000
FXUS61 KOKX 051147
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
747 AM EDT Thu Oct 5 2023
.SYNOPSIS...
High pressure remains in place to our north and east through the
day, before departing farther east tonight into Friday. The high
will give way to an approaching frontal system that will drag a cold
front through the area Saturday into Saturday night. Low pressure
lingers over the Northeast into the middle of next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Fog has been more widespread overnight into this morning than the
past few nights due to the addition of onshore flow along with the
radiation fog. The fog can be seen well on the Nighttime
Microphysics satellite RGB across the northeast. Have expanded
the Dense Fog Advisory and it now includes all of Long Island
and southern CT where widespread 1/4 mile visibilities are
being observed. This is in effect until 10am. Issued an SPS for
the rest of the area, outside of portions of the NYC/NJ metro
area, for patchy dense fog where only isolated dense fog is
being observed. Will continue to monitor these areas.
The upper level ridge axis has shifted east of the area as well as
surface high pressure. The orientation of the high well to our north
and east will continue the E-SE onshore flow. Today will be the last
day of above normal temperatures before a long period of at or below
normal temperatures. Highs today will be in the 70s.
The aforementioned onshore flow will advect an increasingly
humid airmass into the area. Some patchy light rain or drizzle
is possible at the very end of the tonight period.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
A digging upper level trough approaches from our west, becoming
negatively tilted before closing off. At the same time, TC Phillipe
approaches from the south and east. Phillipe will stay well to our
east, but aid in increasing the moisture over our area before
getting pulled back west into northern New England. A surface low
associated with the approaching upper level trough will pass well to
our north, but drag a cold front through our area Saturday into
Saturday night.
After a dry week, this set up will allow rain chances to increase
through the day on Friday, and become likely Friday night through
Saturday. Expecting the showers ahead of the cold front Friday
through Friday night to be mostly light. The ECMWF is currently an
outlier showing a higher band of QPF during this time frame and does
not seem to be supported given the expected moisture and
instability. Will have to continue to monitor this trend especially
as the CAMs start to come into play. For now, the WPC as outlined
the area in a marginal risk for Day 2. There is potential for
this to be upgraded to a slight risk as WPC mentions in their
Day 2 ERO based on today`s 12z CAM guidance. Moderate to heavy
showers are then expected with the passage of a cold front
Saturday into Saturday night. Have removed thunder given the
forecast soundings showing very little CAPE through the profile.
Thunder can not be completely ruled out but thinking it will be
extremely isolated. NBM probabilities for 1 inch of rain over
any 6 hour period have actually lowered to less than 10%.
However, probabilities for 1 inch of rain over the 24 hr period
ending 00z Sunday have increased significantly to 65-85% for
most.
Rain tapers off late Saturday night into Sunday morning. Cool
air filters in behind the cold front, with lows Sunday morning
in the 40s.
Refer to the National Hurricane Center, https:/www.nhc.noaa.gov for
official forecasts on Philippe.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
For much of the long term, the area is positioned at the base of a
large trough and associated cut off low pressure system positioned
well to the north centered over Southern Canada. Behind the cold
frontal passage and through much of the week, winds will be
generally out of W/SW. Wind speeds will be a bit breezy Sunday and
into early Monday as the pressure gradient remains fairly tight over
the area as the low pressure initially occludes closer to the area.
Wind speeds lower into Tuesday as the center of the low moves
northward.
Lower heights and a cooler airmass will be advected into the area
allowing temperatures each day in the extended period to be
generally 5 to 10 degrees below average. Highs through the beginning
of the week will only be in the low 60s, eventually rising into the
middle 60s by midweek.
In terms of sensible weather, conditions seems to be generally dry,
though pieces of energy rounding the base of the trough and the cut
off low may result in some showers at times through the week, though
confidence in the timing and placement of any more organized showers
remains low at this time.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
High pressure over the area gradually weakens while slowly pushing
offshore tonight.
Areas of fog are resulting in some IFR/LIFR conditions for
outlying terminals. The NYC terminals remain VFR. There is a low
chance for JFK to briefly go sub-VFR through 14Z. Otherwise,
conditions are expected to become VFR for all terminals by
14-15Z. VFR conditions continue through the evening. Low stratus
and fog are expected to develop once again after 00Z. This will
result in sub-VFR conditions, though the timing and intensity
of any stratus or fog tonight remains uncertain. Some scattered
showers or areas of drizzle also remain possible late tonight
and into Friday morning.
Winds will be light, less than 10 kt, in S to SE component
through the TAF period.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Improvement to VFR may be off by an hour.
Uncertainty with the exact timing and flight category changes
with respect to fog and low stratus development this evening and
overnight.
OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...
Friday: MVFR/IFR with a chance of rain showers.
Saturday: MVFR or lower in rain showers.
Sunday: VFR. W winds 15-20kt with gusts up to 25-30kt.
Monday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Some patchy fog towards the ocean - land interface of the south
shore of LI and along portions of coastal LI Sound early this
morning. Otherwise, sub- SCA conditions are expected through
Friday under a weak pressure gradient.
Ocean seas build to 5 ft Friday night as swells increase from TC
Phillipe. By Saturday night, ocean seas are expected to be 9-10 ft.
Winds also increase with and behind a cold frontal passage late
Saturday. SCA criteria gusts are likely on all waters Saturday
night through Sunday night before subsiding.
Ocean seas remain elevated above SCA criteria into early next week
as long period swells from distant Tropical Storm Philippe move into
the waters.
Refer to the National Hurricane Center, https:/www.nhc.noaa.gov for
official forecasts on Philippe.
&&
.HYDROLOGY...
Chances of showers start Friday and become likely Friday night
through Saturday. Periods of moderate to heavy rain are possible.
The WPC has now outlined the western 2/3 of the area in a
marginal risk for Day 2 (Friday) and much of the area in a
marginal risk, with a slight risk for portions of western
Connecticut, for Day 3 (Saturday). Much of the area will likely
see an inch to an inch and a half of rainfall in total. The
main threat is minor nuisance flooding, but there is potential
for isolated flash flooding.
&&
.EQUIPMENT...
Data from the Peconic River at Riverhead NY tidal gauge appears
to have improved. Will monitor the gauge over the next few days
to make sure it is in line with other nearby gauges.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Dense Fog Advisory until 10 AM EDT this morning for CTZ005>012.
NY...Dense Fog Advisory until 10 AM EDT this morning for NYZ078>081-
177-179.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JT/MW
NEAR TERM...JT
SHORT TERM...JT
LONG TERM...MW
AVIATION...MW
MARINE...JT/MW
HYDROLOGY...JT/MW
EQUIPMENT...