000
FXUS61 KOKX 032057
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
457 PM EDT Wed Apr 3 2024
.SYNOPSIS...
Deepening low pressure over the Mid Atlantic states will track
slowly northeast this evening, passing to the south of Long
Island tonight. The low tracks northeast along the New England
coast Thursday, then weakens east of New England Friday into
Saturday. High pressure builds in from the west Sunday into
early next week. A back door cold front may approach from the
northeast Tuesday into Wednesday as a weakening frontal system
approaches from the west.
&&
.NEAR TERM /THROUGH THURSDAY/...
A large upper low over centered over the Great Lakes and Ohio
Valley states will send a deepening secondary low over the Mid
Atlantic states northeast, passing to the south of Long Island
tonight. Strong dynamics and thermal forcing will produce moderate
to occasionally heavy rain across the area through the first
half of the night. In addition, steepening mid-level lapse rates
may result in an isolated thunderstorm. Rainfall rates will
generally be between 0.1 to 0.2"/hour, with pockets of 0.2 to
0.50"/hour. Localized rates, but brief, could get to around
0.75"/hour. A flood watch remains up for NE NJ, NYC, and LI.
The main threat across the watch area is urban/poor drainage
flooding, however, the faster responding smaller rivers, creeks,
and streams across NE NJ could exceed their banks. This looks
to be localized.
In addition, a strong pressure gradient to the north of the
low, featuring a 50 to 55 kt easterly LLJ at the base of the
inversion, has the potential to bring high winds to coastal
locations. Coastal areas remain under a High Wind Warning for
the potential of sustained winds exceeding 40 mph and gusts up
to 60 mph. Just inland, there is a complementing wind advisory
for slightly weaker winds, except for Orange County NY and
western Passaic County NJ. The end time for the wind hazards has
been shortened and will now expire at 2 am.
Once the low passes farther to the east tonight, winds will back
around to a more northerly direction and weaken, drawing some
colder air into the area. Inland areas, especially the higher
elevations of Orange and Putnam counties in NY may see some wet
snow. This could even get into interior portions of SW CT.
Little to no snow accumulation is expected with surface
temperatures above freezing. In addition, mid-level drying may
hinder snow growth.
Rain tonight will transition to a more showery precipitation
toward daybreak with the approach of the upper low from the
west, The threat of showers will linger into Thursday afternoon.
Much of the guidance shows a more organized area of showers
passing just to the south and west of the NYC metro Thursday
afternoon. This will need to be watched as a subtle shift of the
upper low to the north could bring this into the forecast area.
Winds on Thursday will be out of the NW with a few gusts up to
20 mph possible.
Lows tonight will show a small diurnal change, remaining in the
upper 30s inland to around 40 at the coast. Highs Thursday are
expected in the mid 40s inland to the upper 40s/around 50 at the
coast. This is a few degrees above normal for lows and a few
degrees above for the highs.
&&
.SHORT TERM /THURSDAY NIGHT/...
The upper low slowly departs to the east Thursday night with a
slight chance of rain and/or snow showers. Lows will mainly be
in the 30s. W/NW winds continue during this time.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
Not too much change from earlier forecast reasoning for this time
frame, with an omega block over North America and translating slowly
east influencing local wx for the most part. Friday looks mainly dry
and brisk, with mostly cloudy skies via cyclonic flow around the low
as it spins over or just E of the ern New England coast. As the
associated upper low starts to move southward on Sat, with a leading
spoke of mid level vorticity moving across late Fri night, chances
for light rain/snow showers should increase inland Fri evening, and
mainly E of NYC late Fri night into Sat. Precip chances should end
by Sat night, and Sunday looks dry with partly sunny skies across S
CT/Long Island and mostly sunny skies to the west.
Noticeably milder wx arrives on Mon with high pressure sfc and aloft
building in, with high temps mostly in the lower/mid 60s, except
upper 50s across ern Long Island and along south facing shorelines.
Model fcsts also continue to show a mid level shortwave trough to the
west riding atop the upper ridge axis Mon afternoon, which could
produce a fair amt of high clouds during the time of the solar
eclipse.
Fcst details become more uncertain beyond Mon night as guidance
shows the upper ridge strengthening a little, while a closed low
drops SE across the Canadian Maritimes, which should send a back
door cold front toward the area from New England, and an upper low
either approaches the western Great Lakes or gets shunted into
central Canada. Splitting the difference between the GFS and ECMWF
on timing of any back door cold fropa, with Tue on the mild side (a
few deg warmer than Mon) and somewhat cooler temps for Wed, also
slight chance PoP from Tue night into Wed.-- End Changed Discussion --
&&
.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
...HIGH IMPACT AVIATION EVENT INTO TONIGHT...
Low pres deepens near srn NJ this eve, tracks just SE of NYC
tngt, and near BOS on Thu.
Rain, with a few breaks possible, thru this eve. The rain tapers off
aft 4-6Z, with a few shwrs possible on Thu. Coverage and prob was
too low to include shwrs for Thu aftn attm. Generally IFR until Thu
12-14Z, when MVFR is expected for the rest of the TAF period. There
is a chance cigs rise abv 3000 ft aft 18Z.
Some snow may mix in at SWF late tngt and Thu.
Isold-sct tstms possible 22-03Z. Included a TEMPO for NYC and LI
arpts.
E winds increase thru 00Z, peaking thru about 3Z. Winds then back as
the low passes near or over the region. Speeds less as they back,
with a possible lull invof the low center. N to NW winds on the
backside of the low, but gusts peaking at around 30 kt.
Winds of 50-55 kt at 2kft for the coastal terminals thru this eve.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments likely through the TAF period for changing and possible
fluctuations in flight categories.
