000
FXUS61 KOKX 282155
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
555 PM EDT Fri Apr 28 2023

.SYNOPSIS...
A wave of low pressure along a warm front over the Carolinas will
lift slowly north through Saturday. The wave dissipates and passes
to the south and east Saturday night. A stronger low impacts
the region Sunday into Sunday night. The low then meanders over
the Northeast into the middle of next week before moving off
the New England coast at the end of the week.

&&

.NEAR TERM /THROUGH SATURDAY/...
-- Changed Discussion --
Forecast on track this evening with just minor adjustments to
PoPs as precip is struggling making its way north and east into
surface ridging.

An area of low pressure along a warm front over the Mid
Atlantic states will approach from the southwest tonight. At the
same time, ridging along the New England coast will act as
block as mainly light rain tries to overspread the area from SW
to NE, first moving into the NY/NJ metro area this evening.
However, it may take as long as daybreak to move into far
southeast CT. The rainfall will generally be light with some
moderate pockets, mainly from NYC and points north and west.

The period of strongest lift will be near daybreak as a 40 to 50
kt LLJ works into the area, slowly lifting to the NE and up into
New England Saturday night. The theme for Saturday will be
periods of light rain, which at times could be moderate. In
addition, mid level drying during the late morning and afternoon
hours may allow for a transition to more of a drizzle and rain.
There is still enough lift to support warm rain processes.
Rainfall amounts will be highest across the western third of the
area, NYC metro, NE NJ, and the Lower Hudson Valley, with up to
around an inch. The amounts will then drop off from west to
east with up to half an inch across interior and eastern CT and
eastern LI.

Easterly winds ahead of the low will ramp up through the night
with gusts up to 30 mph at the coast by daybreak, and 15 to 20
mph inland. Winds will get a bit stronger during the daytime
hours Saturday. This should limit the fog to patchy in nature on
Saturday, but possibly becoming more widespread Saturday night
with the diminishing winds.

As for temperatures, there will be a small diurnal range due to
the cloud cover, easterly flow, and rain/drizzle. Lows will be
about 5 degrees above normal, but 5 to 10 degrees below normal
during the daytime Saturday.
-- End Changed Discussion --

&&

.SHORT TERM /SATURDAY NIGHT/...
The rain and drizzle then lifts slowly NE Saturday night with
conditions briefly drying out toward daybreak ahead of the next
system quickly on its heels. Areas of fog may become more
prevalent as well with weakening low pressure passing to the
south and east and diminishing east winds.

Lows will be in mid 40s to around 50, only a few degrees cooler
than the daytime high on Saturday.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
The weather pattern will remain unsettled Sunday through much of the
upcoming week. Overall, there has been little change to the forecast
thinking during this time period.

A brief lull from precipitation is still expected to continue Sunday
morning as the system impacting the area Saturday/Saturday night
lifts to the north. The next low pressure will begin moving in from
the south and west through the afternoon. The upper flow pattern
will be quite amplified Sunday with a southern stream wave lifting
towards the Carolinas and a deeper closed low spinning over the
Great Lakes region. The larger upper low is going to force the
southern stream wave northeastward towards the region through the
evening. The interaction of the two waves will help deepen low
pressure through Sunday night. The low is expected to track out of
the Carolinas Sunday afternoon and then over the Middle Atlantic and
northeast Sunday evening and night. The 12z models seem to be in
fairly good agreement with the low tracking over or just west of the
area Sunday evening. The system then interacts with the upper low
and becomes one large stacked low that meanders over southeast
Canada and the northeast into the middle of the week.

The main concern with the low for Sunday afternoon into Sunday
evening will be potential for moderate to heavy rainfall. There is
still some uncertainty with the magnitude and positioning of low
level jet. The low develops rapidly, but is also going to pivot in
such a fashion that may push some of the strongest wind field to the
south and east. Much of the model guidance has a strong jet at 850
mb, but the question remains on the strength and position of the jet
closer to 925 mb. Despite this uncertainty, there is still a window
Sunday afternoon and evening for moderate to locally heavy rainfall
from strong large scale lift and a plume of subtropical moisture.
There is still some elevated instability supporting a chance for
some thunder Sunday evening. The SE-E flow during this time will
limit surface instability, so no severe weather is expected at this
time.

The duration of the rain has sped a bit in the last several model
cycles, predominately occurring between 18z Sunday and 06z Monday.
Still looking like 1 to 1.50 inches with locally higher amounts
possible. Rainfall rates of 0.50 inches an hour are possible late
Sunday afternoon and evening. The precip should quickly lift
northeast of the area late Sunday night into early Monday morning as
dry air rapidly pivots in around the large upper cyclone.

SE-E winds will increase during the day Sunday, with gusts 25-35 mph
in the afternoon and evening, strongest near the immediate coast. A
strong low level inversion from warmer air moving over the colder
nearby waters will prevent stronger winds from mixing down to the
surface.

