341
FXUS61 KOKX 210046
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
846 PM EDT Thu Mar 20 2025
.SYNOPSIS...
A cold front with developing low pressure will impact the region
tonight, and pass east on Friday. A high pressure ridge will
briefly slide in for late Friday into Friday night. Another cold
front will move through Saturday night. High pressure will
briefly return again on Sunday before a stronger frontal
system moves through on Monday. Weak high pressure will return
on Tuesday, with another low pressure system possible for
mid week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --
A quick update to include a slight chance for thunder, mainly
for the western half of the forecast area through midnight as
lightning was observed across portions of NYC and points north
and west. Current SPC mesoanalysis is showing MUCAPE of up to
1000 J/kg, so the instability is elevated.
The forecast has been updated to include drizzle across most
of the coastal areas. Anticipating areas of dense fog for the
same areas, so a special weather statement has been issued to
address this for the next few hours. The dense fog has persisted
and become more widespread. A Dense Fog Advisory has been issued
for Long Island and portions of southern Connecticut (excluding
souther Fairfield) until 1 am Friday. As the cold front
approaches and rain enters these areas, the dense fog is
expected to improve somewhat. There is a chance that conditions
improve prior to this time frame.
Leading edge or rain should hold off in our CWA until about
00Z, and progress slowly east through 06Z.
Areas from NYC north/west should see the most rainfall (1/2 to
3/4 inch) via best combo of forcing from the right rear quadrant
of an upper level jet streak to the north, mid level positive
cyclonic vorticity advection and frontogenesis moving directly
across, and low level moisture transport from the S-SE. A weak
sfc low developing directly over the region from 03Z-06Z will
interrupt the low level moisture transport enough to keep
rainfall mostly light across Long Island and S CT, though it may
recover enough for far SE CT to see some moderate rainfall late
tonight. As the rain moves in, vsby out east should gradually
improve as well.
As the developing low passes to the east, SE winds should
quickly shift out of the NW late and gust as high as to 25-30
mph before daybreak.
Low temps will be a fairly uniform upper 30s to lower 40s, warm
enough to preclude any snowfall well north/west except maybe on
the highest hills of far wrn Orange County.-- End Changed Discussion --
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
A gusty NW flow will take hold and the air mass will dry out
quickly on Fri as the pressure gradient tightens between the
departing low and high pressure off to the west. Gusts 35-45 mph
(just shy of wind advy criteria) likely from late morning into
early afternoon as the blyr destabilizes and stronger winds mix
down from aloft, and a few spots may see sustained winds 25-30
mph for a time as well. High temps on Fri close to a MOS blend,
in the lower/mid 50s.
Skies will be clear to start Fri night, then some high clouds
will slide across late as the upper ridge axis slides across.
Diminishing NW winds will become light as winds back SW and the
blyr decouples, with good radiational cooling. Low temps should
range from the lower 40s in NYC, to the 30s most elsewhere in
the urban corridor and along the coast, to 25-30 inland.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
A weakening shortwave and surface cold front approach on
Saturday and pass through late in the day into the evening.
The system is moisture starved, with upstream shower activity
likely weakening as it enters the area. Left in a slight chance
of a shower NW of the city for Saturday afternoon/early evening.
Mild and breezy conditions ahead of the cold front with quick
shot of waa and deep mixing, giving way to glancing shot of
polar air Sat night/Sun AM on gusty NW winds in wake of front.
Highs for Saturday ranging from the mid 50s for south-facing
coasts to the low 60s in parts of NE NJ.
Brief ridging surface/aloft Sunday in wake of this system with
temps running close to seasonable. 500mb trough and attendant
surface low then move eastward through the western Great Lakes
Region during Sunday night. Models have sped up the timing of
this system in the past 24 hours. Lift ahead of an approaching
warm front to the south interacts with increasing moisture for a
chance of precip before midnight, but then becoming likely
after midnight for roughly the western half of the forecast
area. Thermal profiles would support a wintry mix for inland
areas north of the city. Profiles then warm up for rain across
the entire area during Monday. Although the rain could be
briefly moderate to heavy with help from lift via a llj, rain
impacts appear to minimal at this time. No wind impacts
anticipated either as the llj looks to weak with a strong enough
inversion below it. Lingering chances of showers for Monday
night, then dry for Tuesday with weak high pressure.
Models still disagree regarding the strength of a low center
potentially passing through here sometime on Wednesday or Wednesday
night. At the least, a cyclonic flow aloft with a surface trough
will probably be around. Slight chance to chance (20-30%) of precip
for this period. High pressure would then probably return for dry
weather on Thursday. High temperatures Tuesday through Thursday at
or slightly above normal.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
A cold front approaches this evening and crosses the terminals
tonight. High pressure gradually builds in through Friday.
