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.

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Post-Hurricane Season – December

19 12 2020

Dale C. S. Destin|

Named tropical cyclones (tropical storms or hurricanes) during December are virtually unheard of for Antigua and Barbuda. However, in 2007, Tropical Storm Olga came close and affected us. Its centre passed around 39 and 78 miles north of Barbuda and Antigua respectively – at least brushing our islands. Its impact was minimal.

Tropical Storm Olga – December 11, 2007. Credit Wikipedia.

Olga went on to become the most destructive and deadly tropical cyclone originating in December. The storm went on to made landfall on Puerto Rico and Hispaniola with peak sustained winds of 95 km/h (60 mph). It killed at least 40 people and caused US$45 million in damage across the Greater Antilles.

In the history of Atlantic named tropical cyclones, which dates back to 1851, only 16 have had their origin in December, according to NOAA. Of the 16, 5 (31 percent) were hurricanes.

All 16 tropical storms and hurricanes originating in December – 1851 to 2019

Of the 16 total December tropical storms and hurricanes, four impacted the Caribbean i.e. passing within 120 miles of the region. The last to do so was Olga. Based on the climate period 1981-2010, the chance of a storm impacting Antigua is about 3 percent, while the chance of the Caribbean being impacted is about 9.5 percent.

The strongest tropical cyclone owing its origin to December is Alice of 1954 – a Category 1 hurricane. Alice formed in late December and crossed over to January 1955 and impacted Antigua and the rest of the Leeward Islands with Category 1 winds. It eventually reached peak sustained winds of 150 km/h (90 mph) about 100-130 miles northeast of Barbuda. Alice is known to be the only post-season hurricane (forming in December, January or February) to impact the Caribbean.

The last Atlantic storm to have its origin in December is an unnamed subtropical storm of 2013. It formed over the northern eastern Atlantic, near the Azores. It had peak sustained winds of 85 km/h (50 mph). Lost of life and damage caused by it were nil.

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November 2020 Hurricane Summary

9 12 2020

Dale C. S. Destin|

The hurricane season saved the worst for last. November, the last month of the official season, produced the strongest Atlantic hurricane for the year – Category 5 Hurricane Iota, with peak winds of 260 km/h (160 mph).

Category 5 Hurricane Iota making landfall on Nicaragua – 17 Nov 2020

Iota devastated Central America, particularly Honduras and Nicaragua, killing 61 and causing at least US$564 million in damage. However, long before Iota was Iota, her precursor – Tropical Disturbance AL98, was quite destructive to Antigua. It dumped over 373 mm (over 14 in) of rain in 24-hours across parts of mainly western Antigua. This Lenny-type-rainfall caused massive flooding, resulting in inevitable damage in the hundreds of millions of dollars.

Iota not only became the only Category 5 hurricane for the season, but also the first Category 5 hurricane to have its origin in November. The 1932 Cuba hurricane, also known as the Hurricane of Santa Cruz del Sur or the 1932 Camagüey hurricane, became a Category 5 hurricane in November but has its origin in October, unlike Iota.

Iota’s late rise to Category 5 status also keeps the undesirable record streak of seasons going, with at least one such maximum category hurricane. The streak is at five seasons, dating back to 2016.

Tropical Storm Theta was the other named tropical cyclone to have its origin in November. It had peak winds of 110 km/h (70 mph) and minimal impact to the Canary Islands and Madeira.

Eta had its origin in October but developed into a Category 4 hurricane in November and impacted Nicaragua, less than two weeks ahead of Iota. This November tied with November 2005, 2001, 1961 and 1931 for the most storms named in the month.

With the formation of Iota, we were nine deep into the Greek Alphabet – the back up list for naming storms. Notwithstanding, Antigua and Barbuda and the rest of the Eastern Caribbean remained hurricane-free right through the season and was happy to see the back of November.

The hurricane season officially ended November 30, with a record 30 named storms, 13 hurricanes and 6 major hurricanes. Only 2005 is close with 28 named storms, a record that most never thought would ever be broken.  

Recall that an average season produces 12 named storms, 6 hurricanes and 3 major hurricanes, Thus, this season produced 250 percent of the average number of named storms, 217 percent of the average number of hurricane and 200 percent of the average number of major hurricanes.

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

Record-breaking 2020 Atlantic Hurricane Season Ends

1 12 2020

Dale C. S. Destin|

Five tropical cyclones present in the Atlantic – September 14, 2020

The busiest Atlantic hurricane season ever ended last night. The season produced a record-breaking 30 named storms. It also produced 13 hurricanes, the second highest on record dating back to 1851. Further, there were six major hurricanes, Category 3 and over, which tied for the second highest on record. The record season took over 400 lives and caused over US$41 billion in damage.

