618
FXUS61 KOKX 060007
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
807 PM EDT Mon May 5 2025
.SYNOPSIS...
A weak frontal boundary will remain in close proximity to the
area through Tuesday with high pressure tracking across the
Canadian Maritimes. At the same time, a broad area of low
pressure over the Ohio Valley will track slowly east. Between
the two, bands of rain will work in off the ocean. The front
gradually lifts back the north on Tuesday, while low pressure
approaches from the west. Weak low pressure will then slide
northeast through the area on Wednesday. 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. Coastal low pressure will track over or just
southeast of the region Friday into early Saturday, before
heading up the New England coast. Another cold front will
approach from the northwest on Sunday.
&&
.NEAR TERM /THROUGH TUESDAY/...
-- Changed Discussion --
Forecast on track with focus area of heavy rainfall across
central and eastern LI and much of southern CT, as an easterly
LLJ of 40kt will lift across the area this evening, followed by
surface wave off the NJ coast and associated warm front.
Latest CAMs take the current area of rain associated with
easterly jet and lift it north through this evening. There may
be be a brief break in the action late this evening before WCB
band moves in from the south. Signs of the convective
development in this N/S oriented axis can be seen in satellite
imagery, with a focus is mainly over LI and S CT. Instability will
gradually increase overnight into Tuesday in response.
1 to 2 inches of additional rainfall likely across central and
eastern LI overnight, with 2 to 4 inches of likely across
southern CT due to orographic enhancement. Hourly rainfall
rates of up to 1"/hr are possible, but generally looking at 1/4
to 1/2"/hr rates. SPC HREF PMM hourly and three-hourly amounts
remain below FFG through tonight, but localized storm total
amounts as high as 5" inches are possible across the higher
elevations in CT if training convection lingers over any one
areas for a few hours. This would present a conditional risk
for scattered instances of flash flooding, but the primary
threat is for isolated instances.
Elsewhere, the Lower Hudson Valley, NYC, and NE NJ can expect
an additional quarter to one- inch, possibly up to 1.5 inches
across some of the higher elevations north and west.
Gusty easterly winds this evening will veer around to the SE
tonight with mild conditions. Lows will be in the mid and upper
50s. Then onshore flow and high dew point air will also result
in fog, some of which could be locally dense.
On Tuesday, a bit more instability is expected, especially west
of the NYC metro in the afternoon with the potential for some
partial clearing. However, there still looks to be enough of a
marine influence to keep it more elevated and unlikely to
reach severe limits. With the upper low approaching, impulses
will move in from the south with additional bands/pockets of
rain, but looking less organized than what is expected tonight.
Localized amounts up to an inch will be possibly with potential
training of cells in a deep-layered southerly flow. Minor
nuisance flooding will continue to be possible.
Highs Wednesday will be warmer in the mid 60s to around 70. This
closer to normal.-- End Changed Discussion --
&&
.SHORT TERM /TUESDAY NIGHT/...
Widely scattered to scattered showers can be expected Tuesday
night with emphasis to the west of NYC early in the evening
where the airmass will be most unstable. The upper low will
near the area by daybreak Wednesday. Expect some additional fog
with a southerly flow and high dew point air in place. Lows
will be in the 50s, which is about 5 to 10 degrees above
normal.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Good model agreement in persistent cutoff upper low to the SW of the
area the last few days shearing NE through the region on Wed, ahead
of a digging northern stream trough sliding from Ontario into
Quebec. This trough will slide into the NE US for late week, with
good agreement in another closed low developing at its based in the
to the SW the region Thu Night/Friday and then pivoting ne through
Saturday.
At the surface, the stalled frontal system over the region should
lift ne thru the area Wed into Wed eve, with drying conditions Wed
Night into Thu AM. Cold pool aloft plus daytime heating should
generate enough instability for sct to numerous shra/tstms late Wed
AM into Wed eve ahead/along surface wave/frontal trough,
particularly N&NW of NYC.
