580
FXUS61 KOKX 262326
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
726 PM EDT Wed Jun 26 2024

.SYNOPSIS...
A cold front arrives this evening into tonight with high
pressure slowly building in afterwards. A warm front lifts
north Saturday followed by a cold front on Sunday. High pressure
returns for the a start of next week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Severe Thunderstorm Watch in effect till midnight for entire
area, as an organized line of strong to severe thunderstorm
moves east into the region this evening into a marginal to
locally moderate instability and a strengthening effective deep
layer shear environment. Main threat is for scattered areas of
damaging winds gusts, particularly across NE NJ, NYC, LoHUD, SW
CT and W LI through 10pm. Depth of marine layer increases across
east LI and SE CT, and combined with waning diurnal
instability, severe threat will likely be diminishing. Secondary
threat of large hail in strongest discrete cells, and even an
isolated tornado along breaks and book-ends in the convective
line and where it interacts with perpendicular boundaries
(seabreeze/earlier convective outflow).

Localized flash flood threat where there is training of
convection over the same area. Potentially favored across
interior S CT and LoHud with interaction of linear convection
with discrete cells.

Previous Discussion...

Otherwise, a cold front will arrive this evening into tonight
with as an upper- level trough tracks over the northeast.

A current southwest flow has left the atmosphere over the area in a
warm and moist state with current dewpoints in the mid-60s to low-
70s. The latest guidance has the cold front arriving quite late this
evening into tonight. Along this boundary, a line of showers and
thunderstorms are expected to push through the area west to east. A
prefrontal trough may lead to one or two isolated
showers/thunderstorms early this evening before the main line
of storms arrives tonight. The primary line of
showers/thunderstorms is expected to arrive around 8-10pm for
western portions of the area, then push eastward through 2-4am.
Some of the CAMs have some discrepancy on this timing with a few
of them not bringing the majority of the rain in until after
midnight, so there is still some uncertainty on timing with
these storms.

There is a risk of severe weather with tonight`s storms with SPC
having the entire CWA until a Slight Risk. The main threat of
concern is strong to damaging winds in thunderstorms that may gust
in excess of 58 mph. An isolated large hail and isolated tornado
risk also exists with steep lapse rates and pockets of stronger SRH
west and north of NYC being contributing factors. A deep marine
layer will likely mean much of the severe risk will be limited to
areas north and west of NYC. Any intense storms that do develop may
become less intense as they track eastward, particularly on Long
Island. The timing of the storms will also play a factor into the
prevalence of the severe risk as the storms are expected to arrive
past the peak heating of the day with some models not bringing in
much of it until later than originally anticipated. The latest CAMs
show things quickly stabilizing after 10-11pm with the 12Z HREF
showing all SBCAPE values falling too low past 11pm. Things may
be more elevated after this time. Bulk Shear, however, remains
40-60 kts after midnight.

PWATs are currently around 1.5 inches and may peak around 1.9-2.1
inches tonight which with right around the max moving average
according to SPC`s sounding climatology page. However, with the
lining up on a mainly north to south axis along and ahead of
the front and tracking west to east, no significant training of
storms is expected. Localized instances of flash flooding are
possible, but mostly likely will only seen minor urban and poor
drainage flooding. The 12Z HREF brings around 0.5"/hr rates for
most with some areas of western and central Connecticut and
parts of the Lower Hudson Valley having a 40-60% chance of 1"/hr
rainfall rates in stronger thunderstorms. Rainfall totals are
projected to be around 0.5-1" across the area with totals an
inch or two higher than this possible in stronger thunderstorms.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
The surface cold front and upper trough will be exiting the region
early Thursday morning by 12Z. The surface low will be slowly
tracking northward Thursday and the trailing cold front may linger
just to the east and south of Long Island through much of Thursday.
High pressure will be slow to build east as the upper trough remains
across the northeast into Friday morning. There is a chance showers
linger longer into Thursday morning, however, once the front moves
east dry weather is then expected. Clearing is expected, but could
still see some lingering cloud cover around the lingering front to
the southeast until mid/late afternoon Thursday.

