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000
FXUS61 KOKX 280822
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
422 AM EDT Wed Sep 28 2016

.SYNOPSIS...
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Strong high pressure builds in from the north today forcing an old
frontal boundary further south and east. Meanwhile...low pressure
will meander about the Ohio Valley and Mid Atlantic regions into
the weekend resulting in an extended period of unsettled weather.
The low will weaken and move slowly northeast early next week.
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&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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Low clouds and fog have developed across eastern Long Island and
southern CT early this morning...as well as patchy fog further
west where radiational cooling has been occurring. The fog should
burn off this morning...although the low clouds are expected to
expand wwd as the day progresses with an increasing easterly low
level flow trapping moisture beneath an inversion.

Strong high pressure over the Canadian Maritimes will start to
build southward today with a CAD signature becoming established in
New England. Meanwhile...a closed low pressure system moves into
the Ohio Valley. All guidance except for the NAM is indicating
light rain or DZ developing across the area this afternoon as a
result of increasing WAA aloft...although this will depend on the
degree of dry air that moves in from the high to the north. East
winds increase later this morning with sustained speeds between 10
and 20 mph with gusts of 15 to 25 mph...highest at the coast.

Temperatures will be near normal.

There is a moderate risk of rip current development at Atlantic
ocean beaches today.
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&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
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The main weather story will be the influence of the large cutoff
low pressure system meandering around the Ohio Valley has on the
local area. The strong high will remain to the north through
Thursday which now looks to keep pcpn mainly confined to western
portions of the forecast area. Thus...have maintained likely pops
only for this area with lower PoPs elsewhere. Again the degree of
dry air that works in from the north will determine when and where
it will rain. Think that places west of the Hudson River have the
highest chance for a few tenths of an inch through this time.
Light rain or drizzle possible to the east with a moderate east
flow continuing. Winds strengthen slightly on Thu with gusts up to
30 mph at the coast.

Little diurnal range in temps Wed Night/Thu with abundant cloud
cover and a maritime airmass.
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&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
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NWP guidance remains in good agreement on the big picture through
the weekend with a large upper low completely cutting off from the
westerlies and stalling over the Ohio Valley through Saturday, then
lifting across the Great Lakes on Sunday and weakening into an upper
trough that slides across the Northeast on Monday. Meanwhile, as a
strong upper high builds over the Western Atlantic, upper level
confluence to its north where it meets the westerlies will maintain
strong surface high pressure over northern New England and the
Canadian Maritimes,that should nose down into our area and keep a
warm front to our south.

This combination will keep us in an unsettled weather pattern
through at least the weekend with periods of rain, possibly heavy at
times. The heavier rain could occur late Thursday night into Friday
morning via strengthening easterly low level Atlantic inflow,
moistening mid levels via deep southerly flow aloft, a mid level
vort max riding up the coast, and increasingly difluent flow aloft.
Another period of heavy rain may come to Long Island and southern CT
on Saturday as another mid level impulse rides up the coast and as a
weak wave of low pressure forms along the front just to the south.
In between these bouts of relatively heavier rain, skies should
remain overcast, with periods of intermittent light rain. A triple
point low could pass through Saturday night into Sunday morning.
Associated lift and elevated instability could result in a rumble or
two of thunder during this period. And with the triple point low,
winds diminish somewhat for a period with plenty of moisture still
around, resulting in a decent chance of some fog.

As the upper low lifts into the Great Lakes on Sunday, the triple-
point low and/or occluded front should slowly lift across, with
precip becoming more showery in nature. The upper low will continue
to weaken and move east, but still close enough to mention at least
a slight chance of a shower on Monday. High pressure then likely
keeps Tuesday dry.
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&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
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Fog has developed across KGON, reducing vsbys and cigs to IFR or
less. This will need to be monitored to see if this spreads to any
of the other terminals. Otherwise, other than some mid level clouds
impacting the eastern terminals, expect mainly VFR conditions
overnight. The forecast then transitions over to a prolonged period
of sub-VFR conditions starting this morning and likely persists into
the first half of the weekend.

