Updated Hurricane Season Forecast – July Stand By 2020

13 07 2020

Dale C. S. Destin|

My “July stand by” 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 hyperactive – well above normal.

My forecast calls for 23 named storms (up 2), including Arthur, Bertha, Cristobal and Dolly, with 9 becoming hurricanes (unchanged) and 5 becoming major hurricanes (unchanged). The accumulated cyclone energy (ACE) index is forecast to be 200 (down 2). Further, there is a 70% confidence of

  • 17 to 28 named storms;
  • 6 to 13 becoming hurricanes;
  • 3 to 7 becoming major hurricanes and
  • 122 to 283 ACE.

If the forecast materialises, the ACE would be top 10 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 10 of all times.

To date, the season has produced an ACE of 7.8, twice the usual amount for January through July 13. A normal season produces 106 ACE. Also, there have been six named storms to date, five time the average of 1.2. 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:

  1. the continuation of a warmer than usual tropical North Atlantic (TNA) and
  2. a developing La Niña.

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 July and into the peak of the season – 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 – 32% 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.

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Drought Deepens…Relief Uncertain

9 07 2020

Dale Destin|

The paltry rainfall for the last three months for Antigua, has caused the meteorological drought to plunge from moderate to severe levels. The rainfall for April-June (AMJ) amounted to only 82.6 mm (3.25 in). This is the sixth driest AMJ on record, dating back to 1928. Further, the rainfall for AMJ represents only meagre 32 percent of the normal total of 274.6 mm (10.81 in). 

Potworks Dam in the background, going on three months, without a drop of its billion-gallon-water capacity. (“Normal” corrected for units Jul 14, 2020)

Other droughts have also tumbled with the meteotological drought, which is considered the mother of them all. These others are at moderate or worse intensity.

The rainfall for June was below normal for the third month in a row. The rainfall of 45.7 mm (1.80 in) was only 66 percent of the normal total for the month of 69.3 mm (2.73 in).

Although drier than normal, it was wetter than the last two Junes combined and more than the last two months combined. This is an indication of just how dry those months were.

Recall that we had very happy first-quarter rainfall. The first three months of the year was wetter than normal. However, since then, things have gone south. Rainfall for the year, thus far, for the dry season – Jan to June, stands at below normal.

The dry season rainfall of 320 mm (12.6 in) amounts to just 74 percent of the normal total of 434.3 mm (17.1 in). It is the driest three-month period since June-August 2018.

The woefully low rainfall since March looks to be mainly due to higher than normal pressure at the lower levels of the atmosphere. This unusual arrangement of pressure resulted in, more often than usual, sinking air, which inhibited warm rising air needed for cloud formation and rainfall.  A record amount of Saharan Dust during June would have also played a huge role in stifling rainfall.

Low level pessure anomaly across the Caribbean Basin and parts of the North Atlantic – April 1 to June 30, 2020. Higher that usual low level pressure inhibits the water cycle and hence, rainfall.
High-level Omega anomaly across the Caribbean Basin and parts of the North Atlantic – April 1 to June 30, 2020. Positive values indicate sinking motion, which is bad for rainfall.

Relief from the drought weather is becoming uncertain. The forecast for July-September (JAS) is for a 45 percent chance of above normal rainfall. This means that rainfall required to bring us out of drought is unlikely.

Looking beyond JAS, my latest forecast calls for less than 40 percent chance of above normal rainfall for the rest of the year, the wet season – July to December. This means that near or below normal rainfall is more likely than drought busting rainfall.  

Considering the whole year, 2020 will most likely be drier than usual. My latest projection is for a 50 percent chance of below normal rainfall, 30 percent chance of the usual rainfall and 20 percent chance of the year getting more than usual rainfall.

How dry it is projected to be? At this time, Antigua’s most likely rainfall for 2020 is 1026 mm (40.4 mm) with a 70 percent confidence that it will fall in the range of 760 to 1349 mm (30 to 53 in). Normally, the island gets 1207 mm (47.5 in).

Projected rainfall for Antigua in inches. There is a 20% chance of it being above normal (A 20%), 30% chance of it being near normal (N 30%) and 50% chance of it being below normal (B 50%). Background pic courtesy Karen Corbin of the Humane Society.

The parched weather was not restricted to Antigua and Barbuda. Much of the rest of the region have been suffering the same fate. There are a few exceptions, most notably is Cuba.

