947
FXUS61 KOKX 301937
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
337 PM EDT Tue Apr 30 2024

.SYNOPSIS...
Weak low pressure and a frontal boundary shift farther offshore
tonight into Wednesday. High pressure then takes control of the
weather Wednesday afternoon through at least Friday. A weakening
frontal system approaches for the second half of the weekend,
followed by high pressure building towards Monday. A warm front
will approach late Tuesday and Tuesday night.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Weak surface low and frontal boundary will be shifting through the
forecast area this evening. Additional lift from aloft will be in
the from of PVA as a mid-level shortwave shifts through. CAMs in
agreement for early evening that an area of showers pushes in from
the west with a diminishing convective potential as it shifts east
into limited CAPE and overall stabilization with the loss of solar
heating. Will leave in thunderstorm chances from around the city to
points north and west where MUCAPES can still be up to around 500
J/kg. This is also roughly where the highest overall chances of
rainfall will be. Mid level winds with a weakly veering profile
could supply just enough shear for a chance of strong to severe
thunderstorms over Orange County and adjacent zones. Main threats
would be large hail and damaging wind gusts. Overall chances of
reaching severe levels are low however. Not expecting a flash
flooding threat due to the anticipated speed of the storm cells.
Rain chances then drop for the late night hours, but with a moisture
convergence boundary nearby and still some lift from aloft, cannot
completely remove PoPs from the forecast anywhere. Moisture trapped
under an inversion keeps us cloudy through the night. Low
temperatures in the upper 40s to lower 50s, which is pretty close to
normal.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Cloudy with a low chance of lingering showers to start the day
Wednesday. Expecting the threat of showers to end by noon as high
pressure slowly builds in. Anticipating partial sunshine for the
afternoon, but there`s low confidence in the cloud cover forecast
during this time. Some guidance even suggests a chance of afternoon
showers in spots with lingering moisture and weak shortwave lift.
The cloud uncertainty has implications on the high temperature
forecast as well. Would be more inclined to go with NBM 50th
percentile if there was higher confidence in a mostly sunny
afternoon. Hedged by going with an even blend of 50th percentile and
the cooler deterministic NBM (which was closer to the 25th
percentile). High temperatures will be above normal, especially west
of the Hudson River, where highs are expected to be in the mid 70s.
Dry weather for Wednesday night with weak high pressure in control.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
There remains a fair amount of uncertainty in the long term. A
repeating question throughout the period will be how long mid and
upper level ridging can hold as disturbances from the west will
attempt to break down any ridging that is in place from time to
time.

On Thursday modest ridging works into the area as thicknesses climb
some. Clouds likely linger through a good portion of the morning
with an inversion down low in the profile which may prevent mixing
initially. Towards afternoon expect more mixing with partial
sunshine with 850 mb temps getting at or just above 10 C expect
temperatures to get above normal, and potentially well above normal
further inland away from the coast. Interior locations will have a
chance of reaching the lower 80s. Went above NBM deterministic as
probabilities point to a warmer day. It should remain primarily dry
with only a minimal / slight shower chance across northeastern
zones. Thursday night the winds will shift to the NE as high
pressure begins to nudge down from the north across Eastern Canada
and the frontal boundary is sent further south into Friday. A cooler
day across the region takes place Friday with a NE to E onshore wind
bringing temperatures closer to normal. It may take awhile for the
cooler ocean air to entrain further inland so went above the NBM
with regard to temps, especially further west.

The progression of the next disturbance during the weekend continues
to slow. Have kept all of Saturday dry despite plenty of mid and
upper level cloud cover. The upper level ridge axis doesn`t pass
until Saturday evening. Primarily have kept Saturday dry and
introduce low end PoPs for the afternoon and evening, and further
west. Have the high end chance PoPs coming in towards daybreak
Sunday and continue through the day for the most part. Stuck fairly
close to NBM PoPs with just a few manual tweaks. The frontal
boundary will weaken as it slams into the ridge in place, thus
precip amounts are expected to be light. Amounts at this time look
to be on the order of a half inch or less.

There appears to be good model agreement that the cold frontal
boundary falls apart as it moves through late Sunday night into
early Monday. The mid levels should dry out and bring precip to an
end, however the question remains as to how quickly the low levels
will dry out for the day Monday. This will greatly impact the
temperatures forecast for Monday. The global guidance suggests
enough ridging works in to provide enough drying and mixing and a
return to some sun resulting in seasonably warm temperatures as 850
mb temps warm again into early next week. A warm front will then
attempt to approach from the west and possibly lift north later
Tuesday of next week. There remains uncertainty as to whether the
warm front will remain nearby or lift to the north late Tuesday and
will thus affect temperatures across the area.  Mid level energy
from the west will attempt to break down any riding in the mid
levels.

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
A wave of low pressure along a stationary front south and west of
the area will pass to the south and east of Long Island tonight.
Weak high pressure follows for Wednesday.

This is a challenging ceiling forecast with ceilings varying from
MVFR to VFR through early this evening. However, the NYC terminals
likely remain VFR for the remainder of this afternoon.
MVFR or lower conditions return tonight along with a chance of
showers. An isolated thunderstorm can not be ruled out for the NYC
and Lower Hudson Valley terminals from 23Z to 03Z. Any convection
will likely be in a weakened state across the eastern terminals.
Spotty showers are then expected for the remainder of the overnight.
VFR conditions return by Wednesday afternoon.

Winds will be ENE-E through this evening, generally 10 kt or less.
The flow backs towards the N-NNE late tonight and early Wednesday
morning, with speeds 5 kt or less. SE winds generally less than 10
kt will develop during the late morning and early afternoon hours on
Wednesday.

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

Occasional MVFR late this afternoon, but mainly VFR.

MVFR returns tonight, but IFR is possible.

Timing of showers this evening could vary by 1-2 hours. A
thunderstorm is possible, but confidence is too low to include in
TAF at this time.

OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...

Wednesday Afternoon: Improving to VFR at all terminals.

Thursday-Friday: VFR.

Saturday: Mainly VFR. Chance of showers and MVFR afternoon into the
night.

Sunday...Chance of MVFR or lower in showers. ESE winds G15-20kt

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

&&

.MARINE...
A weak pressure gradient remains in place over the coastal waters
leading to an extended period of sub small craft conditions. Ocean
seas are expected to be at 2-3 feet through the remainder of the
week. Ocean seas won`t start to climb until late in the weekend,
probably late Sunday and Sunday night when marginal small craft
conditions may develop ahead of a frontal boundary.


&&

.HYDROLOGY...
There are no hydrologic concerns through the long term period.

&&

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

&&

$$

SYNOPSIS...JC/JE
NEAR TERM...JC
SHORT TERM...JC
LONG TERM...JE
AVIATION...DW
MARINE...JC/JE
HYDROLOGY...JC/JE