The Caribbean Basin is about to see another round of large and damaging swells reaching its shorelines starting Saturday, from a bomb cyclone.
Dale Destin, Meteorologist/Climatologist for the Antigua and Barbuda Meteorological Service Climate Section confirmed that the swells are forecast to exceed 3.5 metres (12 feet) and break at higher heights, as surfs, on coastlines. This is likely to be the biggest swell event since Swellmageddon of March 2018.
Destin stated that the event will be kicked off by a relatively inconspicuous low-pressure system (LPS), currently over the northeast United States. The LPS will go through explosive development (bombogenesis) over the next 24 hours and become a ginormous and powerful bomb cyclone (extratropical cyclone) over the northwest North Atlantic, with hurricane-force winds.
The Meteorologist said, although this system will form over 3220 km (2000 miles) away, it will have a significant impact on the region, through its strong winds pushing unusually high waves to our shores. The first set of these swells will reach the Bahamas on Saturday; the northeast Caribbean on Sunday. The event will likely last three days from its start time. So, for the northeast Caribbean, it’s Sunday through Tuesday.
Destin disclosed that the swells will rise to in excess of 3.5 metres across most of the Atlantic waters of the islands. Their swells will produce even higher surfs or breaking waves.
These surfs could be as much as twice the height of the incoming swells, depending on the bathymetry/topography of the nearshore seafloor. This is expected to cause beach closures, as swimming conditions will become quite hazardous. Other impacts include:
• 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 and warnings will be required for the weekend and or the first half of next week.
The Meteorologist/Climatologist disclosed that 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. Moderately sloping, shallow, north and or north-facing shorelines are expected to see the highest swells and surfs.
The bomb cyclone will go from a central pressure of 1004 millibars to around 968 millibars in 24 hours and to a minimum of 955 millibars in 48 hours, just east of Newfoundland and Labrador, Canada. This represents an explosive drop of 59 millibars – more than one millibar per hour; thus, meeting the definition of a bomb cyclone – a drop in pressure of an extratropical cyclone of at least 24 millibars in 24 hours or less.
By Saturday, this weather bomb will be packing Category 1, hurricane-force winds – 119 to 153 km/h (74 to 95 mph). These are the winds that will, in turn, generate large waves that will traverse the Atlantic and pound the shorelines of the Caribbean, inundating some low-lying coastal areas.
Of course, the hurricane-force winds do not even have the remotest chance of reaching the Islands; however, some of the wind energy, transferred into the seas will reach us in the form of ocean waves – ground swells. As you may know, waves do not transport water; they transport energy, which can be destructive when they break on shorelines.
Talking about winds, they are expected to surge – getting to the general range of 25 to 45 (16 to 28 mph), across the region again late Saturday and likely continue into Monday. Storm-force gusts to near 65 km/h (40 mph) are expected, especially in showers. Thus, both high wind advisories and small craft warnings are highly possible late Saturday through Monday morning.
Our (Caribbean) weather will also become wet again over the weekend and into midweek. There is a very high chance of occasional brief showers, as the high winds will destabilise the atmosphere via mixing and low-level convergence.