Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 242037
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
437 PM EDT Mon Jul 24 2017

.SYNOPSIS...
High pressure builds north of the area this evening, while
another frontal wave passes just south of Long Island late
tonight into Tuesday. High pressure then builds into the area
Tuesday night into Wednesday before moving offshore Wednesday
night ahead of a cold front to the west. The cold front will
slowly approach the area through late week before passing to the
east on Friday. Brief high pressure builds across the area
again before a surface low passes to the south early next week.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Conditions have dried out across the area as low pressure
passes to the south and east of southern New England early this
evening. In its wake, high pressure builds across New England
with Northerly winds. In fact, the north winds have drawn
anomalously cool air into the region with most locations in the
upper 50s to lower 60s, the exception being the western third of
the area where some thinning of the overcast has allowed
temperatures to rise to around 70.

The airmass across the region remains stable with the N/NE flow.
Convection firing up across eastern PA this afternoon is
unlikely to make it this far east, but nevertheless is
something that needs be watched if the cloud cover across
western section erodes and allow airmass to destabilize
further.

An approaching upper trough over the Great Lakes tonight aids
the development of a frontal wave near the Delmarva that passes
just south of LI. Based on latest guidance, it appears the low
will pass far enough south to spare the region anything more
than showers, with the best chance for measurable rain across
LI.

Overnight lows will range from the mid 50s inland, to the lower
60s at the coast. This about 5 to 10 degrees below normal.

There remains a high risk of rip currents at ocean beaches
through Tuesday.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Low pressure passes to the south and east in the morning with
lingering showers possible into the afternoon as the upper
trough moves across the area. A continued N/NE flow will result
in mostly cloudy conditions with temperatures in the 60s to
lower 70s. This is well below normal by about 10-15 degrees.


There could be some late day clearing with subsidence on the
backside of the upper trough and high pressure building in from
the west. High temperatures could be warmer than forecast
across wester sections if this clearing happens earlier in the
day.

Another unseasonably cool night is on tap for Tuesday night with
continued clearing.

There remains a high risk of rip currents at ocean beaches
through Tuesday.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Initially zonal flow will give way to a blocking pattern as high
pressure builds across the western US and the western Atlantic,
placing the Northeast in an unsettled pattern dominated by multiple
low pressure systems. Wednesday will be one of the quieter days in
the extended as high pressure builds across the area, eventually
moving offshore overnight. Given the prolonged period of
northeasterly flow, there is a low chance of some morning clouds and
drizzle, although lower dew points suggest anything ongoing will
likely dissipate quickly. Temperatures will be a few degrees below
normal. By Thursday, the area returns to a more southerly flow ahead
of a slow moving cold front, with a chance of afternoon showers and
thunderstorms, especially to the north and west of the NYC metro.
High temperatures will still be a few degrees cooler than
climatological normals, though there will be a marked increase in
humidity amidst moist advection which in turn will lead to low
temperatures closer to normal. By Thursday night into Friday, the
front will slowly move through the area bringing the greatest
possibility of showers and thunderstorms to the area before drying
out as high pressure builds eastward on Saturday into early next
week. There is a little bit more uncertainty towards the weekend
depending on the placement of a coastal low, which is currently
forecast to pass well to the south but subsequent forecasts will
need to be monitored.

&&

.AVIATION /21Z MONDAY THROUGH SATURDAY/...
A frontal boundary will remain south of the area through Tuesday.

The rain is mostly over. There however will be another chance of
showers this evening into late at night, but should mostly pass
south of the terminals.

Otherwise mainly MVFR conditions are expected. MVFR this evening
will prevail before lowering to IFR heading into daybreak Tuesday
after which conditions are expected to return to MVFR by late
morning.

NE winds near 10-15 kt gusting 20-25 kt are backing to a more
northerly flow but will return to a NE flow tonight and closer to
10 kt for sustained winds.


     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: Amendments possible in 00-08Z timeframe to
include SHRA in TAFs. Possible brief reductions in vsby to MVFR/IFR
during that timeframe.

KLGA TAF Comments: Amendments possible in 00-08Z timeframe to
include SHRA in TAFs. Possible brief reductions in vsby to MVFR/IFR
during that timeframe.

KEWR TAF Comments: Amendments possible in 00-08Z timeframe to
include SHRA in TAFs. Possible brief reductions in vsby to MVFR/IFR
during that timeframe.

KTEB TAF Comments: Amendments possible in 00-08Z timeframe to
include SHRA in TAFs. Possible brief reductions in vsby to MVFR/IFR
during that timeframe.

KHPN TAF Comments: Amendments possible in 00-08Z timeframe to
include SHRA in TAFs. Possible brief reductions in vsby to MVFR/IFR
during that timeframe.

KISP TAF Comments: Amendments possible in 00-08Z timeframe to
include SHRA in TAFs. Possible brief reductions in vsby to MVFR/IFR
during that timeframe.

.OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY...
.Tuesday...VFR. NE winds 10-15 kt.
.Tuesday night...Patchy fog with MVFR vsby possible late at
KSWF, KHPN, otherwise VFR.
.Wednesday and Wednesday night...VFR.
.Thursday...Chance of showers and possibly a tstm with MVFR or
lower conds NW of the NYC metros in the afternoon, otherwise
VFR.
.Thursday night-Friday night...MVFR or lower conditions
possible, with chance of showers/tstms.
.Saturday...Mainly VFR.

&&

.MARINE...
E/NE winds will gradually ramp down over the next few hours as
low pressure passes to the south and east. Another wave of low
pressure then passes off the Delmarva late tonight into Tuesday.
This will keep a NE flow over the waters with seas slow to come
down. SCA conditions are likely to linger on the ocean through
at least Tuesday, primarily for seas.

Easterly flow continues into Wednesday before gradually diminishing
as high pressure builds across the area. Southerly flow will briefly
allow seas to build ahead of a cold front that will pass through the
area Thursday night into Friday, though seas should remain below SCA
levels. High pressure builds again through early next week which
will keep winds and seas low.

&&

.HYDROLOGY...
Light rainfall overnight, mainly along the coast, is not
forecast to pose any hydrologic issues.

Additional rainfall is possible Thursday through Friday night.
Hydrologic impacts are not expected at this time.

&&

.TIDES/COASTAL FLOODING...
With the new moon that occurred early yesterday morning and the
current easterly flow, tides are running astronomically high.
Tidal departures of 1/2 to 1 ft departures are needed tonight.

A coastal flood advisory has been issued for the south shore
back bays of Nassau and Queens for tonight with statements
across the NY Harbor and Western LI Sound for more localized
flooding.

Thereafter, any minor coastal flooding is forecast to be
localized into Tuesday.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...High Rip Current Risk through Tuesday evening for NYZ075-080-
     081-178-179.
     Coastal Flood Advisory from 9 PM to 11 PM EDT this evening for
     NYZ178-179.
NJ...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ330-
     335-340.
     Small Craft Advisory until 6 PM EDT Tuesday for ANZ350-353-355.

&&

$$
SYNOPSIS...MD/DW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...MD
AVIATION...JM
MARINE...MD/DW
HYDROLOGY...MD/DW
TIDES/COASTAL FLOODING...



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