957
FXUS61 KOKX 070247
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1047 PM EDT Mon May 6 2024

.SYNOPSIS...
A weak cold front moves through the area overnight, followed by
weak high pressure building in on Tuesday. The high gives way
to an approaching warm front Tuesday night that moves across the
area on Wednesday. A lingering frontal boundary south of the
area Wednesday night into Thursday will eventually strengthen as
low pressure approaches from the west. Low pressure moves
across Thursday night into Friday. The low will be east of the
region Friday night into next weekend. High pressure thereafter
will be weak with more areas of low pressure potentially
impacting the area late weekend into early next week.

&&

.NEAR TERM /THROUGH TODAY/...
The flow remains light ahead of a slow moving cold front just
entering the northern portions of the region at 02Z. With a
light southerly component to the winds along the shore stratus
and fog moved into portions of southern Long Island. There may
be a few locations of dense fog, however most visibilities were
greater than 1/2 mile.

Seeing as how multiple CAMs indicate in their reflectivity
fields the presence of spotty coverage of rain showers this
evening into part of overnight, left the slight chance of
showers as contained in the previous forecast.

Shortwave energy rounding the base of an upper low over eastern
Canada will give a cold front to the NW enough of a push to
pass through the area tonight. The front is forecast to pass
south of Long Island during the early morning hours with light
and variable winds becoming light northerly. A spotty shower is
possible this evening along and ahead of the front, but the
forcing is weak and the airmass is relatively stable.

There is one area of concern tonight and that is with the
extent of low clouds/fog that could potentially develop ahead
of the cold front. This looks more likely near the coast and
patchy inland. Confidence for widespread dense fog is low at
this time as model soundings show drying of the vertical
moisture profile. However, coastal locations do maintain some
shallow moisture.

It will be a mild night with lows 5 to 10 degrees above normal,
ranging from the around 50s well north and west, to the mid and
upper 50s along the coast.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...
Quiet and warm for Tuesday as weak high pressure builds behind
a cold front continuing to work south of the area. Ridging
building aloft with warmer temperatures and mostly sunny skies
should allow temperatures to get into the lower and mid 70s most
locations, and even around 80 across portions of the NYC metro.
Immediate coastal locations, especially along the south shore
of LI will likely be cooler with a weak onshore flow. There is
also some uncertainty with 85h moisture poised just south and
west along our doorstep. This could impact cloud cover.

For Tuesday night, the upper ridge weakens and translates
eastward, while another piece of energy kicks out of the mid
Mississippi Valley. This will send a frontal wave across the
Ohio Valley Tuesday night and across New England on Wednesday.
The best thermal forcing will be during the morning hours with
a good chance of showers. Instability is marginal but increasing
into Wednesday. So have a mention of a slight chance of
thunder. The area then gets into the warm sector from west to
east on Wednesday, with perhaps the exception of eastern LI and
SE CT. This will be tricky for temperatures as the western half
of the area could get into the lower 80s, possibly higher
depending on when the clearing takes place. NBM box and whisker
plots show a decent range between the 25th and 75th percentiles
of about 10 degrees. For KEWR, the 75th percentile is in the
lower 90s. The deterministic (which is not the mean) is below
the 10th percentile in many cases. This is likely due to bias
correction in the springtime here which is a big challenge in
forecasting due to onshore flow, low clouds and fog.

The warm sector does get moderately unstable to the north and
west of NYC Wednesday afternoon, but vertical profiles are
drying and there is a strengthening mid level cap with little
if any lift to get above the LFC. Should get a better handle on
this in the next 24h as CAMs get into the period of interest.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Mid levels show nearly zonal flow Wednesday night with a trough
moving in Thursday into Friday. Local region gets brief mid level
ridging Saturday before another trough approaches for Sunday into
early next week.

Weakening wave of low pressure moves farther east of the region
Wednesday night into Thursday with a trailing cold front that will
weaken and linger to the south of the area. Models depict a lull in
the rain, with mainly dry conditions anticipated Wednesday night
into early Thursday.

This front will eventually strengthen and move northward back
towards the area Thursday as low pressure approaches from the west.
The front will return north as a warm front but stay south of Long
Island. Vertical forcing with low level omega increases Thursday
afternoon into Thursday night.

