Southampton, New York 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

812
FXUS61 KOKX 192002
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
402 PM EDT Sat Jul 19 2025

.SYNOPSIS...
A warm front lifts through late tonight into early Sunday morning. A
cold front follows for Sunday afternoon and evening. High pressure
builds in Monday into Tuesday, and centers over the area Tuesday
night into Wednesday. The high shifts offshore Wednesday night into
Thursday. A low passing into east Quebec Friday will bring through a
cold front late Friday into Friday night.

&&

.NEAR TERM /THROUGH SUNDAY/...
A frontal boundary which stalled over the Del Marva region is now
beginning to nudge further north. The front which sagged south and
gave the region a reprieve in terms of humidity is now moving north
and northeast as a warm front and is expected to arrive later
tonight into early Sunday morning. More clouds overall tonight as
high pressure gets east and off the New England coast tonight.
Therefore expect more in the way of clouds. With the warm front
pushing up from the south some patchy fog could very well develop
for later in the overnight into early Sunday morning. The
development of fog will have some dependence on whether shower
activity with the warm front can become widespread. The relatively
stronger mid-level trough / shortwave pivots through late tonight.
Although PWATs climb quickly, instability appears to be lacking.
Thus have only included mainly slight chance thunder with slight
chance to chance showers. Look for dewpoints to gradually rise
overnight. Therefore it gets uncomfortable again into the morning
with dewpoint readings getting into the lower and middle 70s making
for quite a muggy feel.

For Sunday the relatively higher chance of shower activity will be
further east early on in association with the exiting shortwave and
warm frontal boundary. Towards late morning most NWP guidance has a
break in any shower activity with likely partly sunny conditions
developing. This will allow things to heat up quite a bit. By early
afternoon most heat indices will get into the middle and upper 90s,
with a few locales in urban NE NJ and around NYC perhaps reaching
100. A heat advisory was not issued with minimal areal coverage of
100 degree heat indice values, but it was close. In any event, quite
uncomfortable with hot and muggy conditions in place as the region
gets behind the warm front and into the warm sector.

A cold front approach for the late afternoon and early evening. This
is expected to be the trigger for scattered to isolated thunderstorm
activity. SPC continues to split the region with a marginal risk of
severe weather for portions of LI, and a slight risk for the
remainder of the region. The main hazard with any thunderstorm will
be strong, to possibly damaging winds in any storm that could become
severe. This is in relation to a unidirectional wind / hodograph
profile along with some mid-level dry air. With a more skinny CAPE
profile and the lack of colder mid-level lapse rates (mainly above
650 mb) hail would be a lower end / more limited hazard risk.
Therefore the quantity of robust updraft occurrence is in question
with some storms perhaps struggling to become more intense. Also the
lack of a more discernible mid-level shortwave embedded in the
cyclonic flow during the late afternoon could limit thunderstorm
coverage. Overall bulk shear values look to get to or just above 30
kt with higher values just north of our area, so somewhat marginal
and not a lock for more organized, sustainable convection. Therefore
there remains conditionality to thunderstorm development, but if a
few get going they have the potential to become severe. Storms are
expected to progress along so any flash flooding risk appears
limited despite high PWATs, high mean column RH values, and warm
cloud layer heights. See the hydrology sections for further
details.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/...
The cold front is expected to swing through for the very late
afternoon across far western locations, and by 0z further east.
Behind the cold front another significant air mass change takes
place with a return to much less humid and more comfortable warmth.
As skies clear late Sunday evening and Sunday night dew point
readings fall back into the 60s early Sunday morning, and into the
50s during the day on Monday.  Monday will feature plenty of
sunshine and comfortably warm and seasonable temperatures with
mainly lower and middle 80s.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Key Messages:

 * Dry Mon Night through Thu night.

 * Showers & thunderstorms possible with cold front Fri/Fri night.

 * Seasonal/below seasonal temps Mon night - Tue night.

 * Temps climb Wed into Thu. Heat index may exceed 100 by Fri.

In the upper-levels, a ridge builds in from the west and amplifies
over the eastern US Monday night through Wednesday night. This ridge
then flattens Thursday into Thursday night. Shortwave energy passes
late Friday into Friday night.

