May Updated Forecast for the 2022 Atlantic Hurricane Season

17 05 2022

Dale C. S. Destin |

My May updated forecast for the 2022 Atlantic Hurricane Season is out, and it continues to call for a very busy and active season with the potential of being super hyperactive. As of May 18, the forecast is for 20 named storms (down 1), 9 hurricanes (unchanged) and 4 major hurricanes (unchanged).

Recall that the accumulated cyclone energy index (ACE) is the universally accepted metric used to classify the overall activity of a hurricane season. The ACE forecast for this year is 175, 23 above the threshold for an active season, based on 1991-2020 data.

A super hyperactive season like 2017 also remains possible. There is a 33 percent chance of the ACE exceeding 223. Further, there is a 42 percent chance of more than 19 named storms; 27 percent chance of more than 11 hurricanes and also a 27 percent chance of more than 6 major hurricanes.

If the forecast pans out, this season would be the third most active since 2017, in terms of ACE, and the 16th most active on record dating back to 1851. It would also tie with 1933 for the fourth highest number of named storms.  

The survey of other forecasts reveals a consensus for an above normal season. The consensus is for an ACE of 159, 18 named storms, 9 hurricanes and 4 major hurricanes, a busy and active season. This is generally consistent with my forecast. However, regardless of the forecast, you should always be well prepared each season, as it only takes one hurricane to ruin your year and or life.

The ACE forecast from several models, including that of 268Weather’s for April. The overall average is 159

The main reason for the above normal forecasts is the current La Niña, which is forecast to last through the hurricane season, causing favourable conditions for higher than usual tropical cyclone formation.  

Recall, a typical season, based on the new standard climate period 1991-2020, has 14 named storms, 7 hurricanes and 4 major hurricanes. Major hurricanes have sustained wind speeds of at least 178 km/h or 111 miles per hour (e.g., Category 3 or higher), according to the Saffir Simpson Hurricane Wind Scale.

This forecast will be updated monthly around the 14th of each month until August. The first update will be issued around June 14.

The Atlantic hurricane season officially begins on June 1 and concludes on November 30; nevertheless, in the last six years, there have been preseason tropical cyclones–be prepared!

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June Updated Forecast for the 2021 Atlantic Hurricane Season

19 06 2021

Dale C. S. Destin |

The numbers for this hurricane season are likely to be very high once again. My updated forecast for the 2021 season is out, and it continues to call for an above normal season being likely. The confidence of an above normal season has grown from 69 to 78%. It is also possible that the season could be super hyperactive with more than 19 named storms likely.

The prediction is still for 22 named storms (tropical storms and hurricanes), with a 70 percent confidence or high confidence of the number ranging between 17 to 28. It is also likely–56 percent chance (down 2), that the number of named storms will exceed 19 and be in the top 10 percentile of the historical record, dating back to 1851.

My forecast also calls for an accumulated cyclone energy (ACE) index of 186 (up 7) with a high confidence of the range being 112 to 286. There is also a 44 percent chance (up 9) of the ACE index exceeding 223. Also predicted are 9 hurricanes (down 1) with a 70 percent confidence of  the total being 6 to 13, and 5 major hurricanes (up 1) with high confidence of 2 to 7.

If this forecast pans out, this season would be the most active since 2017, in terms of ACE, and the 10th most active on record dating back to 1851. It would also be ranked third for the highest number of named storms and tied for 11th and 17th for the most hurricanes and major hurricanes respectively.

The main reasons for the above normal forecasts are the likely above normal sea surface temperatures across the tropical North Atlantic and a weak La Niño and or cold-neutral El Niño Southern Oscillation (ENSO) during August to October–the peak of the hurricane season.

A typical season, based on the standard climate period 1991-2020, has 14 named storms, 7 hurricanes and 3 major hurricanes. Major hurricanes have sustained wind speeds of at least 178 km/h or 111 miles per hour (e.g., Category 3 or higher), according to the Saffir Simpson Hurricane Wind Scale.

This forecast is updated monthly around the 15th each month until August. The next update will be issued around July 15.

The Atlantic hurricane season officially began on June 1 and will conclude on November 30. Be prepared! Please share this blog, if you found it useful and follow me for more on the ongoing hurricane season, which unfortunately could be another wild one, and for all things weather and climate – TwitterFacebook and Instagram.





May Updated Forecast for the 2021 Atlantic Hurricane Season

12 05 2021

Dale C. S. Destin |

The numbers for this Atlantic hurricane season could challenge those of the record breaking 2020 Season. My updated forecast for the 2021 Season is out, and it continues to call for an above normal season being likely. It is also possible that the season could be super hyperactive.

The prediction is for 22 named storms (tropical storms and hurricanes), with a 70 confidence or high confidence of the number ranging between 15 to 29. It is also likely–58 percent chance, that the number of named storms will exceed 19 and be in the top 10 percentile of the historical record, dating back to 1851.

My forecast also calls for an accumulated cyclone energy (ACE) index of 179 (down 5) with a high confidence of the range being 89 to 266. There is also a 35 percent chance chance of the ACE index exceeding 223, super hyperactive or in the top 10 percentile of the 1991-2020 climatology. Also predicted are 10 hurricanes (up 1) with a 70 percent confidence of  the total being 6 to 14, and 4 major hurricanes (down 1) with high confidence of 2 to 7.

If this forecast pans out, this season would be the third most active since 2005, in terms of ACE, and the 14th most active on record dating back to 1851. It would also be ranked third for the highest number of named storms and tied for 9th and 19th for the most hurricanes and major hurricanes respectively. Further, the season would be deemed extremely active (hyperactive) according to the National Oceanic Atmospheric Administration (NOAA) criteria i.e. ACE greater than 159.6.

According to other forecasts surveyed, the consensus is for an ACE of 152, 18 named storms, 8 hurricanes and 4 major hurricanes – an above normal season. This is generally consistent with my forecast but with a notable 18 percent less activity (ACE); notwithstanding, I am very confident in the 268Weather forecast. Nevertheless, regardless of the forecast, you should always prepare the same each season, as it only takes one hurricane to ruin your year and or life.

The 2020 hurricane season had a record 30 named storms, 14 hurricanes and a record tying 7 major hurricanes. There was also an ACE index of 185. Overall, the 2020 season is ranked 10th, based on ACE. The most active season, since record began in 1851, remains 1933, with an ACE of 259. Note, based on post-analysis, Tropical Storm Gamma was upgraded to a Category 1 hurricane on 17 April 2021 and Category 2 Hurricane Zeta was upgraded to Category 3 on 10 May 2021.

The main reasons for the above normal forecasts are the likely above normal sea surface temperatures across the tropical North Atlantic and a weak La Niño and or cold-neutral El Niño Southern Oscillation (ENSO) during August to October–the peak of the hurricane season.

A typical season, based on the standard climate period 1991-2020, has 14 named storms, 7 hurricanes and 3 major hurricanes. Major hurricanes have sustained wind speeds of at least 178 km/h or 111 miles per hour (e.g., Category 3 or higher), according to the Saffir Simpson Hurricane Wind Scale.

This forecast will be updated monthly around the 10th each month until August. The next update will be issued around June 10.

