508
FXUS61 KOKX 261739
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
139 PM EDT Mon Aug 26 2024
.SYNOPSIS...
Offshore high pressure remains in place early this week.
However, a weak low pressure trough develops within the region
today and prevails into tonight before moving farther south of
the area Tuesday. A warm front moves through Wednesday,
followed by a cold front Wednesday night. High pressure returns
Thursday into Friday. A warm front approaches to begin the
weekend, with a cold front likely to follow later in the
weekend.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
Severe Thunderstorm Watch was hoisted for the eastern half of
the region, including all of southern Connecticut and Suffolk Co
on Long Island until 7 pm this evening. Primary hazards from
this activity are large hail and damaging winds. Farther west,
isolated strong to severe thunderstorms cannot be ruled out, but
weaker forcing should limit coverage.
SPC mesoanalysis at 1730Z has over 1500 J/kg of MLCAPE across
interior CT, and with a relatively moist air mass for the time
of year and effective shear near 30 kt, scattered thunderstorms
should pop up as forcing with the trough and cold pool shifts
south through the region. Convective activity is blossoming
across southern New England as of this update, and latest hi
res CAMs keep the bulk of convective initiation generally after
18Z, then waning toward 00Z. Locally heavy downpours with any
storms and a slow moving forward motion could introduce some
hydro concerns as well, primarily nuisance flooding of urban or
poor drainage areas. Forecast remains on track and previous
discussion follows.
Aloft, an upper level low moves southward into Northern New
England today, allowing for a strong shortwave with substantial
positive vorticity advection to traverse the area this
afternoon. In the upper levels, a northerly jet streak
approaches and the local region will be near the left front
quadrant or left exit region with respect to its jet speed
maximum. This will enhance synoptic lift this morning and
afternoon. While surface high pressure remains offshore, it is
weakening. A low pressure trough develops within the region
today. This will act as a focus for developing convection.
Forecast high temperatures today are once again expected to be
well within the 80s across the region. Dewpoints today mostly in
the mid 60s.-- End Changed Discussion --
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
Ongoing convection to start this evening along the surface low
pressure trough. Still a severe thunderstorm threat early so
possible damaging winds and large hail. This severe threat is
expected to subside mid to late this evening.
The convection will begin to decay with the loss of diurnal
instability and the strong shortwave pushing farther south of
the region. Also, the region will be in a less favorable
position with respect to the upper jet. Expecting mainly dry
conditions late this evening through the overnight. With
moisture laden grounds and light winds, expecting patchy fog to
develop late tonight into early Tuesday morning.
For Tuesday, the low pressure trough eventually moves south of
the region. High pressure returns but remains weak. Dry
conditions are expected Tuesday and Tuesday night.
Not much of an airmass change is expected. Forecast high
temperatures Tuesday are expected to be very similar to those of
the previous day, well into the 80s. Dewpoints generally in the
mid 60s.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
A low pressure system begins to impact the area on Wednesday with a
warm frontal passage expected to move through Wednesday morning.
Depending on how quickly skies can clear out during the day will
determine how warm temperatures are able to rise. As of now, highs
are forecast to be in the middle 80s to middle 90s. Some spots in NE
NJ and the western half of the CWA may have heat index values rise
into the upper 90s to low 100s. Additionally, showers and
thunderstorms will be possible as ample heating and moisture will
allow for the development of instability. The cold front associated
with the low pressure is poised to move through the area Wednesday
afternoon into Wednesday night.
Behind the frontal passage, high pressure builds in from the north,
allowing for a much cooler and drier airmass to move in under a
primarily NE flow. WHile some scattered showers can`t be entirely
ruled out during the end of the week with the low pressure to the
south and an approaching frontal system to the west into the
weekend, much of the area should be dry as high pressure should be
able to remain in place over the area through Friday, however, a NE
flow will keep high temperatures cooler, generally only in the
middle to upper 70s for Thursday through Saturday.
Another frontal system may move in from the west going into the
weekend which may result in some additional showers and
thunderstorms. As of now, left chance PoPs for eventual refining of
timing and coverage of any precipitation.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
Weak low pressure moves across the area this afternoon and
evening.
Mainly VFR through the TAF period. Showers and thunderstorms remain
possible this afternoon and early evening, especially for eastern
Long Island and southeast Connecticut terminals. A few of these
storms could contain strong gusty winds and some hail. Probabilities
for showers/thunderstorms continue to be lower for NYC and Lower
Hudson Valley terminals. Will continue to mention a VCTS for these
terminals around 21z-01z, but it is possible that it ends up being
VCSH or just a few isolated showers.
MVFR or IFR stratus is possible tonight, mainly across SE CT.
Winds will continue to shift to the S-SE along the coast.
Elsewhere, winds will be a bit more variable with prevailing flow
WNW-NE. Sea breezes may not make it completely through KEWR, KTEB
and KHPN. Winds will weaken this evening and become light and
variable overnight.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Low confidence in timing and coverage of showers/storms this
afternoon and evening. The bulk of any activity will likely be east
of the NYC terminals and the VCTS may just be a VCSH.
Timing of S-SE wind shift at KLGA may be off by 1-2 hours and winds
at KEWR may remain W-WNW into the evening if sea breeze stays just
east.
OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY...
Tuesday PM: VFR.
Wednesday: Chance of MVFR or lower in afternoon/evening
showers/thunderstorms.
Thursday-Friday: Mainly VFR. Slight chance of afternoon/evening
showers/thunderstorms north and west of the NYC terminals.
Saturday: Chance of showers, possible thunderstorms and MVFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
With the pressure gradient remaining weak, conditions are
expected to remain well below SCA criteria through Tuesday
night.
Sub small craft conditions prevail into the middle of the week with
ocean seas likely not getting above 3 ft through Wednesday.
Marginal small craft seas then become possible late Thursday
through early Friday for eastern portions of the ocean.
&&
.HYDROLOGY...
A marginal flood threat mainly for eastern sections of the
region, for SE Connecticut and Eastern Long Island, where
multiple rounds of heavy showers and thunderstorms are forecast.
Here rainfall totals could reach up to near 1 to 1.5 inches
locally. Otherwise, basin average amounts with the showers and
thunderstorms are expected to remain below a quarter of an inch
with no other hydrologic problems anticipated today through
Tuesday night.
While QPF amounts for Wednesday`s showers and storms remains a bit
uncertain, there will be a chance for minor hydrologic impacts,
generally nuisance or minor urban related flooding. Rainfall amounts
across northern portions of the area could average close to an inch,
with locally higher amounts possible in association with any
thunderstorms.
&&
.TIDES/COASTAL FLOODING...
There will be a low rip current risk for the ocean beaches today.
The low risk is expected to prevail with the primary waves
being under 5-6 second period. The low risk continues overall
into Tuesday. Surf heights will generally be 1 to 2 ft. The risk
should increase into Wednesday with more of a southerly wind
wave and therefore more of a moderate rip current risk.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
NY...Air Quality Alert until 7 PM EDT this evening for NYZ078>081-
177-179.
NJ...None.
MARINE...None.-- End Changed Discussion --
&&
$$
SYNOPSIS...JM/MW
NEAR TERM...JM/DR
SHORT TERM...JM
LONG TERM...MW
AVIATION...DS
MARINE...JM/MW
HYDROLOGY...JM/MW
TIDES/COASTAL FLOODING...