449
FXUS61 KOKX 061954
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
354 PM EDT Tue May 6 2025
.SYNOPSIS...
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A cold front pushes offshore tonight. Meanwhile, a cut off low over
the easter Great Lakes tracks northeast into northern New England by
Wednesday into Wednesday night. A cold front will approach from
the northwest on Thursday and stall nearby Thursday night as
low pressure develops along it over the Mid Atlantic region. Low
pressure will track over or just southeast of the region Friday
into Friday Night, before heading up the New England coast on
Saturday. A weak cold front will cross Saturday night, with
high pressure building in for early next week.-- End Changed Discussion --
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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Line of showers and isolated thunderstorms stretching from Lake
Ontario southeast to the Twin Forks of Long Island and then south to
off the North Carolina coast will move east this evening. Conditions
at the surface remain relatively stable with the easterly to
southeasterly flow. However, conditions are unstable around 750 to
800 mb, with lapse rates approaching 9 C/km in some of the BUFKIT
sounding. Additionally, there is a few hundred J/kg of MUCAPE across
the forecast area. With the lift from the cold front, this will be
enough for an isolated thunderstorm for the eastern areas.
Western areas will begin to see convection move into the area from
the west in association with the upper low and cold pool aloft,
which is forecast to track northeast overnight into northern New
England by Wednesday morning. The best dynamics appears to be
west of our forecast area, however the 3 km NAM is outputting
close to 1000 J/kg of MUCAPE. However, the NAM is the only model
outputting this amount of CAPE, while other models are 500 J/kg
or less and the SPC HREF indicates decreasing instability as
the showers and thunderstorms from PA move into the slightly
more stable region in Orange and Western Passaic. So, do expect
any convection to weaken as they make their way into the
aforementioned areas. SPC has a slight risk of severe
thunderstorms for these areas, and there is a Severe
Thunderstorm Watch in effect just to the west of these counties.
Therefore, added gusty winds to the forecast with these showers
and thunderstorms that move through tonight. An isolated severe
thunderstorm cannot be ruled out with damaging winds and large
hail the main threats. This will be for only a short period of
time, through around 8 am this evening. Thereafter, stability
increases across the area.
With recent wet conditions, and continued low level moisture,
patty fog will continue. However, things look to improve after
midnight as winds turn more to the southwest and a slightly
drier air mass moves in.
Upper level shortwave associated with the upper low moving into
northern New England will move through late tonight and track east
along with a surface trough. This will bring the chance for showers
for the area. CAMs are in pretty good agreement on a line of showers
developing across western portions of the forecast area and tracking
east during the night.-- End Changed Discussion --
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
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The surface trough continues to track east over eastern areas, so
lingering showers are expected for the Twin Forks of Long Island and
southeast CT Wednesday morning, ending by mid morning. Then, another
surface trough looks to move through western areas,weakening as it
moves east during the afternoon, so just a slight chance is expected
for much of Long Island and southeast CT for Wednesday, while
northeast NJ, NYC, and the Lower Hudson Valley see a chance for
showers. With much of the dynamics north of the area, now thunder is
expected from late tonight through Wednesday.
Dry conditions return for Wednesday night as the stacked low
heads into the Canadian Maritimes.
Temperatures are expected to be seasonably warm through the period,
with highs in the upper 60s to middle 70s on Wednesday and lows
in the 50s for the entire forecast area.-- End Changed Discussion --
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
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Good general model agreement in a northern stream trough digging
from southern Ontario/Quebec Thu/Fri, with another closed low
developing at its based to the W/SW of the region Thu Night/Friday,
and then pivoting ne through the area on Saturday.
At the surface, after brief drying conds Wed Night into Thu AM, the
next cold front approaches the region Thu aft/eve. Scattered
shra/isolated tsra activity possible N&W of NYC Thu aft/eve in a
weakly unstable/sheared environment.
Main focus though is on sfc cyclogenesis over the Mid Atlantic
coastal plain along the cold front Thu Night into Friday AM as the
digging northern stream trough phases with southern jet and closes
off at its base across the Central Appalachians. The trend of the
last 24 hrs has been a bit earlier closed low developing and moreso
to the west versus SW of the region, which is resulting in low
pressure developing closer/over the coast. Trend has also been for a
more progressive closed low/surface low, with improving conditions
for Saturday.