The Atlantic hurricane season officially begins on June 1 and concludes on November 30; nevertheless, in the last five years, there have been preseason tropical cyclones–be prepared early!

Please share this blog, if you found it useful and follow me for more on the upcoming hurricane season, which unfortunately could be a repeat of last year, for and all things weather and climate – TwitterFacebook and Instagram.





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.





October Not Over 2020 Hurricane Summary

2 11 2020

Dale C. S. Destin|

The hurricane season was certainly not over in October. There was a record-tying number of major hurricanes – two, Delta and Epsilon; this represents over 665 percent of average (normal). The number of named storms – five, was 250 percent of average. Further, the number of hurricanes – four, was over 360 percent of average.

October Not Over 2020 Summary. Note, although Eta became a storm in November it is credited to October to which it owes its origin, according to the international standard

October 2020 is only the fifth October on record with two major hurricanes. The last time there were two major hurricanes in October was 2005. The month averages a major hurricane once every three to four years. Previous years with two major hurricanes are 2005, 2001, 1950 and 1894.

It was a very active October. The metric that speaks more completely to the activity of a month or a hurricane season is called the accumulated cyclone energy (ACE) index. Normally, the month produces an ACE index of 14.5 – that was more than doubled for this October – 39.2. Compared with the activity for September, although it was a record-setting month regarding named storms, the ACE index of 63 was only 1.23 the average – 51.4. Hence, October was more active relative to itself than September was.

Using the ACE index metric, this October was more active that 28 previous full hurricane seasons of 169, including the 2013 season, which had 14 named storms but an ACE of 36. Also, the two major hurricanes during the month were more than or equal to 125 full seasons. We would have also seen more or the same number of hurricanes than 71 full seasons, including 2015.

Every named storm in October was earlier than those with the same names that formed during October of the 2005 hurricane season, which is the only other season with more than 20 named storms, on record. The records were broken by as many as 41 days. This may be an omen for this season setting a record for the highest number of named storms.

Thankfully, none of these storms threatened Antigua and Barbuda and the rest of the Eastern Caribbean. The most we got were moderate to large swells from Epsilon along with minimal showers from a few very weak feeder bands. The rest of the Caribbean Islands fared well also with none experiencing storm or hurricane conditions. Delta was a relatively close call for Jamaica, the Cayman Islands and Cuba.

We are through the season, except for one more month, officially – November. Thus far, there have been 28 named storms – the most through October and tied with 2005 for the most on record, for a season. The 2005 record is now expected to be broken. There have also been 11 hurricanes of which 4 were major hurricanes – Category 3 or over.

2020 Atlantic hurricane season summary map.png

Recall that an average season produces 12 named storms, 6 hurricanes and 3 major hurricanes. Thus, this season has produced, thus far, 233 percent of average number of named storms, 183 percent of average number of hurricanes and 133 percent average number of major hurricanes.

Notwithstanding the record number of named storms, the season is very far from being a record active one. Recall that the activity of a season is based on the ACE index. The ACE index, thus far for 2020, is 143.9; this is only 136 percent of the average – 105.5.

This season is not even ranked in the top 20 with respect to ACE. It is currently at 27th and is unlikely to reach the top 10. The ACE index for a season is also a measure of the potential destructiveness of the collective named storms. This means that although 2020 has produced a record number of storms, there are several seasons that were potentially more destructive, including the 2017 season with and ACE index of 223.

Top 20 Most Active Atlantic Hurricane Season. TS – Tropical Storms; HU – Hurricanes; MH – Major Hurricanes. Credit Wikipedia.

The most active season on record, using the ACE index metric, remains 1933, with an index of 259, produced by “just” 20 named storms. This is nine more ACE than the 2005 season, which had eight (40 percent) more named storms.  

Delta – 5 to 11 October, became the record-tying fourth named storm of 2020 to strike Louisiana, as well as the record-breaking 10th named storm to strike the United States. It was a very destructive Category 4 hurricane with 1-minute peak sustained winds of 230 km/h (145 mph). It caused, at least, US$2 billion in damage and killed 6 people. It also affected Jamaica, the Cayman Islands, The Yucatán Peninsula, the Gulf Coast, Southeastern and Northeastern United States.  

Hurricane Delta, Across the Western Caribbean Sea – Oct 6, 2020

Epsilon – 19 to 26 October, impacted Bermuda minimally, passing about 190 to its east. It had peak sustained winds of 185 km/h (115 mph), making it a Category 3 hurricane. Exact damage to date is unknown but it generated moderate to large swells across most Atlantic coastlines of the Caribbean, the Bahamas, the United States and Canada.

Hurricane Epsilon, Passing Northeast of Bermuda, Oct 23, 2020

Zeta – 24 to 30 October, became the record-tying sixth hurricane to make landfall on the United states in one year. It was also the record fifth named storm to make landfall on Louisiana in one year. Zeta had peak 1-minute sustained winds of 175 km/h (110 mph) and caused eight fatalities and over US$13.7 million in damage across Jamaica alone. It also impacted the Cayman Islands, Central America, the Yucatán Peninsula and the Mid-Atlantic United States.  

Hurricane Zeta Across the Western Caribbean Sea – Oct 26, 2020

Eta – 31 October to present, became the record-tying 28th named storm for the year, placing 2020 level with 2005 for highest number of named storms. Eta is currently a Category 1 hurricane with the potential to reach Category 3 intensity. It is an extreme threat to Nicaragua and Honduras with the potential to cause Catastrophic damage.

Hurricane Eta Across the Western Caribbean Seas – Nov 2, 2020

The month also produced Tropical Storm Gamma – 2 to 6 October. Gamma made landfall on the Yucatán Peninsula with peak 1-minute sustained winds of 110 km/h (70 mph), killing 7 with the damage amount presently unknown.  

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.





Busy Week Ahead for the Caribbean

16 08 2020

Dale C. S. Destin |

Looks like the Caribbean is set for another busy week. There is the potential for two tropical cyclones – tropical depressions, tropical storms or hurricanes, impacting the area.

Tropical Disturbances AL97 (near the Caribbean) and AL96 (near Africa)

It is the start of a new week but the continuation of a record-breaking hurricane season, which could add two more storms to its tally, in days. There are two new disturbances between Africa and the Caribbean, taking aim at the islands.

Satellite picture animation showing the locations of the distrubances

It is uncertain as to whether these disturbances will become tropical cyclones, where they will go and what hazards, they will bring to the area. However, at this time of the year, most disturbances do develop into tropical cyclones, as conditions are generally conducive, like they are currently, bar the dry and dusty Saharan air.

Today, we saw the end of Tropical Storm Josephine, which threatened the area but eventually passed a safe distance north of all the islands.

Tropical Storm Josephine passing by on Saturday afternoon, 15 August, 2020

With Josephine gone, all attention is now on Disturbances AL96 and AL97. They both have a 50 percent chance of formation. And they both have tracks that take them through the Caribbean.

The second of the two systems, AL96, appears to be more of a future threat to the Caribbean, particularly the Leeward Islands. AL97 is perhaps moving too rapidly for much development to take place before reaching the Eastern Caribbean tomorrow; however, it is forecast to slow down in the Caribbean Sea where it will encounter favourable conditions for formation Wednesday.

