Area Forecast Discussion
Issued by NWS Upton, NY

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FXUS61 KOKX 250910
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
510 AM EDT Mon Sep 25 2017

.SYNOPSIS...
High pressure prevails through Tuesday then slowly retreats to
the east Tuesday night and Wednesday as Hurricane Maria moves
northeast off the Mid-Atlantic Coast. Refer to the latest
National Hurricane Center advisories for the official forecast
of Maria. A cold front crosses the Tri-State Wednesday night,
followed by high pressure building in from the west through
Thursday night. Another cold front approaches from the west
Friday, then crosses the area Friday night, followed by Canadian
High pressure building in for the upcoming weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
High pressure over the region will result in a sunny day with above
normal temperatures. Some low stratus may however roll in late in
the day right along the coast. 850 mb temperatures are forecast to
be around 17C, so highs away from the sea breeze will be well into
the 80s with perhaps a few spots reaching 90. Even the coolest spots
should be able to reach at least into the upper 70s in spite of a
sea breeze. Highs will likely fall short of records, however. See
the climate section below for more details.

There is a high rip current risk at the ocean beaches through this
evening due to southerly swells from Hurricane Maria. Will also keep
up the high surf advisory for the south shores of Suffolk County
today into this evening, although it looks like widespread surf
heights might not reach 7 feet across the area. Not enough
confidence to drop the advisory altogether.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Looks like low stratus and fog will push in from the ocean as
tonight progresses. Models suggest just enough turbulent mixing to
preclude widespread dense fog, but there is a chance that a few
spots end up with dense fog before the night is through. Clouds will
help keep low temperatures above normal.

The tricky part of the forecast for Tuesday comes from the
uncertainty of the magnitude of stratus and fog that happens
tonight. Models at least appear to be in agreement that there will
be less lower level moisture during the afternoon hours. Inland
areas will have a better chance of seeing lower clouds break up
sooner in the day, but there could still be a pretty good deal of
cirrus from Hurricane Maria. Temperatures aloft will still be quite
warm under high pressure, so in spite of the cloud cover, expecting
high temperatures to be above normal once again.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
The axis of a northern stream shortwave ridge passes to the north
Tuesday night, with associated subsidence keeping things dry. Lows
Tuesday night should be around 10-15 degrees above normal.

A northern stream trough passing to the N Wednesday and Wednesday
night, should help create a sufficient weakness in the ridge to the
east of Hurricane Maria, to allow the storm to track well SE of Long
Island. There could be some isolated to scattered showers due to a
combination of some moisture from Maria and the passing shortwave.
The associated cold fronts passage late Wednesday night could
provide enough lift for a rumble of thunder or two as well. Highs
Wednesday should be around 10 degrees above normal and lows
Wednesday night around 15 degrees above normal.

WSW-SW flow aloft settles over the area Thursday-Friday, helping to
continue to push Maria well offshore. Do have slight chance pops
Thursday and Thursday night (diminishing from W to E) as there is
some question on exactly how fast the surface cold front exits to
the east, and whether it could become anafrontal. Friday should be
dry, with the cold front expected to be well to the east and no
significant shortwave progged to move over the area.

A positively tilted trough approaches Friday night, then crosses the
area Saturday. This warrants slight chance pops, initially over W
zones late Friday night, then over the entire area by Saturday
afternoon. If confidence increases in the amount of low level
moisture available for the system to work with, pops could end up
needing to be raised to chance on Saturday.

Deep layered northern stream ridging then builds in behind the
departing trough. There is some question how fast it begins to
build in (As soon as Saturday night or waiting until Sunday) for now
went with a blended timing based on the ECMWF/GFS/CMC. It should be
dry regardless of the timing of the ridge.

Temperatures Thursday-Sunday start out above normal Thursday, should
be near normal Friday, then below normal Saturday and Sunday.

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
High pressure remains across the region through the TAF period.

Fog or stratus has had difficulty getting into eastern
terminals, therefore updated TAFS and have generally VFR into
the morning push with just a few locally MVFR vsbys possible through
11z or so. VFR is expected for all terminals during the day
Monday. Stratus and fog likely to make a better push to the west
tonight into early Tue morning and is expected to be more
widespread, however timing is uncertain and could be several
hours off from current forecast.

