Marine Weather Net

Long Island Sound West of New Haven CT / Port Jefferson NY Marine Forecast


TONIGHT

SW
WINDS
10 - 15
KNOTS

SAT

SW
WINDS
10 - 15
KNOTS

SAT NIGHT

SW
WINDS
10 - 15
KNOTS

SUN

NW
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
ANZ335 Forecast Issued: 1033 PM EDT Fri Apr 18 2025

SMALL CRAFT ADVISORY IN EFFECT THROUGH SATURDAY EVENING
Tonight...Sw Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 1 To 2 Ft. Wave Detail: Sw 2 Ft At 3 Seconds.
Sat...Sw Winds 10 To 15 Kt, Increasing To 15 To 20 Kt In The Afternoon. Seas Around 2 Ft. Wave Detail: Sw 2 Ft At 2 Seconds.
Sat Night...Sw Winds 10 To 15 Kt, Becoming W After Midnight. Gusts Up To 25 Kt. Seas Around 2 Ft. Wave Detail: W 2 Ft At 3 Seconds. Slight Chance Of Showers And Tstms In The Evening.
Sun...Nw Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas Around 2 Ft In The Morning, Then 1 Ft Or Less. Wave Detail: Nw 1 Ft At 3 Seconds, Becoming Nw 1 Ft At 2 Seconds.
Sun Night...N Winds 5 To 10 Kt. Seas 1 Ft Or Less. Wave Detail: Nw 1 Ft At 2 Seconds.
Mon...E Winds Around 5 Kt, Becoming Se In The Afternoon. Seas 1 Ft Or Less.
Mon Night...S Winds 5 To 10 Kt. Seas 1 Ft Or Less. Chance Of Showers.
Tue...Sw Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas Around 2 Ft. Chance Of Showers.
Tue Night...Nw Winds 10 To 15 Kt. Seas Around 2 Ft.
Wed...W Winds 5 To 10 Kt. Seas 1 Ft Or Less.
Wed Night...S Winds 5 To 10 Kt. Seas 1 Ft Or Less. Winds And Seas May Be Higher In And Near Tstms.
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Area Forecast Discussion
National Weather Service New York NY
821pm EDT Fri April 18 2025

Synopsis
A warm front moves north of the area tonight, with a cold front moving through Saturday evening. High pressure builds over the northeast Sunday into Monday. A frontal system then moves across the region Monday night into Tuesday. High pressure returns for Wednesday and Thursday with potential of another frontal system for the end of next week.

Near Term - Until 6am Saturday Morning
Gusty S winds diminish quickly this evening, but an occasional gusts up to 20 mph will be possible along the coast through the overnight, Otherwise, the pressure gradient remains tight over the area tonight with high pressure shifting farther southeast offshore and a low tracking to our north and west. The orientation of these surface features will gradually shift the winds to more of a SW/WSW direction. The area will become warm sectored overnight with a warm front passing to the north. With some mid level cloud cover tonight and winds staying up some, temperatures will not be able to drop too much. Lows from NYC and north and west will bottom out in the mid to upper 50s with Long Island and CT mainly in the lower 50s.

.SHORT TERM /6am SATURDAY MORNING THROUGH SUNDAY/... Towards daybreak, some shortwave energy rounding the top of a mid-level ridge will pass overhead. Some CAMs are hinting at some showers across the interior. Thinking the 12z HRRR (High-Resolution Rapid Refresh) is way too aggressive and went more in line with the 12z ARW for Probability of Precipitation Saturday morning.

Aforementioned low pressure to our north will continue moving east and drag a cold front toward the area. Out ahead of the front, deep SW/W flow through the layer will help the area warm up. The NBM deterministic temperature guidance continues to trend upward while still falling at or below the NBM25th percentile for MaxT. Given the anomalous warm air mass and the upward trending NBM have bumped up MaxTs a few degrees. Used a blend of the previous forecast, the NBM90th, the HRRR (High-Resolution Rapid Refresh) and bias corrected guidance. One concern though is the amount of cloud cover that will be around. This may cause highs to end up a few degrees low than forecast.

With the warm, moist airmass ahead of the cold front, the area looks to become marginally unstable. MLCAPE values look to max out around 500J/kg, mainly across the interior. Some convective activity looks to fire up along the approaching cold front/pre frontal trough and move into our area. The activity is forecast to enter the Lower Hudson Valley area around 5 to 7 pm. The thinking right now is any of this earlier activity would be able to produce lighting with some of the CAPE profile getting into the -10 to -20 layer. Forecast soundings show a decrease in CAPE at this level after 8pm, so went only showers after that. At this time, no organized severe convection is expected.

The cold front moves through Saturday night and then high pressure builds in through Sunday. Cooler and drier air mass filters in and temperatures will be back down in the 60s.

Long Term - Sunday Night Through Friday
There has been little change to the overall forecast thinking in the long term and have stuck close to the previous forecast/NBM.

Deep layered ridging will be in place Sunday night and gradually slide east of the area by late Monday. A progressive shortwave and associated frontal system will then move across the region Monday night into Tuesday. The warm front will lift to our north early Tuesday with the trailing cold front passage likely occurring Tuesday afternoon and evening. The shortwave lifts over southeast Canada Tuesday night into Wednesday leaving behind a SW flow aloft. There were some hints at another shortwave for Thursday in previous model cycles. However, the latest guidance has shifted towards ridging, which potentially could last through the end of the week.

For sensible weather, mainly dry conditions are expected with the highest probabilities of showers occurring Monday night into Tuesday morning with the aforementioned warm front. The trailing cold front appears to have limited moisture and lift to work with so it likely comes through dry Tuesday afternoon and evening. Have left in low probabilities (20-30 percent) Thursday night into Friday, consistent with the NBM. However, it is very possible these probabilities are adjusted down if ridging ends up persisting for the rest of the week, similar to much of the 12z guidance.

Temperatures on Monday will likely be the coolest for this period due to onshore flow from retreating high pressure. Highs will be a bit below normal in the upper 50s to around 60 degrees. Temperatures for the rest of the week look to range from the middle 60s to lower 70s, warmest away from the immediate coast.

Marine
Small Craft Advisories in effect on all waters tonight except the western and central Sound and Peconic and Gardiners Bays. Once nearshore gusts pick up Saturday morning then those areas will be added to the Advisory. Additionally, all non-ocean waters tonight could see a lull in wind gusts.

SCA (Small Craft Advisory) conditions gradually lower Saturday night, with some 5-7ft seas lingering in the ocean zones. Conditions will then remain below SCA (Small Craft Advisory) levels Sunday night through the middle of next week with a relatively weak pressure gradient over the waters.

Fire Weather
Although still windy Saturday, RH will be higher so not expecting any headlines. Continue to exercise caution handling any potential ignition sources, including machinery, cigarettes, and matches. Any fires that ignite will have the potential to spread quickly.

Hydrology
There are no hydrologic issues through next week.

NOAA New York NY Office: Watches - Warnings - Advisories
CT...None. NY...None. NJ...None.

Marine
Small Craft Advisory from 8am to 8pm EDT Saturday for ANZ331- 332-340. Small Craft Advisory until 8pm EDT Saturday for ANZ335-338- 345. Small Craft Advisory until 8am EDT Sunday for ANZ350-353-355.