Strong Howling Winds to Continue to Impact the Caribbean

11 01 2020

Dale C.S. Destin, updated January 12, 2020 |

Strong howling winds are expected to continue across much of the Caribbean Basin through Tuesday. These huffing and puffing, big bad wolf winds are causing notable socio-economic impacts to the islands.

As the winds go up, so also do the seas; hence, hazardous seas have engulfed the region – from the Bahamas to the Guyanas, including the Caribbean Sea.

The winds have risen to the range of 29 to 52 km/h or (18 to 32 mph) over land and are expected to persist until Tuesday. Further, gusts as high as 80 km/h (50 mph) are possible for some areas. Over the Caribbean Sea, the winds are forecast to be stronger than some places over land. One such area is between Jamaica and Columbia, where sustained winds – 70 km/h (44 mph), are forecast. With respect to land, the highest sustained winds are forecast for the Eastern Caribbean.

The blustery winds will cause the seas to remain very angry with significant wave heights of 2.5 to over 4 metres (8 to 14 feet) and occasionally reaching over 5 metres (18 feet). There is an area between Jamaica and Columbia where the significant wave heights are predicted to be over 5 metres (18 feet), occasionally reaching 7 metres (23 feet).

Over the past 24 hours, above normal swells, from distant strong winds, have added to the hazards across the area. So, not only there are concerns for high winds and hazardous marine conditions in open waters, there is now also a concern for the impact of life-threatening surfs (breaking waves) along, mainly northern and north-facing shorelines; hence, a high surf advisory has or will be required for most islands. Already, a high surf advisory is in effect for much of the Caribbean.

Beachgoers should be extremely cautious; bathe only where lifeguards are present or the sheltered, less affected beaches, mainly to the south. See the bulletins from your national weater service for detail and specific guidance for you local.

Such conditions are very conducive fo rip currents – powerful channels of water flowing quickly away from 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.

As a result of the weather, more so the strong winds, three cruise ships had to abort berthing at the St. John’s Harbour in Antigua. These, I am informed, were The Anthem of the Seas, Norwegian Dawn and Crown Princess. Ferry service between Antigua and Montserrat has been cancelled until Thursday. The have also been aborted attempts by LIAT to land in Dominica. There are also reports of downed banana and other trees in the Windward Islands and Trinidad and Tobago, and there have been power outage in the British Virgin Islands and Trinidad and Tobago attributed to the strong winds.

Thus far, the highest winds (10-minute sustained and gusts) have been observed at:

  • Grantley Adams International Airport (GAIA), Barbados;
  • George F.L. Charles Airport (GFLCA), St Lucia and
  • Norman Manley International Airport, Jamaica.
The winds by the numbers. One mph = 1.61 km/h. Multiply 10-minute sustaned winds by 1.11 and 1.40 to get 1-minute sustained winds and 3 second gusts respectively. *Harper et al. 2010 is the World Meteorological Organization (WMO) standard.

Looking at the winds by the numbers. Speeds of 39 mph or more are storm-force or gale-force winds, gusts in this case. However, when dealing with tropical cyclones, categorization is based on a maximum 1-minute sustaned wind speed. To convert from 10-minute wind speeds to 1-minute wind speeds, multiply by 1.11. Thus, parts of Barbados, Jamaica and St. Lucia had sustained storm-force windsstorm conditions (35×1.11 = 39 mph or 63 km/h). However, note that there are no tropical cyclones in the area.

Winds blow because of the differential of pressure across the Earth’s surface. The higher the horizontal differential or the higher the pressure gradient, the stronger the winds. The strong winds, over the next several days, will continue to be due to a very steep pressure gradient. The pressure will be that steep largely due to a 1042 millibar high-pressure system moving off the US east coast.

Pressure pattern forecast for 2 am Saturday, January 11, 2020
The ususal pressure pattern across the North Atlantic for January. Note that the usual difference of pressure between Bermuda High and the Caribbean is around 6 to 8 mb.

Immediately above is the usual pressure pattern for the North Atlantic. Note that the usual difference in pressure between the Bermuda High and the Caribbean is around 6 to 8 millibars. However, compare the graphic below to the one above and you will observed that the difference in pressure between the Bermuda High and the Caribbean (at 2 am, Sat, 11 Jan 2020) was 20 to 24 millibars. Thus, the pressure difference and gradient were two to four times higher that usual or 200 to 400% of normal; hence, the very strong winds.

North Atlantiuc surface chart – 2 am, Saturday, 11 January 2020

The highest and most dangerous waves will take place across the waters of the western Caribbean – between Jamaica and Columbia. This area will also experience the strongest winds – 51 to 64 km/h (32 to 40 mph), gale-force/storm-force winds, with gusts in excess of 96 km/h (60 mph).

Advisories and or warnings to mariners have been issued by a number of islands, including Antigua and Barbuda, Puerto Rico and Barbados.

As a small craft operator, if an advisory is issued – inexperienced mariners, especially those operating smaller vessels should avoid navigating in these conditions. If a small craft warning is issued – you should stay in or very near port.

Potential impacts from this hazardous sea event include injuries or loss of life, damage or loss of boats and fishing equipment and disruption to sea transportation. Other possible impacts comprise of:

  • disruptions to sea search and rescue;
  • scarcity of seafood;
  • disruptions to off shore marine recreation and businesses;
  • business and economic losses.

On the other hand, the strong winds could result in further disruptions to transportation and outdoor sporting activities, soil erosion, vehicular accidents and financial losses.

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Storm-Force Wind Gusts and Hazardous Seas Are Returning to the Area

7 03 2017

Storm-force wind gusts and hazardous seas are returning to the area. The weather will be generally good but the increased winds will cause the lower atmosphere to become somewhat unsettled, giving rise to occasional showers.

The Met Office has already issued a small craft warning and this is expected to continue in place through, at least, Friday. Given the expected conditions, small craft operators should not venture far from port, especially on the windward side of the islands. Beachgoers should avoid the waters of the north and east facing beaches.

The expected strong gusts will also make some outdoor activities very uncomfortable if not dangerous. At least, light objects should be secured, as minimal storm conditions are possible. Please be guided accordingly.

The wind speed will steadily rise to 28 to 44 km/h (17 to 28 mph) by late Tuesday and continue in that range until Thursday; thereafter, subsiding. Wind gusts as high as 67 km/h (41 mph) are possible in showers. The prevailing winds will be east-northeast.

The major concern about the winds is the impact on the seas. They will cause the seas to become very hazardous, with heights reaching 4 metres (13 ft), occasionally reaching 5 metres (17 ft) late Tuesday and staying at those heights until Friday, when they will start to subside.

These conditions, especially the seas, will not be dissimilar to what would obtain during the passage of a tropical storm through the area. However, no such system will be around.

The brunt of this windy weather will be felt mainly over open waters on the windward side of the islands, windward coastlines and elevated places.

The gale-force or storm-force wind gusts and associated strong winds will be as a result of a very steep pressure gradient across the area. Recall that winds blow due to pressure differences or pressure gradients, and the greater the gradients the stronger the winds and vice versa.

The last episode of similarly strong winds and rough seas was a recent as last week.

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