Another Windy, Rough and Wet Week Ahead

16 12 2019

Dale C. S. Destin|

Rough Seas – Photo by Getty Images

This is a new week, but similar weather is expected to last week’s – windy and wet with rough seas. Winds are expected to surge over the next 24 hours, resulting in the winds becoming fresh to strong by Monday night. This will in turn cause hazardous seas and wet weather across much of the Caribbean Basin, including Antigua and Barbuda.

The winds and seas will be a threat to the life and property of mainly mariners. Some outdoor activities, on land, could also become dangerous.

By late Monday, the winds will rise to the range of 26 to 42 km/h (16 to 26 mph) with stronger gusts . It is expected that the winds will gusts to near storm-force/gale-force – 63 km/h (39 mph), mainly over open waters, exposed coastal areas and elevated terrains.

Given the expected winds, a high wind advisory may be required, particularly for the areas listed above. If a high wind advisory is issued, residents should secure loose and light outdoor items, which can be blown away, and caution should be taken when driving.

As the winds go, so go the seas – as the winds go up, the seas will go up also and become hazardous. Seas (significant wave height – SWH) are forecast to rise to a range of 2 to 3 metres (7-10 feet) with the potential extreme (10% chance) of reaching over 3.5 metres or 12 feet. Notwithstanding, the potential extreme SWH, seas are expected to occasionally reach near 4 metres (13 feet).  

Recall that seas are given as SWH, which is the average height of the highest 1/3 of the waves. Individual waves may be twice the SWH.

Given the expected height of the seas, particularly wind waves, a small craft warning is expected to go into effect for much of the waters of the Eastern Caribbean Monday night through Thursday morning. An advisory is in effect and one will be in effect after the warning.

Recall that a small craft warning generally means that wind speeds of 38 to 61 km/h (24 to 38 mph) and or seas of 9 feet or greater are expected to produce hazardous wave conditions to small crafts. If or when a warning is issued, small craft operators should stay in or near port and safeguard their vessels.

Impacts possible/likely/expected from hazardous seas include the following:

  • Loss of life;
  • injuries;
  • sea search and rescue disruptions;
  • disruptions to sea transportation;
  • scarcity of sea food;
  • damage or loss of boats and fishing equipment;
  • disruptions to marine recreation and businesses
  • and economic losses. 

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

  • injuries;
  • soil erosion;
  • localized disruptions of businesses;
  • disruption to outdoor and sporting activities;
  • disruption of transportation (air and especially sea) and
  • vehicular accidents and financial losses.

Wind of this strength could make some outdoor activities uncomfortable, if not outright dangerous. High winds can create dangerous fallen or blowing objects.

The strongest winds and the highest and most dangerous seas will take place on Tuesday. The highest seas will take place in the Atlantic waters of the islands.

The strong winds will be due to a very steep pressure gradient. Think of the pressure gradient like a hill and the wind as a car. The steeper the hill the faster the car will roll down the hill and vice versa. On a weather map, the steepest gradient and strongest winds are where the lines of equal pressure (isobars) are closest.

The higher than usual winds will destabilize the atmosphere, resulting in brief passing showers from time to time. Possible rainfall total for the week across the Eastern Caribbean is 25 to 150 mm (1-6 inches). The highest totals are likely across the southern Caribbean.

Last week, similar type weather took place. The area had fresh to strong winds with gusts in excess of 48 km/h (30 mph). The whole of the Eastern Caribbean had wet weather with some areas experiencing rainfall in excess of 150 mm (6 inches).

Seas will subside from warning to advisory levels by Thusday; however, it is unclear as to when seas will return to safe levels – when no warning, advisory or caution is required.

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