527
FXUS61 KOKX 261436
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1036 AM 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 --
Any lingering fog has burned off, and a mix of sun and clouds
prevails this afternoon. A couple rogue showers have popped up
over NE NJ this morning with some weak elevated instability,
and these continue to push through NYC. This activity should
remain isolated until later today, likely mid to late afternoon
when coverage expands as forcing increases, especially across
eastern areas. Latest hi res CAMs keep the bulk of convective
initiation generally after 18Z, then waning toward 00Z.
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.
With the mesoscale models appearing to be under-estimating the
amount of convection thus far for the previous night, manually
increased POPs in expectation of better ingredients for
convection today.
The models continue to show surface CAPE up to near 2000 J/kg,
highest across eastern sections as well as 0-6 km AGL bulk shear
of 35-40 kt, so some thunderstorms could be strong to severe.
The CAPE in the model BUFKIT soundings extend vertically into
the upper levels with temperatures between -10 and -30 degrees
C. Main threats with severe thunderstorms will be large hail and
damaging wind gusts.
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 /14Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
Weak low pressure moves across the area this afternoon and
evening.
Mainly VFR through the TAF period. Showers and thunderstorms are
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 are lower for NYC and
Lower Hudson Valley terminals and will continue to mention a
VCTS for these terminals around 21z-01z.
There is also low chance of low stratus development for some
coastal terminals late tonight which may bring categories down
to MVFR/IFR briefly.
Winds will be light and generally a NW-N flow this morning
around 5 kt. Winds will become southerly at coastal terminals
around 10 kt late morning into the afternoon. Winds will weaken
this evening and become light and variable overnight.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Shower briefly possible near KLGA and KJFK through 16z
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.
Timing of S-SE wind shift 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 12Z TUESDAY THROUGH FRIDAY...
Tuesday: VFR.
Wednesday: Chance of MVFR or lower in aft/eve SHRA/TSRA.
Thursday-Friday: Mainly VFR. Chance of aft/eve SHRA/TSRA, mainly
north and west of the NYC terminals.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
-- Changed Discussion --
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.-- End Changed Discussion --
&&
.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 11 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/MW
MARINE...JM/MW
HYDROLOGY...JM/MW
TIDES/COASTAL FLOODING...