804
FXUS61 KOKX 281001
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
601 AM EDT Wed Aug 28 2024
.SYNOPSIS...
A cold front moves through the area today followed by a high
pressure system moving into the area Thursday into Friday. A
frontal system will affect the area for the weekend, with
Canadian high pressure building in for early next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Forecast remains on track with only minor adjustments to account
for the latest observations of temperature and dew points.
High pressure shifts offshore to the south today as a cold front
moves into the area from the northwest into the afternoon. AHead of
the cold front, a primarily SW flow advects moisture and warmth into
the area. Mostly clear to partly cloudy skies will aide in
temperatures rising into the upper 80s and low 90s for much of the
area. The NYC metro may rise into the middle 90s. Heat index values
in and around the NYC metro, NE NJ, and Lower Hudson Valley may rise
into the low 100s. Heat Advisories remain in effect for these areas.
The cold front approaches and moves through this afternoon into this
evening. Much of the forcing for ascent and greatest instability
will be positioned south of the area and as such, SPC has shifted
the slight risk for severe weather to the south. Some isolated to
widely scattered convection is possible, especially later in
the day and early evening, but widespread severe weather is
unlikely. Much of the area remains in a marginal risk for severe
storms with the primary threat being gusty winds and small
hail.
The front moves through in the evening allowing the wind to shift
out of the NW and eventually N as high pressure begins to build
in behind the frontal passage. Drier air moves in late tonight
with lows dropping into the 60s.-- End Changed Discussion --
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY/...
High pressure builds in to the north of the area with a
primarily NE to E flow. Some midlevel energy and approaching
remnant convection from the west may eventually make it into
the area despite the high pressure over the area, so kept a
slight chance of showers with isolated thunderstorms during much
of the late Thursday through Friday time period. Some models
keep a disturbance just south of the area that may result in
some additional cloud cover or isolated showers through Friday,
but will be trying to fight off a drier airmass being advected
in from the NE courtesy of the high pressure positioned over the
Canadian Maritimes.
The more significant aspect of Thursday and Friday will be the
noticeably cooler temperatures as highs both days are expected
to be generally in the low to middle 70s.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
The biggest change over the last 24h is better agreement in the
timing of the frontal systems over the weekend, the first of which
passes through Saturday night into Sunday morning, followed by a
stronger cold frontal passage Sunday night. The GFS and Canadian in
particular have picked up some speed, while the ECMWF has maintained
good run to run continuity. The GFS is the most progressive, faster
by about 6h, with the second cold front passing through by 06Z
Monday. The ECMWF and Canadian bring the front through later Monday
morning. Before that time, Friday night into the first half of
Saturday, shortwave ridging moves through the area with increasing
chances of showers and thunderstorms during the afternoon and
nighttime. The first front will have the best moisture availability
(PWATs +2SD) and thermal forcing. It`s quite possible that the the
second front with the amplifying upper trough tracking across the
Great Lakes and into the Northeast, will be moisture starved by a
westerly flow behind the first cold frontal passage. GFS is showing
weak lapse rates and loss any daytime instability as the second cold
front comes through at night. Still maintain a chance for scattered
convection Sunday afternoon with the pre- frontal trough and then at
night with the actual cold front.
Temps moderating to near seasonable levels over the weekend, with
increasing humidity levels with Tds in upper 60s/lower 70s.
Drying conditions Monday on NW flow as Canadian high pressure builds
from the NW. Temps near seasonable.
&&
.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
An approaching cold front will pass through during the afternoon and
early evening hours. High pressure builds in from eastern Canada
behind the front tonight into Thursday.
Mainly a VFR forecast. The cold front is forecast to move through
the area largely dry, but cannot rule out an isolated thunderstorm.
The best chance at this time will be across the NYC terminals.
Winds will be SW at 10 kt or less overnight, highest at the coastaL
terminals. Winds will then veer through the morning ahead of the
approaching cold front, becoming W to NW during the late morning
into the afternoon, increasing to 10-15kt G20kt. There is a bit of
uncertainty with the timing of the cold front, especially for the
terminals east of NYC, where winds may remains W/SW for much of the
day before becoming NW. Winds will become more northerly Wednesday
evening, diminishing 10 kt or less.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
There is a low probability of a shower/thunderstorm this afternoon
and evening, but confidence is too low to include in TAF at this
time.
In addition, the timing of the cold frontal passage could vary by 1-
2 hours, mainly on the later side
OUTLOOK FOR 08Z THURSDAY THROUGH SUNDAY...
Late Wednesday night: VFR.
Thursday: Mainly VFR. Slight chance of an afternoon/evening
showers/thunderstorm north and west of the NYC terminals.
Friday: VFR.
Saturday: Chance of showers, possible thunderstorms and MVFR or
lower.
Sunday: Mainly VFR. Chance of a shower/thunderstorm, mainly in the
afternoon and evening.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
A persistent SW flow today ahead of a cold front may bring
marginally brief gusts near 25 kts, particularly for the eastern
ocean zone, but should largely remain sub-SCA criteria.
By early Thursday morning a period of marginal small craft wind
gusts are possible for the southern near shore and ocean waters
via a tightening NE flow. Small craft, or at least marginal
small craft conditions will remain possible for the ocean waters
through much of the day Thursday with gusts 20-25 kt and
easterly wind waves of 4-5 ft.
Winds and seas gradually subside on Friday, with a weak pressure
gradient keeping all waters below SCA criteria Friday night this
weekend.
&&
.HYDROLOGY...
No hydrological impacts are anticipated today with any storms
that do form being widely scattered to isolated. Any hydro
impacts over the weekend appear minimal at this time.
&&
.TIDES/COASTAL FLOODING...
There is a moderate risk of rip currents today as southerly
wind waves build to 3 ft, combined with a lingering 1 ft SE
swell. Moderate to possibly high rip/longshore current risk (rip
current risk will be enhanced especially along jetties and
groins) Thursday with a strong E to W sweep of 2 to 4 ft surf.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Heat Advisory from 11 AM this morning to 8 PM EDT this evening
for NYZ069>075-176>178.
NJ...Heat Advisory from 11 AM this morning to 8 PM EDT this evening
for NJZ004-006-103>108.
MARINE...None.
&&
$$
SYNOPSIS...DW/MW
NEAR TERM...MW
SHORT TERM...MW
LONG TERM...DW
AVIATION...DW
MARINE...DW/MW
HYDROLOGY...DW/MW
TIDES/COASTAL FLOODING...