981
FXUS61 KOKX 270248
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
1048 PM EDT Wed Jun 26 2024

.SYNOPSIS...
A cold front moves through overnight into Thursday 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/...
Line of strong to severe thunderstorms continue to advance east
through southern Connecticut as of 230Z, with isolated sub
severe cells farther back toward the NYC metro. This activity
should gradually weaken over the next couple of hours, but
additional showers, perhaps with a few embedded thunderstorms,
may approach once again from the west as the cold front moves
through into the early overnight hours. Severe Thunderstorm
Watch remains in effect til midnight for the entire region, and
damaging winds or large hail remain possible. The activity
appears to be moving quickly enough to preclude flooding more
than the localized nuisance issues as long as cells don`t train
over a particular area.

Previous Discussion...

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.

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 FRIDAY/...
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 NIGHT THROUGH TUESDAY/...
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 /03Z THURSDAY THROUGH MONDAY/...
A cold front moves through late tonight into Thursday morning.

VFR this evening outside of TSRA. MVFR conditions possible in
with any thunderstorms. Thunder chances lower after 4Z, but
showers likely persist toward early morning before exiting west
to east and drying out.

MVFR conditions are possible overnight should low stratus or
mist be able to develop, close to daybreak, though there
remains uncertainty in exactly where. Highest confidence for
eastern terminals, such as KGON and less confidence for western
terminals such as KEWR and KTEB.

Flow is a bit chaotic into the early overnight with nearby
front, but general W-NW wind expected to develop after midnight
as the front moves through, but this off +/- a couple of hours
than forecast due to uncertainty in the actual cold frontal
passage. Increasing WNW flow Thu afternoon 10-15G20-25kt, and
sea breeze development likely shifts coastal terminals S or SW.

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

Amendments possible overnight due to possible stratus.

OUTLOOK FOR 00Z THURSDAY THROUGH MONDAY...

Thursday PM: VFR. WNW gusts 20-25 kt.

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 Thursday. The rip current risk 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 6 AM EDT Thursday for ANZ350-353-
     355.

&&

$$

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