The center of the low reaches near the forecast area Thursday
evening and eventually moves east of the area Friday. There are some
model differences in terms of the number of waves of low pressure
and their movement.

There is forecast an increasing chance for rainfall Thursday into
Thursday night. Rain expected mid afternoon Thursday afternoon
through Thursday evening. Some elevated instability is shown to be a
possibility so there could be a few thunderstorms. Chances for rain
decrease for late Thursday night into Friday but become higher
across interior locations Friday afternoon into early Friday evening.

The model exhibit more coherence in pressure Friday night into
Saturday as GFS, ECMWF and Canadian in that they depict low
pressure getting farther east of the region with weak high
pressure moving into the local area for the weekend. Chances for
rain lower Friday night.

Would expect mainly dry conditions for the first half of the weekend
with brief return of high pressure. However the high pressure will
be of weak magnitude and very transient, allowing for a large trough
to approach Sunday into Sunday night before flattening out
going into early next week.

At the surface, more low pressure areas approach Sunday through
potentially Monday as well. However, model differences become
more apparent in this timeframe as well. Chances for rain
increase Sunday and Monday, mainly in the afternoon into early
evening hours.

Temperatures overall are forecast to not deviate too significantly
from seasonal normal values.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
A cold front moving into the lower Hudson Valley passes through
the terminals through 07Z/09Z. Weak high pressure will briefly
return on Tuesday.

Mainly VFR, with KISP at LIFR as stratus moved into coastal Long
Island. Before the passage of the front the stratus may expand,
and MVFR to IFR is possible at KJFK, KHPN, KBDR, and KGON.
However, remain uncertain how extensive the lowered conditions
will be. Winds light and variable to light SW into late tonight.
And then timing of improvement back to VFR will also depend of
the timing of the front, with winds shifting to the west and
then north to northwest.

VFR Tuesday with N to NE winds, and afternoon sea breezes.


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

Low confidence fcst regarding the development and extent of
stratus and fog with MVFR to IFR. Timing of improvement will be
dependent of cold frontal passage and wind shift to the north.

Unscheduled AMD likely.


OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...

Tuesday night: Mainly VFR. Chance of showers late with MVFR
possible. Slight chance of a thunderstorm inland.

Wednesday: MVFR cond expected, IFR possible. Cond improving to
VFR late day. Chance of showers. Tstms possible mainly in the
afternoon.

Thursday: MVFR/IFR. Showers likely and possibly a tstm,
especially in the afternoon and at night.

Friday: MVFR/VFR with chance of showers.

Saturday: Chance of showers with MVFR cond at KSWF, otherwise
VFR.

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

&&

.MARINE...
Marine dense fog advisory in effect for ocean from Moriches to
Montauk out 20 NM. Expecting the fog to persist into the
overnight, so marine dense fog advisory is in effect until 6AM
Tuesday.

Otherwise, areas of fog are likely to redevelop this evening,
especially on the rest of the forecast ocean waters. There is
the potential for a period of dense fog for these other forecast
ocean waters. A cold front moves through during the early
morning hours with improving conditions. Otherwise, winds and
seas are expected to remain below SCA conditions through
Wednesday.

SCA conditions possible within the Thursday through Friday
night timeframe for most of the waters with highest chances
across the ocean zones. Otherwise, mainly below SCA conditions
forecast in the marine long term Wednesday night through
Saturday night.

&&

.HYDROLOGY...
There are currently no hydrologic concerns through the period.

&&

.TIDES/COASTAL FLOODING...
Astronomical tides are running high with the approach of a new
moon Tuesday night.

A statement remains in effect  for localized minor flooding
with tonight`s high tide cycle for Southern Fairfield County and
the south shore back bays of Nassau County.

A more widespread minor flooding event that would necessitate
advisories for these two locations plus Southern Queens will more
likely occur with the nighttime cycles from Tuesday night through
at least Thursday night. Statements for these 3 high tide cycles
may be needed for other parts along western LI Sound, SW Suffolk
County, as well as lower NY Harbor and Brooklyn.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Dense Fog Advisory until 6 AM EDT Tuesday for ANZ350.

&&

$$

SYNOPSIS...JM/DW
NEAR TERM...JM/DR/MET/DW
SHORT TERM...DW
LONG TERM...JM
AVIATION...MET
MARINE...JM/DW
HYDROLOGY...JM/DW
TIDES/COASTAL FLOODING...