May was a record dry month for Anguilla and St. Thomas. Parts of the Dominican Republic and Belize saw record low rainfall for April. Severe or worse droughts are being experienced in many islands, including Aruba, Barbados, Martinique and St. Lucia.

Rainfall anomaly across the Caribbean Basin – January 7 to July 4, 2020 based on CPC CMORPH

Large scale atmospheric and ocean conditions continue to trend in the direction that would usually cause relief across the Caribbean Basin, including Antigua and Barbuda. However, models continue to not be very enthusiastic about forecasting significant rainfall for much of the region.

The favourable conditions for rainfall for our area are: warmer than usual tropical North Atlantic and cooling of the central to eastern equatorial Pacific i.e. a developing La Nina. Once these two things happen together, we invariably get good rainfall. However, what we can’t predict beyond a week, could negate the positive conditions – Saharan Dust, the x-factor. If it does not let up, it will suppress rainfall and wipe out any optimism in the forecasts for drought-stopping rain.

From all that have been examined, the drought is unlikely to end for the foreseeable future and if it were to, it would only be temporary. This is not to say that we won’t see more rainfall in the second half of the year than the first. We will; however, it is unlikely to end the drought.

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The Hurricane Season in July Stand By

5 07 2020

Dale C. S. Destin |

Updated July 7, 2022

Unlike June, we have been impacted by tropical cyclones – tropical depressions, tropical storms or hurricanes, in July. Hence, as the 1898 poem by R. Inwards said “stand by” for news of storms that may be coming our way. Notwithstanding, July is still a relatively slow month for tropical cyclone activity.

The last hurricane to impact Antigua and Barbuda, in July, was Hurricane Bertha of 1996. Bertha hit while we were still recovering from one of our busiest hurricane seasons in modern times – 1995, the year of Hurricanes Luis (Category 4) and Marilyn and Tropical Storm Iris.  

134 named storms for July with Hurricane Bertha of 1996 highlighted

The centre of Bertha passed just south of Barbuda, likely causing the island to experience all its 137 km/h (85 mph) winds it was packing, at the time. Passing north of Antigua, the system caused peak sustained winds of only 63 km/h (39 mph). Damage to Antigua was minimal but unclear for Barbuda. Regardless of the damage, the psychological trauma would have been extreme for many, coming 10 months after the horror of Luis.

Bertha also caused damage across 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 12 fatalities and at least US$330 million in damage.

Category 3 Hurricane Bertha – July 9, 1996

The probability of us (Antigua and Barbuda) being impacted by a named storm – a tropical storm or hurricane, in July is around 3 percent. This means that we are impacted by a named storm every 33 years, on average; hence, we are not due for a named storm, in July, for another seven years.

Surprisingly, we have never been affect by a tropical cyclone in July when there was and La Niña, as there is now. The same is true when there is an El Niño; it is Neutral ENSOs that bring us tropical cyclones in July.

The probability of us being impacted by a hurricane is the same as indicated above for named storms. In our history, there have been six named storms of which one was a hurricane – Bertha.

July is also a relatively slow month for tropical cyclone activity across the Eastern Caribbean. The region has seen 25 named storms, 7 of which were hurricanes and 1 major hurricane – Category 3 Hurricane Emily of 2005, the strongest to pass through the islands in July.

Satellite image of Category 5 Hurricane Emily south of Jamaica – 16 July, 2005
The track of Category 5 Hurricane Emily – July, 2005
Storms to have pass through the Eastern Caribbean – 1851 to 2021

Elsa of 2021 is the last hurricane to impact the Caribbean in July and the strongest since Emily. It’s centre passed just south of Barbados and then just north of St. Vincent, significantly impacting those islands. It then travelled west-northwest across the Caribbean Sea, impacting Hispaniola, Jamaica and Cuba, as a tropical storm.

Elsa became the first tropical cyclone to cause sustained hurricane-force winds to impact Barbados since Janet of 1955. The system caused a total of 13 deaths and at least US$1.2 billion dollars in damage. One persons was killed in Martinique, two in the Dominican Republic, ten in the United States. In Barbados, more than 1,300 homes were damaged, including 62 homes which were completely destroyed. 

Elsa going from Tropical Storm to a Category 1 Hurricane and impacting Barbados and the Windward Islands on 2 July 2021

The probability of a hurricane impacting the Eastern Caribbean annually, in July, is around 6%. This means that the region gets a hurricane every 16 years, on average. With the last hurricane occurring last year, we are not due for another hurricane in July for another 15 years. The probability of a hurricane in July, across the central and western Caribbean is a little higher – 10%.

