Leslie to Cause a Mini Swellmageddon Across the Caribbean

28 09 2018

Dale C. S. Destin |

Ex-Tropical Storm Leslie is about to cause a mini Swellmageddon across much the Caribbean, after the passage of Kirk. The system is expected to be a major swell-maker, which will become very evident in 24 hours; hence, Swimming conditions at many beaches will become very hazardous.

Fort James Beach During Swellmageddon – Mar 2018

Fort James Beach During Swellmageddon – Mar 2018

Currently, Leslie is not a tropical cyclone. It transitioned into an extratropical cyclone, a few days ago. However, it has not gone any place. The cyclone is forecast to be resurrected. She will strengthen, return to tropical cyclone status in the next 48 hours and eventually become the sixth hurricane for the season.

The hurricane-force winds, to be produced by the cyclone, will never reach us, but they will push, dangerous and damaging sea swells to our shorelines, particularly the Atlantic-facing ones.

Swell height at a NOAA buoy located about 370 NNE of Antigua

Swell Heights at a NOAA Buoy Located About 370 NNE of Antigua

Swells are forecast to steeply climb to 3 metres (10 feet) on Saturday. These large and dangerous battering swells are expected to pummel our shorelines over the upcoming weekend before subsiding to safe levels by mid next week.

Swells Forecast by ECWMF

Swells (colour coded) and Pressure (lines in ATM/Torr) Forecast by the ECMWF WAM 11km Model for Sat Sep 28, 2018

Recall the swell event I dubbed Swellmageddon earlier this year – March 4-7, 2018. It was a swell episode of epic proportion – almost unheard of in the Caribbean. This upcoming swell episode is not expected to be as severe, but it won’t be your garden-variety event either.

The large swells will produce even higher breaking swells or surfs, which could be as much as twice the height of the swells. This means that surfs are expected to range between 3 and 6 metres (10 to 20 feet) this weekend, depending on the bathymetry/topography of the near shore seafloor. This is expected to cause some beach closures, as swimming conditions will become very dangerous for beachgoers, by tomorrow.

This mini Swellmageddon will likely, among other things, also cause:

  • major beach erosion;
  • flooding of some low-lying coastal roads;
  • disruptions to marine recreation and businesses;
  • disruptions to potable water from desalination;
  • damage to coral reefs and
  • Financial losses.

Advisories have already been issued by a few of the region’s national meteorological services. More advisories and or warnings are expected to be issued over the upcoming days. This event will be felt as far west as the Bahamas and as far south as Guyana, Brazil and beyond. The event will also be felt along the East Coast of the United States, Canada and perhaps, as far away as, West Africa.

The impact on shorelines will not be the same everywhere. Depending on the depth and the natural shelter of the coastal waters, the impact will be different. Shallow north-facing shorelines are expected to see the highest swells and surfs. Surfs could rise to as high as 6 metres (20 feet), at some locations.

In open waters, the swells from Mini Swellmageddon will be virtually harmless to small craft operators, as they will be long-period waves with gentle gradients.

There is no chance of any of the destructive winds, from the cyclone at the centre of this significant swell event, reaching the Caribbean. Normal seasonal winds will prevail.

Keep following us for more on this significant swell event and for everything weather and climate. Actual images of the high surfs will be posted on facebook.com/anumetservice and twitter.com/anumetservice.

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