Most available models have AL97 becoming a tropical storm in 48 hours – Tuesday night/Wednesday
Most available models have AL97 going through the southern Caribbean, at most, as a Tropical Depression

The gold standard of models – the ECMWF IFS or European model is very sweet on AL96. It gives it a relatively high chance of becoming a tropical storm and track towards our “neck of the woods” – the Leeward Islands this upcoming weekend. This week could end similarly to the one just gone – with us under a Tropical Cyclone Alert or worse.

Already for the season, there have been 11 named storms, the most to have ever occurred this early in the year, with the more active half of the hurricane season just getting started. With half of the season to go, only 48 out a total of 169 seasons, dating back to 1851, has seen more storms.

Be prepared! Based on the forecast, the season is likely to produce, at least, nine more named storms, five more hurricanes and three major hurricanes. It is likely to be a very long season.

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Updated Hurricane Season Forecast – August Look Out You Must, 2020

12 08 2020

Dale C. S. Destin |

My “August look out you must” updated forecast for the 2020 Atlantic Hurricane Season is out, and it continues to call for an above normal season, which is likely to be very active/hyperactive – well above normal.

My forecast calls for 26 named storms (up 3), including ArthurBerthaCristobal, Dolly, Edouard, Fay, Gonzalo, Hanna and Isaias, with 10 becoming hurricanes (up 1) and 4 becoming major hurricanes (down 1). The accumulated cyclone energy (ACE) index is forecast to be 218 (up 18). Further, there is a 70% confidence of

  • 20 to 32 named storms;
  • 7 to 15 becoming hurricanes;
  • 3 to 7 becoming major hurricanes and
  • 141 to 305 ACE.

If the forecast materializes, the ACE would be top 8 of all times. And if we use the ACE as an indicator of destructive potential, as some do, it means that the season’s destructive potential would also be top 8 of all times.

To date, the season has produced an ACE of 23.1, more than twice the usual amount for January through July. A normal season produces 106 ACE. Also, there have been nine named storms to date, two of which became hurricanes – over five time the average number of hurricanes of 1.9 and four times the usual number of hurricanes of 0.2. So, it has been a record busy season. Never before in history have we seen this many Atlantic tropical storms this early in the year.

If the forecast materializes, the ACE would be top 8 of all times. And if we use the ACE as an indicator of destructive potential, as some do, it means that the season’s destructive potential would also be top 8 of all times.

To date, the season has produced an ACE of 23.1, more than twice the usual amount for January through July. A normal season produces 106 ACE. Also, there have been nine named storms to date, two of which became hurricanes – over five time the average number of hurricanes of 1.9 and four times the usual number of hurricanes of 0.2. So, it has been a record busy season. Never before in history have we seen this many Atlantic tropical storms this early in the year.

The main reasons for the above normal forecast are the continuation of a much warmer than usual tropical North Atlantic (TNA) and a developing La Niña.

Tropical North Atlantic (TNA) Index – Reds for warmer than usual and blues for the opposite.
Pacific Ocean Niño3.4 – Reds for warmer than usual and blues for the opposite

The greater the likelihood of these two things happening at the same time – August to October, the greater the chances for an above normal season.

There is one thing that may mitigate these developing near perfect conditions for tropical cyclone formation – more than usual Saharan Dust, streaming across the area. If this were to continue, the forecast numbers would be lower. Unfortunately, we have no skill in forecasting the dust beyond a week; hence, we do not know if the dust will continue beyond August and deep into the peak of the months – August to October.

Compared to my forecast, most other forecasts continue to call for an above normal season. However, compared with most other forecasts, my forecast is calling for a much more active season – 34% more, on average.

Accumulated Cyclone Energy (ACE) based on 15 forecasting entities, including 268Weather.

Clearly, we have no control over the numbers for the season. But notwithstanding the forecast, you should always prepare the same each season, as it only takes one hurricane to ruin your year and or life.

This is my last forecast for this hurricane season. My first forecast for the 2021 season will be available around April 10. All the best for the rest of this 2020 season.

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The Hurricane Season in August Look Out You Must

8 08 2020

Dale C. S. Destin |

August is the second most busy month of the hurricane season, behind September. We in Antigua and Barbuda and the rest of the Caribbean have been impacted by tropical cyclones (TCs) – tropical depressions and named storms (tropical storms or hurricanes), many times in August. Hence, “look out you must” act to become hurricane strong.

Storms and hurricanes for August – 1851 to 2019. The 1899 Ciriaco Hurricane highlighted

The Atlantic Basin, including the Caribbean, averages in August: 3 to 4 named storms, including 2 hurricanes and 1 major hurricane – Category 3 intensity or more, based on the current climatological standard normal period, 1981-2010. The month sees a Category 5 hurricane every 7-8 years; the last one was Dorian of last year. Note that we credit TCs to the month in which they were formed.

Super Category 5 Hurricane Dorian in the northern Bahamas – Sep 1, 2019

The last hurricane to impact Antigua and Barbuda, in August, was Hurricane Earl of 2010. The centre of the hurricane passed within 40 km (25 mi) and 89 km (55 mi) north of Barbuda and Antigua respectively. At the time of impacting the islands, Earl was a Category 2 hurricane with maximum sustained winds of 169 km/h (105 mph). 

Category 2 Hurricane Earl with eye just northwest of Anguilla – August 30, 2010

Barbuda likely got close to the maximum impact from Earl. At the V. C. Bird International Airport in Antigua, maximum winds measured were 82 km/h (51 mph) gusting to 105 km/h (65 mph). The damage to both islands amounted to around US$13 million, and there was one fatality.

Earl also caused damage to the rest of the Leeward Islands, the Virgin Islands, Puerto Rico, the East Coast of the United States and Canada. The system caused a total of 8 fatalities and around US$45 million in damage.

The probability of Antigua and Barbuda being impacted by a storm or hurricane, in August, is around 18 percent, based on the current base period of 1981-2010. The probability increases to 38 percent for the active period being experienced by the Atlantic since 1995. This means that we have been impacted by a storm or hurricane every 2 to 3 years since the mid-1990s.

August Hurricane Climatology
The zones of origin and tracks of storms in August during the hurricane season

The probability of us being impacted by a hurricane, in August, is around 6 percent based on 1981-2010 data and around 11 percent for the current active period. This means that we are affected by a hurricane, in August, every nine years.

Antigua and Barbuda have been affected by 22 tropical storms and 18 hurricanes, in august, dating back to 1851. Our most powerful August hurricane was a Category 4 system nicknamed the San Ciriaco Hurricane of 1899. This is the longest-lived Atlantic hurricane on record – 28 days.

Since 1851, the Eastern Caribbean (EC) has been affected by 99 named storms; 37 were hurricanes and 10 were major hurricanes.

Storms to have pass through the Eastern Caribbean in August – 1851 to 2019

The last hurricane to impact the Caribbean in August was Dorian of 2019. It passed through the Windward Islands as a tropical storm, then turned north-northwest and brushed Antigua and most of the Leeward Islands. Dorian became a hurricane over the Virgin Islands. After leaving the Caribbean, it intensified into the second strongest Atlantic hurricane, tied with the Labour Day Hurricane of 1935 and (Wild) Gilbert of 1988, then literally flattened the northern Bahamas, over a three day period, in which it moved at a “snail’s pace”. It left in its wake 84 fatalities, 245 missing and US$4.6 billion. Dorian became the strongest hurricane, on record, to form in August.

