Extreme Winds and Seas to Usher in the New Year

28 12 2020

Dale C. S. Destin |

Extreme wind and marine events are forecast for this week across the northeast Caribbean, including Antigua and Barbuda. The howling wind event will take place Thursday – NEW YEAR’S EVE, through Saturday – January 2, whereas the life-threatening marine event will take place New Year’s Eve night through Sunday – January 3. Warnings and advisories for strong winds, rough seas and high surfs will be required for most islands.

Northeast Caribbean: Estimated max 3-second gusts; max sustained 10-minute winds; average of the top 10% of significant wave heights and average of top 10% of swells

The angry winds and seas could cause notable socio-economic impacts to the islands. Similar actions by nature, earlier this year, caused ships to turn away from Antigua and Barbuda and cancelled ferry services. There were also reports of LIAT aborting landings in some islands; banana trees being downed in some countries and power outage in some areas.

The kick-off of these unwelcome but not unusual events is expected on Thursday. The pressure gradient will rapidly and significantly steepen, which will become evident by the closeness of the isobars – lines of equal pressure, on our weather maps. The closer the isobars, the steeper the pressure gradient, the stronger the winds and vice versa.

Gale-force gusts, the equivalent to tropical storm-force gusts, are likely – gusts exceeding 78 km/h (over 48 mph). Otherwise, the winds will frequently be above 40 km/h (over 25 mph). The maximum sustained 10-minute wind speeds will likely reach around 50 km/h (31 mph), whereas the maximum sustained 1-minute winds will reach around 56 km/h (35 mph). The strongest winds are forecast for New Year’s Day, especially across open waters, windward coastal areas and elevated places. The prevailing wind direction will be northeast.

Visualization of wind gusts (shaded) wind direction (short solid lines) and isobars (long solid lines with numbers – pressure in millibars) – December 31 2020 to January 4 2021

As the winds go, so go the seas. The tumultuous winds will cause the seas to rise and become extremely threatening – very rough in open waters on Thursday through Sunday. Significant wave heights could peak at or above 4 metres (over 13 feet), locally exceeding 5 metres (near 17 feet). The highest seas are also expected on New Year’s Day. These seas will be non-navigational for small craft and even some non-small-craft operators.

Significant wave heights according to the ECMWF WAM Model – December 31 2020 to January 5 2021

High swells and surfs (breaking waves) are also forecast for Sunday. Swells in excess of 2.5 metres (over 8 feet) and surfs in excess of 3 metres (over 10 feet) are likely. These breaking waves will make for very dangerous conditions for beachgoers and others using the coastlines.

The events will make for a high threat to the life and livelihood and property and infrastructure of mariners and users of the nearshore areas. There is also the potential for extensive impacts including the following:

  • Loss of life
  • Injuries
  • Damage or loss of boats and fishing equipment
  • Saltwater intrusion and disruptions to potable water from desalination
  • Coastal flooding from sea water splashing onto low lying coastal roads
  • Sea search and rescue disruptions
  • Cancellations to transportation (especially by sea)
  • Scarcity of sea food
  • Disruption or cancellation to sporting and recreation events (especially marine activities)
  • Businesses and economic losses

To be safe, mariners should stay in or near port and beachgoers should stay out of the waters for affected coastlines. Also, residents should secure light and loose objects, which can be blown away, and caution should be taken when driving. The anticipated blustery winds could make some outdoor activities uncomfortable, if not outright dangerous. These winds can also create dangerous fallen or blowing objects.

The turbulent winds will unsettle the atmosphere, resulting in brief heavy showers. However, rainfall accumulations will only be of minimal concern, at most.

These events will affect virtually the entire Caribbean Basin, at different times. They will start across the Bahamas and the Western Caribbean on Tuesday and reach the northeast Caribbean on Thursday. Then, they will spread across the southern Caribbean by Friday – New Year’s Day. The extreme events will come to an end by Sunday, January 3, 2021, although seas will likely still be hazardous for some areas, beyond Sunday.

At times, it may feel like there is a tropical storm in the area, but I can ashore you that there is none. The hurricane season remains over.

Check and monitor your local forecasts, from your national weather service, for details specific to your location. This is a relatively broad scale view; hence, the numbers WILL change either way.

Please continue to follow me for more on these extreme events and all things weather and climate via TwitterFacebook and Instagram. Also, share this blog, if you found it useful.





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.

Please share this blog, if you find it useful and keep following it and my other media – TwitterFacebook and Instagram for more on this event and all things weather and climate.





Dangerous Surfs to Threaten Beachgoers in Antigua and Barbuda Easter Monday

17 04 2017

Dale C. S. Destin |

Those heading to the beaches in Antigua and Barbuda should be wary of the threat of strong rip currents Easter Monday through Wednesday.

