Area Forecast Discussion
Issued by NWS Upton, NY

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985
FXUS61 KOKX 231813
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
213 PM EDT Fri Jun 23 2017

.SYNOPSIS...
A warm front remains well north of the region this afternoon. A
cold front approaches tonight and moves across the area
Saturday. A series of frontal boundaries will move across the
Tri-State area Sunday through Tuesday. A large area of high
pressure builds in thereafter.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A warm front is located well north of the region with a pre-
frontal trough developing in the lee of the Appalachians. The
local region is in the warm sector with a warm and humid airmass
in place. Temperatures range from upper 70s to mid 80s this
afternoon although much of the region will be in the upper 70s
to lower 80s. Dewpoints are in the lower 70s.

Showers are located near and north of NYC with overall shower
activity expected to be isolated in coverage but by late
afternoon expecting scattered showers as well as thunderstorms.
These will be mostly north and west of NYC.

The clouds have been abundant so this has limited the surface
based CAPE and instability. There is some shear that increases
towards the evening as winds at 3kft increase to near 30kt. This
will allow for convection to become more organized.

The moderate risk of rip current development continues through
this afternoon, due to building southerly winds waves and a 2
ft long period SE swell.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/...
Northern stream longwave trough continues to deepen into the
Upper Mississippi River Valley and Great lakes through the
period...with the shortwave remnants of Cindy shearing northeast
towards the region late tonight into Saturday morning. At the
surface...a cold front over the Great Lakes will slide east
towards the region tonight...with the remnant circulation of
Cindy riding NE towards the region along the front.

Leading edge of southern stream shortwave energy and pre-
frontal trough approach the region this evening. Will have to
watch for convection developing over Central/Eastern PA this
afternoon...and whether line segments can translate east in the
moderate mid- level flow into the Lower Hudson Valley/NE NJ
before instability begins to wane. A conditional low threat for
severe winds gusts exists mainly NW & W of NYC if this activity
survives.

The parade of shortwaves late evening into the overnight and
tropical airmass will keep a threat for iso convection with
heavy downpours overnight. Coastal stratus/fog development
possible with high dewpoint airmass advecting across E LI/SE
CT late today/this evening.

Main concern during this period will be approach of cold front
and remnant low of Cindy late tonight/Saturday morning.
Environment presents a threat for flash flooding along and just
to the south of the path of this low...with PWATS in excess of
2+ inches and Corfidi vectors indicating potential for slow
moving or back building convective elements. Also can`t rule out
an isolated severe wind/tornado threat if any MCS type activity
develops in a weak instability but high shear/helicity and low-
LCL environment.

745am Update...06z guidance is indicating that this feature may
track to the south of the region. If 12z guidance continues
with this theme...the above mentioned severe/flash flood threat
may end up south of the region.

Drying conditions in the wake of the cold front and Cindy
circulation Saturday afternoon...with highs in the mid to upper
80s.

A high risk of rip current is likely Saturday with building
southerly swells and wind waves.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
NWP is in agreement that a broad upper level trough will remain east
of the Rockies into early next week. The H5 flow then flattens from
west to east as a cutoff low pres system moves through the western
Canadian provinces...eventually consolidating with a vortex over
northern Quebec. This will sharpen the trough with its axis passing
through Tue night followed by weak ridging for the remainder of the
forecast period.

In terms of sensible weather...not a whole lot to talk about. A
few cool frontal boundaries will pass through the local
area...the first Sunday aftn/eve with just a chance of isold
showers. Mid level warming will keep instability in check so no
tstms in the forecast.

The second boundary approaches on Monday and is very slow to
move through the area. It may become hung up...before pushing
east Tue night. Despite a decent shortwave and being in the RRQ
of a 120+ kt upper jet...moisture looks very meager...thus have
kept the forecast dry. Moisture is still limited on Tue...but
there could be enough for isold showers/tstms in the aftn.

Dry and seasonable weather then returns for the remainder of the
forecast period.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
Low pressure tracks through eastern Canada this afternoon into
Saturday morning with an associated cold front approaching this
evening and moving through the terminals 12Z to 16Z Saturday.

