750
FXUS61 KOKX 041210
AFDOKX

Area Forecast Discussion
National Weather Service New York NY
810 AM EDT Sun May 4 2025

.SYNOPSIS...
Frontal boundary shifts farther north into early today. It is
expected to stay to the north of Long Island through tonight. The
frontal boundary eventually moves farther south within the region
Monday into Tuesday. The system will then pass through on
Wednesday, with a cold front passing through on Thursday. The
area will then remain between high pressure to the west and low
pressure developing east of New England on Friday. The low
should slowly pull away from New England on Saturday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
Mainly dry through this morning. Localized low clouds and
localized fog for some locations. Higher chance of showers this
afternoon. Only weak instability this afternoon so only have a
slight chance thunderstorms where the models show this
instability, which is within the western half of the region.

SE winds stabilize surface layer with cooler temperatures overall.
However, noting temperatures a little above MOS initially so went
with NBM for the high temperature forecast which seems plausible
given sufficient diurnal warming this morning into early afternoon
before more showers develop. Upper 60s to lower 70s for the high
temperature forecast for most locations but relatively cooler along
the southern half of Long Island and NYC, which are more in the
low to mid 60s.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/...
-- Changed Discussion --
Cutoff upper level low continues to approach from the west.
Continued southerly lower to upper level flow will be parallel.
Omega increases.

With synoptic lift increasing and some time periods where there
will be more elevated instability, especially Monday night
through Tuesday, there will be more coverage of showers and
thunderstorms.

Tonight showers continue but not expecting too much heavy
rainfall. Instability lowering so no thunderstorms tonight.
There will be more low clouds and fog. Uncertain how dense or
extensive the fog gets. Kept fog with patchy coverage. Less rain
than forecast will probably lead to more extent of fog and
increase the possibility for some dense fog for some locations.

Monday is when the rain showers become more widespread and this
is expected to continue Monday night through Tuesday.
Combination of highest synoptic forcing and relatively more
instability will lead to a greater chance for heavy rain as well
especially for any thunderstorms that develop. Parallel flow
from lower to upper levels will lead to training of convection
allowing for multiple rounds of heavy showers and thunderstorms.

Synoptic forcing decreases Tuesday night with highest positive
vorticity advection areas shifting east of the area as upper
level low center moves in. Low levels not expected to be as
unstable also, so less heavy rain potential. However, still have
rain showers in the forecast.

Monday night both winds at 925mb and 250mb increase and are
southerly. They both have some easterly component.

Tuesday, showers linger and could potentially be heavy as right
rear quad of upper level jet moves into the region.

Divergence increases Monday into Tuesday with the upper level
winds increasing.

Regarding temperatures, for tonight used a combination of MAV
and MET MOS as well as the NBM. Then blended in more raw data
for Monday through Tuesday night as diurnal temperature
differences become smaller.
-- End Changed Discussion --

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Upper level low and weak sfc reflection pass through on Wed with
chance of showers. An upper trough digging SE from Ontario and
Quebec in their wake will send a cold front through on Thu with
another chance for showers. The trough is progged to close off over
the Northeast Fri into Sat, with a developing weak sfc low SE of
Long Island on Fri pivoting to E of New England. With the upper low
and associated cold pool aloft/low level cyclonic flow have partly
cloudy skies and slight chance for showers for both Fri/Sat.

Above normal temps on Wed should return to near normal on Thu and a
few deg below normal on Fri. Temps on Sat could moderate to a few
deg above normal, but this will depend on how quickly the upper low
pulls away on Sat. If slower to exit temps on Sat could be more
similar to those fcst for Fri.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
-- Changed Discussion --
Frontal boundary shifts north into early today. A lull in the rain
shower activity expected until late this morning. Then more rain
showers develop and gradually make their way farther east within the
region this afternoon into tonight.

Mainly VFR conditions through this morning although there is
forecast to be some localized MVFR to LIFR conditions. MVFR chances
with increasing chance of rain showers this afternoon. Higher chance
of IFR and localized LIFR tonight.

Winds remain southerly through today and then become more easterly
tonight. Wind speeds vary from near 5 kts to near 15 kts. Some gusts
can be expected to near 20 kt at times although this is not expected
to be widespread. Wind speeds tonight lower to less than 10 kts.

 ...NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty...

Possible MVFR to IFR this morning. Amendments possible.

Amendments likely to refine timing of showers and thunderstorms.

.OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY...

Monday: Showers likely with MVFR or lower expected. A chance of
tstms mainly at night. E winds G15-20kt.

Tuesday: Showers with MVFR or lower expected. A chance of
thunderstorms. SE winds G15-20kt day into early eve possible.

Wednesday: Chance of MVFR or lower with a slight chance of
showers/thunderstorms.

Thursday: VFR.

Detailed information, including hourly TAF wind component
forecasts, can be found at: https:/www.weather.gov/zny/n90
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
Expecting all waters to remain below SCA this morning and
through Monday morning. Thereafter, SCA potential increases
through Tuesday night on the ocean as forecast seas reach near 5
to 6 ft at times.

Quiet for Wed/Thu with winds/seas below SCA thresholds.
-- End Changed Discussion --

&&

.HYDROLOGY...
-- Changed Discussion --
Marginal flash flood risk for much of the area through early
this week. Hourly rain rates at times could reach near 1 inch in
1 hour. Isolated flash flooding possible. Layer precipitable
water reaches near 1.5 inches.

Total rainfall forecast from this afternoon through Tuesday
evening is near 2 to 3.5 inches. Locally higher amounts will be
possible.

Current forecast shows enough time period to keep flash flood
risk marginal. Would expect a relatively greater chance of minor
nuisance flooding in the low lying, urban, and other poor
drainage areas.

No hydrologic concerns mid to late this week.
-- End Changed Discussion --

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
CT...None.
NY...None.
NJ...None.
MARINE...None.
-- End Changed Discussion --

&&

$$

SYNOPSIS...BG/JM
NEAR TERM...JM
SHORT TERM...JM
LONG TERM...BG
AVIATION...JM
MARINE...BG/JM
HYDROLOGY...BG/JM