North Hempstead, New York 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

036
FXUS61 KOKX 022224
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
624 PM EDT Fri May 2 2025

.SYNOPSIS...
A cold front slowly approaches and stalls nearby into Sunday.
A large cut-off low pressure system will bring unsettled
conditions to the area from the weekend through at least mid
week. High pressure may move in for the end of the week.

&&

.NEAR TERM /THROUGH SATURDAY/...
Forecast remains on track with only minor adjustments to account
for the latest observations. Any showers or isolated
thunderstorms should diminish through the evening as they move
into a more stable environment.

For tonight with the region clearly in the warm sector look for mild
and slightly humid conditions. Closer to the immediate shore,
especially early on in will be a bit cooler with an onshore wind.
Wind lighten during the night with well above normal temperatures
overall. Lows will mainly be in the lower half of the 60s across the
NYC / NE NJ metro, with mainly middle through upper 50s elsewhere on
a light S flow. Regarding precip chances there is some instability
indicated by mesoanalysis, especially just upstream and also revealed
in the mid levels via BUFKIT fx soundings. With the loss of daytime
heating any shower activity will be random due to a lack of forcing.
Cannot totally rule out a random shower / thundershower popping up
during the night with mainly slight chance PoPs.

During Saturday look for a good start to the day, with mainly
partial sunshine and it will warm up once again like the previous
day. With the cold front drawing closer the synoptic flow out of the
south should increase some.  This will have coastal communities
cooler down a bit earlier in the day compared to the previous day.
There will be a rather large spread in temperatures by later in the
afternoon with inland locations towards and west of the NYC / NJ
metro getting into lower and middle 80s once again, and closer to
the coast residing in the 70s, and 60s closer to the immediate
coast. The Storm Prediction Center (SPC) has mainly the western
third of the CWA, mainly from the city and the Hudson River more or
less to the west in a marginal risk of severe weather to begin the
weekend on Saturday. The latest mandatory levels forecast of mass
fields indicate some ridging, mainly further aloft for eastern
portions of the region. This helps to explain why CAM guidance is
showing convection, especially organized quasi-linear convection
having difficulty moving further east later Saturday and Saturday
night. This results in going with a PoP profile that has likely and
categorical PoPs across the more NW portions of the area, with PoPs
trailing off further east and south. There are discrepancies in the
severe indices, especially with regard to CAPE later Saturday and
Saturday evening. The RAP and NAM 3km guidance indicated CAPE
approaching and exceeding 1000 J/kg, with other guidance showing
less CAPE with this all being location dependent. For now have gone
with enhanced wording of gusty winds and small hail with any
convection that initiates Saturday afternoon and evening. The
convection will attempt to initiate along a thermal pre-frontal
trough in the afternoon and evening. Since the cold front is progged
to stall just to the western border of the CWA, there remains how
far east any organized convection and steadier rainfall will get.
Thus have maintained chance to even slight chance PoPs along with
slight chance thunder further east across the area.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY/...
Any convection should gradually dissipate Saturday night with the
region still being east of the cold front it will be rather mild and
a touch humid with cloud cover lingering. Look for minimum
temperatures to be similar to the previous night with mainly middle
50s to lower half of the 60s. Some patchy fog may even form, more so
where any convection occurred previously during the evening.

On Sunday look for clouds to linger with a S to SE onshore flow. Low
pressure becomes more or less vertically stacked back to our WSW.
This will gradually draw closer during the second half of the
weekend. Most guidance keeps the region primarily dry through the
morning and perhaps the start of the afternoon. By later in the day
PoPs increase as per NWP as moisture begins to lift north from the
south. Moisture begins to advect in off the ocean and rain chances
increase later in the day. There remains uncertainty as to how far
north and where the moisture advection access sets up. For this
reason, have chosen to begin main lower end PoPs earlier in the day,
then raise PoPs throughout the afternoon to mainly chance, and
likely across western areas. WPC has placed mainly the western half
of the area in a marginal risk of excessive rainfall for both
Saturday and Sunday. See the hydrology section for further details.
With thicker cloud cover overall and a bit more of an easterly
component to the near sfc winds, have temperatures mainly in the
upper half of the 60s, to the middle 70s across inland locations on
Sunday.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
The extended period will be dominated by a large cut-off low
pressure system which will bring periods of rain, possibly with
embedded thunderstorms, from the weekend through at least the middle
of next week.

The large cut-off mid-level low spinning nearly stationary over the
Ohio Valley on Sunday night will allow for a surface frontal system
to develop downstream, just to our west. This frontal system will
likely set up and evolve in such a way that our area will be under a
deep southerly flow for the better part of next week. Meanwhile, a
mid-level ridge to the east will allow for a surface high pressure
system to prevent the progression of the cut-off low and enforce a
S to SE flow much of the period.