Winds will be generally from the southwest 220 true, with gusts to
around 20 kt. Sea breeze influence will keep the winds more
southerly along the coastal areas this afternoon. With the passage
of the cold front winds shift to west to northwest, to the left of
310 true, and become gusty Saturday morning.

Generally VFR with occasional MVFR ceilings this afternoon.
Restrictions in fog and showers develops after 06Z, isolated to
scattered thunder is possible late this afternoon and this evening.
Another round of showers develops late tonight with the chance of
heavy rain and IFR visibilities.


     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: Amendments possible late this afternoon and this
evening for developing thunderstorms.

KLGA TAF Comments: Amendments possible late this afternoon and this
evening for developing thunderstorms.

KEWR TAF Comments: Amendments possible late this afternoon and this
evening for developing thunderstorms.

The afternoon KEWR haze potential forecast is GREEN...which implies
slant range visibility greater than 6SM outside of cloud.

KTEB TAF Comments: Amendments possible late this afternoon and this
evening for developing thunderstorms.

KHPN TAF Comments: Amendments possible late this afternoon and this
evening for developing thunderstorms.

KISP TAF Comments: Amendments possible late this afternoon and this
evening for developing thunderstorms. The chance of thunder is less
likely east of the NYC terminals.


.OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...
.Saturday...VFR. WNW winds gusting around 20 kt.
.Saturday night-Sunday Night...VFR.
.Monday-Tuesday...VFR. A chance of shra/tsra Monday afternoon into
Tuesday.
.Wednesday...VFR.

&&

.MARINE...
Ocean seas have increased to 3 ft with gusts near 20 kt that
have developed. The wind gusts will further increase to 25 kt
late this afternoon.

Southerly winds at SCA levels likely continues into tonight.
Occasional gusts to 25 kt possible on nearshore waters this
afternoon. Ocean seas likely building to SCA levels late this
afternoon...and to 4 to 7 ft tonight. Winds subside and
Saturday...but southerly swells are expected to keep ocean seas
at 4 to 7 ft on Sat.

The other hazards for mariners will be rounds of
showers/thunderstorms this today into Saturday morning, and
potential for dense fog development on the ocean waters and
eastern LI nearshore waters this afternoon and continuing into
tonight.

Seas begin to subside Sat night...but could take until Sun morning
to drop below SCA levels east of Moriches Inlet. A weak pressure
field is then expected to prevail through Tue...keeping conds at sub-
advsy levels.

&&

.HYDROLOGY...
Localized minor urban and poor drainage flooding is possible
with showers and thunderstorm activity this afternoon into the
first half of tonight.

There is a threat for flash flooding late tonight through
Saturday morning from a likely complex of showers and
thunderstorm associated with a frontal wave (remnants of Cindy)
moving through the areas. Uncertainty exists on the
exact track of this wave...which could be from the Northern Mid-
Atlantic to Southern New England.

745am Update...06z guidance is indicating that this feature may
track to the south of the region. If 12z guidance continues
with this theme...the above mentioned flash flood threat may
end up south of the region.

Otherwise, no other hydrologic concerns.

&&

.TIDES/COASTAL FLOODING...
Astronomical tides are running very high, especially during the
evening high tide cycles today and Saturday.

Less than 1 ft of surge is needed during these evening high tide
cycles for minor flooding, and in some cases less then 1/2 ft.
The expected S/SW flow is not favorable for surge, but a
background anomaly will likely be enough for minor coastal
flooding of the most vulnerable coastal locales along the south
shore bays of Western Long Island, along Jamaica Bay, and along
western Long Island Sound during this time.

&&

.EQUIPMENT...
KOKX weather radar is scheduled for maintenance starting today June
23rd for a period of 3 days.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 2 AM EDT Sunday for ANZ350-353-355.

&&

$$
SYNOPSIS...24/JM
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...24
AVIATION...MET
MARINE...24/JM/NV
HYDROLOGY...24/NV
TIDES/COASTAL FLOODING...
EQUIPMENT...



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