807
FXUS61 KOKX 091133
AFDOKX
Area Forecast Discussion
National Weather Service New York NY
733 AM EDT Fri May 9 2025
.SYNOPSIS...
A frontal system and associated low will slowly track across the
area today. A weak cold front will cross the region Saturday night,
with high pressure building in for early next week. Another low
pressure system approaches for the middle of next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Key Messages:
* A slow-moving low pressure system will bring soaking rainfall to
the area today into early tonight.
* 1-2" total additional rainfall expected through tonight. Isolated
higher totals possible.
* A Flood Watch is in effect for Bergen, Passaic, Lower Hudson
Valley, southern Connecticut, and Long Island.
The forecast remains on track for this morning`s update with a
line of showers west and north of NYC gradually making their way
eastward.
An upper-level low will drop towards the area this morning from the
Great Lakes region as a low at the surface approaches from the
southwest this morning.
This will lead to increasing precipitation across the region,
overspreading west to east. Some of the more persistent rain with
higher rain totals this morning into early afternoon is expected to
be along the northern tier of the low approaching from our
southwest, leading to more soaking rain in areas north and
northwest of NYC.
By late afternoon, the low is expected to near or over NYC. This
will lead to most rain tapering at this time over NE NJ and NYC with
mainly isolated to spotty showers left over. More light showers
may continue at this time north of the low, north of NYC.
As the low positions itself over NYC this afternoon, a strong 30-40
kt LLJ will develop on the east side of the low, fueling strong warm
air advection and frontogenesis. This will lead to banded heavier
rainfall on the eastern side of the low with some elevated
thunderstorms into the early evening. Unfortunately, the location of
this band varies among the 00Z HREF CAMS, MPAS and RRFS due to
slightly different positions of the low. The consensus seems to be a
heavier band of rainfall may set up across Suffolk county and extend
into SE CT late afternoon to early evening. While most guidance
agrees setting this up in Suffolk county and SE CT, some still
bring this band a little farther west into Nassau and parts of
New Haven or eastern Fairfield counties. It seems as the low
spins over NYC, east of the low, this band may move slower for a
2-4 hour period before it begins to quicken its exit,
progressing faster to the east as the low eventually moves north
and east of NYC later in the evening. This happens when the
surface low essentially gets captured and becomes stacked with
the upper low.
Overall, expected rainfall this morning into tonight will be an
additional 1-2 inches on top of what we have already seen. Highest
totals are expected to be on Long Island, S CT and northern portions
of the Lower Hudson Valley. Some isolated higher totals of 3-4" is
not out of the realm of possibility. Rainfall rates mainly look to
range 0.5"/hr to 1.0"/hr this afternoon and evening. However, peak
rates in some stronger banded rainfall or convection east of the low
this afternoon and evening could be between 1.5-2"/hr in isolated
spots. The 00Z HREF 40-km neighborhood probabilities of rain rates
greater than 1"/hr peak at 70% across most of Nassau and Suffolk
county, while 10-km neighborhood probabilities peak around 50-60%
mainly for Suffolk county.
A Flood Watch has been continued for Bergen & Passaic counties, the
Lower Hudson Valley, and for S CT. Suffolk and Nassau counties on
Long Island have been added to the Flood Watch, based on trends in
the latest guidance. Hydrologic river and stream issues are possible
in areas north and northwest of NYC and into S CT given already wet
soils and streams running higher than normal. There is a chance some
streams could reach minor flood stage. Areas of southern Connecticut
and Long Island may see isolated instances of flash flooding.
Wherever the heaviest rain bands set up could see flash flood
guidance met in these spots. Flash flooding will mainly be limited
to urban, poor-drainage, and low-lying trouble spots, should it
occur. Significant flash flooding is not currently expected.
Rainfall will taper into tonight as low pressure moves north and
west of the area. Only isolated or spotty light showers are expected
on the backside of the low, with the best chances in northern
interior portions of NY & CT in our CWA.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Dry weather is expected by midday Saturday and into the weekend with
the low exiting to the northeast and high pressure gradually
beginning to take over.
Another shortwave and associated surface cold front moves across the
area Saturday night into early Sunday morning with Canadian high
pressure building into its wake and gradually rising heights.
