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567
FXUS61 KOKX 062017
AFDOKX

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

.SYNOPSIS...
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A weak cold front moves through the area tonight, 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.
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&&

.NEAR TERM /THROUGH TUESDAY/...
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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 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.
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&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY/...
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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.
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&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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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 all 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 longwave
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.
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&&

.AVIATION /20Z MONDAY THROUGH SATURDAY/...
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A cold front approaching from the west will pass through tonight.
Weak high pressure will briefly return on Tuesday.

Some MVFR cigs are still hanging around mainly from KEWR/KTEB north
and west. Still think these will lift to VFR at some point late this
afternoon.

IFR/LIFR cond appear likely to return tonight to KISP/KGON, but the
situation is highly uncertain for the NYC metro terminals. Shallow
moisture ahead of the approaching front could lead to redevelopment
of low clouds/fog with MVFR or IFR conditions.
Confidence high enough to mention IFR cond for KJFK for a few
hours (04Z-07Z) just ahead of the cold front, but these
conditions could very well expand to the other metros as well as
KHPN, and would be handled via later amendments if necessary.

After cold fropa, conds should improve to VFR from the NYC
metros north/west, with N-NE flow less than 10 kt after daybreak
Tue. Improvement to VFR will take longer farther east as winds
after fropa will remain light until close to daybreak. Coastal
sea breezes possible by late morning/early afternoon.

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

Low confidence fcst for tonight. IFR cond could begin sooner at
KJFK this evening and also expand to the other terminals.
Unscheduled AMD likely.

OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY...

Tuesday afternoon: VFR.

Tuesday night: Mainly VFR. Chance of showers late with MVFR
cond possible.

Wednesday: MVFR cond expected, IFR possible. Cond improving to
VFR mid to late afternoon. 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
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&&

.MARINE...
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Areas of fog are likely to redevelop this evening, especially on
the ocean waters. There is the potential for a period of dense
fog. 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. Otherwise, mainly below SCA forecast in the
marine long term Wednesday night through Saturday night.
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&&

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

.TIDES/COASTAL FLOODING...
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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.
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&&

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

$$

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