871
FXUS61 KOKX 180230
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1030 PM EDT Sat Aug 17 2024
.SYNOPSIS...
A weak low tracks slowly eastward through the Great Lakes region
tonight, and approaches Sunday. Meanwhile another low develops
during Sunday over southeastern Pennsylvania and eastern
Maryland. This low then deepens Sunday night into Monday and
tracks northeast bringing a cold front across the area late
Sunday night into Monday. A secondary frontal passage moves
through Tuesday. High pressure builds in for the middle and end
of the week.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Forecast generally on track. Made some adjustments to PoPs
over the next few hours to account the latest radar trends.
There is still the potential for one round of moderate to heavy
rainfall late tonight into early Sunday morning. The Flood Watch
remains in effect for NE NJ into the Lower Hudson Valley at 06z
and continues through into Sunday night. The 00z HRRR has backed
off on its depiction from earlier of a more organized band of
heavy rain across the watch area early Sunday morning. Heavy
downpours may end up more scattered, but would like to see the
rest of the 00z CAMs before making any changes to the rest of
the forecast. Rainfall rates may peak late tonight around 1
inch per hour. Isolated flash flooding is also possible a little
farther to the east, into New York City and Putnam and
Westchester counties, with poor drainage and urban flooding
possible.
With the upper ridge remaining into the western Atlantic,
showers will continue to struggle to move eastward across Long
Island and CT with many locations remaining mostly dry out east
through the night.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
A Flood Watch is in effect from late tonight, 06Z Sunday,
through late Sunday night, 06Z Monday, for the potential for
scattered flash flooding, urban and poor drainage flooding, and
possibly fast responding streams of northeastern New Jersey.
Rainfall rates could be near 1 inch per hour, and at times
approach 2 inches per hour. Total rainfall in the watch area
will be around 2 inches to 2.5 inches with locally as much as 3
inches possible. This will be with a slow moving frontal system
and with training showers and isolated thunderstorms, as the
flow nearly parallels the trough. Also, precipitable waters
increase to just over two inches Sunday, and warm cloud process
increase along with a 20-230kt low level jet during Sunday and
into Sunday night. This system will be slow moving eastward as
downstream riding remains across the western North Atlantic. An
then during Sunday a frontal wave develops near the mid Atlantic
coast, across southeastern Pennsylvania into the Delmarva. This
low provides lift for heavy rainfall as this low tracks slowly
northeast to east across northeastern New Jersey into New York
City and then to the northeast of the area during Monday.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
The area remains under a large-scale trough with vorticity
maxima moving through Monday night and into Tuesday. As the
trough tries to lift during the day on Tuesday, additional
energy descends from the north to allow for another round of
forcing. At the surface, this should translate into the form of
a secondary frontal passage that brings another round of showers
with possible embedded thunderstorms, especially Monday night
into Tuesday morning. Any residual showers should diminish into
the afternoon on Tuesday with the passage of the surface cold
front.
There is still some uncertainty as to how quickly the trough
lifts with the upper-level energy rotating over New England,
but consensus has been that the trough departs late Wednesday
into Thursday and ridging begins to move over the area from the
west. At the surface, a relatively strong high pressure system
builds into the Mid- Atlantic and Northeast from Wednesday
through the weekend. This will provide fairly calm and dry
conditions through the rest of next week.
This high pressure will be accompanied with primarily N/NW winds
and a much cooler airmass. The airmass should be fairly
anomalously cool for middle to late August. High temperatures on
Tuesday and Wednesday may not rise out of the upper 60s to low
70s for much of the area. Even coastal areas, highs will only be
in the low to maybe middle 70s. Lows Wednesday night and
Thursday night will likely be fairly chilly, with some locations
for the interior and outlying areas possibly dropping into the
low 50s or upper 40s, depending on the strength of any
radiational cooling. Temperatures will gradually moderate into
late week and the weekend with highs by Friday and Saturday
rising back into the upper 70s to low 80s.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
A frontal system slowly approaches the terminals through the
TAF period.
VFR to start for NYC terminals on north and west with MVFR with
some local IFR further east. Conditions should slowly lower to
MVFR overnight at all terminals. Scattered showers are possible
at any time through 09z, especially from KISP and KBDR on west.
More widespread showers 09-15z, possibly heavy at times, are
expected especially NYC terminals on north and west.
MVFR conditions are likely to continue through Sunday evening
although there could be some brief improvement to VFR at times
in the afternoon. Showers remain possible into Sunday evening,
especially along and west of the Hudson River corridor. Further
east, a brief shower is possible, but the most widespread shower
activity likely holds off until after 00z Monday.
There could be an isolated thunderstorm early Sunday morning,
mainly NYC metro terminals on north and west. Potential for
thunderstorms increases a bit Sunday afternoon/evening for the
same terminals and have included a PROB30 for this time period.
