Long Island Sound West of New Haven CT / Port Jefferson NY Marine Forecast (2024)

Area Forecast Discussion
National Weather Service New York NY
801am EDT Wednesday July 10 2024

Synopsis
A stalled frontal boundary lifts north as a warm front today. The remnants of Beryl will approach today, and then lift north of the area while dragging a cold front through tonight into Thursday. The frontal boundary remains within the vicinity of the local area Friday and into next week.

Near Term - Through Thursday
Forecast mainly on track.

This morning some fog and low stratus may linger into the morning for far eastern sections of the CWA, before clearing by the afternoon as wind starts to pick up from the south due to a passing warm front. It looks like strong capping in place during the morning will prevent any convection from getting started with the warm front, but this weakens later in the day.

After the warm front's passage, the remnants of Beryl will pass to our north and west late today into tomorrow with a cold front. This cold front will approach late today then stall into Thursday. Being in close proximity to the Remnants of Beryl, which comes from the Gulf of Mexico, increased tropical moisture is expected. PWATs (Precipitable Waters) are expected to rise into the 2.2-2.4" tonight which exceeds the maximum average for our region of 2.1" per SPC's Sounding Climatology Page. Given the increased moisture, any showers or thunderstorms that do occur, bring with them the risk for heavy rainfall.

As far as coverage is concerned, expecting a dry morning. In the afternoon as the front approaches, isolated to spotty showers and thunderstorms may Probability of Precipitation up north and west of NYC as strong surface heating ramps up. Not all of the latest CAMs buy into the chances, with some popping to keep us dry through the evening, so have only low end chance and slight chance POPs in the forecast through early this evening. Should anything Probability of Precipitation up, a thunderstorm would be likely to come from it, considering the strong instability this afternoon and early evening.

Tonight into Thursday morning, as the front approaches, a line of showers and thunderstorms appears likely for far interior areas north and west of NYC late tonight. This will push eastward through the CWA (County Warning Area) into the morning on Thursday. Instability will be much lower given the line moves through late at night and in the early morning, but with forcing occurring along the frontal boundary and with other sources of synoptic lift falling into place, thunderstorms remain a possibility. And with the strongest PWATs (Precipitable Waters) expected tonight as the Remnants of Beryl passes nearby, heavy rainfall could occur in any showers or thunderstorms that do occur.

The front looks to stall over the area during the day on Thursday and could lead to continued chances for isolated to scattered showers and thunderstorms.

As for winds, a strong southerly 30-40 kt LLJ sets up this evening into tomorrow morning aided by an increasing pressure gradient by strong high pressure to our east and the passing Remnants of Beryl to our west. Currently expecting sustained winds this evening into Thursday morning to peak around 15-20 mph with the strongest gust along southern coastal areas to peak around 35 mph. Winds should remain elevated into Thursday with area gusts ranging between 20 and 30 mph, as the LLJ exits and the Remnants of Beryl passes with the stalling front.

Temperatures will meet Heat Advisory criteria for much of the area today. No changes have been made to the Heat Advisories since they were last issued. Still expected heat indices to peak around 100 in Orange county and NE NJ, with other areas still ranging between 95 and 98. Tomorrow, dewpoints are expected to lower with the front, particularly in western areas. Temperatures may also be a degree or two lower with increased cloud cover along the frontal boundary. Heat Advisory criteria is not expected to be met.

Short Term - Thursday Night Through Friday Night
As far as Friday is concerned, not much has changed. A stalled frontal boundary is still forecast to remain over or near the western portion of the forecast area Friday and Friday night. Surface based lift will be limited, however mid-level lift from shortwave energy arriving from the SW will tap into a moist atmosphere and help bring the likelihood of showers for a good portion of the area. Additional lift may arrive in the form of a shortwave moving clockwise around the periphery of a western Atlantic ridge. Both areas of lift aloft should lose influence by the end of Friday night. Shear is fairly weak, so severe thunderstorms are not anticipated at this time. However, scattered thunderstorms with downpours may bring some flooding issues, since lingering tropical moisture have PWATs (Precipitable Waters) remaining at anomalous values (2-2.25"). Guidance still varies on the location of the axis of heaviest rainfall. See the hydrology section for more details.

