Long Period Swells, King Tides to Affect T&T This Week

A combination of King Tides and long-period swells are forecast to affect coastal areas of Trinidad and Tobago beginning on Sunday 8th March 2020 through Saturday 14th March 2020. These conditions may produce hazardous conditions in nearshore areas (bays and beaches) for mariners and beachgoers alike.

A Hazardous Seas alert/watch/warning from the Trinidad and Tobago Meteorological Service has not been issued but those with marine interests are advised to exercise extreme caution, particularly between late Monday 9th March through late Wednesday 11th March 2020.

Update: A Hazardous Seas Alert has been issued at 11:26 AM Monday 9th March 2020 by the Trinidad and Tobago Meteorological Service for both Trinidad and Tobago.

The Supermoon & King Tides

As with all supermoons, King Tides tend to occur. These are some of the highest high tides and lowest low tides for the year. This can result in minor coastal flooding in low-lying coastal areas.

During the low tide periods, scenes like those below may become common, as the ocean retreats further out to sea than normal.

Receded Seas at Moruga, Southern Trinidad during a Spring Tide event in February 2020.

Don’t panic if you do see such an occurrence as the water will gradually return. There isn’t an impending tsunami – but if there was, you can always check the University of the West Indies Seismic Research Center and the United States Pacific Tsunami Warning Center for more information.

Bomb Cyclone In The North Atlantic To Produce Long Period Swells Across the Caribbean

A strong low-pressure system in the North Atlantic is forecast to develop over the next 24 hours, producing large and potentially damaging swells to parts of the Caribbean. Thankfully for Trinidad and Tobago, this won’t be a particularly severe event. For our neighbors to our north in the Greater Antilles and Leewards, they may have to contend with swells up to 3 meters and even higher surf.

NHC/TAFB 18Z March 7th 2020 Surface Analysis showing the strong low-pressure system just east of the United States in the North Atlantic.
NHC/TAFB 18Z March 7th 2020 Surface Analysis showing the strong low-pressure system just east of the United States in the North Atlantic.

The event will be caused by an average extratropical cyclone transitioning to a bomb cyclone – a drop of 24 millibars or more in 24 hours or less. This will result in the system developing hurricane-force winds that will push large waves to the Caribbean.

You can read more about the event here.

Seas Forecast

Sea state forecast through the next 7 days, as moderate seas with long period swells (and King Tides) occur across Trinidad and Tobago.
Sea state forecast through the next 7 days, as moderate seas with long period swells (and King Tides) occur across Trinidad and Tobago.

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

Saturday 7th March to Sunday 8th March: Moderate. Low-level winds between 10-15 knots, predominantly from the east, are forecast across the region. Generally, in open waters, waves up to 2.0 meters and below 1.0 meter in sheltered areas. King tides begin on Sunday 8th March 2020, so minor coastal flooding possible in low-lying coastal areas.

Monday 9th March to Wednesday 11th March 2020: Moderate. Low-level winds between 15-20 knots, predominantly from the east to northeast, are forecast across the region. Generally, in open waters, waves up to 2.5 meters and near 1 meter in sheltered areas. However, with a combination of King tides and long period swells, large battering waves are possible beginning Monday night through Wednesday afternoon, affecting northern and eastern coastlines of both islands.

Thursday 12th March through Saturday 14th March 2020: Moderate, with waves generally returning to up to 2.0 meters in open waters. In sheltered areas, near or below 1.0 meters. Long-period swells are forecast to subside, with King Tides ending on Saturday.

Approximate high tides for Port of Spain, Trinidad, and Scarborough, Tobago are seen below. Low-lying coastal areas may experience coastal flooding, particularly 30 minutes prior and 30 minutes after when peak high tides occur though this week.

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

As of 5:00 PM Saturday 7th March 2020, there are no alerts, watches or warnings in effect from the Trinidad and Tobago Meteorological Service.

Update: A Hazardous Seas Alert has been issued at 11:26 AM Monday 9th March 2020 by the Trinidad and Tobago Meteorological Service for both Trinidad and Tobago.

Impacts on T&T’s Shorelines (Mainly Monday through Wednesday)

Impacts possible from rough seas include the following:

  • Loss of life;
  • Injuries;
  • Sea search and rescue disruptions;
  • Disruptions to sea transportation;
  • Scarcity of seafood;
  • Damage or loss of boats and fishing equipment;
  • Disruptions to marine recreation and businesses
  • Economic losses.

Other impacts from the high winds, apart from hazardous seas, include:

  • Injuries;
  • Coastal erosion;
  • Localized disruptions of businesses;
  • Disruption to outdoor and sporting activities;
  • Disruption of transportation (air and especially sea) and

There is also the potential for loss of life. There is a high 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, which 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.

There is also the potential for injuries to beachgoers; beach closures; localized disruptions to marine recreation and businesses and financial losses.

High tides combined with onshore wind and swell actions could result in localized coastal flooding and beach erosion.

High surfs can knock spectators off exposed rocks and jetties. Breaking waves may occasionally impact harbors making navigating the harbor channel dangerous.

Saltwater will likely splash onto low-lying coastal roads such as the South Trunk Road at Mosquito Creek, the Guayaguayare Mayaro Road at the Guayaguayare Sea Wall, and the Manzanilla-Mayaro Road. Bays and beaches may become inundated.

Coral reefs may experience increased stress and damages, in addition to localized beach erosion, particularly in areas where battering waves focus.

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