Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 170001
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
801 PM EDT Wed Aug 16 2017

.SYNOPSIS...
An area of high pressure will build into the region through
tonight, then slowly shift offshore Thursday. A warm front will
approach Thursday night. A cold front slowly approaches from
the west on Friday, moving across the region on Saturday. High
pressure returns on Sunday into Monday before the next cold
front approaches from the west on Tuesday.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Only minor updates needed to the forecast this evening to
reflect current temperature and dew point trends.

Dry conditions tonight and into tomorrow as high pressure
continues to move eastward then offshore by Thursday.
Temperatures tonight will be in the lower to mid 60s along the
coast and mid 50s inland. Patchy fog possible late tonight and
through early Thursday morning.

A high rip current risk will continue this evening for the
ocean beaches as the largest swells from distant Hurricane Gert
arrive. For details on Gert, please refer to National Hurricane
Center products.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Mostly sunny conditions expected on Thursday as high pressure
begins to shift offshore Thursday allowing for the return of
a southerly flow. As a low pressure system lifts through the
Great Lakes, a warm front will lift northward towards the area
late Thursday afternoon. Showers and possible thunderstorms
will start to develop north and along the warm front late
Thursday afternoon then spread across the region Thursday night.

Temperatures on Thursday will be in the upper 70s to lower 80s
with nighttime temperatures in the upper 60s to lower 70s.

There will be a moderate risk of rip currents at ocean beaches
for Thursday.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Main concern in the long term period surrounds a frontal system
progged to affect the area Friday into the first portion of
Saturday. The parent low pressure system will be spinning across the
northern Great Lakes Friday morning, with its warm front draped near
the region. Low level warm advection near the warm front is the main
source for lift with the expectation that showers will grow in
coverage through the morning. The warm front should lift to the
north in the afternoon, but abundant cloud cover should preclude any
significant instability. Will continue to mention chance of thunder,
with showers becoming likely through the morning and afternoon. The
new 12z suite of models and ensembles are in good agreement that the
main cold front will still be off to the west across upstate NY and
PA Friday evening. With the main upper trough still located well to
the west, do not think there will be any severe weather, with the
latest Day 3 SPC outlook confining a marginal risk closer to the
cold front. The front will gradually move to the east Friday night
into Saturday morning, but will not completely move offshore until
Saturday night. Showers with possible thunder will continue Friday
night before tapering off Saturday morning out east.

Locally heavy rain is possible anywhere Friday into early Saturday,
but difficult to pinpoint since convection will throw off QPF on
models, especially at this time range. Three quarters to one inch of
rainfall is possible on average Friday through Friday night.

The main moisture feed and lifting mechanism will then be offshore
Saturday afternoon, with just a slight chance for a shower or storm
as the cold front moves through. The upper trough is still expected
to lag behind the front Saturday night, but have elected to remove
PoPs due to cold advection behind the front and much drier air
moving in.

The upper trough should be offshore Sunday morning, with rising
heights aloft expected through early next week as ridging takes
shape across the southeastern US. This should bring a brief warming
trend, with higher humidity levels and temperatures warmer than
normal for this time of year in the middle and upper 80s. However,
we still lie near the main belt of the westerlies to our north and m
models signal a longwave trough developing over the eastern states
late Tuesday into Wednesday along with the next cold front.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
High pressure builds into the area tonight and slides offshore
on Thu as a warm front approaches from the SW.

VFR through the TAF period outside any overnight patchy fog.
Dewpoints are forecast to drop overnight, so fog development
is expected to be less widespread compared to last night.

Northerly winds 5kt or less prevail tonight. Flow has weakened
enough for the seabreeze to finally make it into KJFK, but this
S flow should only last an hour or two before shifting back
around. Boundary has now become so diffuse and with TJFK down
it has been tough to see on radar. As the high shifts offshore
on Thu winds will veer to the SE-S with seabreeze enhancement
possible in the aftn.

     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: Winds may be slightly higher and 20 degrees
further to the left than forecast aft 18z.

KLGA TAF Comments: Winds may be slightly higher and 20 degrees
further to the left than forecast aft 20z.

KEWR TAF Comments: Winds may be slightly higher aft 20z.

KTEB TAF Comments: Winds may be slightly higher aft 20z.

KISP TAF Comments: Winds may be slightly higher and 20-30
degrees further to the left than forecast aft 19z.

.OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...
.Thursday night through Saturday night...MVFR or lower flight
cat possible in showers/tstms.
.Sunday And Monday...VFR.

&&

.MARINE...
Long period southerly swells from Hurricane Gert should slowly
subside tonight into Thursday as the hurricane moves farther
out to sea. Thursday night winds and seas will remain below
advisory levels as a cold front approaches from the west.

Increasing southerly flow on Friday ahead of a cold front will bring
the chance for some gusts close to SCA levels on the ocean waters
west of Fire Island inlet, with gusts closer to 20 kt elsewhere on
the ocean. Ocean seas could build near 5 ft as well late Friday into
Friday night. The front should cross the waters through the day on
Saturday with subsiding seas and winds remaining below SCA levels.
Sub-SCA conditions are forecast Sunday and Monday.

&&

.HYDROLOGY...
Locally heavy rainfall is possible Friday into early Saturday.
An average of 3/4 to 1 inch of rainfall is forecast. However, it is
difficult to pinpoint where heavier showers/storms will develop at
this time. No significant hydrologic impacts are expected, but some
minor urban flooding is possible.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...High Rip Current Risk until 9 PM EDT this evening for NYZ075-
     080-081-178-179.
NJ...None.
MARINE...Small Craft Advisory for hazardous seas until 2 AM EDT
     Thursday for ANZ353-355.
     Small Craft Advisory for hazardous seas until 8 AM EDT
     Thursday for ANZ350.

&&

$$



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