Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 230152
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
952 PM EDT Mon May 22 2017

.SYNOPSIS...
A weak frontal system passes through the region tonight, stalling
in the mid Atlantic region Tuesday. Weak high pressure builds
in for Tuesday. Meanwhile, a wave of low pressure will move
along the frontal boundary, south of the region, Tuesday and
Tuesday night. Weak high pressure builds in on Wednesday,
followed by low pressure Thursday into Friday. High pressure
returns for the beginning half of the upcoming holiday weekend,
but low pressure may bring some unsettled weather during the
latter half.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Weak frontal system is beginning to enter western portions of
the area. This boundary will continue to move east through the
remainder of the night.

Widespread rain has moved to the east of the area with just a
few sct showers across the Forks of Long Island and SE CT. Have
adjusted PoPs downward based on the latest radar trends. Weak
wave of low pressure near the DelMarva continues to slide to the
east. High resolution models continue to show this system
linking up with the front as it moves to the east tonight.
Latest trends however have any redevelopment of rain staying
offshore as deepest moisture and lift likely remain to the east.
Have therefore lowered PoPs after midnight to account for these
trends.

Areas of fog are possible this evening as well. Dense fog is not
anticipated at this time. Visibilities should gradually improve
from west to east late tonight as the frontal boundary moves
across.

Gradual clearing is expected behind the front. Temperatures
remain nearly steady for much of the night, but could fall into
the upper 40s/lower 50s NW of the city towards daybreak.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
The cold frontal boundary will remain stalled to the south,
through the mid Atlantic region and DELMARVA Tuesday, and weak
mid and low level ridging builds. Will keep the area dry through
most of the day and then bring in probabilities late in the day
to the south as a wave begins to move along the frontal
boundary.

The wave passes to the south with some differences in placement
Tuesday and Tuesday night with the NAM just about totally dry
while the GFS is a little farther north. At this time leaned a
little more closer to the GFS and brought chance across about
the south half of the area.

The wave does pass through quickly and precipitation may be
ended across the eastern zones by Wednesday morning.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Weak high pressure builds in behind a departing offshore low on
Wednesday. Only a slight chance of a shower in the morning mainly
over Long Island. Partly sunny otherwise, and a blend of MAV/NAM MOS
looked good for high temperatures.

The next system to bring rainfall to the area arrives late Wednesday
night, with rainfall being most likely Thursday into Thursday night.
Went a little cooler than most guidance, particularly over western
zones as a triple point low approaches, but the associated warm
front extending to its east might only push through some of the
eastern zones, if at all. Some elevated instability should be
present, so have included isolated TSTMs for Thurs and Thurs night.
Also included areas of fog for late Weds night into Thurs morning
with the warm front not too far off to the south.

For Friday, the storm exits to the NE, but is still close enough for
a chance of showers, especially over the NE zones. Some lower level
instability combined with a cold pool aloft may also result in a
TSTM over parts of CT as well.

Weak high pressure then returns for Saturday. Will go with a dry
forecast and slightly above normal temperatures for now. The timing
of the next low pressure system is still uncertain at this point.
Some overrunning rainfall could move in by daybreak Sunday. The
system would figure to move slowly enough for Monday to be affected
as well. Will go with CHC PoP for now for both days.

&&

.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
A front will cross the area tonight, as a series of weak lows
track south of Long Island into Tuesday evening.

IFR/LIFR conditions should continue through at least 6z, and
probably last until after the front passes (4-9z from W to E).
It appears conditions should improve fairly rapidly behind the
front, so expect most areas to be VFR by around 12z.

Light and variable winds shift to the N-NE at 10KT behind the
front. An afternoon seabreeze is probable at all but
KSWF/KHPN/KTEB - where winds should be mainly light and
variable all day Tuesday. Occasional gusts to 15-20kt are
possible Tuesday 12-16z Tuesday.

     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 due to changes in
ceilings and visibilities.

KLGA TAF Comments: Amendments possible due to changes in
ceilings and visibilities.

KEWR TAF Comments: Amendments possible due to changes in
ceilings and visibilities.

KTEB TAF Comments: Amendments possible due to changes in
ceilings and visibilities.

KHPN TAF Comments: Amendments possible due to changes in
ceilings and visibilities.

KISP TAF Comments: Amendments possible due to changes in
ceilings and visibilities.

.OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...
.Tuesday night-Wednesday evening...VFR. NE winds G15-20KT
possible Wednesday.
.Wednesday night-Friday night...MVFR or lower possible. Slight
chance of thunderstorms Thursday evening. LLWS possible
Thursday-Thursday evening. NW winds G15-20KT possible Friday.
.Saturday...VFR.

&&

.MARINE...
Forecast remains on track over the waters this evening. Winds
and seas are expected to remain below small craft levels from
tonight through Tuesday night.

A weak pressure gradient will be over the waters on Wednesday with
weak high pressure ridging in behind a departing offshore low. NE
winds at 10 KT or less shift SE in the afternoon, and seas should
remain below 5 FT. The next storm system so far would not appear to
create a pressure gradient strong enough for advisory level winds
over the region. Relatively stronger winds associated with this
system would be on Friday when the center of this system is
northeast of the waters. Winds are therefore forecast to remain
below advisory levels through this period and should remain that way
on Saturday as winds diminish. However on the ocean, guidance
suggests a significant swell. Have gone with a forecast of wave
heights below guidance, but still at advisory criteria Wednesday
night through Saturday morning.

&&

.HYDROLOGY...
No hydrologic impacts are anticipated tonight through the end of
the week.

&&

.TIDES/COASTAL FLOODING...
Minor coastal flooding thresholds may be reached with Wednesday
night`s high tide cycle for southern sections of NY Harbor, the
south shore back bays of western LI/Queens/Brooklyn, and western
Long Island. A better chance of minor flooding arrives for Thursday
night, with northern NY Harbor and parts of central LI sound also
included. Chances then lower on Friday night as winds likely shift
offshore.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$
SYNOPSIS...JC/MET
NEAR TERM...DS/MET
SHORT TERM...MET
LONG TERM...JC
AVIATION...Maloit
MARINE...JC/MET
HYDROLOGY...JC/DS
TIDES/COASTAL FLOODING...



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