Hurricane Dorian with centre near St. Croix, US Virgin Islands – August 30, 2019

The probability of at least a storm or hurricane impacting the EC annually, in August, is 41 percent; the probability of a hurricane is 15 percent and the probability of a major hurricane is 6 percent. It means that the EC is impacted by a storm or hurricane, in August, every 2-3 years; a hurricane every 6-7 years and a major hurricane every 16-17 years.

The probability of a storm or hurricane across the western Caribbean is around 33 percent. For the central Caribbean, this probability is around 26 percent.

August has produced 392 named storms of which 247 were hurricanes, 120 were major hurricanes and 14 were Category 5 hurricanes, based on NOAA. We note that there are likely storms that were missed prior to the Satellite era – prior to the mid-1960s. For climate period – 1981 to 2010, there have been 101 named storms of which 51 were hurricanes and 26 major hurricanes.

August has trice had a maximum of 8 named storms in a given year – 2012, 2011 and 2004. On two occasions, there were 3 hurricanes – 1966 and 1916. Further, on four occasions there were three major hurricanes – 1969, 1933, 1893 and 1886.

Like July, above normal tropical cyclone activity in August normally signals a busy hurricane season. What will this August bring? We can’t be sure, but the forecast is for an above normal to hyperactive season. Whatever it brings, let’s be prepared! Be hurricane strong!

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July Stand By 2020 Hurricane Summary

1 08 2020

Dale C. S. Destin|

July stand by turned out to be a historic month. This July tied with July 2005 for the greatest number of Atlantic named storms – five, for the month, on record dating back to 1851. It was also the first time since 1996 Antigua and Barbuda experienced sustained storm-force winds.

Tropical cyclone tracks through July 30 courtesy the Weather Channel

The month produced five named storms: Edouard, Fay, Gonzalo, Hanna and Isaias. Hanna and Isaias went on to become Category 1 hurricanes. This is over 450% the usual number of storms for July or 4.5 times the average. Further, the two hurricanes represent 400% the average amount.

We are just one-third the way through the 2020 hurricane season; however, we have seen more storms than what was observed in 80 full seasons. Further, the nine named storms, for the year thus far, are more than or equal to the total storms for 92 individual seasons – more than half of all previous 169 seasons, on record. An average season produces 12 named storms, 6 hurricanes and 3 major hurricanes.

Nine storms down, 8 to 19 more are forecast; the list is likely to be exhausted.

All the storms in July were the earliest in their positions, on record. Thus, Edouard, Fay, Gonzalo, Hanna and Isaias were the earliest 5th, 6th, 7th, 8th and 9th named storms, on record, respectively. In other words, there has never been this many storms, this early, in the hurricane season. On average, the season through July 31, produces ONLY two named storms, a hurricane every other year and a major hurricane every 5 years.

The 2020 season, thus far, has nearly 5 times the average number of storm, nearly four times the average number of hurricanes and over twice the average amount of ACE.

Gonzalo – 21 to 25 July, is one of two storms that impacted the Caribbean. The other storm was Isaias, which formed July 30, went on to become a hurricane and continues at present across the Bahamas and threatening the East Coast of the United States. Gonzalo caused minimal impacts to the southern Caribbean. Meanwhile the impacts from Isaias are ongoing and are expected to be extensive.

Isaias caused sustained storm-force winds across Antigua and Barbuda while it was still Potential Tropical Cyclone (PTC) Nine. In Antigua, peak winds of 69 km/h (43 mph) were recorded at the V.C. Bird international Airport, on July 29, at 07:09 UTC (3:09 am local time). Peak gusts of 82 km/h (51 mph) was recorded at the Sir Vivian Richards Stadium.

Over in Barbuda, PTC caused peak winds 63 km/h (39 mph), which were observed at the Hannah Thomas Hospital, July 29, at 09:54 UTC (5:54 am local time). It also produced peak gusts of 74 km/h (46 mph). The last time Antigua and Barbuda had sustained storm-force winds was 24 years ago from Hurricane Bertha.

PTC Nine also produced 25 to 75 mm (1 to 3 in) of rain, in 36 hours, resulting in minor flooding.

Potential Tropical Cyclone Nine moving across the Caribbean Jul 29, 2020. Antigua and Barbuda circled in yellow

Fay – 9 to 11 July, was the most deadly and destructive of the July storms. It killed six persons and caused US$400 million in damage across Southeastern and Northeastern United States and Eastern Canada.

Hanna – 23 to 27 July, was the second most deadly and destructive. It killed 5 persons and caused over US$395 million in damage. It impacted Hispaniola, Cuba, the Gulf Coast of the United States and Mexico.

Edouard – 4 to 6 July, was the weakest and least impacting of the storms. It affected Bermuda and the British Isles.

While writing this blog, Tropical Depression Ten formed near the coast of Africa. It is forecast to become a storm but not expected to impact any landmass.

Recall that July averages one named storm per year, a hurricane every other year and a major hurricane every 6 to 7 years. Compared to the numbers above for this year, this July was momentous, almost unprecedented.  

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The Hurricane Season in June Too Soon

14 06 2020

Dale C. S. Destin|

We, Antigua and Barbuda, have never had a tropical cyclone – tropical depression, tropical storm or hurricane, in June (knock wood). The same is true for much of the Caribbean east of Cuba.

All 107 Named Storms for June 1851-2019, based on data from NOAA

There has only been one hurricane to impact the Eastern Caribbean in June – Unnamed Category 1 Hurricane of 1933, also called the Trinidad Hurricane. It was a deadly hurricane – killing 13 people in Trinidad, 22 in Cuba and killing, at least, 35 people in total across Trinidad, Venezuela, Jamaica and Cuba. It also caused deaths and destruction across Mexico.

The hurricane season in June for the Caribbean – 1851 to 2019

June averages one named storm (tropical storm or hurricane) every other year; one hurricane every 8 years and a major hurricane – Category 3 or higher intensity, every 50 years, on average. It is the least active month of the hurricane season.

Before this year, the last storm in June was Cindy in 2017; the last hurricane was Arthur of 2014 and the last major hurricane was Alma in 1966.

Given the current season, it may be said that Cristobal, of this June, was overdue by a year; the next June hurricane is due around 2022 and the next June major hurricane is overdue by about 3 years. Will this be the year for what would be the fourth major hurricane for the month? Unfortunately, there are no tools available currently to answer this question.

Interestingly, over the relatively reliable data period of 1966-2019, there is no significant difference in the average number of hurricanes in June for above and below normal seasons. A hurricane forms in June around every five above normal seasons and every four below normal seasons. The mentioned period has no hurricanes in June for normal seasons.

There have been three major hurricanes in June based on record dating back to 1851; however, over the period 1966 to 2019, there has only been one major hurricane – Alma of 1966.

