571
FXUS61 KOKX 111815
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
215 PM EDT Fri Apr 11 2025
.SYNOPSIS...
Low pressure developing along the Mid Atlantic coast this
afternoon will track slowly northeast through the weekend,
passing to the south and east of Long Island Saturday, and
then east of New England on Sunday. Weak high pressure builds
in through Monday. A frontal system will approach from the west
Monday night, with a cold frontal passage expected late Monday
night into early Tuesday morning. Another cold front will move
through Tuesday night. High pressure then remains centered to
the south and west thereafter through next Thursday.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A small area of light rain has worked in from the SW across NJ
into the NYC metro. This appears to be associated with weak
warm advection. Much of the guidance dissipates this area into
this afternoon before a more widespread area moves in later this
evening.
Otherwise, a secondary low will develop along the Mid Atlantic
coast this afternoon in response to a digging upper trough. Much
of the rain today will remain to the south and west along a
surface trough. Highs today will be in the upper 40s to near
50, being kept below average by an increasing easterly flow off
of the ocean.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
The low pressure developing along the Mid-Atlantic coast will
slowly approach the area from the south tonight. Much of the
area on the north side of the low pressure system will see
fairly strong frontogenetical forcing allowing for the
blossoming of precipitation, primarily in the form of rain, this
evening and into the overnight period. As the low approaches
and strengthens, an increasing easterly and then northerly
component to the wind will usher in colder air from the north.
While much of the moisture will fall in the form of a widespread
moderate rainfall, some areas in the Lower Hudson Valley and
interior southern Connecticut may cool off enough to mix with
some snow late tonight and into the early morning on Saturday.
There remains an unusual amount of uncertainty as to the
occurrence and duration of any snowfall as any snow
accumulations will likely be heavily dependent on the timing and
intensity of any snowfall. Dynamic cooling of the column may
support the transition to primarily snow for at least a brief
time, which would increase confidence in and accumulating
snowfall for portions of the interior, however this is also
difficult to pinpoint until it occurs as temperatures will be
marginal. As of now, snowfall accumulations through Saturday
morning are expected to be 1 inch or less, mainly for the higher
elevations of the Lower Hudson Valley and interior SW
Connecticut, though it`s possible some locations see more than 1
inch depending on any mesoscale features and intensity of
precipitation.
By Saturday morning, the low stalls south of the area and drifts
slowly eastward through the day and into Saturday night. Much of
the strongest forcing should move north of the area and along
with it the more persistent precipitation. Residual showers
remain possible through the day Saturday, but chances decrease
fairly quickly later in the day. Highs Saturday will be much
cooler than average under a northerly flow, with highs only in
the low to middle 40s.
Thew low slowly drifts into the Canadian Maritimes Sunday with a
weakening northerly flow. Isolated showers remain possible,
especially for the easternmost areas. As the low pulls away,
some breaks in the clouds are possible Sunday as temperatures
rise into the middle 50s.
Total rainfall amounts of around an inch are possible, with a
bulk of the rainfall occurring tonight and into early Saturday.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
Models in good agreement with a 500mb ridge moving into the area
Sunday night, with its axis shifting through during Monday night.
This along with weak surface high pressure keeps us dry through the
daytime on Monday. A digging 500mb trough will help push a cold
front through during the earlier hours of Tuesday morning. Ahead of
it, a 50% chance of warm advection rainfall. Still a chance of
showers during the rest of Tuesday with a cyclonic flow aloft, but
most of the day should be dry. Moderate to high confidence of no
significant impacts anticipated with this system, even if a rumble
of thunder can`t be ruled out during Monday night.
A stronger, but moisture-starved cold front follows for late Tuesday
night, then upper ridging doesn`t return until Wednesday night into
Thursday, resulting in a slow return of high pressure. Dry weather
expected for Tuesday night through Thursday.
NBM looked good for temperatures through the long term forecast with
generally no more than about a 5 degree difference between the 25th
and 75th percentiles.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
High pressure off the northern New England coast weakens late
tonight as low pressure along the mid Atlantic coast tracks
slowly north to northeast tonight through Saturday.