Approaching closed upper low and resultant strengthening coastal low
pressure will bring increasing likelihood of overrunning rain Thu
Night into Fri AM from the Mid Atlantic up the NE US coast in
response to deep layered lift (strong PVA and divergence aloft, and
deep moisture convergence of Gulf/sub-tropical moisture feed over
the region) as low pressure tracks up the coast. Exact location of
cold front and track/intensification of low pressure will determine
location, axis and duration of heavy stratiform rainfall, but
ingredients are there for a widespread moderate to heavy rainfall
late Thu Night through Friday. Orographic enhancement looks evident
across the interior based on low-level easterly flow as well.
GEFS/ECE ensemble indicating moderate potential (30-60% prob) for 1"
rainfall in 24 hrs, with slight potential (less than 20% prob) of 2"
in 24 hrs.
Improving conditions Fri night into Saturday AM in wake of low
pressure and closed low, with forecast trending to dry and
seasonably mild conditions.
Subsequent shortwave likely crosses the NE US Sat night with
associated weak cold frontal passage, with dry and seasonably mild
conditions to follow for early next week with Canadian high pressure
building into its wake and gradually rising heights.
Temps near to slightly above seasonable for Thu ahead of weak cold
front, falling to a few to several degrees below seasonable Fri with
low pressure affecting the area, then a gradual moderating process
from near seasonable for Sat to a few to several degrees above
seasonable into early next week.-- End Changed Discussion --
&&
.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
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Frontal system lingers nearby through this evening, exiting
north and east into Wednesday.
Mainly MVFR or IFR to start with lingering SHRA and mist. Showers
taper thru 00Z or so, and conds improve to VFR during this time at
most terminals. Restrictions likely linger with mist and fog at
KGON, with improvement toward 6Z Wed. A thunderstorm also can`t be
entirely ruled out at KSWF thru around 2Z Wed before threat lowers.
A few spotty showers possible on Wed, but coverage and chances too
low to include in TAF at this time.
SE flow late today, speeds around 10 kt. A few gusts toward 20 kt
could develop, but expected to largely remain more occasional. Flow
lightens and veers southerly tonight, then WSW or SW on Wed with
speeds once again near 10 kt.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Conditions may fluctuate between categories late this afternoon.
Timing of improvement could be off by a couple of hours.
.OUTLOOK FOR 18Z WEDNESDAY THROUGH SUNDAY...
Wednesday: Mainly VFR. Chance of showers and slight chance of
thunderstorms.
Thursday: MVFR possible with a chance of showers, mainly at night.
Friday: MVFR or lower possible with a chance of showers. A slight
chance of thunderstorms.
Saturday: Mainly VFR, except MVFR or lower possible in slight chance
of showers.
Sunday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
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SCA for seas around 5 ft continue this evening on the ocean
zones in an E/SE flow. Waves begin to diminish early tonight for
the western ocean zone and continue to diminish from west to
east overnight. The eastern ocean zone falls below 5 ft before
daybreak Wednesday.
Sub SCA conditions likely on Thu under a weak pressure gradient.
Next potential for SCA conditions is Friday into Friday Night,
particularly on the ocean waters, with coastal low pressure. The
potential for gales on the ocean has decreased over the last 24
hrs.-- End Changed Discussion --
&&
.HYDROLOGY...
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Up to an additional 0.5 inch or so of rainfall will be possible
with locally higher amounts possible in any thunderstorms through
tonight. Light amounts of rain of a few hundredths of an inch
is expected on Wednesday. Therefore, looking at nuisance
ponding of water with just an isolated flash flood threat. The
highest threat would be across western Orange County and
western Passaic with the threat of strong to isolated severe
storms in these areas.
There is likelihood of a widespread moderate to heavy stratiform
rain event for late Thursday night and Friday time period. There is
moderate potential for a 1"+ rainfall, but at this point, flood
impacts look to be minor.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ350-353-
355.
&&
$$
SYNOPSIS...JP/NV
NEAR TERM...JP
SHORT TERM...JP
LONG TERM...NV
AVIATION...DR
MARINE...JP/NV
HYDROLOGY...JP/NV