Overall, July averages one named storm per year, a hurricane every other year and a major hurricane every 6 to 7 years. The last major hurricane was Bertha of 2008 and the last Category 5 hurricane was Emily of 2005.

Based on record since 1851, July has produced 134 named storms of which 62 became hurricanes and 12 became major hurricanes. We note that there are likely storms that were missed prior to the Satellite era – prior to the mid-1960s. For the current standard climate period – 1981 to 2010, there have been 33 named storms, with 16 becoming hurricanes and 5 becoming major hurricanes.

July has had a maximum of 5 named storms in a given year – 2005. On two occasions, there have been 3 hurricanes – 1966 and 1916. Further, on two occasions there were two major hurricanes – 2005 and 1926.

The strongest hurricane on record – Hurricane Allen of 1980, formed on July 31. It slammed Martinique, St Lucia and St Vincent on August 3 with Category 4 winds. It then reached Category 5 in the Eastern Caribbean Sea before pummelling parts of the Dominica Republic, Haiti, Jamaica and Cuba, on August 6. Allen then reach maximum strength of 306 km/h (190 mph) near the western tip of Cuba, on August 7. Earlier on that day, it severely impacted parts of the Cayman Islands.

Category 5 Hurricane Allen of 1980 – the strongest Atlantic hurricane on record

It goes without saying that Allen left a long trail of death and or damage and destruction from Eastern Caribbean to the United States. Some damage was catastrophic, for example, St Lucia had 6 fatalities and over US$230 million in damage. Deaths from Allen totalled 269 and damage over US$1.5 billion.

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

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June Too Soon 2020 Hurricane Summary

1 07 2020

Dale C. S. Destin|

June too soon is over, one month down and five more to go for the Atlantic hurricane season. This June had two named storms – Tropical Storms Cristobal and Dolly, the most since 2017. Only four seasons have seen more named storms in June – 1968, 1936, 1909 and 1886.

2020 Tropical Cyclone Tracks Through June 30

Tropical Storm Cristobal became the third named storm for the year – June 1 to 10. It also became the earliest third named storm on record – previous was Tropical Storm Collin of 2016.

Clouds from Tropical Storm Cristobal covering much of Mexico and Central America

Interestingly, Cristobal formed from the remnants of Tropical Storm Amanda. Amanda was the first named storm of the East Pacific hurricane season. It formed on May 30, just south of Guatemala and west El Salvador and moved onshore that area May 31, then rapidly dissipated the same day. That was the end of Amanda but the start of Cristobal.

Together, Tropical Storms Amanda and Cristobal, left a trail of destruction and death caused mainly by torrential rainfall, amounting to up to 1016 mm (40 in), in some areas. The trail runs from Central America to Canada, passing through eastern Mexico, central United States and Canada.

Dolly – June 22 to 24, was a “sheep of a storm”. It formed over the Atlantic, hundreds of miles east of New York and travelled parallel to the east coasts of the United States and Canada, never making landfall.

Upon formation, Dolly became the third earliest fourth named storm in a year, on record. Only Tropical Storm Debby of 2012 and Tropical Storm Danielle of 2016, were earlier. Dolly also became the farthest north forming Atlantic tropical storm, on record, before July 1.

Four down, 13 to 22 more are forecast

Recall that there is a storm in June every other year; one hurricane every 8 years and a major hurricane every 50 years, on average. The month has now gone six years without a hurricane and 54 years without a major hurricane. A good “drought” to have, right?

Recall also the we (Antigua and Barbuda) has never had a storm in June, so the happy streak continues. This is also true for most islands of the Caribbean east of Cuba.

The season is certainly off to a busy record tying start. Thus far, there have been four named storms – Tropical Storms Arthur, Bertha, Cristobal and Dolly. This year ties with 2012 and 1954 for the most named storms by July 1.

Although it was an active June, it may have been more active, if not for record levels of Saharan Dust traversing the tropical North Atlantic, the Caribbean and especially the Western Caribbean and the Gulf of Mexico, the main development regions during June. It was certainly a dust event for the ages.  

Saharan Dust as seen by Goes 16 Satellite at mid day June 23, 2020

So, it’s 30 days down and 152 more to go for the 2020 Atlantic hurricane season. Attention now turns to July stand by. Be prepared, be hurricane strong!

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.

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