From Severe Drought to Average Rainfall

By Dale C. S. Destin – Published 22 February 2023 |

Notwithstanding drought continuing through most of 2022 in Antigua, the year ended with near normal rainfall, the middle third/tercile of all annual rainfall totals for the 1991-2020 standard climate period.

The rainfall for Antigua for 2022 was 1069.3 mm (42.1 in); the long-term (1991-2020) average/normal is 1155.7 mm (45.5 in).

The severe drought which started in January 2021 continued through August 2022, with fluctuation in intensity. Notwithstanding, 2022 ended with near-normal rainfall; this was due largely to the above-normal rainfall (579.1 mm/22.8 in) for the last third of the year–September to December, forced by mainly September and November.

The fall rains ended the meteorological drought; they also likely ended the agricultural and ecological droughts but not the hydrological and socioeconomic droughts. This is particularly evident from the continued absence of extractable water from Potworks Dam.

The month with the least rainfall for the year was May with 24.6 mm (0.97 in). This was the 4^th driest May since 2001 and the 9^th driest on record dating back to 1928. This is the third year in a row that May has been this parched with well below normal rainfall of less than an inch.

The month with the most rainfall was September; it had 208.3 mm (8.20 in), the most since 2017. This is the wettest September since the faithful September of 2017, when Irma and Maria drenched and flattened much of the northern Caribbean.

Usually, the most rain falls on Antigua in November and the least in March. For 2022, five months had below normal rainfall–bottom tercile of the historical data, and four had above normal–top tercile of the historical data.

The average for the year certainly does not fully capture the rainfall picture for the year. The first half of the year was drier than normal with 297.4 mm (11.71 in), ranking 20^th of 94 for similar January to June periods. Contrastingly, the second half of the year had near-normal rainfall of 772.2 mm (30.4 in) compared to an average of  746.8 mm (29.4 in).

The year has started out wet; however, this is unlikely to be sustained as El Niño is forecast to prevail during the wet season–July to December. Recall that in our part of the world, EL Niño is a harbinger of drought while La Niño usually heralds the opposite. The first rainfall outlook for the year will be issued in April.

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2022 Worst Swell Event for the Northeast Caribbean

By Dale C. S. Destin – Published 9 December 2022 |

The Northeast Caribbean is in the midst of its most significant swell event for the year. Strong winds associated with Tropical Disturbance AL99, which has morphed into a large and powerful extratropical cyclone, centred about 2500 km (1500 miles) away, are pushing relatively large swells toward the Northeast Caribbean, including Antigua and Barbuda and the rest of the Leeward Islands and the British Virgin Islands.

Wind gusts (colour coded) and pressure (solid lines in mb) forecast by the ECMWF WAM 11km model for Thu Dec 8, 2022 UTC

Swells started to arrive last Sunday and will continue through next week. Swells peaked over 2.7 metres (9 feet) on Monday and will peak even higher, above 3.5 metres (12 feet), over the next 24 hours. Swells are expected to decline a bit after the next 24 hours and will again peak at over 3 metres (10 feet) on Monday.

NOAA Station 41044 – NE ST MARTIN – 330 NM NE St Martin Is showing relatively tall swells heading toward the northern Caribbean

Animation of forecast swells moving across the region from Tropical Disturbance AL99, as predicted by the European Centre for Medium-Range Weather Forecasts (ECMWF) wave model (WAM). Time in UTC.

This will be no Swellmageddon but neither is it your garden variety swell event. It will be one of the worst swell events for the Northeast Caribbean and easily the worst swell event, thus far, for the year and of the swell season: December to April. Swells could occasionally exceed 4.5 metres (15 feet) tomorrow Friday. Naturally, a high surf warning is in effect for a number of islands.

As usual, these swells will be virtually harmless in open waters, but they will be a very different “kettle of fish” when they run up on reefs and particularly northern and north-facing coastlines which are relatively shallow and gentle to moderately sloping. In these environs, surfs (breaking swells) could be as much as twice the height of swells, as they crash onto shorelines.

Precautionary actions: No one should enter the waters of the main warning areas: northern and eastern coastlines. All are also urged to stay away from rocky and or coastal structures along affected coastlines.

The year’s worst swell event could cause, will likely continue to cause or cause, among other things:

• loss of life–strong currents that can carry even the strongest swimmers out to sea;
• injuries to beachgoers;
• beach closures;
• major beach erosion;
• flooding of some low-lying coastal roads;
• disruptions to marine recreation and businesses;
• salt-water intrusion and disruptions to potable water from desalination;
• damage to coral reefs;
• harbour closure–making the navigation of some harbour channels dangerous and
• financial losses.

The low-pressure area generating the current swells has the potential to become a tropical cyclone. The probability of this happening stands at 10 percent but earlier this week stood at 50 percent. A second low-pressure area will power the swells across the area late next week as the present one moves to the distant North Atlantic.

The impact of the associated swell event will be felt well beyond the Northeast Caribbean. Powerful swells are expected to reach Guyana in the south and the Bahamas, in the west. Impacts will also be felt along the East Coast of the United States, Canada and eventually Northwest Africa and Europe.

