Easter to See More Hazardous Marine Weather Across Most of the Caribbean

26 03 2016

Dale C. S. Destin |

Fresh to strong gusty winds are causing hazardous seas across most of the Caribbean. This is expected to continue beyond Easter Monday (March 28).

Credit UCAR

Hazardous seas; Credit UCAR

Based on observations from met. offices and weather buoys, the winds were in the range of 15 to 22 knots (17-25 mph) with gusts in excess of 32 knots (37 mph).

In some areas, the winds were much stronger. At the Norman Manley International Airport, Jamaica, peak sustained winds of 26 knots (30 mph) were measured. No doubt parts of that island had gusts in excess of 34 knots (39 mph) – the equivalent to gale force or tropical storm force winds.

Weather report

Weather report from Norman Manley Int’l Airport – Mar 25, 2016, 2 pm local time

Winds were strongest across the Caribbean Sea, south of Jamaica. Today, Buoy 42058 measured winds in the range of 21 to 25 knots (24-29 mph) with gusts reaching 32 knots (37 mph).

Buoy data show the Caribbean Sea, especially south of Jamaica, is basically impassable by boat due to tremendously hazardous seas reaching as high as 4 metres (13 feet). Across the waters Eastern Caribbean, seas are near 2.5 metres (8 feet) and building.

Buoy data for March 25, 2016

Buoy data, seas for Mar 22-26, 2016 GMT/UTC

Buoy Data

Buoy data, wind speed Mar 22-26, 2016 GMT/UTC

The strong winds are in response to the high pressure gradient across the region. Winds blow as a result of differential pressure. The greater this differential is i.e. higher the pressure gradient, the stronger the winds and vice versa.

Surface chart depicting high pressure gradient evident by the closeness of the isobars (black lines)

Surface chart depicting high pressure gradient evident by the closeness and high quantity of the isobars (black lines)

As the winds increase, the friction on the underlying sea surface results in building seas or wind-driven waves. The stronger the winds, the higher the wind-driven waves and vice versa.

A further increase in the pressure gradient is forecast over the next 24 hours. Hence, winds and seas are expected to get higher. Thus, marine conditions are expected to become even more treacherous tomorrow.

Seas could exceed 4.5 metres (15 feet) across the waters between Jamaica and Panama. Meanwhile seas and could exceed 2.7 metres (9 feet) mainly on the Atlantic (east) side of Barbuda, Antigua, Guadeloupe, Dominica and Martinique.

Forecast Seas

Forecast Seas (feet), valid 2 pm (1800 UTC), Sat, March 26, 2016

The winds could increase by another 2 to 5 knots (2-6 mph) with gusts in the upper 20s to lower 40s knots ( upper 20s to upper 40s mph).

Forecast Winds

Forecast Winds (knots), valid around 11 am (1500 UTC) Sat, Mar 26, 2016

Forecast Gusts

Forecast Gusts (knots), valid around 11 am Sat, Mar 26, 2016

Clearly, it goes without saying that mariners should not venture far from port and sea-bathers should be extremely careful. As a matter of fact, sea-bathers should avoid the beaches on the northern and eastern sides of the islands. For Hispaniola and Jamaica, beach-goers should also avoid the waters on the southern side of those islands.

The strong winds could also make some outdoor activities very uncomfortable to perform, if not outright dangerous. This is especially true of work at elevations. Please be guided accordingly.

The winds will start to subside on Sunday. However, seas will not return to safe levels until around Wednesday.

Cuba is the only Island being spared by the strong winds and hazardous seas.

We will keep you updated via our social media platform, which includes twitter, facebook, wordpress, instagram, tumblr, and google+. You are invited to follow for all things weather and climate.

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2 responses

26 03 2016
Joseph Bahri

And the cause of these high winds ?………..is it tight pressure gradient, the strength of the high pressure system, the location of the high pressure system?
And how does this affect the “Feels like” temperature? Cooler days, warmer nights? Just asking!!

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26 03 2016
Dale C. S. Destin - Antigua Met Service

Thanks for subscribing and reading my blog! The blog does mention the reason for the strong winds being the HIGH (tight) pressure gradient. It talks about the reason why winds blow as being the differential in pressure and the greater the differential, the stronger the winds and vice versa (there is also a link the further explains this concept). A “strong” Atlantic High does not necessarily translate into high winds nor is the converse necessarily true. It has to do with the gradient it sets up across the islands. The location and strength plays apart but fundamentally it’s the pressure gradient what determines the wind strength. The blog was meant to highlight the danger of winds and seas; hence no mention of temperature, but of course the high winds in our context keep things relatively cooler.

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