Area Forecast Discussion
Issued by NWS Upton, NY

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KOKX 231135
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
735 AM EDT Tue Oct 23 2018

.SYNOPSIS...
A warm front lies north of the area this morning. A cold front
move through this afternoon and evening. High pressure will
gradually build towards the region through the end of the week.
A coastal low then likely impacts the area over the weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Forecast is on track with only minor changes made to reflect
current conditions.

Low pressure will move across New England today along a digging
middle and upper level shortwave trough. A warm front will be
situated just north of the area this morning. This will be the
focus of some showers for eastern areas late this morning,
mainly across southeastern Connecticut and the Twin Forks of
Long Island, where instability will be the greatest (though
there is not much in the way of MUCAPE at a couple of hundred
J/kg noted in the models). Thereafter, chances increase for
western areas, such as northeast New Jersey and into the Lower
Hudson Valley as the cold front approaches and moves through.
Some of the mesoscale models seem to be keying in on a line of
showers in the afternoon and early evening hours with the cold
front, so increased chances for precipitation in these areas to
generally low end chance. Although instability is low, a stray
thunderstorm cannot be ruled out, though chances were too low to
include in the forecast.

Southerly flow out ahead of the approaching cold front will mean
seasonable temperatures, with highs in the upper 50s to lower
60s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Chances for showers continue early tonight as the cold front
moves through. The best chances for showers will be for northern
areas across the Lower Hudson Valley and southern Connecticut
as these areas will be closer to the weak low moving over New
England. Dry conditions should return to the entire area after
midnight as the low departs and high pressure builds in at the
surface. Despite cold air advection into the area, lows will
not drop off too much as winds will not die off, keeping the
boundary layer well mixed. Lows will be in the upper 30s to
middle 40s.

High pressure at the surface will remain centered to the west of
the area on Wednesday, allowing a northwesterly flow. This will
usher in a cooler air mass, with highs in the lower to middle
50s. It will also be on the breezy side, especially along the
coast.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
High pressure builds into the region through Friday before moving
offshore. Dry weather is expected through this period with below-
normal temperatures. Highs only around 50 for both Thursday and
Friday with low temperatures mostly in the 30s Wednesday night, then
below freezing for inland areas Thursday night.

Global models agree that a longwave trough digs towards the
Southeast states Friday night through Saturday night with a coastal
low traveling close to the Mid-Atlantic and Northeast coasts. The
track of this low is still in question as some models track its
center over the Tri-State area while others have it farther
offshore. In either case, it should be close enough to us to
bring likely PoPs Saturday and Saturday night. Rain chances
would begin late Friday night. There is even a chance of some
snow mixed in Friday night/early morning Saturday mainly for the
higher elevations well inland if the center ends up tracking to
our east. Will cap PoPs at 50% for Sunday as the storm slows
down to our north with an occlusion. The 500mb trough axis will
still be to our west on Monday so shower chances continue
through Monday night.

Additional impacts from this storm are potentially advisory-criteria
winds and a chance of at least minor coastal flooding. The degree of
both is uncertain as it depends on the eventual track and strength
of the storm, on which models continue to disagree. Rain amounts
will also be affected by the storm track, but as of right now fresh
water flooding does not appear to be one of the greater impacts.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
A warm front lifts through the region this morning, followed by
a cold front crossing the Tri-State this afternoon and early
this evening. Canadian high pressure then builds towards the
region into Wednesday morning.

Most likely VFR through the TAF period. The possible exception
is this afternoon at KGON and KSWF, where there is a very low
chance of MVFR conditions. At this time, the confidence in this
occurring is too low to reflect in the TAFs.

For now, it appears that any isolated to scattered showers
should be limited to late this afternoon/early this evening,
except at SE CT terminals where they are possible from late
this morning into early this evening.

Winds become SW throughout at around 10kt by late this
morning/early this afternoon. Winds veer to the W, then WNW
behind the cold front with gusts 15-25KT - strongest in city and
Long Island terminals. Cannot rule out isolated gusts to around
30kt within about 3 hours after cold frontal passage early this
evening. NW winds G15-20KT continue through the night.

     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: Timing of changes in wind speed and direction
could be off by +/- 1-2 hours. There is the potential for
isolated gusts to around 30 kt from 21-01Z.

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

KLGA TAF Comments: Timing of changes in wind speed and direction
could be off by +/- 1-2 hours. There is the potential for
isolated gusts to around 30 kt from 21-01Z.

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

KEWR TAF Comments: Timing of changes in wind speed and direction
could be off by +/- 1-2 hours. There is the potential for
isolated gusts to around 30 kt from 21-01Z.

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

KTEB TAF Comments: Timing of changes in wind speed and direction
could be off by +/- 1-2 hours. There is the potential for
isolated gusts to around 30 kt from 21-01Z.

KHPN TAF Comments: Timing of changes in wind speed and
direction could be off by +/- 1-2 hours. There is the potential
for isolated gusts to around 30 kt from 22-02Z.

KISP TAF Comments: Timing of changes in wind speed and
direction could be off by +/- 1-2 hours. There is the potential
for isolated gusts to around 30 kt from 23-03Z.

.OUTLOOK FOR 12Z WEDNESDAY THROUGH SATURDAY...
.Wednesday...VFR. NW winds G15-25KT likely.
.Wednesday night...VFR. NW winds G15-25KT possible.
.Thursday-thursday night...VFR. NW-N winds G15-20KT possible.
.Friday...VFR.
.Friday night-Saturday...MVFR or lower possible. Rain becoming
likely towards Saturday morning, then continuing on Saturday.
NE winds G30-40KT possible late Friday night and Saturday.

&&

.MARINE...
SW flow increases ahead of a cold front today with winds and
seas increasing. Gusts to 25 kt are expected on the ocean waters
by mid-afternoon and should continue overnight tonight. A SCA is
in effect for the ocean waters. The SCA may need to be extended
into Wednesday as 25 kt gusts look to continue over the ocean
waters.

All other coastal zones may also see gusts of 25 kt today,
but the gusts will be more occasional, and thus a SCA was not
needed. However, if gusts end up being stronger, then one may be
issued later today.

Ocean seas will also build to around 5 to 6 ft tonight, then
diminish late tonight, coming below 5 ft by late Wednesday
morning into Wednesday afternoon.

A SCA may be needed on most of the waters Wednesday night as high
pressure building in behind a storm to the NE tightens the pressure
gradient. Winds subside somewhat on Thursday, but SCA conds probably
continue on some of the waters. A high pressure ridge then
approaches the waters with a return to sub-advisory conditions for
all waters by Friday morning, lasting through the day Friday. A
coastal low will then bring increasing winds and seas late Friday
night into Saturday. A potential for gale force winds exists across
all waters during Saturday.

&&

.HYDROLOGY...
Dry weather is then expected through Friday. A half inch to an inch
and a half of rainfall is possible late Friday night through the
upcoming weekend with a coastal storm. Higher totals may be forecast
as the event draws closer, but as of right now any hydrological
impacts do not appear to be significant.

&&

.EQUIPMENT...
NYC NOAA Weather Radio Station KWO35 (162.55 MHz) remains off
the air for an extended period of time.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 2 PM this afternoon to 6 AM EDT
     Wednesday for ANZ350-353-355.

&&

$$
SYNOPSIS...JC/JP
NEAR TERM...JP
SHORT TERM...JP
LONG TERM...JC
AVIATION...Maloit
MARINE...JC/JP
HYDROLOGY...JC/JP
EQUIPMENT...


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.