127
FXUS61 KOKX 060654
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
254 AM EDT Sat Jul 6 2024

.SYNOPSIS...
A trough of low pressure will remain in close proximity
overnight. 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 /THROUGH TONIGHT/...
A prefrontal trough will remain stalled over the area this
morning which most 00Z CAMs have picked up on. They attempt
to redevelop scattered showers with isolated chances for
thunder across portions of the CWA, around daybreak. The best
coverage will be areas north and west of the city, but have
increased POPs across the CWA for early-to-mid morning with this
update and lowered POPs for the afternoon/evening which appears
like it may be a more isolated event. Anomalously high 2"+
PWATs this morning could lead to some moderate to heavy
downpours, but any flash flood concerns should remain isolated.
Patchy fog chances will continue through early/mid-morning. More
discussion to follow in the 4AM update.

&&

.SHORT TERM /SUNDAY/...
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 NIGHT 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 /07Z SATURDAY THROUGH WEDNESDAY/...
A slow moving frontal system impacts the terminals through
Saturday night.

Another round of showers and thunderstorms developing across
eastern PA looks to impact the NYC and Lower Hudson Valley
terminals from 09Z to 13Z. The eastern terminals right now look
to be on the eastern edge and coverage looks more spotty at
this time. Otherwise, expect widespread IFR/LIFR conditions
overnight. KSWF and the NYC terminals will be on the western
edge of the low clouds and ceilings. These areas may see more
variability in flight categories .

VFR conditions are forecast to return to all terminals by
early this afternoon with the exception of KGON where low
clouds/fog are likely to persist into Saturday night. It is
possible that the eastern terminals, KISP and KBDR hold on to
ceilings longer than currently forecast and could also see a
brief return during the evening hours Saturday.

S-SE winds under 10 kt this morning, become S-SW and increase
to 10-15 kt by afternoon. A few gusts up to 20 kt possible in
the afternoon west of the Hudson River.

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

Amendments are likely for changing flight categories as well as
timing of showers and thunderstorms through the day.

The best chance at this time for showers and thunderstorms looks
to be this morning between 09Z-13Z. Another round is possible
late this afternoon/early this evening, but confidence is lower
and activity should be more scattered in nature.

OUTLOOK FOR 06Z SATURDAY THROUGH WEDNESDAY...

Late Saturday Night: MVFR or lower possible, especially Long
Island and Southern CT.

Sunday and Monday: VFR.

Tuesday: Chance of MVFR in showers and thunderstorms in the
afternoon, mainly west of NYC.

Wednesday: Chance of MVFR 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...
Scattered showers and thunderstorms may produce locally heavy
downpours and a continues threat for minor/poor drainage
flooding this evening.

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...
High risk of rip currents until 9pm Saturday evening for all
ocean beaches.

Building onshore swell observed at ocean buoys around 4 ft with
wave period of 6 to 10 seconds going into this evening.

Ocean seas are expected to continue to build Saturday to near 5
ft and then slightly subside Sunday to near 4 ft. Onshore winds
will be relatively higher Saturday along the ocean beaches with
wind speeds of around 10 to 15 mph. The winds become more
variable in direction and decrease in speed for Sunday.

These factors will result in the high risk of rip currents
remaining at all ocean beaches of NYC and Long Island through
Saturday and into the first half of Saturday evening. There is
a moderate risk of rip currents forecast for the ocean beaches
on Sunday.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Heat Advisory from noon today to 8 PM EDT this evening for
     NYZ067-069.
     High Risk for Rip Currents through this evening for NYZ075-080-081-
     178-179.
NJ...Heat Advisory from noon today to 8 PM EDT this evening for
     NJZ002.
     Heat Advisory until 8 PM EDT this evening for NJZ004-006-
     103>108.
MARINE...Small Craft Advisory until 2 PM EDT Sunday for ANZ350-353-355.

&&

$$

SYNOPSIS...BC/JM
NEAR TERM...BC/DBR/BR
SHORT TERM...BC
LONG TERM...JM
AVIATION...DW
MARINE...BC/JM
HYDROLOGY...BC/JM
TIDES/COASTAL FLOODING...