okx-afd on 2025-05-08

003
FXUS61 KOKX 081710
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
110 PM EDT Thu May 8 2025

.SYNOPSIS...
A cold front will slowly sag across the area today, stalling near of
just northwest of New York City by tonight. This will set the stage
for a soaking rainfall late today into early Friday night. A few
showers may linger into early Saturday. A weak cold front will
cross the region Saturday night, with high pressure building in
for early next week. Another low pressure system approaches for
the middle of next week.

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --Updated the gridded fcst to increase pops this aftn across nwrn
areas. Continued the hwo mention of isold flash flooding for
the nwrn third of the cwa for this aftn and eve due to the
potential for slow moving shwrs and tstms.

A weak cold front slows to our northwest on its approach,
possibly stalling to the north of NYC today. This front has some
moisture to work with. We`re expecting dry weather to persist
through the first half of the day, though a few showers could
arrive late this afternoon in NE NJ, lower Hudson Valley, and
even NYC. This will be the beginning of a prolonged rain event,
which is discussed more fully below in the Short Term.

Pressure gradient remains weak today which will allow for coastal
sea breezes this afternoon. Highs will be in the low to mid-70s.-- End Changed Discussion --

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
Key Messages:

* A stalled front and low pressure to bring prolonged period of
rainfall Thursday afternoon into Friday night.

* Periods of moderate to locally heavy rainfall possible.

* 1-2" expected with locally higher totals possible.

* Dry Saturday.

A cold front will slow on its approach today to our northwest. It
will likely stall this evening into tonight, but model guidance
still varies on the location of the front stalling. It will remain
stalled over or nearby into Friday. At the same time, a Mid-Atlantic
low will pass along the front during this time frame. An upper-level
trough will also dig into northern New York Thursday, becoming
closed and moving nearby Thursday night into Friday. The upper-low
and surface low will then become stacked on Friday as it phases with
a southern jet stream, then exit northeast late Friday night into
early Saturday morning.

Low pressure along the stalled front will lead to periods of showers
Thursday afternoon into Friday, with showers tapering west to east
late Friday night into Saturday morning as the system exits.
Thunderstorms will be possible late this afternoon and evening
primarily north and west of NYC closer to the frontal boundary.
Instability will be marginal today, but no thunderstorms expected
into Friday.

00Z guidance vary with QPF amounts due to disagreement among the
models on where the stalled front will be located, and when. Periods
of moderate to locally heavy rainfall are possible given lift from
the stalled front, marginal instability, positive vorticity
advection from the nearby closed upper-low, some orographic
enhancement of precip with easterly flow Thursday night into early
Friday, and warm air advection at 850mb Friday afternoon and
evening. PWATs should peak around 1.10 to 1.50" which is right
around or above the 90th percentile per SPC`s Sounding Climatology
Page.

Current forecasted QPF is between 1-2" Thursday afternoon through
Friday night. Its quite possible some areas could receive a few
inches more than this, depending on where the heaviest
showers/thunderstorms set up along the frontal boundary. Most of the
00Z CAMs are hinting at some banded higher amounts late Thursday
into Thursday night north and west of NYC. However, some of the 00Z
CAMs (HRRR/MPAS) appear to bring this higher banded QPF into NE NJ,
NYC and SW CT due to a more southerly placement of the stalled
front. Following tonight, rainfall will be widespread into early
Friday night before rainfall tapers with the exiting low into early
Saturday. Given the uncertainty, WPC has maintained a Slight Risk
for Excessive Rainfall for parts of Orange county and Passaic
counties with and Marginal Risk for the remainder of the area on
Thursday. Friday also carries a Marginal Risk for the entire area.

Dry weather is expected by midday Saturday with the low exiting to
the northeast and high pressure gradually beginning to take over.

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
Another shortwave and associated surface cold front moves across
the area Saturday night into early Sunday morning with Canadian
high pressure building into its wake and gradually rising heights.

The high will keep conditions dry through Monday night. The next
chance of precip comes on Tuesday or Wednesday with the
approach of the next low pressure system.

Temperatures through the long term will remain at or slightly
above normal with highs in the 70s.

.AVIATION /17Z THURSDAY THROUGH MONDAY/...
An cold front nearby stalls near or just northwest of NYC this
afternoon. Low pressure travels along the front tonight into Friday.

Mainly a VFR forecast through this afternoon, with showers moving
into the area after 18z for NYC and areas to the north and west.
Showers become more widespread, and conditions fall to MVFR/IFR
after 00z. Some of the showers may be moderate to locally heavy
tonight and into Friday morning.

Mainly light winds at many of the terminals through midday. S/SE
winds to develop at the coastal terminals with some locations at
times closer to a true seabreeze into this afternoon. There is some
uncertainly as to how far south the cold front gets this evening,
but is currently forecast to stall near or just northwest of the NYC
terminals. Winds will likely vary from N/NE to E mainly under 10kt
or less than 5 kt across the boundary. Winds tonight into Friday
morning may be light and variable.

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

Multiple wind shifts possible today with timing varying by 1-2
hours. Wind speeds generally less than 10 kt.

Low chance of a few showers earlier than indicated by PROB30
groups in TAFs this afternoon.

.OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY...

Friday: MVFR or lower in moderate to heavy showers. Low chance of a
thunderstorm.

Saturday: Mainly VFR, except MVFR or lower possible isolated showers.

Sunday and Monday: VFR.

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

.MARINE...
Weak pressure gradient will maintain sub-SCA conditions through
early Fri. It`s possible we see marginal SCA conditions on at
least ocean waters as low pressure tracks through region late Fri
into Sat along with widespread rainfall.

Sub-SCA conditions are expected on the area waters Saturday night
through the middle of next week with a weak pressure gradient over
the area.

.HYDROLOGY...
Widespread moderate to locally heavy rainfall is possible Thursday
afternoon into Friday night. Total rainfall amounts will be 1-2",
but could be locally higher for areas north and west of NYC. Flood
impacts are expected to be minor for most, limited to only low-
lying, poor drainage, nuisance issues. We could see isolated flash
flood impacts late Thursday into Thursday night for parts of the far
interior north and west of NYC where banded precipitation could set
up given existing wet soils and higher stream levels from prior
rainfall. Flood Watches may be needed for some of these areas, but
given the disagreement on placement of highest QPF, confidence is
too low for a Flood Watch, at this time.

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

SYNOPSIS...BC/BR
NEAR TERM...JMC/BR
SHORT TERM...BR
LONG TERM...BC
AVIATION...JE
MARINE...BC/BR
HYDROLOGY...BC/BR