Long-Period Swells, Agitated Seas Forecast Due To Tropical Storm Paulette

As Tropical Storm Paulette strengthens in the Central Atlantic, long-period swells have begun to affect parts of the Leeward Islands. These swells will propagate west and south, towards the Greater Antilles and the Windward Islands.

Much of the severe impacts from these swells are forecast to mainly occur across the Leewards and the Greater Antilles, but swells of this nature can produce rip currents in nearshore areas of Eastern and Northern Coasts of T&T.

In addition, strong low-level winds produced from overnight thunderstorms Friday into Saturday are forecast to produce hazardous seas in the Gulf of Paria.

Tropical Storm Paulette northeast of the Leewards, producing a wide area of rough seas and swells moving toward the Leewards and the Greater Antilles on Friday. These swells are forecast to move across the Bahamas and the Southeastern United States over the weekend. (Windy)
Tropical Storm Paulette northeast of the Leewards, producing a wide area of rough seas and swells moving toward the Leewards and the Greater Antilles on Friday. These swells are forecast to move across the Bahamas and the Southeastern United States over the weekend. (Windy)

While swells are forecast to subside by the middle of Sunday, with mostly slight to moderate seas forecast through the next 7 days. However, another tropical system may bring agitated seas to the region by mid to late week next week.

Seas Forecast

Sea state forecast through the next 7 days, as slight to moderate seas are forecast, with long-period swells to affect Trinidad and Tobago.
Sea state forecast through the next 7 days, as slight to moderate seas are forecast, with long-period swells to affect Trinidad and Tobago.
Sea state forecast through the next 7 days, as slight to moderate seas, are forecast, with long-period swells to affect Trinidad and Tobago.

The general sea state through the next 7 days is as follows:

Friday 11th through Sunday 13th September 2020: Slight to Moderate. Across Northern and Southern Coasts of Trinidad, as well as the Western coasts of Tobago, slight seas are anticipated with waves less than 1.5 meters. Across the Atlantic facing coasts of both islands, moderate seas with waves between 1.5 meters to 2.0 meters.

Low-level winds are forecast to initially be from the south to southeast at 10 knots. These winds may become south to southwesterly overnight Friday into Saturday. Winds return with a southeasterly component later on Saturday into Sunday and then predominantly east into Sunday night, remaining at 10 knots, nearing 15 knots into Monday.

In sheltered areas, waves are forecast to be near calm to below 1.0 meter and choppy at times. Long period swells (generally between 10-12 seconds) will produce larger than usual waves in nearshore areas of northern and eastern coasts of T&T through Sunday.

Note: Overnight Friday into Saturday, strong winds and agitated seas are possible in the Gulf of Paria. Particularly along the Northwestern coasts, waves near 1 meter are possible. Particularly if strong thunderstorms persist across the Gulf of Paria as it moves north.

Monday 14th through Tuesday 15th September: Moderate to slight. Low-level winds increase, remaining between 10-15 knots, predominantly from the northeast to east. Seas generally are between 1.5 meters to 2.0 meters in open waters. In sheltered areas, below 1.0 meters to near calm in sheltered areas. No adverse sea impacts anticipated.

Wednesday 16th through Thursday 17th September: Variable: Slight to Rough. Invest 95L, a tropical wave in the far eastern Atlantic with high chances of tropical cyclone formation over the next 5 days, may bring hazardous seas but impacts are highly track-dependent.

Presently, the operational GFS, a top tropical cyclone forecasting model, remains the outlier, bringing a very strong tropical cyclone across the Central Lesser Antilles. All other models keep this system well north and east of the region.

If this system follows the path of the operational GFS, hazardous and rough seas are likely, with long-period swells. If this system remains far away, our main concern would be long period swells. The longer-range forecast remains highly uncertain and is low confidence at this time.

Another variable would be the occurrence of spring tides, which begin on Wednesday. This would increase the chances of adverse coastal impacts beginning Wednesday through the end of the week. However, we continue to monitor the situation and will update accordingly.

Below are approximate high tides for Port of Spain, Trinidad, and Scarborough, Tobago. Low-lying coastal areas may experience coastal flooding when long-period swells are occurring, particularly 30 minutes prior and 30 minutes after when peak high tides.

High Tide Forecast for Trinidad over the next 7 days as long period swells and moderate seas forecast.
High Tide Forecast for Tobago over the next 7 days as long period swells and moderate seas forecast.

There are no alerts, watches or warnings in effect from the Trinidad and Tobago Meteorological Service, as seas remain below yellow-alert-level criteria at the moment.

Impacts on T&T’s Shorelines
(Particularly For This Weekend)

With long period swells, the following impacts are possible:

  • Elevated risk of rip currents in eastern coastal areas.

With hazardous seas in the Gulf of Paria, the following impacts are possible:

  • Minor damage to jetty’s, marinas, and small craft, particularly along the Northwestern Coastlines Friday night into Saturday.

Other impacts, apart from hazardous seas, include:

  • Minor coastal flooding in low-lying areas;

There is a moderate risk of rip currents, strong currents that can carry even the strongest swimmers out to sea.

Rip currents are powerful channels of water flowing quickly away from the shore. These currents occur most often at low spots or breaks in the sandbar and near structures such as groins, jetties, and piers. If caught in a rip current, relax and float. Don’t swim against the current. If able, swim in a direction following the shoreline. If unable to escape, face the shore and call or wave for help.

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