Best chc for tstms 21-03Z.
OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...
Rest of Thursday: Mainly MVFR with decreasing N/NW winds. VFR
possible at times.
Friday: Mainly VFR. Possible rain and/or snow shwrs with pockets of
MVFR. NW flow with gusts 20-25kt.
Saturday: Mainly VFR. Northerly gusts around 20 kt.
Sunday: VFR with northerly gusts near 20 kt.
Monday: VFR with light winds.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
-- Changed Discussion --
A Storm Warning remain in effect for all waters through the
first half of tonight. Deepening low pressure will pass in
close proximity to the ocean waters tonight. A strong pressure
gradient to the north of the low will drive a strengthening
easterly wind, producing a period 50 kt wind gusts. Waves on the
ocean waters likely reach 12 to 15 ft on the ocean waters and 9
to 11 ft across the Sound.
Winds will quickly fall off behind the low for the second half
of the night and any period of gales will be short-lived. SCA
conditions will linger on the ocean waters due to elevated seas
persisting into Thursday night.
Longer term, SCA cond should persist on the ocean from Fri into Sat
morning as low pressure remains nearly stationary over or just E of
the ern New England coast, with NW flow gusting to 25 kt and seas 5-
7 ft. Some gusts up to 25 kt are also possible on the non ocean
waters Fri afternoon/evening. SCA cond also possible in N flow on
the ern ocean waters late Sat night into Sunday morning as low
pressure finally pulls away to the east.-- End Changed Discussion --
&&
.HYDROLOGY...
An additional 1 to 2 inches of rainfall is expected through
early Thursday morning with locally higher totals possible. The
bulk of this rain will fall through the first half of tonight.
A period of higher rainfall rates will be possible this evening,
with 0.20" to 0.50"/hr. Localized and brief higher rates of
0.75"/hr will be possible. The best location for these higher
rates will be in NE NJ, NYC metro and LI, where the Flood Watch
remains in effect. The most recent HRRR continues to supports
these potential rates. 12Z SPC HREF probabilities > 1"/hr less
than 10%.
Poor drainage and urban flooding is possible, as well some minor
flooding of faster responding smaller rivers, creeks, streams
across NE NJ.
&&
.TIDES/COASTAL FLOODING...
Around 2.5-3 ft of surge is needed for minor coastal flood this
aft/eve and around 3.5-4 ft for moderate coastal flooding. With
easterly winds ramping up to storm force during the time of
high tide, as well as building wave action, widespread moderate
coastal flood thresholds are likely to be eclipsed along the
southern and eastern bays of Long Island and along the western
Sound. Elsewhere widespread minor coastal flooding likely. In
addition, the combination of heavy rain and elevated water
levels this afternoon and evening may enhance the localized
flash flood threat along some shoreline roads and properties.
Easterly winds gradually subside late tonight as low pressure
moves over the area, and then switch to NW gales behind the low
Thu AM. High easterly swells will likely inhibit drainage,
particularly bay areas, bringing potential for widespread
moderate flooding (locally major for the southern and eastern
bays of Long Island) late tonight into early Thu morning. The
coverage and areas of greatest coastal flood impact will be
highly dependent on track of the low, and timing of the wind
shift from easterly SCA/Gales to northwest gales. Forecast is
based on a 75th percentile of Stevens, blended with ETSS, STOFS
guidance, which applies a bit of margin for safety. This will be
refined over the next 24 hours.
Along the oceanfront, breaking waves of 6-10 ft this afternoon
into Thursday morning, along with elevated water levels, will
result in widespread beach flooding and erosion. Scattered areas
of dune erosion with localized overwashes are likely during the
times of high tide Wed afternoon into Thursday morning.
Along Long Island Sound, breaking waves of 3-7 ft this evening,
along with elevated water levels, will result in beach erosion
with damage to shoreline structures possible. Wave splashover
over bulkheads and seawalls will likely exacerbate flooding of
shoreline roadways and properties. A similar threat exists for
the twin forks, with breaking waves of 4-8 ft this evening and
Thursday morning.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...Wind Advisory until 2 AM EDT Thursday for CTZ005>008.
Coastal Flood Warning until 10 AM EDT Thursday for CTZ009-010.
High Wind Warning until 2 AM EDT Thursday for CTZ009>012.
Coastal Flood Warning from 4 AM to 10 AM EDT Thursday for
CTZ011-012.
NY...Wind Advisory until 2 AM EDT Thursday for NYZ068>070.
Coastal Flood Warning until 10 AM EDT Thursday for NYZ071-073-
078-176-177.
High Wind Warning until 2 AM EDT Thursday for NYZ071>075-
078>081-176>179.
Flood Watch through late Thursday night for NYZ072>075-078>081-
176>179.
Coastal Flood Advisory until 7 AM EDT Thursday for NYZ072-074-
075.
Coastal Flood Warning until noon EDT Thursday for NYZ079>081-
179.
Coastal Flood Advisory until 7 PM EDT this evening for NYZ178.
Coastal Flood Warning from 3 AM to 7 AM EDT Thursday for
NYZ178.
NJ...Wind Advisory until 2 AM EDT Thursday for NJZ004-103>108.
High Wind Warning until 2 AM EDT Thursday for NJZ006.
Flood Watch through late Thursday night for NJZ002-004-006-
103>108.
Coastal Flood Advisory until 7 AM EDT Thursday for NJZ006-104-
106-108.
MARINE...Storm Warning until 2 AM EDT Thursday for ANZ331-332-335-338-
340-345-350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...BG/DW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...BG
AVIATION...JMC
MARINE...BG/DW
HYDROLOGY...BG/DW
TIDES/COASTAL FLOODING...