Variable conditions at the NYC metro terminals this afternoon
with VFR at KLGA and KJFK with periods of MVFR possible, and
KEWR and KTEB MVFR with periods of VFR. To the east VFR prevails
into this evening. Mainly dry, with scattered light rain around
the NYC metro area this afternoon. Rain moves in from the south
this evening with conditions lowering to MVFR and then IFR by
late tonight. Timing of the lowering conditions is uncertain and
may be off a couple of hours, depending on movement of the low
to the south. IFR then remains through the forecast period.
There is a low chance of LIFR along the coast late tonight into
Saturday morning.
E-ENE winds 10-15 kt with occasional gusts up to 20 kt possible.
Gusts become more frequent late this afternoon 20-25 kt, and by
late tonight 25 to around 30 kt, with the highest winds along
the coast. Winds back to NE this evening, and to N toward 18Z
Saturday. A period of LLWS is likely at KISP, KBDR, and KGON 06Z
to 14Z, with winds at 2K ft up to 50 kt.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Occasional gusts up to 20 kt this afternoon, becoming frequent
this evening. Gusts to around 30 kt possible late tonight. And
there may be a brief period of LLWS around 07Z at KJFK and KLGA,
with 2K ft winds 060 at 50 kt. Timing of flight category changes
could be off by 1-2 hours.
.OUTLOOK FOR 18Z SATURDAY THROUGH WEDNESDAY...
Saturday afternoon: IFR. Rain tapers to a chance of showers
Saturday night, becoming MVFR late at night. NE/N winds 10-20
kt with gusts to around 25 kt.
Sunday: MVFR early becoming VFR. Chance of showers east of the
NYC terminals.
Monday: VFR. Chance of showers late at night.
Tuesday: VFR. Slight chance of showers. W wind gusts 20-25 kt.
Wednesday: VFR. NW wind gusts around 25 kt.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Low pressure developing south of the area and approaching will
allow gusts to increase later today and wave heights to increase
on the ocean as well. Small craft advisories are in effect
beginning at 16Z on the ocean with gusts near 25kt and seas
building above 5 feet. By 22Z, gusts will increase and become
more widespread so SCA conditions will be likely on all waters
with gales likely on the ocean tonight. A Gale Warning is now in
effect for the ocean through 22Z Saturday for wind gusts of
35-40kt possible. SCA conditions then prevail for the ocean with
residual wave heights greater than 5 feet through at least
Sunday.
Sub-advisory conditions for Sunday night through Monday night. Next
chance of SCA conditions will be on Tuesday, mainly on the ocean for
both winds and seas, but there could be a few gusts to 25kt on the
other waters as well.
&&
.HYDROLOGY...
QPF from tonight through Saturday night has trended downward,
averaging around an inch for most places. Long duration of
this rainfall should preclude any impacts.
&&
.TIDES/COASTAL FLOODING...
A persistent ENE-NE flow through Saturday night will likely cause
some tidal piling through the period with chances of minor coastal
flooding in some areas. It appears that all areas will fall short of
flooding benchmarks with tonight`s high tide cycle, and with the
morning high tide cycle being the lower of the astronomical tides,
levels likely fall short during Saturday morning as well. Best
chance will therefore be during Saturday night with the higher
astronomical tide and accumulated piling. At least a statement could
be needed Saturday night for the south shore back bays of Nassau
County and Queens, as well as parts of NY Harbor and far western LI
Sound.
Water levels may approach minor coastal flood benchmarks in
parts of the NY Harbor area with the high tide cycle tonight
and Sat night due to persistent onshore flow and tidal piling.
This may occur on the back bays of Nassau tonight as well.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory from 6 PM this evening to 6 PM EDT
Saturday for ANZ331-332-335-338-340-345.
Small Craft Advisory until 6 PM EDT this evening for ANZ350-
353-355.
Gale Warning from 6 PM this evening to 6 PM EDT Saturday for
ANZ350-353-355.
&&
$$
SYNOPSIS...JC/MW
NEAR TERM...DW/MW
SHORT TERM...MW
LONG TERM...JC
AVIATION...MET
MARINE...JC/DW/MW
HYDROLOGY...JC/MW
TIDES/COASTAL FLOODING...