Light and vrb winds into this morning then increase to 5-10 kt
out of the E-SE during the aftn/early eve and then become
light/vrb again tonight into early Tue morning.

...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: Wind direction may be off up to 30 degrees
from 16z to 19z. Timing of sub VFR visibilities may be off by 2
to 4 hours for Monday eve/night.

The afternoon KJFK haze potential forecast is RED...which
implies slant range visibility less than 4sm outside of cloud.


KLGA TAF Comments: Wind direction may be off up to 30 degrees
from 16z to 19z. Timing of sub VFR visibilities may be off by 2
to 4 hours for Monday eve/night.

The afternoon KLGA haze potential forecast is RED...which
implies slant range visibility less than 4sm outside of cloud.


KEWR TAF Comments: Wind direction may be off up to 30 degrees
from 16z to 19z. Timing of sub VFR visibilities may be off by 2
to 4 hours for Monday night.

The afternoon KEWR haze potential forecast is YELLOW...which
implies slant range visibility 4-6SM outside of cloud.


KTEB TAF Comments: Wind direction may be off up to 30 degrees
from 16z to 19z. Timing of sub VFR visibilities may be off by 2
to 4 hours for Monday night.


KHPN TAF Comments: Wind direction may be off up to 30 degrees
from 16z to 19z. Timing of sub VFR visibilities may be off by 2
to 4 hours for Monday eve/night.


KISP TAF Comments: Wind direction may be off up to 30 degrees
from 16z to 19z. Timing of sub VFR visibilities may be off by 2
to 4 hours for Monday eve/night.

.OUTLOOK FOR 06Z TUESDAY THROUGH FRIDAY...
.Monday night-Tuesday...MVFR or lower conditions possible with areas
of fog and/or stratus outside city terminals.
.Tuesday night-Wednesday...MVFR or lower conditions possible with
patchy fog and/or stratus and a low chance of showers.
.Wednesday night-Thursday...MVFR or lower possible with isolated to
scattered shower activity.
.Thursday night-Friday...Mainly VFR.

&&

.MARINE...
Long period swells will keep ocean seas at advisory levels for
at least Friday. As per local policy limiting a SCA to a
maximum of 4 periods in duration and collaboration with the
surrounding offices, will extend the SCA on the ocean through
Tuesday night for now. The advisory will likely need to be
extended further in time.

A light pressure gradient over the region will limit winds over the
waters to around 10 kt or less through Thursday.

The pressure gradient tightens Thursday night and remains so on
Friday with winds up to around 15 to 20 kt. There is also a chance
for gusts to 25-30 kt, mainly on the coastal ocean waters.

The pressure gradient then relaxes later Friday, with winds
probably returning to being at most around 10 kt by Friday
evening.

&&

.HYDROLOGY...
Dry weather is expected through Tuesday. Any rainfall Tuesday
night through Sunday should total less than 1/2 inch, so no
significant hydrologic impacts are anticipated during this time
frame.

&&

.CLIMATE...
The following are the record high temperatures for Monday
September 25, 2017 along with the forecast high temperatures:

Record High Temperature          Forecast High Temperature
-----------------------------    -------------------------
Central Park........90 (1970)    88
LaGuardia...........90 (2010)    87
Kennedy.............87 (2010)    81
Islip...............87 (2010)    82
Newark..............91 (1970)    88
Bridgeport..........85 (1970)    82

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...High Rip Current Risk through this evening for NYZ075-080-081-
     178-179.
     High Surf Advisory until 9 PM EDT this evening for NYZ080-081.
NJ...None.
MARINE...Small Craft Advisory for hazardous seas until 6 AM EDT
     Wednesday for ANZ350-353-355.

&&

$$
SYNOPSIS...JC/Maloit
NEAR TERM...JC
SHORT TERM...JC
LONG TERM...Maloit
AVIATION...JE
MARINE...JC/Maloit
HYDROLOGY...JC/Maloit
CLIMATE...



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