Issued by NWS Upton, NY
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Versions:
784
FXUS61 KOKX 181921
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
321 PM EDT Sun May 18 2025
.SYNOPSIS...
Low pressure continues to spin over the Northeast through Monday.
high pressure builds in to the north Monday night and through
Tuesday. Low pressure passes south of the area Wednesday into Thursday,
then gradually departs northeast offshore and into the Canadian
Maritimes Thursday night through Saturday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
An occluded surface low pressure system is spinning over northern
New England with an upper level trough coincident with it. As this
low spins, additional pieces of mid-level energy will pivot through
the area, approaching from the northwest. This will be realized at
the surface as a series of secondary cold fronts, the first of which
moves through this evening.
Increasingly cloudy skies this afternoon and evening should begin to
clear out a bit overnight behind a secondary cold frontal passage. A
few showers can`t be completely ruled out this evening, but any
shower should be isolated and fairly light in intensity. Gusty winds
may persist overnight, but given the surface inversion that is
expected to set up, some diminishing in gusts is possible tonight.
Lows tonight are expected to be in the 50s, warmer at the coast.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
By daybreak Monday, the low and trough push a bit more northeast
with another mid-level shortwave approaching from the northwest.
Ample dry air in the mid-levels however should limit the cloud cover
during the day. Despite ample sunshine, the upper trough still
generally overhead will limit the potential for warming at the
surface. Highs are expected to rise into the upper 60s to low 70s,
though some spots may hit the middle 70s. Expect a dry and mostly
clear day with a persistent NW flow, though gusts should be
generally diminishing through the afternoon and evening as high
pressure slowly builds in from the north and west.
Some subtle mid-level ridging will accompany the building surface
high pressure Monday night and into the day Tuesday. Dry and mostly
clear conditions are expected during this time frame. Lows Monday
night will be a bit on the cooler side with outlying spots possibly
radiationally cooling lower than forecast. Lows Monday night will
generally be in the middle 40s to low 50s, but outlying spots may
cool to the low 40s.
High pressure remains overhead on Tuesday with a persistent but
weakening N/NW flow. This should keep high temperatures in the upper
60s to low 70s once again.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Key Messages:
* A frontal system impacts the region Wednesday through Saturday.
* Most rainfall, with periods of moderate intensity, will occur
Wednesday into Thursday.
* An upper-level trough with a surface trough from the departing
low leads to continued clouds and small rain chances Thursday
night through Saturday.
Cloud cover increases Tuesday night as winds turn easterly ahead of
an approaching low. This low will be located over the OH River
Valley Tuesday then move in western NY Tuesday night. However, the
northern jet stream it follows weakens as a stronger southern jet
stream increases. This leads the northern low weakening as a new low
develops in the left exit region of the southern jet stream to our
south off the mid-Atlantic coast Tuesday night. This southern jet
develops along the southern periphery of an upper/mid-level
trough that sets up over the north east on Wednesday.
The mid-Atlantic low, along with the weakening low in western New
York then brings period of rainfall, moderate intensity at times,
Wednesday morning into the day on Thursday. This is aided by PWATs
between 1-1.25", and pieces of mid-level energy passing around the
mid-level trough located over the region. Easterly flow also
increases as the low deepens to our south, increasing the pressure
gradient. Areas near the coast could see easterly gusts of 25 to 35
mph during this time frame, particularly on Thursday as the low gets
deeper and closer to the area to our south.
Thursday night, the low moves east of the area. Most precip will
likely get cut off as this allows winds to turn back N/NW, bringing
in drier air and slight cold air advection aloft.
Friday into Saturday, the low moves farther away from the area to
our northeast. However, a surface trough will linger from the low
over the area while an upper-level trough continues to remain in the
area. This may be all we need to to keep up cloud cover and lead to
small chances for light showers to start the weekend. Confidence in
this is low, given its possible that dry air and weak cold air
advection aloft could be enough to hinder any showers developing.
Saturday night, the upper-level trough finally departs the region to
the east, leading to dry and mostly clear conditions.
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
Low pressure over Northern New England slowly moves towards the
Canadian Maritimes into Monday.
VFR. Brief shower/sprinkle possible at KSWF into early this evening.
W-NW winds 15-20 kt, with gusts 25-35 kt. The highest gusts should
occur NYC and coastal terminals. Winds tonight will be NW at 10-15
kt with gusts 20-25 kt. Some outlying terminals may see gusts
briefly end. NW winds increase after 12z Monday, becoming 15-20 kt
with gusts 25-30 kt into the afternoon.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Gusts may briefly end or become occasional 08-12z.
.OUTLOOK FOR 18Z MONDAY THROUGH FRIDAY...
Monday Afternoon-Night: VFR. NW winds G25-30 kt into the evening.
Gusts up to 20 kt possible overnight, especially Long Island and
Southern Connecticut.
Tuesday: VFR.
Wednesday: MVFR or lower with showers likely, especially in the
afternoon into the night. E wind gusts 15-20kt.
Thursday: MVFR or lower possible in showers. NE winds G20-30kt,
highest across southeastern Connecticut and eastern Long Island.
Friday: MVFR possible. Chance of showers.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
SCA conditions continue on all waters through Monday afternoon with
gusts 25-30kt possible on the water. There may be a lull in gusts
tonight but SCA gusts are expected to ramp back up by daybreak
Monday so kept it extended all the way through Monday evening. Sub-
SCA conditions then expected on all waters Monday night through
Tuesday night.
With the approach of a frontal system during Wednesday, an easterly
flow will be increasing, and by late day SCA conditions are likely
to develop on the ocean waters. With the increased and persistent
east flow Wednesday night SCA conditions become likely across all
the forecast waters Wednesday night and continue into Thursday. A
brief period of near gale force gusts are possible on the ocean
waters east of Moriches Inlet Thursday.
As the low tracks northeast of the area Thursday night a northerly
flow develops and winds diminish west to east, falling below
advisory levels Thursday night. However, ocean seas are likely to
remain elevated through Friday, and possible into Friday
evening.
&&
.HYDROLOGY...
There are no hydrologic concerns through the week.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 PM EDT Monday for ANZ331-332-335-
338-340-345-350-353-355.
&&
$$
SYNOPSIS...BR/MW
NEAR TERM...MW
SHORT TERM...MW
LONG TERM...BR
AVIATION...DS
MARINE...BR/MW
HYDROLOGY...BR/MW