174
FXUS61 KOKX 260804
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
404 AM EDT Thu Sep 26 2024
.SYNOPSIS...
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High pressure weakens and gives way to a frontal system that
moves through today and tonight. High pressure will then
gradually build in from the north on Friday and remain across
the region Friday night through Monday. An area of low pressure
passes to the south early next week with high pressure to the
north. A frontal system will then approach from the west Tuesday
into Wednesday.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
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A stubborn ridge of high pressure remains over the area along
the coast as a frontal system approaches from the west today.
Dry conditions early this morning will persist through daybreak.
Widely scattered shower activity should increase in coverage mid
to late morning, especially for areas to the N and W of NYC.
This precipitation trend is expected to continue with the best
chance of more persistent rain showers for the Lower Hudson
Valley with diminished chances closer to the coast where the
surface ridge is holding on. Enough instability may develop
later in the afternoon that thunderstorms may develop,
especially along the cold frontal passage late this afternoon
and into tonight.
Temperatures today will be at or slightly below average with
highs in the upper 60s to middle 70s.-- End Changed Discussion --
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
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A line of convective showers may develop this evening to the
north of the area, as indicated by the CAMs. This potential
convective line will shift southward over southern CT this
evening and into the overnight. Showers should gradually
dissipate overnight and become much more widely scattered by
Friday morning as the front pushes offshore.
High pressure builds into the region from the north Friday night
and through the weekend as the large upper low over the Ohio and
Mississippi Valley absorbs what is left of Tropical Cyclone
Helene. Global models indicate that while the primary low will
be well outside of our CWA, some residual showers may approach
the area from the southwest during the day on Saturday. Widely
scattered showers remain possible, mainly for extreme southern
areas as the upper level low gradually shifts offshore.
Temperatures during this time frame will be generally in the
upper 60s to low 70s each afternoon with lows in the upper 50s
to low 60s.-- End Changed Discussion --
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
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There is quite a bit of uncertainty during this time period and thus
stayed very close to a consensus forecast using the NBM.
Trends over the last few days have been for a weaker high over the
Northeast for the weekend into early next week with the cutoff low
over the Tennessee Valley trending farther north and east. The 00Z
GFS takes the upper low to the south with a coastal low developing
along the Mid Atlantic on Monday that also passes to the south
through Wednesday. On the other hand, the ECMWF and Canadian attempt
to build a ridge over top of the upper low ahead of a northern
branch shortwave trough racing east out of the Northern Plains,
resulting is less progression. Players include the magnitude of the
offshore ridge and wavelength separation between multiple pieces of
energy riding over top the eastern ridge and the cutoff low to the
south. Right now, not confident in either solution because of the
subtleties that drive them.
For the time, plan on keeping showers just off to the south Sunday
into Monday with high pressure just strong enough to the north.
However, cloud cover from north to south could vary quite bit,
impacting temperatures as well. Chances for showers then increase
late Monday into Tuesday ahead of the frontal system. Part of this
is also because some of the ensemble members, like the ECMWF, bring
what is left of the shearing out upper low across the region. Bottom
line, this a low confidence forecast.
Temperatures during this time will be close to normal.-- End Changed Discussion --
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
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High pressure off the Northeast coast will continue to weaken and
give way to an approaching frontal system over the eastern Great
Lakes. The latter of which will send a warm front across the area
this afternoon, followed by a cold frontal passage at night.
Expect a mainly MVFR forecast for the terminals for Thursday with
KSWF being the one possible exception. It will be likely be right on
the cusp of MVFR/IFR. Brief IFR conditions are also possible this
morning for the NYC and KHPN terminals. As the cold front drops
slowly south across the area tonight, a period of IFR seems likely
for all terminals. Showers will develop and work up from the SW
later this morning, along and ahead of the warm front. The best
chance will be to the north and west of the NYC terminals, although
showers will be in close proximity through the day. A thunderstorm
at this time is only mentioned at KSWF.
Confidence is too low to mention elsewhere. There will also be a
chance of showers with the cold front tonight.
ESE winds less 10kt or less will veer to the south later this
morning into this afternoon, eventually becoming SSW later this
afternoon. As the cold front settles south across the area winds are
likely to go light and variable for a time before becoming light
northerly. Southerly gusts 15-20kt possible for the NYC and eastern
terminals during the late morning and afternoon hours.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Unscheduled amendments likely for changing flight categories due to
timing of cigs and presence of -SHRA through TAF period.
Brief IFR is possible before 12Z.
Brief window of VFR is possible late afternoon at KJFK, LGA and KEWR.
OUTLOOK FOR 06Z FRIDAY THROUGH MONDAY...
Friday: MVFR or lower in the early AM with low stratus, becoming VFR
by late morning.
Saturday: Possible MVFR in slight chance of -SHRA
Sunday-Monday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
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Wave heights remain fairly elevated early this morning so have
decided to extend the SCA on the ocean waters through the day,
as wave heights will remain 5-6 ft. Wave heights gradually fall
below SCA tonight resulting in sub-SCA conditions for all
waters.
As the low to the southwest approaches the area on Saturday
night, the pressure gradient tightens possibly resulting in
brief SCA conditions on the waters for marginal gusts near 25kt
and wave heights of near 5 ft for Saturday and Saturday night.
A continued easterly flow Sunday looks to keep winds and seas just
below marginal SCA conditions for the ocean.-- End Changed Discussion --
&&
.HYDROLOGY...
There are no hydrologic concerns through the middle of next
week.
&&
.TIDES/COASTAL FLOODING...
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A high risk for the development of rip currents continues through
today due to continued long period easterly swells. Swells
begin to slowly diminish Friday and Saturday. The rip current
risk is expected to also diminish to moderate for Friday.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
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CT...None.
NY...High Risk for Rip Currents through this evening for NYZ075-080-081-
178-179.
NJ...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ350-
353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...DW/MW
NEAR TERM...MW
SHORT TERM...MW
LONG TERM...DW
AVIATION...DW
MARINE...DW/MW
HYDROLOGY...DW/MW
TIDES/COASTAL FLOODING...