965
FXUS61 KOKX 280015
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
815 PM EDT Sat Jul 27 2024
.SYNOPSIS...
High pressure remains over the area through Sunday. An offshore
low approaches eastern Long Island and the southern New England
coast Sunday night into Monday before dissipating over New
England. Several disturbances move through the area over the
week resulting in unsettled conditions.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
An upper level trough stalls just south and east of the region
with amplified upper ridging over the Great Lakes region. At the
surface, weak high pressure remains centered NW of the area and
SE of the Canadian maritimes.
Diurnal cu dissipates this evening, as well as coastal
seabreezes. Good radiational cooling conditions tonight under
clear skies and light winds should allow for temps across
outlying areas to fall into the 50s, with 60s to near 70
elsewhere. Some patchy radiative river fog and outlying areas
possible.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY/...
Models in good general agreement with persistent NE US coast
upper troughing developing into a large but weak cutoff upper
low SE of the New England/Mid Atlantic coast tonight into Sun,
that drifts NW across the area Sun Night into Mon, before
eventually shearing N into Canada Monday Night into Tuesday
ahead of approaching shortwave trough from the Central US.
At the surface, the region lies in between two areas of high
pressure, one centered SE of the Canadian Maritimes and another
centered to the west of the area on Sunday. Dry conditions, with
increasing high and mid clouds Sun aft as upper low begins to
drift NE. Light winds giving way to afternoon sea-breeze
development. Temps near seasonable (mid to upper 80s for
city/interior and lower to mid 80s coast)
Meanwhile, models in general agreement with low pressure
strengthening well east of the Carolina coast tonight, in
response to developing the upper low, and retrograde N/NW
towards eastern New England Sun Night into Mon. Models have
converged on this general track (50-75 mile spread) and
1007-1012mb intensity, with Bob hart FSU cyclone phase evolution
analysis indicating this being primarily a cold core system,
with low prob for hybrid warm core characteristics.
Forecast confidence remains low on coverage and magnitude of
rainfall from this low, with inherent NWP convective
parameterization predictability issues with the upper low over
the Gulf Stream setup. General indication of low pressure
weakening Sun Night into Mon as it approaches SE New England and
runs into ridging and driers air over the area and it becomes
increasingly stacked and barotropic under the upper low,
separated from warm conveyor belt moisture feed.
At this point, majority of NWP guidance keeps heavy rain axis
SE and E of the region, with GEFS, CMCE, ECE, NBM ensemble QPF
probs of > 1" of rain in 24 hr for the Sun Night/Mon period very
low for eastern portions of the region (Less than 20% ensemble
frequency). SPC HREF also signaling this weakening trend in QPF
and rates, and 10% prob of 3"/3hr rainfall well offshore Sun
Night. With that said, with the upper low tracking over the
region, weak instability, and modest moisture advection with
closest approach of surface low, potential exists for brief
locally heavy downpours/embedded thunder areawide. There is also
a low potential for a period of gusty N/NW winds (25-30 mph)
Sunday Night into Monday morning for far SE areas with closest
approach. Reasonable worst case scenario, with westward
deviation in the upper low/surface wave, is a period of heavy
rain banding (rainfall around 1") for LI/CT and gusty winds for
far SE CT/E LI.
Temps slight below seasonable with cloud cover and rain shower
activity.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Key Points:
* Multiple rounds of showers and thunderstorms possible through the
week.
* Increasing heat and humidity will increase chances for heat
indices approaching and/or exceeding 95F for the second half
of the week.
A departing upper low over the Northeast at the start of the
period will open up a parade of disturbances in the westerlies
through the upcoming week. Throughout the period there will be
chances for showers and thunderstorms. The best chance at this
time looks to be Wednesday/Wednesday night with an incoming
upper trough. The environment during this time will feature
marginal to moderate instability and generally weak deep-layered
shear. There are some timing issues with the global models in
how quickly the upper low lifts out of the Northeast and with
the disturbances riding the westerlies across the norther tier
of the conus. PWAT values by midweek will get up to around 2
inches, so heavy rainfall is a likelihood with any convection.
Still though, it is too early to be specific with details.
In addition, it will become increasingly humid through mid
week, likely persist into next weekend. The latter half of the
week will feature highs in the mid 80s to the lower 90s with dew
points around 70. This results in heat indices 95 or higher for
a good portion of the area. Timing of convection and associated
cloud cover will be complicating factors in the temperatures
forecast. The high humidity will be courtesy of a prolonged
period of southerly flow. This will also keep overnight lows
several degrees above normal.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
VFR. High pressure remains over or near the terminals through
the TAF period.
Winds become light and variable tonight. Sunday, winds start
off light but become more S-SE 5-10kt.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
No unscheduled amendments expected.
OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY...
Monday: Mainly VFR....MVFR or IFR possible far eastern terminals.
Chance of showers and thunderstorms.
Tuesday and Wednesday: Chance of MVFR or lower in scattered showers
and thunderstorms. S winds G15-20kt.
Thursday: Chance of MVFR in afternoon showers/thunderstorms. SW wind
5-10kts.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Winds and seas remain below small craft advisory criteria on all
waters through Sunday. Low potential for a period of SCA
conditions Sunday Night into Monday Night over ocean water and
eastern LIS and bays dependent on how close to the area an
offshore low tracks. Sub SCA conditions likely for midweek with
a weak pressure gradient.
&&
.HYDROLOGY...
Multiple rounds of showers and thunderstorms are possible through
the upcoming week. However, it is too early to be specific with
hydrologic impacts.
&&
.TIDES/COASTAL FLOODING...
There is a low risk for the development of rip currents at the
ocean beaches through Monday. However, building seas on the
ocean due to an offshore low may increase the risk to moderate
for Monday, especially late in the day.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...NV/DW
NEAR TERM...NV/DW
SHORT TERM...NV
LONG TERM...DW
AVIATION...BC
MARINE...NV/DW
HYDROLOGY...NV/DW
TIDES/COASTAL FLOODING...