Seas Forecast Apr 17, 2017

Beaches on the northern and eastern sides of the islands will be at greatest risk for stronger and more frequent rip currents through midweek, due to large swells. Seas are on the rise and will peak on Tuesday with a combination of wind waves and swells nearing 3.0 metres (10 ft) occasionally reaching 3.8 metres (13 ft).

A huge low pressure system near the centre of the North Atlantic is pushing large swells to the region. Meanwhile, the winds in the area are on the increase, which will cause a rise in the wind waves.

Low pressure systems

Rip currents are not new to our shores. They are always present in situations like this and are characterised by water flowing away from the shore. The strength of the current is usually proportional the height of the swells.

Vacationers and residents should take precautions while at the beach. It would be prudent to seek out only beaches under the watch of lifeguards, if possible, and heed all warnings issued. The west facing beasches should be least affected.

Should you ever get caught in a rip current, never attempt to swim directly back to shore as you will be swimming against the current. Instead, swim parallel to the beach to escape the current’s grip before swimming ashore.

Small craft should use caution and heed all advisories, as seas will also be rough.

Similar sea conditions are forecast for most of the rest of the Leeward Islands, the Virgin Islands, Puerto Rico, Hispaniola, the eastern parts of the Bahamas, the Winward Islands and Barbados. The swells will also eventually reach Trinidad and Tobago and the Guyanas late Tuesday.

It is also likely to be a somewhat wet Easter Monday as the same low pressure system mentioned above is pulling a lot of moisture across the islands. The range of the possible rainfall total is wide – 0 to 12 mm (0 to 0.48 in).

The increasing wind will peak late Easter Monday at around 16 knots (18 mph) over open waters and 13 knots (15 mph) over land. Frequent higher gusts will take place.

Seas will return to near normal levels on Thursday.





Storm-Force Winds and Hurricane-Like Seas to Impact Antigua and Barbuda This Weekend

17 12 2016

Dale C. S. Destin |

Significant tightening of the pressure gradient across the area is expected to cause strong winds with frequent gusts to storm force strength or gale force. The seas will respond to the strong winds and become very rough.

Surface chart

Surface Chart for Sunday 8 am, Showing a Tight Pressure Gradient As Evident by the Closeness of the Isobars (pressure lines)

The winds – they will generally be in excess of 18 mph (16 kt) from late Saturday night to Monday afternoon. The winds will peak as high as 30 mph (26 kt) with frequent gusts between 38 and 46 mph (33 and 38 kt) Sunday morning to Monday morning.

High Sustained Winds

Sustained Winds

Wind Gusts

Wind Gusts

The seas –  they will respond to the winds and become very rough, rising to as high as 3.9 metres (13 ft) on Sunday night. Waves will rise above six feet by Saturday morning and remain above this height through midweek. Waves of 2.7 to 3.9 metres (9 to 13 ft) will prevail from Saturday night to Wednesday. Waves are expected to fall off rapidly after Wednesday.

Seas

Seas

The cause – as indicated above, it is the substantial tightening or steepening of the pressure gradient.  This is in response to a very strong surface high pressure system moving from west to east across the Atlantic from the United States.  This will NOT be due to any tropical cyclone (tropical depression, tropical storms or hurricane).

Fundamentally, wind blow as a result of pressure differential (pressure gradient). The greater the pressure between point A and point B (pressure gradient) the stronger the winds.

Where – the strong winds will mostly take place over open waters, exposed eastern coastal areas and elevated areas of Antigua and Barbuda. The seas will be roughest in the Atlantic coastal waters east of the islands, as the winds will be generally easterly. Similar conditions are expected across most of the rest of the Eastern Caribbean. However, Antigua and Barbuda could get the worst of it.

Precautions – The Antigua and Barbuda Meteorological Services have issued warnings for sea-bather and small craft operators. The former should avoid the beaches, especially those on the Atlantic or eastern side of the islands, and the latter should not venture far from port, at least, until Thursday.

A small craft warning generally means that wind speeds in excess of 16 knots is causing or expected to cause hazardous sea conditions to small craft within 24 hours. Inexperience mariners, especially those operating smaller vessels should avoid navigating these conditions.

According to the Beaufort Scale, gale-force winds run from 39 to 54 mph (34 to 47 kt). Operating a vessel in gale conditions requires special expertise and specially equipped vessels. It is highly recommended that mariners without the proper experience seek safe harbour prior to the onset of gale conditions.

The strong winds, especially if frequently gusting to gale force, could also make some outdoor activities very uncomfortable if not hazardous, please be guided accordingly.

We will be keeping a close eye on this developing situation and keep you informed via our social media platform: twitterfacebookinstagramtumblrflickrgoogle+, and youtube.








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