Category 3 Hurricane Alma of 1966 – the most powerful Atlantic June Cyclone along with Hurricane Audrey of 1957

So, what is the probability of a hurricane this June, given an above normal season? It’s around 19 percent. What is the probability for a major hurricane? About 5 percent. For all seasons considered for 1966-2019, the probability of a hurricane and major hurricane is 17 and 2 percent respectively. No significant difference between an above and below normal season.

The zones of origin and tracks of storms in June during the hurricane season

Based on record for 1851 to 2019, there have been, in June, 107 named storms of which 37 became hurricanes and 3 reached major hurricane status – Category 3 intensity or higher. For more reliable data, the period 1966 to 2019 have seen, in June, 37 named storms, 7 becoming hurricanes and no major hurricane. For the current standard climate or base period of 1981-2010, there have been 21 named storms, 4 hurricanes and no major hurricanes.

It turns out that like May, storms in June say nothing about the overall activity for the season i.e. whether it will be above, near or below normal.  

Using the current climate period 1981-2010, if storms are going to form in June, they will mostly do so during the first or last 10 days of the month. Over 80 percent of all storms in June, for the current climate period, forms between June 1-10 or June 20-30.

June on 5 occasions had a maximum of three named storms in a given season – 1968, 1959, 1936, 1909 and 1886. On one occasion it had three hurricanes, 3 Category 2s – 1886. Note: these ALL occurred outside the climate change era. This year could make six years since there was a hurricane forming in the month.

Recall that the forecast is for this hurricane season to be above or well above normal. And notwithstanding what happens in June or any other month, it only takes one hurricane to ruin your year or life. Thus, you need to be prepared as best as possible for every hurricane season.

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Pre-hurricane Season Summary – 2020

1 06 2020

Dale C. S. Destin|

It is June too soon – the Atlantic hurricane season officially starts today. However, it seems like no one remembered to remind the “storm gods” of this fact. Already, we have seen two named storms – Arthur and Bertha, resulting in a very active pre-hurricane season 2020. Only twice on record before, dating back to 1842, that May has produced two named storms – 2012 and 1887.

Arthur formed on May 16, just north of the northern Bahamas. It moved north to near the Outer Banks of North Carolina, then out over the Atlantic and lost its tropical characteristics. It caused tropical storm force winds across a small portion of North Carolina and reached peak sustained winds of 97 kph (60 mph).

Tracks of Tropical Storms Arthur (right) and Bertha (left)

Bertha was a bit of a surprise storm. Formation was not expected due to strong upper-level wind shear. On the morning of 12:50 am, May 27, it was given a 30% chance of formation and by 8:30 am, it was declared a tropical storm with sustained winds of 72 kph (45 mph). It eventually reached peak sustained wind speed of 80 kph (50 mph), before dissipating on May 28. The system caused one death.

In terms of pre-season storms – storms forming between March and May, there have been only four occasions when there were two named storms – 2012, 1951, 1908 and 1887. Of course, I am mindful that before the satellite era – pre mid-1960s, a number of short-lived storms went undetected, resulting in gaps in the record.

On average, there is a storm in May once every 7 to 8 years, based on record for the period 1981-2010, whereas, there is a preseason storm once every 5 years. Most pre-season storms form in May – about 85%, 9% in April and 6% in March.

Preseason storms say nothing about the season they precede, in terms of how active or inactive they will be. However, this season is expected to be active and likely to be hyperactive – well above normal.

We all need to be prepared for the hurricane season regardless of the number of storms and hurricanes being forecast, as it only takes one hurricane to ruin our year or life.

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May 2020 Updated Hurricane Season Forecast: Hyperactive Season Likely

11 05 2020

Dale C. S. Destin |

Our updated forecast for the 2020 Atlantic Hurricane Season is out, and it calls for higher than normal activity – an above normal season. The forecast predicts an accumulated cyclone energy (ACE) index of 189 (down 6 from the previous forecast), 19 named storms (down 1), 9 hurricanes (unchanged) and 4 major hurricanes (down 1). With these numbers, it is also likely that the season will be hyperactive i.e. well above normal and possibly unusually destructive.

If this forecast, for which there is very high confidence, pans out, this season would be the most active since 2017, in terms of ACE, and the 10th most active on record dating back to 1851.

The season also has the potential to be record breaking in some areas, as there is 70 percent confidence of

  • 14 to 23 named storms;
  • 6 to 12 becoming hurricanes;
  • 2 to 7 becoming major hurricanes and
  • 112 to 276 ACE.

If the higher end of the ranges were to materialise, records would be equalled or broken for the number of major hurricanes and more importantly ACE, which is the universally accepted metric used to classify the overall activity of a hurricane season.

According to other forecasts surveyed, the consensus is for an ACE of 146 (down 3), 17 named storms (up 1), 8 hurricanes (unchanged) and 4 major hurricanes (unchanged) – above normal season. This is generally consistent with my forecast but with less activity. However, regardless of the forecast, you should always prepare the same each season, as it only takes one hurricane to ruin your year and or life.

Accumulated Cyclone Energy (ACE) based on 10 forecasting entities, including 268Weather.

The main reasons for the above normal forecasts are the likely above normal sea surface temperatures across the tropical North Atlantic and a cold-neutral El Niño Southern Oscillation (ENSO) or a weak cold ENSO, i.e. weak La Niña, during the peak of the hurricane season – August to October.

A typical season has 12 named storms, 6 hurricanes, and 3 major hurricanes. Major hurricanes have sustained wind speeds of at least 178 km/h or 111 miles per hour (e.g., Category 3 or higher), according to the Saffir Simpson Hurricane Wind Scale.

Click for pronounciations

With respect to records, the 2005 season has the highest number of named storms and hurricanes – 28 and 15 respectively. The 2005 season also tied with the 1961 season for the highest number of major hurricanes – 7, and the season with the highest ACE – the most active season on record, based on ACE only, is 1933 with 259.

The last Atlantic hurricane season – 2019, was more active than normal and will long be remembered for Super Category 5 Hurricane Dorian’s destruction of the northwest Bahamas. The season had 18 named storms, 6 became hurricanes – winds of at least 119 km/h or 74 miles per hour, and 3 became major hurricanes.

This forecast will be updated monthly until August. The next update will be issued around June 10.

The Atlantic hurricane season begins in days – June 1 and concludes on November 30, be prepared!

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July’s Update: 2019 Atlantic Hurricane Season Forecast

15 07 2019

Dale C. S. Destin |

My updated forecast for the 2019 Atlantic Hurricane Season is out and it continues to call for above normal activity (an active season) being likely. The probability of this happening is up from the previous forecast from 45% to 54%. Thus, I am more confident of an above normal season.

It calls for an accumulated cyclone energy (ACE) index of 127 (up 13), 13 named storms, 6 hurricanes and 3 major hurricanes.

Forecast parameters with 70 percent confidence intervals in (parentheses), right

A typical season has 12 named storms, 6 hurricanes, and 3 major hurricanes. Major hurricanes have sustained wind speeds of at least 178 km/h or 111 miles per hour (e.g., Category 3 or higher), according to the Saffir Simpson Hurricane Wind Scale.