Only once before a season exceeded 20 named storms – 2005 with 28 named storms, which is the record eclipsed by 2020. However, 2020 remains second to 2005 with respect to the number of hurricanes – 15, and the number of major hurricanes – 7. Six other seasons have a similar total of major hurricanes as 2020 – 2017, 2004, 1950 1996, 1933 and 1926. An average hurricane season has 12 named storms, 6 hurricanes and 3 major hurricanes.

Ranking of the 2020 hurricane season based on number of named storms, hurricanes, major hurricanes and ACE, compared to the records

Although the most eye-catching statistic for a given season is the number of storms, this is not the metric used to determine its overall activity. The Accumulated Cyclone Energy (ACE) index is the internationally accepted metric used to categorise the activity of a season. The ACE takes into consideration not only the number of named cyclones but also their strength and duration. Hence, based on the ACE, 2020 is the 13th most active hurricane season on record, with an ACE index of 180. The most active hurricane season on record remains 1933, with an ACE of 259, 44% more than 2020.

Based on NOAA’s classification, the 2020 season was extremely active or hyperactive. However, NOAA’s classification of season has its challenges, allowing for one season to simultaneously have two classifications. A better approach is to classify seasons strictly by the ACE index. This approach would make the 2020 season and above normal season but NOT well above normal or hyperactive, according to 268Weather’s classification. It fell short by seven ACE needed to take it to 187 – 268Weather’s current threshold for a hyperactive season.

268Weather’s seasonal hurricane forecasts accurately predicted a very high likelihood of an above-normal or active season. 268Weather is proud to be among the few to have gotten the forecast right from very early – April. 268Weather was the only entity to forecast over 28 names storms, up to 32 were predicted and 30 formed.

Animated satellite imagery of the named storms that occurred during the 2020 Atlantic Hurricane Season – May 13 through November 18. Credit: NOAA Satellites

It was a relentless hurricane season. It kept forecasters on their toes continuously. There was an average of 4-5 tropical storms per month since June with one forming about every week. Thankfully, we were not significantly impacted by any of the season’s two-and-half dozen named storms, over a dozen hurricanes and half dozen major hurricanes. Also, the Eastern Caribbean virtually got away “scot free” from significant impacts.

The 2020 season got off to an early start with Arthur on 16 May and Bertha 27 May. From May to July, there was a record nine storms. This is more storms than 80 of the previous 169 seasons, including 2014, 1997 and every season from 1991 to 1994. By September 18, the 21-name Atlantic list was exhausted when Tropical Storm Wilfred formed. Thus, the season “went Greek” i.e. the backup Greek List was turned to for names for the remainder of the season. To date, we are 9 names deep into the list with Iota being the last and the most powerful Atlantic hurricane for the year.

The Atlantic has done a 5-peat – produced five active/above normal seasons in a row. This is the longest such streak, on record. Further, it’s the most active hurricane season since 2017 and the second most active since 2005. Eighteen of the last 26 hurricane seasons, dating back to 1995, were above normal.

The reason for the large percentage of active hurricane seasons since 1995 is due to the positive or warm phase of the Atlantic Multidecadal Oscillation (AMO). Positive phases of the AMO are strongly linked to active eras of Atlantic hurricane seasons, which historically last for about 20 to 40 years.

Like other active years, this year’s activity is owed to an interrelated set of oceanic and atmospheric conditions linked to the warm AMO, such as warmer-than-usual North Atlantic sea surface temperatures (SSTs) and cooler-than-normal middle to eastern equatorial Pacific SSTs i.e. La Nina. These conditions which are also associated with weak wind shear caused the record-breaking, extremely active hurricane season.

Other notable records set by the 2020 season include the following:

  • Twenty-seven tropical storms broke the record for the earliest formation by number
  • A record 10 tropical cyclones rapidly intensified, tying 1995
  • This season is the record sixth consecutive year with pre-season named tropical cyclones
  • A record 10 tropical cyclones were named in September with 9 having their origin in the month, the most for any month
  • Iota became the only Category 5 hurricane to have its origin in November and the latest on record

For more details on the 2020 Atlantic hurricane season, our monthly summaries: May, June, July, August, September, October and November (coming soon).

This season has officially ended, but it is possible, although not probable, for additional storms to develop. Stay vigilant and make sure your family is prepared for all hazards, especially those related to weather and climate. The 2021 hurricane season will officially begin June 1 and 268Weather will issue monthly forecasts starting early April.

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