High pressure builds south from eastern Canada and noses into the
area today. Meanwhile, low pressure will drop south across the
Great Lakes and into the Ohio Valley states. This will result in a
strengthening NE flow with overrunning clouds and possible light
rain or drizzle.

Widespread MVFR conditions are forecast to develop from east to
west. Thinking that conditions could start to fall between 09Z and
13Z, from east to west. here is the possibility for these
ceilings to move in earlier than forecast, as well as drop into
the IFR category, especially for the coastal terminals. Light rain
is a possibility, but not expecting restrictions to visibility at
this time. Another potential wrinkle in the forecast is the
magnitude of the high building in from the north. Should the high
build a bit farther south, this could improve conditions for a
time.

Light and variable winds becoming NE around 10 kt around
daybreak. By mid to late morning, NE winds increase to 10-15 kt
and become gusty at times, as high as 20-25 kt at the coast.

...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: Medium/high confidence on winds, lower confidence
on ceilings. Amendments may be needed for changing flight categories.

KLGA TAF Comments: Medium/high confidence on winds, lower confidence
on ceilings. Amendments may be needed for changing flight categories.

KEWR TAF Comments: Medium/high confidence on winds, lower confidence
on ceilings. Amendments may be needed for changing flight categories.

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

KTEB TAF Comments: Medium/high confidence on winds, lower confidence
on ceilings. Amendments may be needed for changing flight categories.

KHPN TAF Comments: Medium/high confidence on winds, lower confidence
on ceilings. Amendments may be needed for changing flight categories.

KISP TAF Comments: Chance of fog development this morning which
could reduce visibilities. Medium/high confidence on winds, lower
confidence on ceilings. Amendments may be needed for changing flight
categories.

.Outlook for 06Z Thursday through Sunday...
.WED NIGHT...Widespread MVFR ceilings, possibly IFR. NE winds
G20-25KT at the coastal terminals.
.THU-SAT...IFR/MVFR in showers. NE winds 15-20 kt with gusts
25-30 kt possible THU-FRI.
.SUN...Mainly VFR but MVFR possible with a chance of showers. N
winds 10-20 kt.
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&&

.MARINE...
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Have maintained SCA east of Moriches inlet due to marginal seas early
this morning. East winds will increase later this morning as well
with SCA conds developing on all waters. Timing could be a few
hours too early...especially on the non-ocean waters but wanted to
give a few hours of padding.

Then as the pressure gradient tightens further, easterly gales
appear likely from Thu into Fri morning mainly on the ocean, but
perhaps also on the nearby bays of eastern Long Island and eastern
Long Island Sound, with SCA conds on the harbor and western Sound.
Issued gale watch for the ocean for Thu into Thu night.

SCA conds are likely to continue thereafter on all waters into Fri
evening, on the eastern Sound/bays into late Fri night, and on the
ocean into Sat.
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&&

.HYDROLOGY...
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Any rain through tonight should light and mainly confined to
areas north and west of NYC, with rainfall totals less than 1/3
inch.

Total basin average rainfall from Thu through Sat should range
from 1 to 2 inches, highest east, with potential for local amounts
of 2-3 inches across parts of Long Island and southern CT. The
rain could potentially be heavy at times late Thursday night into
Friday morning as well as at some point during Saturday. With this
being a long-duration event, major hydrologic impacts are not
expected but at least minor flooding could be possible.
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&&

.TIDES/COASTAL FLOODING...
A persistent moderate easterly flow during mid to late week may
combine with increasing astronomical high tides associated with
the new moon on Friday to cause minor to locally moderate coastal
flooding. The high tide cycles from Thu night into Fri morning
appear to be of most concern.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 8 AM this morning to 6 PM EDT
     Thursday for ANZ330-335-338-340-345.
     Gale Watch from Thursday morning through late Thursday night
     for ANZ350-353-355.
     Small Craft Advisory from 8 AM this morning to 6 AM EDT
     Thursday for ANZ353-355.
     Small Craft Advisory until 6 AM EDT Thursday for ANZ350.
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&&

$$