According to other forecasts surveyed, the consensus is for an ACE of 112, 13 named storms, 7 hurricanes and 3 major hurricanes – above to near normal season. Thus, my forecast is calling for more activity.  However, regardless of the forecast, you should always prepare the same each season, as it only takes one hurricane to ruin your year and or life.

The Atlantic hurricane season began on June 1 and will conclude November 30.

The next update will be issued around August 10.

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Early Forecasts for 2019 Atlantic Hurricane Season

10 04 2019

Dale C. S. Destin |

Our early season forecast for the 2019 Atlantic Hurricane Season is out and it calls for above normal activity (an active season) being most likely. It calls for an accumulated energy (ACE) index of 124, 13 named storms, 7 hurricanes and 3 major hurricanes.

2019 Atl Hurricane Season Forecast

A typical season has 12 named storms, 6 hurricanes, and 3 major hurricanes. Major hurricanes have sustained wind speeds of at least 178 km/h or 111 miles per hour (e.g., Category 3 or higher), according to the Saffir Simpson Hurricane Wind Scale.

The 2018 Atlantic hurricane season, although above normal, did not have any severe impact on the Caribbean, except for Cuba where Hurricane Michael was a factor and to a lesser extend Barbados where Tropical Storm Kirk caused flooding. The season had 15 named storms, 8 became hurricanes – winds of at least 119 km/h or 74 miles per hour, and 2 became major hurricanes.

If this forecast pans out, this season would have similar activity to that of the 2018 season.

The Atlantic hurricane season begins on June 1 and concludes on November 30.

We will be providing monthly updates to the forecast until August. The first update will be issued around May 10.

According to other forecasts surveyed, the consensus is for an ACE of 99, 13 named storms, 6 hurricanes and 2 major hurricanes – near normal season. Thus, our forecast is generally calling for higher activity than most. However, regardless of the forecast, you should always prepare the same each season as it only takes one hurricane to ruin your year and or life.

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The 2018 Atlantic Hurricane Season Summary

2 12 2018

Dale C. S. Destin |

The 2018 Atlantic Hurricane Season came to an uneventful end yesterday. However, it was the third consecutive above normal/active season – leaving deaths and destruction in its wake.HurTracks2018

It will be remembered by the region (Caribbean), not for its activity, but because the islands were generally spared its activity following on the heels of the catastrophic/cataclysmic 2017 season. Many islands in the Caribbean are still very far from full recovery from last year, and another similar such season would have caused things to go from extremely bad to double horrendously bad (so to speak).

The season produced 15 named storms (NSs), 8 of which become hurricanes (Hs) and 2 intensified into major hurricanes (MHs) – Category 3 and over. The Accumulated Cyclone Energy (ACE), a measure of the overall activity of the season, was 128. The ACE last years was 225.

A normal season produces 12 NSs, 6 Hs, 3 MHs and 106 ACE. Relative to a normal season, this season had 25% more NSs than normal, 33% more Hs, 33% less MHs and 21% more ACE than normal.

The active 2018 Atlantic Hurricane Season left in its wake 154 deaths and around 34 billion dollars in damage. The strongest hurricane was Michael with 250 km/h (155 mph) winds. It was also the deadliest with 60 deaths. The most destructive was Florence with over $17.9 billion.

Relative to Antigua and Barbuda

It was an inactive season for our islands. No tropical cyclone (depression, tropical storm, hurricane) affected Antigua and Barbuda i.e. came within 193 km (120 mi). Isaac came the closest but still passed over 222 km (138 mi) to our south – between Dominica and Martinique.

Relative to the Rest of the Caribbean

The Caribbean saw four tropical cyclones entering or forming in the area – Tropical Storms Alberto, Isaac and Kirk, and MH Michael. Alberto proved the deadliest for the region, killing 10 persons in Cuba. Michael was also very impactful to western Cuba; however, no deaths were reported.

Seasonal forecast

I issued five forecasts for the 2018 season – these were for mainly above normal activity:

2018HurricaneSeasonGraphic

Interestingly, my best forecast was issued in April and the second best was issued in May. It is interesting because usually the earlier forecasts are the least skilful, while the latest (August forecasts) are the most skilful. However, in this case, the first was best and the last (August) tied with June for the worst. Notwithstanding, all forecasts captured the numbers for the season within the ranges issued – the 70% confidence interval.

Of the over 25 groups who have submitted their seasonal forecast to the website – http://seasonalhurricanepredictions.bsc.es/, most forecast a near normal season w.r.t. hurricanes – six. Further, as the season went by, most groups downgraded their forecasts – calling for a near to below average season. It is also noted that the average number of hurricanes predicted went from eight in March/April to 5 by July/August. Meanwhile, the number of named storms went from 13 in March/April to 11 by July/August.

Like me, most groups decreased the amount of activity initially forecast for the season. However, (with humility) my forecast was among the better forecasts – doing similar to or better than notable groups such as National Oceanic and Atmospheric Administration (NOAA), Colorado State University (CSU), United Kingdom Met Office (UKMET), and Tropical Storm Risk (TSR).

Notable records

The 2018 season is the first and only on record to see seven storms that were subtropical in nature at some point in their lifetimes. These are (Alberto, Beryl, Debby, Ernesto, Joyce, Leslie, and Oscar).

On October 11, for the first time in history, a tropical storm warning was issued for Madeira. This was due to Leslie, which became the first tropical cyclone to pass within 160 km (100 mi) of the archipelago since reliable record-keeping began in 1851.

Good riddance to you hurricane season. We wish never to see you again but we know only too well that you will be back in seven months – June 1 to November 30. Nevertheless, we will be prepared!





Early Forecasts for 2018 Atlantic Hurricane Season

11 04 2018

Dale C. S. Destin|

Our early season forecast for the 2018 Atlantic Hurricane Season calls for above normal activity. The prediction is for an accumulated energy (ACE) index of 135, 15 named storms, 7 hurricanes and 4 major hurricanes.

Apr2018HurrucaneSeasonForecast

A typical season has 12 named storms, 6 hurricanes, and 3 major hurricanes. Major hurricanes have sustained wind speeds of at least 178 km/h or 111 miles per hour (e.g., Category 3 or higher), based on the Saffir Simpson Hurricane Wind Scale.

The 2017 Atlantic hurricane season was one of the most destructive for the Caribbean; several islands were almost totalled. Barbuda, one half of the twin island state of Antigua and Barbuda was left uninhabitable for a while. Ten of last year’s 17 named storms reached hurricane strength—meaning they had sustained winds of at least 119 km/h or 74 miles per hour—and six of the 10 hurricanes were major ones.

If this forecast pans out, 2018 would be the second most active since 2010; second to last year’s season.

The Atlantic hurricane season begins on June 1 and concludes on November 30.

We will be updating our 2018 forecast by June 10.

According to other forecasts surveyed, the consensus is for an ACE of 105, 14 named storms, 6 hurricanes and 3 major hurricanes. Thus, our forecast is generally calling for higher activity than most; however, regardless of the forecast, you should always prepare well each season, as it only takes one hurricane to ruin your year.

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Tropical Cyclone Frequency and Climate Change

17 10 2017

Dale C. S. Destin |

This is a continuation of our series – Tropical Cyclones and Climate Change – (TCs; tropical depressions, tropical storms, hurricanes). In our previous blog in this series, we looked at Tropical Cyclone Intensity and Climate Change. In this blog, we will look at whether climate change is having an impact on TC frequency.