The stacked low initially meanders near or just northeast of the Great
Lakes Monday into Tuesday and then slowly shifts across the
northeast during the middle of the week. Have continued to mention
low chances of showers NW of the city Monday, but the day could end
up being dry and breezy. With the upper low shifting east through
the week, shower chances will persist, with the highest
probabilities (still in chance category) occurring Tuesday and
Wednesday afternoon. Probabilities then decrease for the end of the
week as the low moves east. Even if no showers occur, it will likely
be mostly cloudy much of the week with the cyclonic flow and cold
pocket aloft.

Temperatures will start the period close to normal and then fall
below normal into at least the middle of the week. Some moderation
closer to normal is possible at the end of the week.

&&

.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
Low pressure approaches from the SW tonight into Saturday.

VFR this afternoon before flight categories lower to MVFR tonight
with rain moving in, possibly as early as 22Z but likely after 00Z
for the NYC terminals. Categories continue to lower overnight to
IFR. Eastern terminals will take longer for categories to drop to
MVFR and IFR.

Light rain showers move in tonight becoming more steady overnight.
Visibilities expected to decrease to less than 3SM in steadier rain
after 6Z, mainly for western terminals and slowly expanding to
eastern terminals through Saturday morning. Light to moderate rain
continues through much of the day on Saturday, possibly becoming
more showery by the afternoon for the NYC terminals.

E/SE winds 10-15kt with some gusts upwards of 20-25kt this
afternoon. Winds increase this evening. Frequent gusts 20-25 kt are
expected this evening increasing to 30-35 kt gusts between 6-12Z
Saturday. Gusty E winds continue through much of the day on Saturday
before slowly weakening into the late afternoon.

LLWS possible after around 09z Sat as E winds at 2KFT potentially
reach 40-45kt for a few hours. Not confident enough to include in
the TAFs at this time.

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

Gusts this afternoon might be only occasional. Timing of rain and
MVFR onset tonight may be 1-2 hours off. Timing of additional
category changes may be off by 1-2 hours.

OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...

Saturday: Rain with MVFR/IFR. E wind gusts near 25-30 kt for most
terminals except KSWF which will be closer to 25 kt. Gusts
eventually subside at night.

Sunday: MVFR or lower. Rain, slight chance of thunderstorms at
night. SE wind gusts near 20 kt during the day. SE-SW wind gusts
near 20 kt at night.

Monday: Slight chance of rain showers and MVFR during the day.
Otherwise VFR. SW wind gusts near 20-25 kt.

Tuesday: Chance of rain showers and MVFR, mainly during the day.
SW wind gusts 15-20kt.

Wednesday: Chance of rain showers and MVFR during the day. W/NW
gusts 15-20kt.

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

&&

.MARINE...
Easterly winds will steadily increase though the night with SCA
conditions on all waters, then gale force gusts of 35 to 40 kt
develop by daybreak across the ocean, NY Harbor, and south
shore bays for Saturday. Elsewhere, a strong SCA can be expected
with gusts just shy of 35 kt. Seas on the ocean are forecast to
increase to 9 to 12 ft, peaking Saturday afternoon. Seas of 3
to 5 ft are expected across LI Sound. Winds and seas will then
begin to diminish late in the day and into the night as the low
weakens and passes to the east.

A brief lull in stronger winds looks likely early Sunday morning
before SE-E flow increase late Sunday morning through the evening.
SCA gusts become likely on all waters, which should continue into
the evening. A strong low level inversion is likely going to prevent
stronger winds from reaching the surface. At this time, gales look
unlikely to occur, but wind gusts around 30 kt are possible Sunday
evening. Otherwise, SCA winds should continue on the waters into
Monday evening. Winds then fall below SCA levels into the middle of
the week. Rough seas are expected Sunday into Monday. Seas will
subside late Monday into Monday night. A lingering swell will keep
ocean seas elevated above 5 ft into Tuesday, possible into Wednesday
east of Moriches Inlet.

&&

.HYDROLOGY...
Rainfall tonight through Saturday will range from about an inch
across the western third of the area to about half an inch
across eastern LI and SE CT. A few pockets of heavier rainfall
could produce mainly minor nuisance flooding.

An additional inch to inch and a half of rain is expected Sunday
afternoon into the first half of Sunday night. The main concern with
this rainfall is minor urban and poor drainage flooding, but an
isolated flash flood occurrence cannot be completely ruled out.

&&

.TIDES/COASTAL FLOODING...
A strong SE flow due to a deepening low pressure on Sunday may bring
Sunday evening high tide levels to minor flood benchmarks. The main
concern at this time appears to be for the south shore Back Bays and
SW CT coast along the Western Long Island Sound. Tides are
relatively low astronomically, so approximately 2 to 3 ft surge is
needed to bring water levels to minor flooding at these locations
Sunday evening.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 2 AM EDT Sunday for ANZ331-332-335-
     340.
     Small Craft Advisory until 6 AM EDT Saturday for ANZ338-345-
     350.
     Gale Warning from 6 AM to 6 PM EDT Saturday for ANZ338-345-350-
     353-355.
     Small Craft Advisory until 6 AM EDT Saturday for ANZ353-355.

&&

$$
SYNOPSIS...DS/DW
NEAR TERM...DS/DW
SHORT TERM...DW
LONG TERM...DS
AVIATION...MW
MARINE...DS/DW
HYDROLOGY...DS/DW
TIDES/COASTAL FLOODING...