885
FXUS61 KOKX 051803
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
203 PM EDT Mon May 5 2025
.SYNOPSIS...
A weak frontal boundary will remain in close proximity to the
area through Tuesday with high pressure building across eastern
Canada. 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 regains movement to
the north Tuesday night and the low approaches, eventually
passing 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. The low will then pass slowly south of Long
Island on Friday and east of New England next weekend. Another
cold front may approach from the northwest on Sunday.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
Complex forecast across the area into tonight as bands of rain
work in off the ocean. Rainfall will also be enhanced by a
strengthening low-level easterly jet, in particular across the
hills of SW CT. However, latest CAMs continue to struggle with
the location of the main band of rain. Some get it far west as
the Lower Hudson Valley. Latest radar trends support more of an
eastward shift with the axis. Bottom line, expect coverage to
increase across the area through this afternoon. Rainfall
amounts and location will likely have to be adjusted. CAMs also
showing initial activity lifting north early this evening with a
possible short break before another band works in off the ocean
later at night. Lots to figure out here in the next 6-12h.
Mid and upper level cutoff low will continue to slowly approach
from the west. At the surface, a frontal boundary settles
within the area, stalling out.
Minor flooding will become more probable with the training of cells
as parallel flow is present from lower to upper levels (S/SE).
Flash flooding still just a slight chance or isolated in coverage.
Max temperatures a blend of CONSraw and NBM but limited to no
more than 63 degrees Fahrenheit.-- End Changed Discussion --
&&
.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
There still remain uncertainty with the orientation of the bands
of rain.
Mid and upper level cutoff low continue to approach from the west
tonight through Tuesday night.
Low level winds eventually become more southeast tonight into
Tuesday. East to southeast winds relatively higher across Long
Island and Southern CT tonight. Low level winds maxima shift
farther east of the region Tuesday into Tuesday night.
Upper level southerly winds increase tonight into Tuesday. For
this time period, the upper level jet streak right rear quadrant
approaches, eventually moving into western parts of the region.
Vertical synoptic lift increases as a result of increasing upper
level divergence.
Elevated instability as shown by model near zero values of Showalter
Indices develops across the region late tonight into Tuesday.
Rain continues tonight across the region and with a higher chance of
heavy rain as well which some CAMs are indicating with their max
reflectivity values. Slight chance of thunderstorms tonight as well.
Tuesday, expecting more shower like nature to the rainfall. For
western areas, some increase in surface CAPE forecast so a
chance of thunderstorms with otherwise slight chance of
thunderstorms. Rain showers widespread during the day with
decreasing coverage at night. Still minor flooding possible with
a marginal risk for flash flooding.
Temperatures forecast a little warmer Tuesday using NBM and CONSraw
blend, getting more into the mid 60s for western areas, lower 60s
for eastern areas. Not much diurnal cooling of temperatures Tuesday
night with lows just in the 50s.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
An upper low and its weak sfc reflection will pass across on Wed.
Cold pool aloft plus daytime heating should generate enough
instability for afternoon showers/tstms especially north/west of NYC
(likely PoP there). Winds aloft will be weak due to the ULL passing
across so severe potential looks nil attm.
After this system passes through, a nrn stream trough digging S
through the Great Lakes will close off over or near the OH Valley
Thu night into Friday. This will send a sfc cold front toward the
area on Thu, then as the low closes off sfc cyclogenesis should take
place over the Mid Atlantic region, with the low passing slowly
south and east Fri into Sat. Have only slight chance PoP for showers
with the cold front, then higher chance PoP with the low development
throughout Thu night-Fri, and for Long Island/S CT Fri night. As the
low pulls away this weekend, have only slight chance PoP for Sat,
and mainly dry for Sunday, though it is possible another cold front
may approach from the NW as another northern stream upper trough
moves across S Canada.
Temps should be a little above normal through most of the period,
except cooler on Fri due to clouds/higher PoP with the low passing
to the south.
&&
.AVIATION /18Z MONDAY THROUGH SATURDAY/...
-- Changed Discussion --
Frontal boundary remains stalled within the region through the
TAF period.
Low clouds and fog expected. Periods of rain through the TAF
period. Mainly IFR to LIFR forecast. Some terminals could see
brief VLIFR (mainly overnight and for outlying areas) or MVFR
conditions at times. MVFR conditions would likely come in
improvements in visibility with lighter rain or a respite from
the rain (though any moderate to briefly heavy rain would be
associated with lower visibility, keeping it in the IFR to LIFR
range).
Winds are easterly around 10 kt. Gusts 15 to 20 kt, mainly for
the metro terminals this afternoon, diminishing this evening.
Southeasterly flow expected Tuesday at around 10 kt.
...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Categories could fluctuate between LIFR and MVFR through the
TAF period.
.OUTLOOK FOR 18Z TUESDAY THROUGH SATURDAY...
Tuesday afternoon and night: Rain/showers and IFR. Possible
thunderstorms. SE gusts around 10 kt, with gusts up to 15 kt.
Wednesday: Chance of MVFR or lower with and a 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...
Conditions start out below SCA. Winds are expected to pick up this
afternoon into tonight with southeasterly wind gusts near 20 kt. An
occasional 25 kt gust will be possible. Non-ocean waters remain
below SCA thresholds through Tuesday night. However, ocean seas are
expected to build to 5 ft starting after 2PM this afternoon and
continuing through the day Tuesday. Hoisted a SCA for the ocean
zones to cover this, which will be mainly due to seas. Fire Island
Inlet to Montauk start at 2PM this afternoon and west of Fire Island
Inlet starts at 6PM this evening. Both SCA segments end at 6PM
Tuesday. The higher ocean SCA seas could very well linger through
Tuesday night.
Residual 5-ft seas should linger on the outer ocean waters E of Fire
Island Inlet into Wed and E of Moriches Inlet Wed night. Otherwise
sub advisory criteria expected longer term from Wed through Fri
night, but with long period 4-ft swells persisting on the ocean and
corresponding rougher conditions at the ocean inlets.
&&
.HYDROLOGY...
A little less than 48 hour storm total QPF going until 2AM Wednesday
has mostly near 2 to 3.5 inches of rain across the region.
Locally higher amounts will be possible.
Hourly rainfall rates at times could reach near 1 inch per hour.
HREF indicates max 3 hr QPF that for small areas within the region
reach near 2 inches.
With overall rainfall amounts increased from prior forecast and a
relatively shorter time window for this storm total, the probability
for flooding has increased through early Tuesday morning. Still
think this will be primarily minor flooding. Still think minor
flooding would be most common type of flooding especially for
low lying, poor drainage and urban areas. However, there will
be a slight chance of flash flooding, near 15 to 20 percent. In
terms of areal coverage of flash flooding, this still equates to
isolated.
Marginal risk for flash flooding with otherwise minor flooding
possible Tuesday latter half of morning through Tuesday evening.
No hydrological impacts expected mid to late week.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
NY...None.
NJ...None.
MARINE...Dense Fog Advisory until 8 PM EDT this evening for ANZ350-353-
355.
Small Craft Advisory until 6 PM EDT Tuesday for ANZ350-353.
Small Craft Advisory from 6 PM this evening to 6 PM EDT
Tuesday for ANZ355.-- End Changed Discussion --
&&
$$
SYNOPSIS...BG/JM
NEAR TERM...JM/DW
SHORT TERM...JM
LONG TERM...BG
AVIATION...JP
MARINE...BG/JM
HYDROLOGY...BG/JM