At the surface, high pressure builds in Monday night into Tuesday,
centers over the area Tuesday night into Wednesday, then shifts
offshore Wednesday night into Thursday. A low passing into east
Quebec Friday moves into the North Atlantic Friday night into
Saturday. This low brings through a cold front late Friday into
Friday night.

Monday night through Tuesday night will be mainly clear and sunny as
high pressure builds in. However, with high pressure to our west,
northerly flow will keep cooler 850 mb temps around, limiting
surface temperature potential. Highs on Tuesday will be below
seasonal norms in the upper 70s to low 80s. Lows both Monday and
Tuesday nights will be in the upper 60s to low 70s at the coast and
down into the low to mid 60s in the interior.

Wednesday through Friday, temperatures will warm each day in
response to the high moving east and higher heights aloft. Heat
index values may exceed 95 on Thursday for parts of the area, then
exceed 100 for large portions of the area on Friday.

With ample heating, shortwave energy passing aloft, high dewpoints &
atmospheric moisture, and lift from an approaching/passing cold
front, scattered showers and thunderstorms are expected late Friday
into early Friday night.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
High pressure moves offshore this afternoon, giving way to a
warm front approaching from the south this evening. The warm
front is forecast to pass over Long Island late tonight into
Sunday morning. A cold front approaches Sun afternoon, crossing
Sun evening.

Spotty shower activity likely developing for aft/early eve
push for NYC/NJ metro terminals, with MVFR cigs possible.
Increasing likelihood of MVFR cigs for most terminals overnight
(aft 00-03z), continuing through Sun AM push. Low prob for IFR
cigs.

Scattered showers and isolated thunderstorm threat late tonight into
Sun am push, highest confidence is for the coastal terminals
east of NYC/Nj metro. Drying conds and becoming VFR later Sun
AM. Then potential for iso-sct line of convection between
19z and 24z Sun with approaching cold front, with a severe wind
gust threat.

Southerly winds at 8-12kt with occasional gusts 15-20kt this
afternoon into early evening, then light SW or variable late
tonight into Sun AM push. SW winds 10-15ktg20kt Sun afternoon.

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

Spotty showers and MVFR cigs possible for late aft/eve push.
Low and sparse coverage of tsra between 08z through Sun AM
push, higher prob to the east. MVFR conds likely after 00z thru
Sun AM push. Low prob of IFR. Timing of MVFR and TSRA may be
off by 1-2 hours and need to refined.

S winds 12-15ktG18kt likely for KJFK, possible for KLGA, btwn
20z and 24z with coastal jet this afternoon.

.OUTLOOK FOR 18Z SUNDAY THROUGH THURSDAY...

Sunday aft/eve: MVFR AM, improving to VFR late morning.
Potential for iso-sct line of convection between 20z and 24z Sun
with approaching cold front, with a severe wind gust threat.
Otherwise, SW winds 10-15g20kt Sun aft/evening.

Sunday night into Monday: VFR. NW winds 15g20kt.

Monday Night through Thursday: VFR.

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

&&

.MARINE...
Winds and waves look to stay below Small Craft Advisory criteria
through the weekend and into next week with a weak pressure
gradient in place. However, there is potential for strong to
possibly a few severe thunderstorms late Sunday afternoon and
evening. Locally stronger wind gusts and higher waves are
possible in any thunderstorms.

Winds & waves are likely to remain below SCA thresholds through
Thursday.

&&

.HYDROLOGY...
WPC has the area in a marginal risk of excessive rainfall through
the day Sunday. At this time more nuisance urban poor drainage type
flooding is anticipated in association with any thunderstorm
activity as storms are expected to progress along.

No hydrologic concerns in the long-term forecast.

&&

.TIDES/COASTAL FLOODING...
Mainly a low rip current risk on Sunday, with the exception being
for the eastern Suffolk ocean beaches where a moderate risk is more
likely by afternoon with lingering E to SE 8 second period swells. A
low rip current risk is expected for all ocean beaches on Monday
with more of a land breeze out of the northwest.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.

&&

$$

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