Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 241419
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1019 AM EDT Thu May 24 2018

.SYNOPSIS...
High pressure will dominate the weather through Saturday. A
backdoor cold front pushes across the area Saturday night into
Sunday morning, becoming nearly stationary just south and west
of the area through Memorial Day. Another cold front follows on
Tuesday with high pressure building in behind.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Minor changes to forecast based on latest observations.

Heights will gradually rise today as a longwave trough to the
east shifts further into the northern Atlantic and ridging to
the west builds.

Sfc high pressure builds from the west today with just some thin
cirrus, and perhaps a few cu this aftn from convergence along
sea breeze boundaries, also along a back door cold front moving
westward across eastern/central CT/Long Island. Highs should
range from the mid 70s to around 80 across much of the Tri-State
area. Lower 80s are expected in metro NY/NJ.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
Upper level ridging over the Great Lakes will flatten through
Fri night as it traverses eastward as a result of vortexes
remaining over the Labrador Sea and northern Greenland and a
shortwave trough over the western Canadian provinces tracking
east.

At the sfc, a return flow develops tonight as high pres shifts
off the New England/Mid Atlantic coasts and continues slowly
into the western Atlantic through Fri night. This will result
in an increasingly warm and humid airmass. Expect mostly clear
skies with just some cirrus and perhaps a few cu Fri aftn/early
eve. There is also the potential for stratus mainly Fri night in
the second night of southerly flow across eastern LI and SE CT.
Have hinted at this in the forecast with partly cloudy skies
developing Fri night. Patchy fog is also a possibility mainly in
rural areas both tonight and Fri night.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
A broad upper level ridge across the southern two thirds of the
country will get suppressed a bit south through early next week
as a short wave trough progresses across the Great Lakes and
Northeast states. Model differences exist with the magnitude of
the latter feature, which sends a weak cold front across the
region Tuesday. In the case of the GFS, the boundary more or
less washes out as frontal wave passes to the south.

The better agreement though comes with sending a backdoor cold
front across the region Saturday night into Sunday morning,
putting an end to a string of days well above normal. Showers
and thunderstorms are also seeming more likely Saturday night
into Sunday morning as the front interacts with modest
instability, but a weakly sheared environment.

Showers will likely linger into Sunday, but chances should
diminish as high pressure builds southward across New England.
Sufficient overrunning ahead of the approaching upper trough
will be worthy of keeping the mention of showers in through
Memorial Day. There could even be some scattered thunderstorms
Sunday afternoon west of NYC, depending on how far to the south
and west the boundary stalls.

Additionally, with an easterly flow, temperatures continue to
trend down Sunday and Monday. It may be a bit more tricky Monday
with breaks in the cloud cover as the high weakens, especially
for locations across the interior.

Warmer weather then returns for the Tuesday through Wednesday
timeframe as high pressure builds both aloft and at the surface.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
High pressure builds over the region today.

VFR conditions are expected through the TAF period, however
there`s a low to moderate chance that IFR stratus shifts into
KGON this afternoon and a low chance that it then spreads into
KISP/KBDR this evening.

NNW winds this morning will shift around to local seabreezes in
the afternoon, except KSWF. Speeds around 10 kt. A few
occasional gusts will be possible late this morning/early
afternoon.

 ...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: Seabreeze timing may be off by 1-2 hours.

The afternoon haze forecast is GREEN, which implies slant range
visibility P6SM outside of cloud.

KLGA TAF Comments: Seabreeze timing may be off by 1-2 hours.

The afternoon haze forecast is GREEN, which implies slant range
visibility P6SM outside of cloud.

KEWR TAF Comments: Seabreeze timing may be off by 1-2 hours.

The afternoon haze forecast is GREEN, which implies slant range
visibility P6SM outside of cloud.

KTEB TAF Comments: Seabreeze timing may be off by 1-2 hours.

KHPN TAF Comments: Seabreeze timing may be off by 1-2 hours.

KISP TAF Comments: Seabreeze timing may be off by 1-2 hours.

.OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
.Friday...VFR. SW winds around 15 kt with gusts 20-25 kt through
early evening.
.Saturday...Mainly VFR. Low chances of showers and
thunderstorms near NYC Metro terminals and to the N and W
starting in the afternoon with possible MVFR. Higher chance of
showers and thunderstorms at night.
.Sunday-Monday...MVFR or lower at times with a chance of
showers and thunderstorms. Otherwise VFR.

&&

.MARINE...
A tightening pres gradient between low pres to the north and
high pres over the western Atlantic on Fri could bring marginal
SCA conds to the ocean waters Fri aftn/eve. A strengthening sfc
inversion will be developing over the waters, so despite
increasing winds aloft mixing potential will be limited.
A 15-20 kt sustained flow could however bring ocean seas up to
5 ft. No SCA at this time since it is marginal and too far out
in time.

Possible frontal wave development to the south on Tuesday will
be watched for potential higher winds and seas.

&&

.HYDROLOGY...
Localized heavy rainfall is possible Sat night into Sunday
morning as a cold front passes through. The main concern would
be training of cells from west to east along the boundary.

&&

.TIDES/COASTAL FLOODING...
Water levels may reach minor flood thresholds along the south
shore back bays of Nassau County and in western Long Island
Sound with the Sunday afternoon/night high tide cycle. Forcing
for increased water levels will be increasing E-NE flow as a
front stalls to the south and strong high pressure sets up E of
New England, along with increasing astronomical high tides with
the full moon on Tue the 29th.

&&

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

&&

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

&&

$$
SYNOPSIS...Goodman/24/DW
NEAR TERM...Goodman/24/DW
SHORT TERM...24
LONG TERM...DW
AVIATION...BC/JC
MARINE...Goodman/24/DW
HYDROLOGY...24/DW
TIDES/COASTAL FLOODING...
EQUIPMENT...



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