Drying conds in wake of the departing low appears short lived, as
the next cold front approaches the region Thu aft/eve. Isolated aft
shra/tsra activity possible in this weakly unstable environment.
Good agreement in sfc cyclogenesis over the Mid Atlantic region
along the cold front on Thu Night into Friday as the digging
northern stream trough phases with southern jet and closes off at
its base across the Central Appalachians. Resultant strengthening
coastal low pressure will bring increasing likelihood of overrunning
rain Thu Night into Fri AM, with potential for a period of moderate
to heavy rain Fri into Sat AM with deep layered lift and convergence
of Gulf/sub-tropical moisture feed over the region as low pressure
tracks over or se of the region.
Improving conditions Sat aft/night in wake of low pressure and
closed low. Subsequent shortwave likely crosses with cold frontal
passage Sun/aft eve, with seasonable 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 Wed/Thu, falling to a
few to several degrees below seasonable Fri/Sat with low pressure
affecting the area, then moderating back to slightly above
seasonable for Sun into early next week.
&&
.AVIATION /23Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
Frontal boundary remains stalled within the region through the
TAF period.
Mainly IFR or lower with low clouds, fog, and periods of rain
through the night. Improvement to MVFR late in the day to early
evening Tuesday. Showers still anticipated through Tuesday.
Winds easterly around 10kt, backing more SE for Tuesday
afternoon.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Vsbys will fluctuate between mostly LIFR and MVFR tonight, but
cigs should remain LIFR. Timing of improvement of each category
on Tuesday/Tuesday night could be off by a couple of hours.
Can`t rule out an isolated tstm tonight and Tuesday.
.OUTLOOK FOR 00Z WEDNESDAY THROUGH SATURDAY...
Tuesday night: VFR, except IFR east of the city terminals.
Chance of showers and iso evening tstm.
Wednesday: VFR/MVFR in the morning with IFR east of the city
terminals, then mainly VFR in the afternoon. Chance of showers
and slight chance of thunderstorms.
Thursday: MVFR possible with a chance of showers, mainly at
night.
Friday: MVFR possible with a chance of showers. A slight chance
of thunderstorms.
Saturday: Mainly VFR, except MVFR or lower possible in slight
chance of showers.
Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Marginal SCA conditions for seas around 5 ft will continue
through the day Tuesday in an E/SE flow. This may need to be
extended into Tuesday night, but confidence is low at this
time.
Marginal 4-5 ft ocean seas possible Wed into Wed night in mainly a
residual E/SE swell, with sub SCA conditions likely on Thu under a
weak pressure gradient.
Next potential for SCA conditions Fri/Sat on all waters with coastal
low pressure. Low prob for gales on the ocean in E/SE flow ahead of
the low if stronger coastal development evolves.
&&
.HYDROLOGY...
-- Changed Discussion --
An additional 1 to 2 inches of rainfall is likely across
central and eastern LI, and 2 to 4 inches across southern CT
due to orographic enhancement through Tuesday AM.
Locally 5" is possible across interior CT due to a combined
easterly LLJ this evening and WCB overnight. WPC has much of the
area under a slight risk of excessive rainfall for tonight,
but primary threat for isolated to scattered instanced of flash
flooding would be across interior S CT.
There is the potential for a period of moderate to heavy
stratiform rain for Fri into Sat AM. NBM probability of 1" in 24
hr is at 20%, with less than 10% prob of 2" in 24 hr.-- End Changed Discussion --
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
NY...None.
NJ...None.
MARINE...Dense Fog Advisory until 11 AM EDT Tuesday for ANZ350-353-355.
Small Craft Advisory until 6 PM EDT Tuesday for ANZ350-353-355.-- End Changed Discussion --
&&
$$
SYNOPSIS...NV/DW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...NV
AVIATION...JC
MARINE...NV/DW
HYDROLOGY...NV/DW