Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 231340
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
940 AM EDT Wed May 23 2018

.SYNOPSIS...
A weak cold front will move south and east of Long Island early
this morning. Meanwhile, high pressure will build toward the
region through Thursday, then remain through Saturday. Another
frontal system will impact the area early next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Forecast update to reflect latest observations. Just a few
isolated showers across Long Island for another hour or so,
then drier weather returns for the afternoon.

A cold front will move across portions of the region this
morning. A northern stream trough will remain across eastern
Canada and into the northeast once the cold front passes.
Clearing will take place late this morning through the afternoon
as the trough begins to move slowly east, with slowly rising
heights.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
A trough continues to exit the northeast as heights rise across
the region tonight as a strong ridge from the Gulf of Mexico to
the southern central Canadian plains shifts east. The ridge axis
builds toward the area Thursday with a surface high over the
region. A dry NW flow will continue tonight through Thursday.
Despite plenty of incoming solar radiation Thursday,
temperatures are expected to be slightly cooler than Wednesday
as the NW flow brings in a cooler and drier airmass from Central
Canada.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Vortexes over the Labrador Sea and northern Greenland, and an
upper level trough moving into south central Canada at the start
of the period will result in the flattening of the upper level
ridge extending from the upper Midwest as it shifts eastward
into Sat. This will result in a continuation of the warm and
increasingly humid weather through the first half of the
weekend. Fri will be a bit breezy as the pressure gradient
tightens between low pres to the north and high pres sliding off
the Mid Atlantic coast. Sat will be the hottest and most humid
day with an established SW flow as a result of the offshore high
remaining anchored over the western Atlantic. Temps are
expected to be in the mid to upper 80s under a sunny sky across
much of the local area, possibly even hit the 90 degree mark in
some locations of metro NY/NJ. The southerly flow off the cooler
waters will result in highs 5-10 degrees cooler along the south
shore of Long Island and coastal CT.

A cold front will be dropping down from the north on Sat and
while the upper level dynamics appear to remain well to the
north during peak heating, there is the possibility of a few
airmass tstms during the aftn and early eve. A trigger will be
needed and any thermal trough or seabreeze boundary would
suffice. The GFS appears to be overdone with its pcpn field Sat
night as sheared energy tracks towards the region from the west
and the front to the north continues to sag southward. Have
maintained SCHC PoPs sat night with the boundary moving into the
local area if not passing through completely by Sun morning.

Global models start to diverge significantly on the details
through the remainder of the period, although the general signal
is for unsettled weather Sun and Mon with the boundary
remaining nearby and a series of shortwaves passing through.
Timing of pcpn will need to be refined in later forecasts once a
there is better agreement.

Another cold front approaches from the west early next week,
although timing is once again in question.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
A cold front moves across the area this morning.

A brief period of IFR/MVFR conditions this morning, otherwise
becoming VFR.

A light W/SW flow at 5 kt or less this morning becomes NW and
increase to around 10 kt. A few gusts into the teens will be
possible this afternoon. KGON will be in close proximity to a
surface trough today which may keep winds W-SW.

     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: Moderate to high confidence of winds right
of 310 for much of the day. A few gusts into the teens possible
the afternoon. Winds back late in the day.

The afternoon KJFK haze potential forecast is GREEN...which implies
slant range visibility 7SM or greater outside of cloud.

KLGA TAF Comments: Moderate to high confidence of winds right
of 310 for much of the day. A few gusts into the teens possible
the afternoon. Winds back late in the day.

The afternoon KLGA haze potential forecast is GREEN...which
implies slant range visibility 7SM or greater outside of cloud.

KEWR TAF Comments: Moderate to high confidence of winds right
of 310 for much of the day. A few gusts into the teens possible
the afternoon. Winds back late in the day.

The afternoon KEWR haze potential forecast is GREEN...which
implies slant range visibility 7SM or greater outside of cloud.

KTEB TAF Comments: Winds back late in the day.

KHPN TAF Comments: Timing of improvement to VFR may be delayed
1-2 hours. Winds back late in the day.

KISP TAF Comments: Winds back late in the day.

.OUTLOOK FOR 12Z THURSDAY THROUGH SUNDAY...
.Thursday...VFR.
.Friday...VFR. SW winds 10-15 kt with gusts up to 20 kt through
early evening.
.Saturday...Mainly VFR. Isolated thunderstorms possible N and W of
the metro terminals starting in the afternoon with possible MVFR.
.Sunday...MVFR or lower at times with a chance of showers and
thunderstorms. Otherwise VFR.

&&

.MARINE...
Winds and seas forecast remains on track.

A weak cold front moves slowly across the forecast waters early
this morning with showers and isolated thunderstorms exiting
the waters as the cold front moves south and east of Long
Island.

High pressure will build toward the waters today through
Thursday. With a weak pressure gradient force across the
forecast waters winds and seas will remain below small craft
advisory levels.

Sub-advsy conds are expected on all waters through Sat night
with a strong sfc inversion in place. Winds could approach SCA
levels on the ocean waters Sun morning and again Sun night.

&&

.HYDROLOGY...
Showers end early this morning with rainfall less than 1/4 inch.
No significant hydrologic impacts are anticipated.

No hydrologic impacts are expected through Sat. While the
details for late this weekend into early next week remain fuzzy,
there is the potential for greater than 1/2 inch of rainfall
from Sun through next Tue.

&&

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

&&

$$
SYNOPSIS...19
NEAR TERM...BC/19
SHORT TERM...19
LONG TERM...24
AVIATION...DW
MARINE...24/19
HYDROLOGY...24/19


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