Hurricanes Katia (left), Irma (middle) and Jose (right)

Hurricanes Katia (left), Irma (middle) and Jose (right) – Sep 8, 2017

To date, the 2017 Atlantic hurricane season has produced 15 named storms – three more than the average or 25% more than usual. This has equalled the number of storms for last year. Meanwhile, there have been 10 hurricanes – four more than the average or 67% more than usual. This tied with 2010 for the most hurricanes since 2012. Further, there have been six major hurricanes – three more than average or 100% more than usual, the most since 2005.

Have TCs become more frequent?

According to the Intergovernmental Panel on Climate Change (IPCC), it is unlikely that TCs have become more frequent. Recall that the IPCC is the United Nations’ body task with assessing climate change.

Here is what the IPCC Assessment Report Five (AR5) actually says: “…recent assessments indicate that it is unlikely that annual numbers of tropical storms, hurricanes and major hurricanes counts have increased over the past 100 years in the North Atlantic basin…”. “No robust trends” exist.

So, having examined hundreds of peer-reviewed scientific research papers on the subject, the IPCC concluded that there has been change in the frequency of tropical cyclones.

One of the many papers cited by the IPCC, explains not only that there has been no change in the annual number of TCs but that there have been previous active Atlantic TC eras similar to the present. These active eras alternate with inactive eras; hence, in the not too distant future, the Atlantic will return to an inactive phase, perhaps similar to the 1970-1994 interval, when fewer storms occurred.

Further, although there has been no change in the number of  TCs over the past 100 years, research suggest that relative to about a thousand years ago, the annual number of TCs have decreased significantly. This is supported by Michael E. Mann et al., Michael J. Burn and Suzanne E. Palmer and others.

The increased greenhouse gases, the cause of climate change, substantially explain the observed SST increases over such places as the Atlantic and North West Pacific during the last 50 years. Added to this, are the apparent significant increases in TCs over this period. However, when the raw dataset is adjusted for short-lived TCs i.e. TCs lasting less than two days, a different picture emerges.

NA_TCs_Raw&Adjusted

Green-shaded curves depict global mean temperature (HadCRUT3 data set) and August–October main development region (MDR; 10° N–20° N, 80° W–20° W) SST anomalies (HadISST data set). Blue-shaded curves represent unadjusted tropical storm counts. Red-shaded curves include time-dependent adjustments for missing storms based on ship-track density. The curve labelled ‘>2-day’ depicts storms with a duration greater than 2.0 days. Orange-shaded curves depict US landfalling tropical storms and hurricanes (no adjustments). Solid black lines are five-year means (1878–2008); dashed black lines are linear trends. Vertical axis ticks represent one standard deviation. Series normalized to unit standard deviation. Only the top three series have significant linear trends (p = 0.05). Source: Knutson et al. 2010

Before the satellite era – pre-1966, a number of storms went undetected due to the fact that they never made landfall and occurred in unfrequented parts of the Atlantic Ocean by ships – the only source of TC detection over open waters before there were satellites. Thus, when the raw data is adjusted for these missing cyclones, no long-term trend is detected.

The trend in major hurricanes is not (statistically) significance. Notwithstanding, the current trend is unreliable since studies have shown that the wind speeds for TCs, over the period 1851 to 1920, were systematically underestimated, a fact supported by paleoclimatology.

To a great extent, the numbers of TCs on record, pre-1966, are there only because they made landfall. Counting landfalling TCs is not a robust method for determining overall trend; nevertheless, the method shows no trend in various regions of the world.

Will TCs become more frequent in the future?

To this question, the IPCC says no! Here are the exact words from the IPCC AR5, “…it is likely that the global frequency…of tropical cyclones will either decrease or remain essentially unchanged…. However, “substantial increases in the frequency of the most intense cyclones and it is more likely than not that this increase will be larger than 10% in some basins”.

One of the main scientific papers used by the IPCC to come to this conclusion is one done by Knutson TR, McBride JL, Chan J, et al. They say that late in this century, there will be a 6 to 34% decrease in TC frequency. However, on the other hand, the same paper projects a 2 to 11% increase in TC winds; hence, by virtue of this, predicts an increased frequency of major hurricanes being more likely than not by year 2100. Notable TC researchers Kevin J.E. Walsh, John L. McBride, Philip J. Klotzbach et al. endorsed this conclusion.

TrendOfTCs

General consensus assessment of the numerical experiments described in Supplementary Material Tables 14.SM.1 to 14.SM.4. All values represent expected percent change in the average over period 2081–2100 relative to 2000–2019, under an A1B-like scenario, based on expert judgement after subjective normalization of the model projections. Four metrics were considered: the percent change in (I) the total annual frequency of tropical storms, (II) the annual frequency of Category 4 and 5 storms, (III) the mean Lifetime Maximum Intensity (LMI; the maximum intensity achieved during a storm’s lifetime) and (IV) the precipitation rate within 200 km of storm centre at the time of LMI. For each metric plotted, the solid blue line is the best guess of the expected percent change, and the coloured bar provides the 67% (likely) confidence interval for this value (note that this interval ranges across –100% to +200% for the annual frequency of Category 4 and 5 storms in the North Atlantic). Where a metric is not plotted, there are insufficient data (denoted ‘insf.d.’) available to complete an assessment. A randomly drawn (and coloured) selection of historical storm tracks are underlain to identify regions of tropical cyclone activity. Source: IPCC AR5

One of the fallacious arguments being advanced for the increase in the frequency of TCs is increasingly warmer SSTs being caused by climate change. But quite obviously, warm SSTs are not the only parameters required for increased frequency. SSTs are very necessary but far from being sufficient for causing increased TC frequency.

A recently issued paper by Jeffrey P. Donnelly & Jonathan D. Woodruff indicates that such high SSTs as at present are not even necessary to support periods of frequent major hurricane activity. There have been eras with similar or higher number of TCs with significantly lower SSTs.

The Kevin J.E. Walsh et al. paper indicates the models used to simulate TCs, produce an increased frequency of TCs as temperature decreases and decreased frequency when temperature increases. Thus, increased SSTs do not necessarily mean increased TC frequency, by consensus, the opposite seems to be true.

Also required for increased number of TCs are conducive atmospheric conditions – unstable Atmosphere, moist middle Atmosphere and the overturning of the tropical Atmosphere caused by the Hadley cell. All three are needed for the formation of tropical disturbances – the precursors of TCs. However, fortunate for us, climate change is causing these things to go in the negative direction; hence, the projected decrease in the frequency of TCs by the end of this century.

Based on the IPCC and the vast majority of the TC researchers, TC frequency has not changed over the last century. By the preponderance of research papers, climate change has NOT caused TCs to become more frequent. However, by late this century the frequency of TCs is projected to decrease or perhaps remain unchanged relative to present. However, the number of major hurricanes is more likely than not to increase late in the current century. This is the conclusion of the IPCC AR5 – we either accept the full report or none at all. And if we accept all of it, we would not be blaming current TC and hurricane frequencies on climate change, at this time.