Global models have some agreement in allowing for a continuous
stream of moisture moving over the area allowing for periods of
widespread light to moderate rainfall Sunday night through Tuesday
night of next week. There still remains some uncertainty as to how
much of the ridging to the east is able to dry out parts of the
area, but at a minimum it should allow a gradient of the heaviest
and more persistent rainfall through the period with eastern areas
receiving less rainfall than western areas.

There may be enough instability during this timeframe to allow for
some embedded thunderstorms to develop as well, and given the deep
moisture profile under a southerly flow, heavy rain will be possible
in any storm or convective cells. WPC has the area in a marginal
risk for excessive rainfall for Monday through Wednesday morning
with a widespread 1-3 inches of rainfall over the area over the next
5 days with lesser amounts for eastern areas and higher amounts for
the west. Any thunderstorms may allow a locally higher rainfall
total of near 4 inches through the next 5 days.

The low pressure is expected to move out of the area sometime
Wednesday night through Friday morning. Models differ on the cut-
off`s reintroduction to the mean flow and as a result opted to keep
at least slight chance PoPs through the timeframe to account for the
uncertainty in its departure, though its possible that high pressure
builds into the area by Friday.

Despite ample cloud cover and rainfall, temperatures through the
timeframe should be fairly seasonable to slightly below average,
with highs each day generally in the 60s, possibly a bit warmer for
the NYC metro. Lows each night will remain in the 50s, courtesy of
the ample amounts of moisture.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
A cold front over the eastern Great Lakes will drop slowly SE
through Saturday, stalling near or just NW of the terminals
Saturday night.

Mainly VFR through the TAF period with a brief period of IFR/MVFR
across the eastern terminals late tonight in low clouds/fog. An
isolated shower or thunderstorm is possible during the time, but
the best chance will be at KSWF from 20Z-24Z Saturday with the
cold front.

Winds will be S/SW this afternoon 10-15kt with g20-25kt. Winds
then diminish to less than 10 kt this evening and in some cases
become light and variable. S winds will then ramp back up
Saturday morning and afternoon.

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

KJFK may be sustained for a time around 20kt late this
afternoon.

An isolated shower or thunderstorm is possible through the
period.

Low-level winds overnight may become light easterly.

There is a low chance of IFR/LIFR at KJFK from 09Z-12Z
timeframe.

.OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...

Saturday Afternoon/Evening: Showers/tstms likely across the
Lower Hudson Valley with scattered activity elsewhere. S winds
G20-25kt in the afternoon.

Sunday: Chance of MVFR or lower in showers/tstms. Best chance
will be in the afternoon and nighttime hours.

Monday: Showers/tstms likely with MVFR or lower cond expected.
E-NE winds G20-25kt.

Tuesday: Showers/tstms likely with MVFR or lower cond expected.
SE winds G15-20kt.

Wednesday: Chance of MVFR or lower in showers.

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

&&

.MARINE...
Sub small craft conditions for the non-ocean waters tonight, with
the ocean waters experiencing small craft conditions much of the
time with gusts to 25 kt marginal small craft seas. By early
Saturday morning sub advisory conditions return briefly before small
craft conditions return out on the ocean for Saturday afternoon and
evening. There will be a chance of thunderstorms, more so on the
western waters Saturday evening. Sub advisory conditions will then
return early Sunday morning and should last through the day with a S
to SE flow at around 10 to 15 kt.

Generally sub-SCA conditions are expected after Sunday night, but
there may be occasional near-SCA gusts and wave heights on the ocean
nearing 5 feet Monday and then again on Tuesday.

&&

.HYDROLOGY...
WPC has placed mainly western portions of the area in a marginal
risk of excessive rainfall during Saturday and Sunday. At this time
mainly minor urban nuisance related flooding is expected in relation
to any thunderstorms that develop mainly across the western half of
the area as antecedent conditions are a bit drier than normal in
much of the area.

Long duration rainfall this weekend through midweek will likely
result in a widespread 1.5-3 inches of rainfall, possibly locally
higher in any thunderstorms. The higher rainfall amounts are
expected to be for the western half of the area. WPC has the area in
a marginal risk for excessive rainfall Monday through Wednesday
morning. While flash flooding isn`t expected, minor urban or poor
drainage flooding is possible at any point Saturday night through
Wednesday.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ350-353.
     Small Craft Advisory until 4 AM EDT Saturday for ANZ355.

&&

$$

SYNOPSIS...JE/MW
NEAR TERM...JE/MW
SHORT TERM...JE
LONG TERM...MW
AVIATION...DW
MARINE...JE/MW
HYDROLOGY...JE/MW