Highs will be in the low to upper-80s on Thursday. Thursday night
lows will drop into the mid-50s to mid-60s under clear
skies with northerly flow around 5-10 mph.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
High pressure will pass off the New England Coast from late day
Friday into Friday night, allowing a warm front to lift through on
Saturday. An unsettled but very warm period will set up for Saturday
night and Sunday as a prefrontal trough and cold front move through,
bringing shower/tstms. The heat index may approach or surpass 95,
mainly in NE NJ and perhaps also in NYC and along the north shore of
Long Island, with temps approaching 90 and dewpoints in the lower
70s, but it is possible that limited daytime heating and better
vertical mixing could lead to cooler temps and/or lower dewpoints so
this remains uncertain, and at any rate would last for only one day.

With the exception of Sunday, and possibly next Wednesday ahead of
another cold front when temps will again be on the rise, temps
should be close to normal.

&&

.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
A cold front approaches and moves through late tonight into
Thursday morning.

VFR this evening outside of TSRA. MVFR conditions possible in
with any thunderstorms. Tempo groups for TSRA 00-04Z for the
western and city terminals. There may be some isolated showers
and thunderstorms prior to this time frame, but coverage is not
high enough to include in TAFs. Any TSRA that develops may
contain strong gusty winds or hail, mainly for the associated
with the showers and thunderstorms before 04z.

MVFR conditions possible overnight, though there is uncertainty in
exactly where. Highest confidence for eastern terminals, such as
KGON and less confidence for western terminals such as KEWR and
KTEB.

SW winds 10-15 kt this evening with gusts to 25 kt. Terminals
that went southerly with sea breeze may shift abruptly to the W
between 02-04z city terminals/points N&W as outflow from
approaching TSTMs overtakes the seabreeze. W-NW wind is expected
after midnight as the cold front moves through, but this off
+/- a couple of hours than forecast due to uncertainty in the
actual cold frontal passage.

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

Amendments expected with TSRA before 04z.  Additional amendments
possible overnight due to possible stratus...especially eastern
terminals.

OUTLOOK FOR 18Z THURSDAY THROUGH MONDAY...

Thursday: Mainly VFR.

Friday: VFR.

Saturday: VFR with a chance of thunderstorms in the afternoon.

Sunday...MVFR possible in a chance of shra and tstms.

Monday...VFR.

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

&&

.MARINE...
With a strong and gusty southwest flow ahead of a cold front,
winds and seas on the ocean waters remain at SCA levels into
tonight. With winds shifting to the northwest and diminishing
ocean seas fall below advisory levels late tonight, and may
remain elevated into early Thursday morning east of Fire Island
Inlet. With the southerly strong gusts a SCA remain in effect
until late tonight for the Long Island south shore bays. Then
sub advisory conditions remain through thursday night. For the
non ocean waters, winds and seas remain below advisory levels
today through Thursday night.

There is the potential for SCA cond mainly on the ocean from Sat
night into Sunday as SW flow increases, with gusts up to 25 kt and
significant wave heights above 5 ft.

&&

.HYDROLOGY...
PWATs are currently around 1.5 inches and may peak around 1.9-2.1
inches tonight which with right around the max moving average
according to SPC`s sounding climatology page. HOwever, with the
lining up on a mainly north to south axis along and ahead of the
front and tracking west to east, no significant training of storms
is expected. Localized instances of flash flooding are possible, but
mostly likely will only seen minor urban and poor drainage flooding.
The 12Z HREF brings around 0.5"/hr rates for most with some areas of
western and central Connecticut having a 40-60% chance of 1"/hr
rainfall rates in stronger thunderstorms. Rainfall totals are
projected to be around 0.5-1" across the area with totals an inch or
two higher than this possible in stronger thunderstorms.

Basin avg QPF of up to an inch may be possible with the passing
frontal system this weekend. Locally higher amts are possible in
heavier tstms. Only nuisance issues anticipated attm.

&&

.TIDES/COASTAL FLOODING...
There is a high rip current risk at all local Atlantic facing
beaches today through early Thursday. The rip current risk likely
lowers to moderate on Friday.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...High Risk for Rip Currents through Thursday evening for NYZ075-080-
     081-178-179.
NJ...None.
MARINE...Small Craft Advisory until 10 PM EDT this evening for ANZ345.
     Small Craft Advisory until 6 AM EDT Thursday for ANZ350-353-
     355.

&&

$$

SYNOPSIS...BG/BR
NEAR TERM...BR/NV
SHORT TERM...BR
LONG TERM...BG
AVIATION...IRD
MARINE...BG/BR
HYDROLOGY...BG/BR
TIDES/COASTAL FLOODING...