758
FXUS61 KOKX 052016
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
416 PM EDT Fri Jul 5 2024

.SYNOPSIS...
A trough of low pressure remains west of the area tonight. A cold
front then approaches on Saturday, slowly moving through the area
Saturday night. A cold front southeast of the region eventually
dissipates and allows for high pressure to briefly build in for
Sunday through Sunday night. Another frontal system approaches
early next week with its associated cold front moving in towards
midweek. This frontal boundary could very well linger nearby
from mid to late week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
A shortwave will move across the region this evening, resulting in
some showers and thunderstorms from late afternoon through late
this evening. Expect scattered convection, with the best
chances mainly for areas N&W of NYC. An isolated strong to
severe thunderstorm is possible, however lack of focus and
stabilizing marine layer to the east across the coast should
limit shra/tsra activity.

Cold front/trough appears to remain stalled across western portions
of the region tonight. here remains a potential for a few heavy
downpours and embedded tstms to develop and move northeast across
the area tonight with strengthening mid/upper support ahead of a
closed low to the west, and strengthening low-level jet ahead of pre-
frontal trough advecting in an increasingly sub-tropical (weak
elevated instability, deep moisture and warm cloud layer, and 2"+
PWATS) environment. One forecast concern is the NWP and CAMs
continue to remain mixed on location and how widespread any
shra/embedded tsra activity is, with the greater potential remaining
NW of NYC in vicinity of trough.

Otherwise, very warm and muggy conditions tonight, with stratus/fog
development likely across much of the area.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
The trough over the Great Lakes continues to lift northeast into
Ontario/Quebec Saturday into Saturday Night, with shortwave axis
pivoting across W PA/NY Saturday Night.

Heat advisory continues for NE NJ through Saturday for second day of
heat indices of 95 to 100 F. Have expanded the Heat Advisory to
include Western Passaic as well as Orange and Rockland in NY. There
is slightly greater coverage of 95 F heat indices likely across the
region on Saturday, but not enough confidence to expand heat
advisory into NYC and the remainder of the the Lower Hudson Valley.
Can not rule out parts of these areas reaching the criteria, however
one concern will be the potential for additional cloud cover/shower
activity which may limit temperatures a bit. Either way, expect
a rather muggy day with dew points in the lower to middle 70s.

The pre-frontal trough remains stalled over the area Saturday, with
the potential for a few rounds of heavy downpours and thunderstorms
ahead of and along it. Sat afternoon and evening appears to be the
best chance for a few strong to severe thunderstorms, once again,
mainly across NYC and points N&W.

The main threat with any storms on Saturday and saturday night will
be the potential for heavy rainfall. PWATS remain above 2"+ inches.

Again one of the forecast challenges remains the differences between
the NWP and CAMs which are varied in timing, location, intensity of
convection. So at this point an isolated severe/flash flood threat
exists on Saturday, mainly for NYC and points N&W.

Any thunderstorm activity should weaken in intensity as it slowly
moves eastward towards the coast Saturday evening and Saturday night
However, there is still the potential for locally heavy downpours
and embedded thunderstorms near the coast.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
After analysis of some large scale numerical weather prediction
models with their MSLP, surface winds, and precipitation forecasts
the following features are noted. The models analyzed were the NAM,
GFS, ECMWF, and the Canadian, although for forecasts of Monday night
onward, just the GFS, ECMWF and Canadian were compared.

The models exhibit better agreement with high pressure over the area
with mainly dry conditions Sunday through Sunday night. They have
agreement with southerly flow across the region for early next week
and more convective potential for Tuesday through Tuesday night. The
models show cold front lingering nearby for Wednesday but vary more
with rain from mid to late week. ECMWF particularly seems to be most
aggressive with convection showing a continual cycle of shower and
thunderstorm development along the front for mid to late week.

Some relatively drier dewpoints Sunday behind a cold front will have
some lower heat indices forecast within the region. Forecast highs
mostly in upper 80s to lower 90s with max heat indices in the lower
90s with some mid 90s for parts of the region, mostly in NE NJ. More
areas in mid 90s with max heat indices forecast for Monday with
relatively higher dewpoints compared to previous day. Forecast highs
are mostly in the 80s for Tuesday and the rest of the days of the
forecast.