Winds will mainly be SE around 10 kt or less through the TAF
period. Coastal terminals could see winds a few kt higher at
times, especially Sunday afternoon. There is also a chance for a
few gusts 15-20 kt Sunday afternoon.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Timing of return to MVFR may be off by 1-3 hours. Amendments
for changing flight categories likely through the TAF period.
Isolated thunderstorms possible 10-16z Sunday.
Timing of PROB30 TSRA Sunday afternoon and evening may be off by
several hours with adjustments likely.
OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY...
Sunday night: Showers with possible thunderstorms. MVFR to
occasional IFR conditions.
Monday: Showers with possible thunderstorms, especially
afternoon and evening. MVFR or lower at times.
Tuesday: Mainly VFR. A chance of showers with MVFR possible. NW
wind gusts 15-20 kt.
Wednesday-Thursday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Rough ocean seas and long period swells, 12 to 15 second, will
persist this weekend and into early next week as distant TC
Ernesto passes well offshore in the open Atlantic. This will
also lead to rough conditions around inlets. Please refer to the
National Hurricane Center for official forecasts regarding
Hurricane Ernesto. A Small Craft Advisory is in effect for the
ocean zones, and was extended through Monday night.
Elevated wave heights on the ocean zones will allow for SCA
conditions to continue Monday night and possibly into the day on
Tuesday with some marginal wind gusts near 20-25kt with the passage
of a cold front. Late Tuesday, wind diminish and wave heights should
fall below 5 feet. Sub-SCA conditions are then expected with high
pressure moving into the area by mid-week.
&&
.HYDROLOGY...
A Flood Watch is in effect late tonight into late Sunday night
for Northeastern New Jersey and into the Lower Hudson Valley
west of the Hudson River.
Locally heavy rainfall is possible late tonight, and again
during Sunday into Sunday night, particularly west of the NYC
metro and Hudson River. The threat of heavy rainfall expands to
the east into Western Long Island and portions of southern
Connecticut, and with the slow movement of low pressure and
lower rainfall amounts and rainfall rate was not confident
enough to go farther to the east with the Flood Watch.
Total rainfall amounts from tonight through Monday night range
from around a half inch east to around 2 inches from NYC metro
on north and west. Locally higher amounts, possibly up to 3
inches, are possible across northeastern New Jersey into the
Lower Hudson Valley. Isolated to scattered instances of flash
flooding are possible across the more flood prone areas of NE
NJ and adjacent areas of the Lower Hudson Valley, and perhaps as
far east as NYC. A more widespread threat for localized flash
flooding, along with nuisance flooding of urban and poor
drainage areas, sets up on Monday.
No hydrologic concerns Tuesday through next weekend.
&&
.TIDES/COASTAL FLOODING...
A high rip current risk is in place through Monday. This is due
to SE to S long period swells from Hurricane Ernesto.
Ocean seas are forecast to be highest Sunday into Monday, with
heights up to 6-7 ft. There is potential for high surf along the
ocean beaches during this time frame as well as beach erosion.
A new moon on the 19th as well as swell from distant Hurricane
Enersto will elevated tide levels Sunday into early this week.
Minor coastal flooding is expected with high tide Sunday
evening across the back bays of Nassau and Western Sound along
the southwest CT and S Westchester coast. Have issued a Coastal
Flood Advisory for these locations. Localized minor coastal
flooding is possible across southern Queens, Southern Brooklyn
and lower NY Harbor. Locations may just touch minor benchmarks
and a statement has been issued. Additional minor flooding is
possible for high tide Monday evening and statements/Advisories
will likely be needed for similar locations as with high tide
Sunday evening.
Please refer to NHC for official forecasts regarding Hurricane
Ernesto.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Coastal Flood Advisory from 10 PM Sunday to 1 AM EDT Monday
for CTZ009.
NY...Coastal Flood Advisory from 10 PM Sunday to 1 AM EDT Monday
for NYZ071.
Flood Watch from 2 AM EDT Sunday through late Sunday night for
NYZ067-069.
High Risk for Rip Currents through Monday evening for NYZ075-080-
081-178-179.
Coastal Flood Advisory from 7 PM to 10 PM EDT Sunday for
NYZ179.
NJ...Flood Watch from 2 AM EDT Sunday through late Sunday night for
NJZ002-004-006-103>108.
MARINE...Small Craft Advisory until 6 AM EDT Tuesday for ANZ350-353-355.
&&
$$
SYNOPSIS...MET/MW
NEAR TERM...DS/MET
SHORT TERM...MET
LONG TERM...MW
AVIATION...DS
MARINE...MET/MW
HYDROLOGY...MET/MW
TIDES/COASTAL FLOODING...