000
FXUS61 KOKX 082251
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
551 PM EST Fri Mar 8 2024
.SYNOPSIS...
High pressure tonight gives way to a low pressure system over the
weekend. Strong low pressure will slowly exit the area, moving through
northern New England Sunday night. Meanwhile, high pressure will
build in from the west, likely moving across the area on Wednesday.
A frontal system will then potentially bring unsettled weather for
the end of next week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
-- Changed Discussion --
The forecast is on track this evening. High clouds can be seen
moving in from the west on latest satellite imagery. Clouds
lower and thicken tonight as high pressure exits to the east and
a storm system approaches from the west. Radiational cooling
may still occur, especially in the evening. Have therefore
blended in MAV/MET MOS for temperatures, but still weighted
towards NBM.-- End Changed Discussion --
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/...
A broad area of low pressure approaches on Saturday. While one
circulation center weakens as it heads NE into Quebec, a secondary
center deepens as it moves through the Mid-Atlantic. This will pass
through the forecast area late Saturday night/early Sunday morning,
then continue NE through New England during the rest of Sunday.
Rain spreads eastward through the forecast area Saturday afternoon
into evening. The rain could be briefly heavy at times starting late
in the evening as deeper moisture and deeper lift (low level jet and
left exit region of an upper jet streak) pass through. Additionally,
some elevated CAPE and marginally unstable mid-level lapse rates may
be present at this point, so there may be a convective element with
this as well - adding to the threat of a heavy downpour. Have added
a slight chance of thunder to the forecast. Given current flash
flood guidance, what was observed during the rain event couple of
days ago, and expected rain amounts, anticipating primarily minor
flooding impacts wherever flooding occurs. However, will go with a
flood watch over NE NJ and Rockland County where rain amounts could
be the highest and where conditions are most sensitive. See the
hydrology section below for more details. The steady rain will
likely end by daybreak Sunday in most spots. With an upper
low/cyclonic flow aloft lagging behind the surface low and
sufficient mid-level present, afternoon showers will be possible.
Snow showers could mix in late in the day NW of the city as freezing
level heights lower.
As for winds during this period, it still appears that the entire
area remains below advisory level thresholds before winds increase
further Sunday night. 925mb winds of 65-75kt anticipated over the
eastern zones late Saturday night, but with a strong low level
inversion, not so confident that 40kt+ gusts would mix down to the
surface even in heavier downpours. If this were to occur, it would
mostly likely happen over Long Island and SE CT. Then after a lull
in the winds with the low center passing through, winds pick up out
of the west late morning Sunday into the afternoon. Deep mixing with
winds at the top of the mixed layer perhaps getting into the 40-50kt
range over the western zones towards the end of the day might be
able to produce a gust or two to advisory levels. Being at the end
of the 4th period, it`s still too early for any advisory
consideration, and better chances for 40kt+ winds to occur start
Sunday night.
High temperatures for both Saturday and Sunday mostly in the upper
40s to around 50.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
By the start of the Sunday night period, the strong surface low that
will bring unsettled weather earlier in the weekend will be centered
over northern New England and slowly departing the area. By that
time, the area will be mostly dry, with just some lingering slight
chances of snow or snow/rain showers as the upper low moves
overhead, mainly for the northern half of the area. No accumulation
is expected.
As the strong surface low pulls away, high pressure starts to build
in from the west and the pressure gradient increases. Strong winds
are possible across the whole area on Monday. Deep mixing can be
seen in model soundings, with both the 12z NAM and GFS showing 45 to
50 kt at the top of the mixed layer. Forecast winds and wind gusts
have bumped up slightly, with much of the area right around Wind
Advisory criteria (sustained 31-39 mph, gusts 46-57 mph) late Monday
morning through the early evening.
The rest of the week will feature mainly quiet and dry conditions,
with a warming trend. A ridge builds over the eastern CONUS aloft as
high pressure remains in control at the surface. Highs Tuesday will
be in the 50s and by Friday they will be in the mid 50s to upper
60s. A frontal system does approach late week and could bring
unsettled weather to the area. For now, stuck close to the NBM
during that time period as there is quite a bit of spread among the
deterministic guidance. This gives slight chance PoPs Friday morning
increasing to chance PoPs by the afternoon. This would be an all
plain rain event.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
High pressure will pass east through tonight. A frontal system
will approach from the west on Saturday.
MVFR cigs tonight are on track to develop earlier than fcst.
Some spots could see TEMPO cigs as early as midnight, but the
most likely time frame should be around 07Z-08Z, perhaps a
little later (09Z-10Z) at KBDR/KGON.
S sea breezes close to 10 kt developed at the coastal
terminals. Winds these should back to the SE 5-10 kt between
sunset and 01Z-02Z. SE winds 5-10 kt tonight should increase to
around or just over 10 kt from 12Z-14Z Sat, with some gusts
15-20 kt along the coast by late morning/early afternoon.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Unscheduled AMD possible if winds back SE earlier than fcst.
OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...
Saturday afternoon: MVFR cigs. Rain developing toward evening.
SE winds G20-25kt along the coast and 15-20kt inland.
Saturday night: IFR in rain. SE winds G25-30kt. Chance of SE
LLWS.
Sunday: MVFR early, then VFR, except at KGON which may still be
IFR early, then become MVFR later in the morning and VFR by
afternoon. SW winds 15-20G25kt early, becoming W 20-25G30-35 kt
by afternoon.
Sunday night: VFR. W winds 15-20G25-30kt.
Monday: VFR. NW winds 25G35-40kt.
Monday night: VFR. NW winds diminishing to 15-20G25kt.
Tuesday: VFR. NW winds G20kt.
Tuesday night and Wednesday: VFR.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Expecting ocean waves to hover around 4-5 feet through tonight due
to swell. There could be an extended period during later tonight
into Saturday morning where prevailing wave heights are below 5ft,
however not enough confidence to shorten the SCA at this time,
especially with the expectation of seas building back up during
Saturday afternoon as onshore winds increase. A gale watch has been
extended in time and is now up for all waters Saturday night through
Sunday night as a strengthening low pressure system passes through
during Saturday night and after a lull Sunday morning, westerly
winds ramp up Saturday afternoon and night as the pressure gradient
tightens.
Gale conditions will likely continue on all waters Monday
through the first half of Monday night. Gusts look to peak
Monday afternoon, with widespread 40 kt gusts, and 40 to 45 on
the ocean waters. Waves will be 9 to 11 feet on the ocean waters
Sunday night through the first half of Monday night, before
lowering. Waves also look to reach 5 ft across the LI Sound.
Gusts lower Monday night, but could remain around Small Craft
Advisory criteria through Tuesday. Thereafter, winds and waves
look to remain below SCA criteria, with the next potential being
with a frontal system at the end of next week.
&&
.HYDROLOGY...
Around an inch to 2 inches of rain is expected to fall Saturday
afternoon through Saturday night. The higher amounts are expected to
be north and west of NYC. There will be the chance of flash
flooding, primarily nearby smaller rivers and streams across NE NJ
into Rockland County due to antecedent wet soils and the anticipated
rain totals. The heaviest rainfall is expected late Saturday evening
into the early morning hours of Sunday. Otherwise, mainly minor/poor
drainage flooding will be possible Saturday night.
There are no hydrologic concerns Sunday night through next week.
&&
.TIDES/COASTAL FLOODING...
Water levels will be on the increase going into this weekend.
Statements and advisories will be needed for the high tide
cycles tonight and Sat morning as water levels approach or
exceed minor thresholds.
Have issued coastal flood watches for Sat night for the western
Sound, and for Sat night into Sunday morning for the south
shore of Long Island and Jamaica Bay. SE winds ramping up to
gale force Sat evening should result in tide departures of about
2.5 to 3 ft in the western Sound and along the south shore of
western Long Island Sat evening per 2:1 blend of NYHOPS 50th and
95th percentile, with water levels likely reaching moderate
thresholds in the watch area, with widespread minor flooding
elsewhere.
As winds shift SW-W Sunday morning higher water levels, with
surge up to 2.5 ft on top of higher astronomical tides, should
lead to another round of minor to moderate flooding. Higher
surge is likely to be pushed eastward into the Great South Bay
and Jamaica Bay as has occurred with a few other events this
winter, with moderate flooding expected there, and at least
minor flooding elsewhere. Blend of Stevens NYHOPS 50th/95th
percentiles and the PETSS 50th percentile (leaning toward PETSS
numbers where higher along the Great South Bay) captures this
scenario.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Coastal Flood Advisory from 9 AM to noon EST Saturday for
CTZ009.
Coastal Flood Watch from Saturday evening through late
Saturday night for CTZ009.
NY...Coastal Flood Advisory from 9 AM to noon EST Saturday for
NYZ071.
Coastal Flood Watch from Saturday evening through late
Saturday night for NYZ071-073-078-176-177.
Flood Watch from Saturday evening through Sunday morning for
NYZ069.
Coastal Flood Watch from Saturday evening through Sunday
afternoon for NYZ080-178-179.
Coastal Flood Watch from Sunday morning through Sunday
afternoon for NYZ081.
Coastal Flood Advisory from 5 AM to 9 AM EST Saturday for
NYZ179.
NJ...Flood Watch from Saturday evening through Sunday morning for
NJZ002-004-006-103>108.
MARINE...Gale Watch from Saturday evening through late Sunday night for
ANZ331-332-335-338-340-345-350-353-355.
Small Craft Advisory until 6 PM EST Saturday for ANZ350-353-
355.
&&
$$
SYNOPSIS...JC/JT
NEAR TERM...JC/JT
SHORT TERM...JC
LONG TERM...JT
AVIATION...BG
MARINE...JC/JT
HYDROLOGY...JC/JT
TIDES/COASTAL FLOODING...BG