Showers with mostly chance POPs return to the forecast Tuesday
afternoon through the rest of the forecast. Forecast has chances of
thunderstorms Tuesday afternoon through Wednesday night. Otherwise,
thunderstorms have slight chance. Highest coverage and thunderstorm
potential appear to be Tuesday afternoon into early Wednesday
surrounding the cold front moving and how fast it makes its way
through.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
A trough of low pressure slowly shifts in from the west into tonight
and remains in the vicinity through Saturday before a cold front
passes through Saturday night.

Mainly VFR with the exception of KGON today, and in any
shra/tstms this aftn/early eve. Lowering flight categories
otherwise tonight, with just about all terminals eventually
IFR/LIFR.

S to SE winds around 10kt this afternoon, then S 5-10kt tonight.

...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

Occasional S wind G20kt possible at KJFK until around 0z.

Chance that tempo TSRA doesn`t happen late today/early evening as it
might be just VCTS or just plain showers/VCSH. Additional showers
possible late tonight into Saturday morning.

Timing for flight category changes tonight through Saturday morning
may be off by 1-2 hours.

OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...

Saturday: MVFR or lower conditions possible at times with
continued chance of showers/tstms.

Sunday and Monday: VFR.

Tuesday: Chance of sub-VFR in showers and thunderstorms in the
afternoon, mainly west of NYC.

Wednesday: Chance of sub-VFR in showers and thunderstorms.

Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90

&&

.MARINE...
Small craft advisories remain in effect for the ocean tonight
through Saturday night as a strengthening S flow increases to
15-20kt and seas build to 4 to 6 ft. Potential for occasional
Great South Bay gusts to 25 kt as well.

With a relatively weak pressure gradient in place, conditions on the
waters are expected to remain below small craft advisory thresholds
Sunday through the middle of next week.

&&

.HYDROLOGY...
Isolated to scattered slow moving thunderstorms producing 1-2"/hr
rainfall rates are likely this eve, primarily W&NW of NYC. Primary
threat is for minor/poor drainage flooding, with an isolated flash
flood threat.

Approaching shortwave and slow moving frontal boundary crossing
tonight into Saturday night will bring potential for localized 1-
2"/hr rainfall rates with isolated to scattered thunderstorms.
Localized flash flood threat exists for the area from any
training convection during this timeframe, with the threat
maximized across NYC/NJ metro and points N&W during peak heating
Sat aft/eve.

Model precipitable waters show an increase up to near 2.2 to 2.4
inches Tuesday into Tuesday night. With cold front moving in, there
will be a marginal risk for excessive rainfall. There will be a
chance for flooding with widespread minor flooding potential as
well as a low percentage probability for localized flash flooding.

Otherwise, no other widespread hydrologic issues are expected.

&&

.TIDES/COASTAL FLOODING...
There is a moderate to high risk for rip current development along
NYC/LI ocean beaches today with a combo of 3-4ft S wind wave and 2
ft E/SE swell. The high risk is for W LI and NYC beaches this
aft/eve due to enhanced seabreeze formation and large tidal range.

There is a high risk of rip currents for all NYC and LI ocean
beaches on Saturday as S wind waves continues to build to 5 ft, with
continued 2 ft E/SE swell.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Heat Advisory from noon to 8 PM EDT Saturday for NYZ067-069.
     High Risk for Rip Currents through Saturday evening for NYZ075-178-
     179.
     High Risk for Rip Currents from Saturday morning through Saturday
     evening for NYZ080-081.
NJ...Heat Advisory from noon to 8 PM EDT Saturday for NJZ002.
     Heat Advisory until 8 PM EDT Saturday for NJZ004-006-103>108.
MARINE...Small Craft Advisory from 8 PM this evening to 2 PM EDT Sunday
     for ANZ350-353.
     Small Craft Advisory until 2 PM EDT Sunday for ANZ355.

&&

$$

SYNOPSIS...BC/JM
NEAR TERM...BC
SHORT TERM...BC
LONG TERM...JM
AVIATION...JC
MARINE...BC/JM
HYDROLOGY...BC/JM
TIDES/COASTAL FLOODING...