Varying conditions across the region for the remainder of the
afternoon. South facing coastal terminals will largely remain
VLIFR to LIFR into early this evening with some brief
improvement to IFR possible. Elsewhere, conditions will be IFR-
VFR (mainly terminals away from the coast). Any terminals that
are VFR are not expected to last long, especially with the
moderate rain expected, which will limit visibility and come
with lower ceilings. Expect LIFR-IFR after 00Z for these
terminals.
Rain will then overspread the terminals from west to east
00Z-05Z, latest for eastern terminals. The rain should largely
end 06Z-09Z from west to east with conditions improving to VFR
through day break Friday. VFR then prevails on Friday.
SE winds 10-15 kt this afternoon with gusts up to 20 kt
possible. Winds and gusts briefly weaken this evening before
shifting to the WNW-NW with the frontal passage 06Z-10Z
NW winds increase behind the front becoming 15-25 kt with
G30-40kt on Friday. Winds and gusts should start weakening
late Friday afternoon and into Friday evening.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Gusts of 15 to 20 kt possible through 06Z. Brief VFR possible
at KSWF/KTEB thru 01Z. Thereafter, moderate rain is expected to
lower conditions LIFR to IFR.
Timing of lowering conditions this evening may be off by 1-2
hours.
Timing of rain may be off by 1-2 hours this evening with
conditions settling to IFR.
.OUTLOOK FOR 00Z SATURDAY THROUGH TUESDAY...
Friday night: VFR. NW winds 15-25g30-40kt in the afternoon. NW
gusts 20-25kt in the evening, diminishing at night. Winds at
some terminals may become light and variable.
Saturday: VFR. Slight chance of a shower NW of NYC in the
afternoon. SW gusts 20-25kt in the afternoon, becoming W/NW in
the evening.
Sunday: VFR. NW gusts 15-20kt.
Sunday Night and Monday: Becoming IFR with rain. Possible onset
as snow for KSWF. S gusts 15-20kt near the coast on Monday.
Tuesday: VFR.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90
&&
.MARINE...
Marine dense fog advy issued for all waters til 2 AM as vsby
once again lowers throughout to less than 1 nm in a maritime air
mass. As a frontal system moves across tonight, rain should
scour out the fog with vsbys improving.
SCA remains in effect for the ocean waters for tonight as SE
flow increases to 20 kt and pushes current 4-5 ft seas to 5-7 ft
late tonight.
The gale warning for daytime Fri also remains in effect, with
gusts up to 35 kt expected on all waters mainly from late
morning into early afternoon in strong NW flow.
Sub advisory conditions for Saturday morning, then winds and
seas build in a SW flow. Advisory conditions mainly on the
ocean Saturday afternoon through Sunday morning. Elsewhere, a
few gusts to 25 kt possible during Saturday night. Sub-SCA conds
for Sunday afternoon and night as a high pressure ridge shifts
through. The next potential for SCA conds is then on Monday
ahead of a frontal system, particularly on the ocean.
Elevated seas may linger through a good portion of Tuesday.
&&
.FIRE WEATHER...
Strong NW flow gusting to 35-45 mph and RH quickly lowering to
25-30 percent may present an elevated risk of fire growth/spread
daytime Fri. A wetting rain of 1/2 to 3/4 inch expected from
NYC north/west tonight and about 1/4 inch to the east, so fuel
moisture and drying are uncertain, and may lessen the risk. In
collab with NY State land managers have decided to hold off on
any product issuance and re-evaluate depending on how much rain
fall tonight and how quickly conds dry out daytime Fri.
&&
.HYDROLOGY...
Rainfall tonight should be from 1/2 to 3/4 inch from NYC
north/west, with lesser amts to the east, mostly around 1/4 inch
but possibly as much as 1/2 inch across far SE CT. No hydrologic
impacts expected.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Dense Fog Advisory until 1 AM EDT Friday for CTZ010>012.
NY...Dense Fog Advisory until 1 AM EDT Friday for NYZ078>081-177-
179.
NJ...None.
MARINE...Dense Fog Advisory until 2 AM EDT Friday for ANZ331-332-335-
338-340-345-350-353-355.
Gale Warning from 6 AM to 6 PM EDT Friday for ANZ331-332-335-
338-340-345-350-353-355.
Small Craft Advisory until 6 AM EDT Friday for ANZ350-353-355.
&&
$$
SYNOPSIS...JC/BG
NEAR TERM...BG/JP
SHORT TERM...BG
LONG TERM...JC
AVIATION...JP
MARINE...JC/BG
FIRE WEATHER...
HYDROLOGY...JC/BG