799
FXUS61 KOKX 210010
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
810 PM EDT Mon May 20 2024

.SYNOPSIS...
High pressure will be in control through Wednesday. Offshore high
pressure going into midweek gives way to an approaching cold front
Thursday. This cold front moves across Thursday night and eventually
slows down south of Long Island Friday before dissipating. High
pressure returns to the local area thereafter for Friday night
into early Saturday. Another low pressure system approaches the
area next weekend. A stronger frontal system approaches for early
next week

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Forecast on track with forecast and observed temperatures and
dewpoints within a few degrees of each other this evening.
Added in more clouds late tonight into Tuesday morning as well
as more fog late tonight into Tuesday morning. Both are conveyed
by mesoscale and short term forecast models to develop and move
from east to west. It is uncertain how far west these low
clouds and fog ultimately reach but general indication from the
consensus of models is that Long Island and coastal SE CT have
greatest likelihood of getting these low clouds and fog.

Deep-layered ridging will be over the region tonight. Mainly clear
this evening, then perhaps some cirrus overnight. Given very
light winds from the surface up through the bottom of a low
level inversion aloft and low dewpoint depressions, thinking
there will be areas of fog for coastal areas getting more
patchy away from the coast. As always, not very high confidence
in the areal coverage and density of the fog, but something to
keep an eye on tonight. Dense fog will be a possibility,
especially for Long Island and coastal SE CT.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/...
The ridge aloft flattens Tuesday through Wednesday, but surface high
pressure will remain in control. After any early stratus/fog, it
should be a mostly sunny day for Tuesday, and mostly sunny for
Wednesday as well. Showers well ahead of a pre-frontal trough
approach late Wednesday, but will go with a dry forecast through the
afternoon.

Regarding high temperatures, deterministic NBM continues to run
closer to the 10th and 25th percentiles. Blended the deterministic
with the 50th percentile for both days based on forecast
temperatures at the top of the mixed layer. Might need to lean even
closer to the 50th percentile for Wednesday with a better chance of
mixing through 850mb away from the coast given wind direction and
weaker subsidence from aloft as ridging flattens. Highs will be
above normal both days with Wednesday being the warmer day. No
records anticipated, but highs on Wednesday around 90 for NE NJ and
parts of the Lower Hudson Valley and city. Dewpoints will be low
enough to keep heat indices right around the ambient
temperature.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
The key points pertain to Thursday and Thursday night.

First, another day with well above normal temperatures is
anticipated for Thursday with high temperatures ranging from the
upper 60s to mid 70s along the coast and across much of Long Island
to upper 70s to upper 80s across parts of the north shore of Long
Island, NYC, NE NJ, Lower Hudson Valley and interior Southern CT.
Some interior spots could have heat indices reach around 90.

Second, there is a low change, marginal, threat for severe
thunderstorms Thursday into Thursday evening with potential for
downbursts and perhaps some hail.

High pressure will eventually give way to an approaching cold front
Wednesday night into Thursday. The parent low attached to this front
will be weakening as it moves farther north of the Great Lakes. This
will lead thereby to a weakening of the cold front.

High temperatures forecast on Thursday are more in the low 70s to
mid 80s range, with a lot of locations forecast to be slightly
cooler due to increased clouds. However, some locations on Long
Island are actually having high temperatures forecast slightly
warmer than the previous day due to a more westerly component to the
winds.

There will be a chance for showers and thunderstorms out ahead and
along the cold front for Thursday into Thursday night. The cold
front is forecast to move across Thursday night. Chances for showers
and thunderstorms decrease late Thursday night after the cold
frontal passage.

There is potential for some thunderstorms to be strong to severe
with the cold front with surface CAPE forecast to be up to near 2000
J/kg and forecast 0-6 km AGL bulk shear of 30 to 35 kt. With these
factors, severe threat level is more on the marginal side with the
coverage expected to be mostly isolated to scattered of the showers
and thunderstorms themselves. This combination is forecast to be
across some locations north and west of NYC. No hydrologic concerns
at this time as showers and thunderstorms will be fast moving,
really limiting total rainfall accumulations.

Mainly dry conditions are forecast Friday through Friday night with
the eventual return of weak high pressure. High temperatures Friday
are forecast still to be above normal but cooler, with a range
mainly from the lower 70s to lower 80s for much of the area.

Rain showers return to the forecast for the weekend but
probabilities are low initially with more of a chance Saturday night
through Sunday night. This will be as another low pressure system
makes its approach and gets close enough to the local region to give
higher chances of rain. Another frontal system approaches for early
next week, keeping the chances for showers in the forecast.

Temperatures more of a decline with more easterly component to the
wind weekend into early next week. Highs get more in the 70s for
much of the area with more 60s along the coast.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Weak surface high pressure remains over the area through the TAF
period.

Growing confidence for IFR or lower conditions to overspread the
terminals tonight with stratus lingering offshore. More of the
hi-res guidance is indicating the area of stratus over the
Atlantic will move over the terminals between 02-06z tonight.
Have trended the TAFs in the direction of expecting more IFR
tonight into early Tuesday morning.

What remains uncertain is:

1- Exact timing the low cigs moving into the area. Timing maybe
off be 1-3 hours.

2- how far inland does the stratus get? Thinking most terminals
are impacted, except KSWF.

3- How much do vsbys fall (if at all)? Best chance for fog will
be the far eastern terminals (KISP/KGON).

Expect a return to VFR between 13-16z Tuesday. Once we become
VFR, we should remain VFR through the remainder of the TAF
period.

Winds will be from the S for much of the TAF period, however
winds should become light and variable overnight. Winds speeds
increase to around 10kt on Tuesday. Sea breeze enhancements are
expected once again Tuesday afternoon.

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

Still some uncertainty with IFR cigs tonight into Tuesday
morning.

OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...

Tuesday night-Wednesday: Mainly VFR. Low chance of MVFR cigs
across some of the terminals Tuesday night into Wed morning. Chc
S-SW gusts around 20kt in the afternoon.

Thursday: VFR in the morning, then a chance of afternoon and evening
MVFR with showers and thunderstorms. Chc SW gusts around 20kt.

Friday: VFR. Chc NW gusts around 20kt.

Saturday: VFR.

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

&&

.MARINE...
There is the possibility of dense fog late tonight into Tuesday
morning with light winds and elevated low level RH. Areas of fog
are in the forecast for most of the waters overnight into
Tuesday morning. Visibilities near 2 NM are forecast late this
evening into overnight with visibilities closer to 1 NM
expected late overnight towards daybreak Tuesday. Fog coverage
is not expected at this time to be widespread with the 1 NM or
less fog and confidence overall in this occurring is still low
enough so holding off at this time on any marine dense fog
advisory issuance.

Otherwise, sub-advisory conditions are expected across all
waters through the end of next week. However, Tuesday and
Wednesday afternoons are likely to see a coastal jet produce
gusts up to 20-25 kt, especially on Wednesday, and seas of 3 to
4 ft in the NY Bight along with seas possibly touching 5 ft.

For the marine long term forecast from Wednesday night through
Saturday night, conditions are forecast to remain mainly below SCA
thresholds on all forecast marine zones. Only exception would be
Wednesday night with some SCA level wind gusts on the ocean.

&&

.HYDROLOGY...
No hydrologic impacts expected through the forecast period.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$

SYNOPSIS...JC/JM
NEAR TERM...JC/JM
SHORT TERM...JC
LONG TERM...JM
AVIATION...BC
MARINE...JC/JM
HYDROLOGY...JC/JM