Our next blog in this series will look at the impact, if any, of climate change on tropical cyclone rainfall.





Tropical Storm Bret 2017: Firsts or Firsts in a Long Time

9 07 2017

Dale C. S. Destin |

Tropical Storm Bret making landfall on Trinidad during the early morning hours of June 20, 2017.

Tropical Storm Bret making landfall on Trinidad during the early morning hours of June 20, 2017.

The formation of Tropical Storm Bret, a few weeks ago, resulted in several firsts or firsts in a long time for the Atlantic hurricane season, for the Eastern Caribbean and for Trinidad. Here are some we have noted:

  • 1st named storm to pass south of La Brea, Trinidad.
  • 1st named storm to form between Africa and the Caribbean before summer (June 21).
  • 1st time there were two named storms (Bret and Cindy) in June alive at the same time – June 20, 2017.
  • 1st designated potential tropical cyclone ever by the U.S. National Hurricane Center.
  • 1st named storm to impact the Eastern Caribbean before summer, since an unnamed hurricane in March 1908 impacted Antigua and the northeast Caribbean – the only other such system to impact the area before June 21; it formed in the Caribbean Sea.
  • 1st named storm to impact Trinidad in June since an unnamed hurricane in 1933. There is no other June storm on record for Trinidad.

All named storm on record for June - 1851 to 2016

All named storm on record for June – 1851 to 2016. Only three storms have affected the Eastern Caribbean in June since 1851. Two seen above plus Bret.

  • 1st named storm to form between African and the Caribbean in June since Tropical Storm Anna of 1979. There has ONLY been one other in June – an unnamed hurricane of 1933. So, there have ONLY been three named storms to impact the Eastern Caribbean in June on record.
  • 1st named storm to make landfall (pass over land) in Trinidad since Tropical Storm Bret of 1993. This has ONLY happened three other times – Fran of 1990, Alma of 1974 and an unnamed storm of 1933.
  • 1st named storm to pass within 65 nuatical miles (nm) or 120 km of Port of Spain, Trinidad, since Joyce of 2000. There have ONLY been 11 named storms in history, dating back to 1851, to have passed within 65 nm of Port of Spain, Trinidad; ONLY four were hurricanes, the last one being Hurricane Flora of 1963.

All named storms to have passed within 65 nm of Port of Spain, Trinidad on Record - 1851 to 2016

All named storms to have passed within 65 nm of Port of Spain, Trinidad on Record – 1851 to 2016

  • 1st time two named storms (Bret and Cindy) formed in June since 1909. It has happened ONLY two other times – 1906 and 1886. Both 1906 and 1886 turned out to be very active years; 1909 had near normal activity.
  • 1st named storm in June since Barry of 2013.

This June was quite active, in terms of named storms. The average for the month is 0.5 or one every other year. So, the two named storms which formed in this past June amount to the total we normally get in four Junes.

Is the activity of June an omen for the rest of the season? Well, the sample  size – three, is way too small to so say anything remotely definitive; however, FYI, of the three Junes with two named storms, two were quite active. Further, of the 10 seasons with at least 3 named storms forming between January 1 and June 30, six have been near or below normal.

All named storms for Jan-Jun 1851 to 2016

All Jan-Jun named storms on record, 1851 to 2016

Our most recent forecast of the season calls for above normal activity with 16 named storms, 7 becoming hurricanes and 4 becoming major hurricanes.

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Our Inaugural Forecast of the Atlantic Hurricane Season

5 07 2017

Dale C. S. Destin |

We have just released our first inhouse-produced forecast of the Atlantic hurricane season. It calls for an above normal season with 16 named storms, 7 becoming hurricanes and 4 reaching major hurricane status.

The main reasons for the above normal forecast are the warmer than usual tropical North Atlantic and the unlikely development of an El Nino. This season could turn our similar to last year’s and be one of the most active since 2010.

We hope that you find this forecast to be a useful resource in your hurricane season preparations. Please feel free to share you feedback with us as usual.  Click here for the full forecast.

Become hurricane strong!

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The 2017 Atlantic Hurricane Season Early Forecast

7 04 2017

Dale C. S. Destin |

Good news! The early forecasts just issued for the upcoming 2017 Atlantic hurricane season (AHS) indicate a below normal season is most likely. This is forecast to be most evident in the number of hurricanes that forms (see graphic below). It could be as quiet as the 2014 and 2015 seasons. Nevertheless, the usual complete preparations are still very much required.

Ensemble forecast

The ensemble (mean) forecast, based on predictions from Klotzbach of Colorado State University, Saunders and Lea of Tropical Storm Risk.com (TSR) and AccuWeather.com, is for 11 named storms, 4 becoming hurricanes and 2 becoming major hurricanes.

2017HurricaneSeason

A better indicator of the activity for the season is the accumulated cyclone energy (ACE) index which is a measurement of the strength and duration of each tropical cyclone. Summing together the ACE of each cyclone, provides a more complete picture of how active the season is likely to be outside of just the number of storms.

This year, the ensemble forecast calls for an ACE index of 71. If this forecast pans out, the 2016 season would be around 30% less active than normal.

It must be noted though that there is very low skill in forecasting the AHS (June to November) in April. However, this is the best available forecast for the season, from this vantage point, and can be used as a guide for what is possible. A more skilful forecast will be available around June 1.

El Nino

 The development of an El Nino is the main climate factor that is forecasts to cause the hurricane season to be quieter than normal. El Nino is virtually synonymous with inactive AHSs, as it causes unfavourable conditions for tropical cyclones (tropical depressions, tropical storms and hurricanes). The main one being the creation of strong winds aloft that inhibits or rips tropical cyclones apart.

However, regardless of the above probabilities and forecasts, this is not a licence to do anything differently for this hurricane season. The same comprehensive preparations are required to deal successfully with any eventuality. It only takes one tropical cyclone to set you back for years. Recall – Gonzalo struck us in a quiet year – 2014.

New and improved products

As is the case annually, there are new and improved products that will be on show. The most significant of which will be the issuing of watches, warnings and advisories for potential tropical cyclones.  A potential tropical cyclone is being defined as a disturbance that has the potential to produce tropical storm or hurricane conditions to land areas within 48 hours.

This new product is expected to be a game-changer as it will eliminate surprise storms and hurricanes and increase the lead time for preparations for rapidly developing disturbances approaching land. If such a product were in place for Gonzalo of 2014, Antigua would have likely fared much better.

Click here for other new and improved products.

2016 hurricane season summary

The 2016 AHS was active – the first active (above normal) season since 2012 and the most active since 2010, based on the ACE index. It produced 15 named storms. Of the 15, 7 became hurricanes and 4 reached major hurricane status – at least Category 3 on the Saffir-Simpson Hurricane Wind Scale. The strongest tropical cyclone for the season was Major Hurricane (MH) Matthew with peak winds of 160 mph and minimum pressure of 934 millibars.

Hurricane Matthew caused the most devastation. In total, up to 600 deaths have been attributed to the storm, including over 500 in Haiti, making it the deadliest Atlantic hurricane since Stan in 2005.

The 2016 season is the first year since 2008 no tropical cyclone passed within 121 miles of Antigua. It was likely the least stressful AHS for the island in, at least, eight years.

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