okx-afd on 2024-12-17

874
FXUS61 KOKX 171800
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
100 PM EST Tue Dec 17 2024

.SYNOPSIS...
-- Changed Discussion --A cold front passes through the area this afternoon, followed
briefly by high pressure tonight into early Wednesday. Another
frontal system will approach on Wednesday and pass through the
area Wednesday night. High pressure briefly builds in again
Thursday into early Friday before an offshore low pressure
system potentially impacts the area late Friday into Saturday.
High pressure returns late in the weekend into early next week.-- End Changed Discussion --

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --Forecast on track with just a few minor adjustments to reflect
current observations. Otherwise, a warm front remain north of
the area with temperatures generally in the lower 50s except for
some locations well north and west of the NYC metro. An
approaching cold front will work east of the area this afternoon
with high pressure over the Tennessee Valley building into the
area later late this afternoon through tonight. S

It will be mild day as the airmass lags in response to the cold
advection. Highs will top out in the 50s, about 10-13 degrees
above normal.

High pressure builds in tonight with light winds and clear
skies. Low will drop into the 30s for most locations, with a few
upper 20s possible in the normally colder spots. This is still
several degrees above normal.-- End Changed Discussion --

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
Another fast moving northern stream shortwave trough will drop
across the Great Lakes on Wednesday, sending another frontal
system toward the area. The associated warm front and cold front
pass through quickly during the first half of Wednesday night
with a quick shot of moderate rainfall, producing about 0.50 to
0.75". Rain will overspread the area from SW to NE Wednesday
afternoon, and should end across eastern sections before
daybreak Thursday. Cold air advection lags sufficiently behind
the cold front that no wintry weather is expected on the
backside of the system.

Highs on Wednesday will remain above normal, topping out in the
mid 40s to lower 50s, with lows dropping into the 30s for most
locations by daybreak Thursday.

.LONG TERM /THURSDAY THROUGH MONDAY/...
Key Points:

*Forecast area looks to be on the western periphery of an
offshore low that develops over the western Atlantic Friday
into Saturday.

*Below normal temperatures expected over the weekend into early
next week, with highs on Sunday likely not getting out of the
20s.

Guidance continues to show low pressure Friday into Saturday to
be well enough offshore to not impact the area, but there is
still uncertainty with model ensembles with a definite NW jog
sine the 12Z guidance. This will have to be watched, but the
area is still well removed from any significant precipitation.
There is also some interaction with the offshore low that develops
and an approaching shortwave trough that could produce some
precipitation across the area. There would be enough cold air
in place for a snow or rain/snow mix event. Even if this ended
up being all snow, the QPF at this time looks light.

Behind this system, high pressure will build in through the start of
next week and bring a very cold airmass. Highs on Sunday will likely
not get out of the 20s, with some interior locations potentially not
getting out of the teens. There is also potential for 10 to 15 mph
winds Sunday given the pressure gradient between the building high
and offshore low. This will result in max wind chill values in the
teens and single digits.

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
A cold front moves through the area this afternoon. High
pressure follows.

VFR expected through Wednesday afternoon.

SW/W winds will be sustained 10-15 kts this afternoon. There
remains uncertainty regarding whether we will see gusts this
afternoon. Have left out of TAFs due to low confidence.
However, for your awareness, if we see gusts, they will likely
not be higher than 20-25 kts. Winds drop below 10kts this
evening and become light and variable tonight into Wednesday.

...NY Metro (KEWR/KLGA/KJFK/KTEB)TAF Uncertainty...

20 to 25 kt gusts are possible this afternoon, but will likely
be occasional if at all.

OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...

Wednesday Afternoon-Wednesday night: Becoming MVFR-IFR during
the late afternoon with rain developing and continuing into the
night. NW gusts 15-20 kt late Wednesday night.

Thursday: VFR. NW gusts 15-20kt.

Friday: VFR, becoming MVFR, IFR at times, afternoon into night.
A chance of rain and/or snow during afternoon. A chance of snow at
night. NW gusts late at night 15-20 kt.

Saturday: MVFR to IFR with a slight chance of snow, ending late in
the afternoon. NW gusts 20-25 kt.

Sunday: VFR.

Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90

.MARINE...
Wind gusts have fallen below 25 kt on the non-ocean waters, so
have gone ahead and cancelled the SCA for those areas. A SCA
remains in effect for the ocean waters.

Some gusts to 25 kt will remain possible today on the ocean
waters along with lingering seas above 5 ft through the first
half of tonight. High pressure then briefly builds across the
waters tonight into Wednesday morning with sub-SCA conditions.

There are two periods in the long term forecast where SCA conditions
are possible. The first is Wednesday night into Thursday with a
low pressure system that will pass right over or near the area.
Wind gusts will be close to 25 kts, especially on the ocean waters
where seas of 5 to 6 ft are expected. The next chance for SCA
conditions will be late Friday through the weekend due to
deepening offshore low pressure. There is some uncertainty as to
how far west the low will be.

.HYDROLOGY...
There are no hydrologic concerns through the beginning of next
week.

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 1 AM EST Wednesday for ANZ350-353-
355.

SYNOPSIS...DW
NEAR TERM...BC/DW
SHORT TERM...DW
LONG TERM...JT/DW
AVIATION...JT
MARINE...JT/DW
HYDROLOGY...DW