624
FXUS61 KOKX 301450
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
1050 AM EDT Fri May 30 2025
.SYNOPSIS...
An area of low pressure will pass well to the south early today
followed by a stronger approaching low late today. This low
will pass late tonight then exit northeast into New England
Saturday night. This sends a cold front through on Saturday into
Saturday night. High pressure will then gradually build in
through the middle of next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
Forecast generally on track with just some minor adjustments to
current observations.
Otherwise, a weak wave of low pressure/surface trough feature
passes well to the south over the Atlantic early today as a much
stronger low approaches us today. This well-developed low will
pass near or just east of NYC late tonight into early tomorrow
morning.
A few showers and thunderstorms are possible ahead of the
approaching low this evening, with rainfall coverage increasing
significantly with the arrival of the main shield of precip tonight.
Given the location of the low near or slightly east of NYC late
tonight (which 00Z CAMs seem to be in good agreement on), expecting
the heaviest axis of QPF (with some moments of moderate to heavy
rainfall) in the Lower Hudson Valley and western Passaic county.
Minor nuisance flooding is possible, but much of the precip
should occur over a long enough time frame to negate most
concerns for flash flooding. However, an isolated occurrence of
this can still not be ruled out for this area of higher QPF.
This would mainly occur from a 3 to 6 hour window Friday night
when the heaviest rainfall is expected.
Given ample forcing and instability ahead of the low with PWATs
around the 90th percentile to near max moving average, have included
a chance for thunderstorms in the forecast. Other parameters do not
seem to indicate a good chance for severe weather, so sticking with
just general thunderstorms with this system.-- End Changed Discussion --
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
A mid-level shortwave trough embedded in the longwave trough
passes early Saturday which aids in surface low pressure exiting
the CWA and into New England. This is followed by a longwave
trough further developing into the northeast late Saturday into
Saturday night.
As the surface low exiting, a cold front will get sent through late
on Saturday. Prior to this, light showers may still be prevalent
in the area. With and just prior to the frontal passage, enhance
lift may lead to marginal instability and a returning chance
for thunderstorms. With the thunderstorm chances comes another
brief round of possible downpours, the coverage of which will be
lower than on Friday night.
Total rainfall from Friday night through Saturday is expected to be
1.5-1.75" in the Lower Hudson, closer to 1" for NYC, dropping closer
to 0.75" for eastern Long Island and SE CT.
Following the front`s exit, drier air gets filtered in, cutting off
precip, under steady NW winds. The winds should become breezy, at
times, under an increased pressure gradient from the low exiting
northeast.
Dry, cold air advection from the cold front will lead to lows Sat
night back into the low-50s to mid-40s. Cooling will continue
through Sunday as an upper-level trough remains over the region with
highs on Saturday in the low-70s to upper-60s dropping to the
mid/upper-60s on Sunday.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Upper trough axis and shortwave lift will maintain shower chances
during Saturday night with a higher likelihood being east of the
city and before midnight.
Upper troughing will remain over the Northeast into eastern Canada
early next week. High pressure off to our west will be slow to build
eastward with low pressure meandering over eastern Canada during
this time period. The forecast remains dry Sunday night into Monday
despite cyclonic flow aloft. However, multiple shortwaves spinning
around the larger trough could introduce scattered to broken clouds
at times, especially Monday afternoon. The axis of the trough should
shift to our east Monday night into Tuesday allowing ridging to
build towards the area into late Tuesday through Wednesday with the
continuation of dry conditions. Models continue to differ regarding
potential development of a cutoff h5 low over the western Atlantic,
which if it forms would get trapped underneath upper ridging over
the eastern seaboard. There is also potential for showers and
thunderstorms from a potential cold front as the ridge weakens on
Thursday. Capped PoPs at 30 percent given this is a week out.
Temperatures for Monday will trend closer to normal in the lower to
middle 70s. A warming trend then continues through mid week with
temperatures by Wednesday more summer-like. Highs based on the
latest model consensus (NBM) will be in the 80s for much of the area
except near the coast where sea breezes may hold temperatures in the
upper 70s. Similar conditions are possible on Thursday.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
A weak low pressure trough remains nearby today, then a low
pressure center passes through early Saturday morning.
VFR at NYC and Lower Hudson Valley terminals through early this
evening. Across Long Island and coastal Connecticut terminals,
IFR-MVFR should continue this morning with improvements
expected into the afternoon. An isolated shower possible
through this afternoon.
Conditions will begin lowering early this evening across Long
Island and southeast CT terminals with LIFR-IFR becoming likely
towards 23-00z. Elsewhere, MVFR-IFR should develop as rain
begins to overspread the terminals from southwest to northeast.
IFR is likely overnight with moderate to heavy rain. There is
also a chance for a few thunderstorms and will continue with a
PROB30 for this potential. Conditions should start improving
early Saturday morning as low pressure begins lifting northeast
of the terminals, with VFR returning around day break.
Light S-SSW flow to start will become S-SSE through the
afternoon, generally 10 kt or less. The flow weakens briefly
tonight before strengthening as winds shift to the E-NE and then
NW by day break Saturday.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Tempo MVFR-IFR cigs at KJFK possible before 17-18z.
Isolated shower possible through this afternoon.
Amendments expected for timing of lowering conditions, rain, and
possible thunderstorms tonight into early Saturday morning.
.OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY...
Saturday: Showers possible with a chance of thunderstorms,
especially in the afternoon into the evening. SW-W winds G15-20kt
possible.
Sunday through Tuesday...VFR.-- End Changed Discussion --
&&
.MARINE...
A weak gradient will reside across the waters with sub-SCA
conditions through Friday night. A building southerly swell is
forecast to bring SCA conditions to ocean waters on Saturday
afternoon lasting into Saturday night. There is still some
question on if marginal SCA conditions will linger into early
Sunday or subside. Late Sunday into Sunday night, sub-SCA
conditions are expected.
A relatively weak pressure gradient should lead to conditions
below SCA levels Sunday night through Tuesday.
&&
.HYDROLOGY...
Total rainfall from Friday night through Saturday is expected to be
1.5-1.75" in the Lower Hudson, closer to 1" for NYC, dropping closer
to 0.75" for eastern Long Island and SE CT.
Minor nuisance flooding is expected primarily in urban or poor
drainage spots N & W of NYC. While there is not a significant
concern for flash flooding, an isolated instance of flash
flooding can not be ruled out for a 3 to 6 hour window, when
rain rates are expected to be locally enhanced, late Friday
night in western Passaic county and the Lower Hudson Valley. WPC
has also drawn a Slight Risk for Excessive Rainfall through
much of Orange county and into western Passaic county, for this
risk.
&&
.TIDES/COASTAL FLOODING...
Water levels may just barely touch minor flood benchmarks possible
in the most vulnerable spots with the high tide cycles tonight due
the passage of a deepening low pressure system. No statements have
been issued. No additional coastal flooding is expected this weekend
into early next week.
There is a moderate risk for rip current development through
this evening with SE swells lowering to 4 to 5 ft. A moderate
risk for rip current development continues on Saturday with the
continuation of SW swells.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...BR/DS
NEAR TERM...BC/BR
SHORT TERM...BR
LONG TERM...DS
AVIATION...JC/DS
MARINE...BR/DS
HYDROLOGY...BR/DS
TIDES/COASTAL FLOODING...