Long Term - Saturday Through Tuesday
Main points

* Saturday appears to be relatively speaking the coolest and rainiest day of the long term. Forecast highs are still well into the 80s for most locations.

* Potentially another heat wave Sunday into next week. Max heat indices forecast get near the 90 to 100 degree range for much of the area.

* Chances for showers and thunderstorms Monday through Wednesday next week, mainly north and west of NYC.

* Precipitable waters potentially in the 1.5 to 1.75 range for early to mid next week, making heavy rain a possibility with any thunderstorms that form.

Synoptic pattern transitions from Western Atlantic ridge to more of a zonal flow. The Western Atlantic ridge flattens out this weekend with more zonal flow getting established Sunday and going into next week. Next main trough moves into SE Canada towards the middle of next week.

At the surface, a frontal boundary remains near the region this weekend with low pressure to the south and west. This pattern does not change too much going into the early to mid part of next week.

Airmass will transition eventually back to a hot and humid airmass for the end of the weekend and into next week. While the forecast area with forecast high temperatures appears to get more into the 90s, the dewpoints forecast are not quite as high as those recently seen. Max dewpoints forecast are more in the lower 70s.

Marine
Marine dense fog advisories are in effect into early this afternoon for the ocean, and the eastern and south shore bays of Long Island, along with the eastern most portion of LI Sound.

Sub small craft conditions for all waters through tonight. A southerly flow gradually increases during the day Wednesday with small craft conditions towards the afternoon for the ocean waters into Wednesday night. Small craft conditions will likely persist on the ocean waters through Friday night with 5-6 ft seas and gusts of 25 kt through Thursday. Marginal small craft conditions are likely for the southern and eastern most near shore waters during much of this time frame.

With a relatively weak pressure gradient in place across the forecast waters this weekend, conditions are forecast to remain below SCA (Small Craft Advisory) thresholds.

Hydrology
With a very humid airmass locked in across the region and a frontal boundary drawing closer for the mid and late week period WPC maintains a marginal risk of excessive rainfall northwest portions of the area today and for most of the area on Thursday and Friday. At any point a stronger thunderstorm could produce localized flooding impacts. Friday is expected to be the wettest day with an average of half inch to an inch of rainfall across the area, although locally higher totals are possible wherever a stronger axis of rainfall sets up. Primarily minor urban/poor drainage small stream flooding will be possible, but there is a low threat of flash flooding.

With building humidity and higher precipitable waters moving into place for early to mid next week, heavy rain will be a possibility with any thunderstorms that develop. Too early to ascertain any specific rainfall amounts, but localized heavier rainfall can be expected.

Tides / Coastal Flooding
There is a high risk of rip current development along all ocean beaches today through Thursday. Onshore flow becomes more gusty with building ocean seas.

NOAA New York NY Office: Watches - Warnings - Advisories
CT...
Heat Advisory until 8pm EDT this evening for CTZ005>010. NY...
Heat Advisory until 8pm EDT this evening for NYZ067>075-078- 176>179. High Risk for Rip Currents through Thursday evening for NYZ075-080- 081-178-179. NJ...
Heat Advisory until 8pm EDT this evening for NJZ002-004-006- 103>108.

Marine
Dense Fog Advisory until noon EDT today for ANZ332-340-345. Dense Fog Advisory until 2pm EDT this afternoon for ANZ350- 353-355. Small Craft Advisory from 2pm this afternoon to 8pm EDT Thursday for ANZ350-353-355.

Long Island Sound West of New Haven CT / Port Jefferson NY Marine Forecast (2024)
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