMENT...//