Breezy NW/WNW winds are expected through the day Saturday due to
an increased pressure gradient at the surface from low pressure
departing northeast.
Highs will remain at or slightly above normal in the upper-60s to
low-70s on Saturday and Sunday.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
High pressure will keep conditions dry through at least much of
Tuesday. The next chance of precip comes by later Tuesday or
Wednesday with the approach of the next low pressure system.
Temperatures through the long term will remain at or slightly above
normal with highs in the 70s.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
A frontal system stalled across the area this morning will allow
for as a series of frontal waves to track along it. The front
will be dragged east in the afternoon and early evening as low
pressure lifts northeast of the area.
ANy MVFR conditions will lower to IFR today and remain through
much of the night and into early Saturday morning. LIFR
conditions remain possible locally for low ceilings. Rainfall
will continue to become more widespread in coverage and increase
in intensity through the morning and into the early afternoon.
Embedded TSRA remain possible, particularly for the eastern
coastal terminals such as KJFK, KISP, KBDR, KGON and possibly
KHPN and KLGA. Covered this chance with a PROB 30 for the time
being as confidence in occurrence and timing is low, especially
for the NYC metro. Rain gradually comes to an end this evening
into the overnight. IFR to MVFR conditions expected near the
morning push Saturday morning, eventually improving to VFR by
Saturday late morning.
A light N/NE flow should become mainly E this morning around 10
kt. NYC and LI terminals could become SE for time in the late
morning/early afternoon. There also could be a few gusts
15-18kt at the coastal terminals. By this evening, the frontal
system moves northeast with winds in its wake becoming W or NW
and increasing in speed into Saturday morning.
NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...
Amendments likely through tonight with changing flight
categories and wind shifts. Winds could go SE late morning/early
afternoon, especially at KJFK. A few gusts 15-18kt possible.
There is low chance for thunderstorms generally from 14-18Z for
KJFK and KLGA. Confidence is too low at this time to include in
TAFs at KTEB and KEWR.
.OUTLOOK FOR 12Z SATURDAY THROUGH TUESDAY...
Saturday: Mainly VFR, except MVFR or lower possible isolated
showers. NW gusts 25-30kt possible.
Sunday through Tuesday: VFR.
Detailed information, including hourly TAF wind component forecasts,
can be found at: https:/www.weather.gov/zny/n90-- End Changed Discussion --
&&
.MARINE...
Seas build on Fri as low pres develops S of the waters and then
tracks across LI. A SCA has been issued on the ocean for this. Winds
increase all areas late Fri ngt. Speeds are mrgnl so did not issue a
sca on any of the protected waters for this.
SCA conditions could continue on the ocean waters through Saturday
for marginal 25kt gusts and 5 ft seas. Thereafter, conditions look
to remain below SCA.
&&
.HYDROLOGY...
1-2 inches of rainfall is expected this morning into tonight with
isolated higher totals possible. A Flood Watch has been continued
for Bergen & Passaic counties, the Lower Hudson Valley, and for S
CT. Suffolk and Nassau counties on Long Island have been added to
the Flood Watch, based on trends in the latest guidance. Hydrologic
river and stream issues are possible in areas north and northwest of
NYC and into S CT given already wet soils and streams running higher
than normal. There is a chance some streams could reach minor flood
stage. Areas of southern Connecticut and Long Island may see
isolated instances of flash flooding from heavy rainfall. Wherever
the heaviest rain bands set up could see flash flood guidance met in
these spots. Flash flooding will mainly be limited to urban, poor-
drainage, and low-lying trouble spots, should it occur. Significant
flash flooding is not currently expected.
There are no hydrologic concerns Saturday through mid next
week.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch through late tonight for CTZ005>012.
NY...Flood Watch through late tonight for NYZ067>071-078>081-177-
179.
NJ...Flood Watch through late tonight for NJZ002-004-103-104.
MARINE...Small Craft Advisory from noon today to 5 PM EDT Saturday for
ANZ350-353-355.
&&
$$
SYNOPSIS...BR
NEAR TERM...BR
SHORT TERM...BR
LONG TERM...JT
AVIATION...MW
MARINE...BR/JT
HYDROLOGY...BR/JT