Tropical Disturbance AL99 does not have the structure to be declared a tropical cyclone; however, it has winds of tropical storm strength and gusts to hurricane force. Clearly, none of these harsh winds will reach our shores but the sea swells they are pushing will.

Satellite image of Tropical Disturbance AL99 circles in yellow

The impact on shorelines will not be the same everywhere. Depending on the depth, size, shape and the natural shelter of the coastal waters, the impact will be different. Shallow north-facing shorelines are expected to see the highest swells and surfs.

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From Record-Breaking Dry 21 Months to Wettest Month and Day in Over 21 Months

By Dale C. S. Destin – Published 20 October 2022 |

The past 21 months, ending August, is the driest such period on record for Antigua, dating back to at least 1928, the furthest distance back for reliable data. Since the heavens opened in November 2020, for the following 21 months – December 2020 to August 2022, drought reigns. The island-average rainfall for the record dry period was 1179.3 mm (46.43 in). The previous record for the 21 months ending August was 1209.5 mm (47.62 in) set for December 2014 to August 2016.

Rainfall for Dec 2020 to Aug 2022: 1179.3 mm (46.43 in) vs the normal total for the same period, 1868.9 mm (73.58 in). Dec 2020 to Aug 2022 is the driest such 21 months on record.

The past 21-month period has also seen no month coming remotely close to exceeding 200 mm (8 in) of rainfall, with only one exceeding 100 mm (4 in). September 2022 has brought an end to that streak of months sub 200 mm. The streak owes its end largely to the wettest day in over 21 months: September 17, 2022 amassed a one-day total of 45 to 119.8 mm (1.77 to 4.72 in), easily the wettest day in 676 days. The one-day total at the V.C. Bird International Airport of 84.6 mm (3.33 in) was more than the total for every full month since November 2020, except September 2021. 

Usually, 21 months ending August averages 1868.9 mm (73.58 in). This translates to only 65 percent of the normal rainfall falling since the November 2020 flash floods. The rainfall total for the last 21 months was just 5.6 percent more than the annual total. The last 21 months almost had the same rainfall as what usually falls in 12 months. The deficit of 659.4 mm (25.96 in), 35 percent, is more than the average for the first eight months of the year.

Such an extremely low rainfall total for the last 21 months has a 1 percent chance of occurring.  This translates to the dryness for December 2020 to August 2022 having a return period of 1-in-100 years, on average. Only about a handful of persons were around the last time the heavens closed like this and likely only a few persons living now will witness the next time this record is broken.

The ongoing dryness is reminiscent of the dryness of the Great Drought of 2013-2016. At no time during that historic period was the aridity this intense for a similar 21 months.

The rainfall for September has end the meteorological and agricultural droughts, which dates back to January 2021; however, it was insufficient to end the hydrological and socioeconomical droughts. This is evident by the absence of water from Potworks Dam and the continued water outage in a number of places, which sometimes last for weeks.   It is unclear if the wet weather will continue through October and the rest of the year. At this stage, there is just about an equal chance of below, near or above normal rainfall for the remaining months of 2022.

Graphic courtesy https://www.drought.gov/what-is-drought/drought-basics

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Stormless August

By Dale C. S. Destin – Published 1 September 2022, Updated 8 September 2022 |

We have just passed the mid-point of the 2022 Atlantic hurricane season–93 days gone, 90 more to go. And for the first time in 25 years, we had a stormless August–no tropical storm (or hurricane) in August across the Atlantic. The last time there was a stormless August was in 1997.

Atlantic in August 2022 was quieter than the library on Good Friday

The Atlantic in August 2022 was quieter than the library after midnight on Good Friday. Based on reliable data dating back to 1971, a storm-free August has only occurred in two other previous years – 1997 and 1988. The chance of such an August is about 2 percent or once every 50 years on average.

It is clearly rare for the second most active month of the season to score a duck or not score a single storm. It is almost equivalent to Michael Jordon or Vivian Richards going scoreless in a match. On average, using the climatological period of 1991-2020, August usually produces four named storms, two hurricanes, one major hurricane and an Accumulated Cyclone Energy (ACE) index of 27.

According to ACE, August usually accounts for 22 percent of the activity for the season. By comparison, September usually accounts for 47 percent of the season’s activity with ACE of 57.6, named storms of 5.5, hurricanes of 3.3 and major hurricanes of 1.6.

The most active August on record, dating back to 1851, is 1893 with an ACE of 120.3. The Augusts with the most named storms are those of 2012, 2004 and 1995 with 8. The record for the number of hurricanes for the month is 5 – 2004, 1995 and 1893. A maximum of 3 major hurricanes formed in the month in 2004, 1983 and 1886.

Recall the old mariner’s poem which says, “August look out you must”, you must take action to protect your life and property from tropical cyclones in August. Not that I am complaining, but no such action was required for this August.

Based on the ACE, August has a strong bearing on the overall activity of the hurricane season. Examining data dating back to 1971, given that this August had below normal ACE, the chance of the season turning out active or above normal has plummeted to 4 percent from 73 percent. There is now a 61 percent chance of a below-normal or quiet season and a 35 percent chance of a near-normal season. In other words, only once has August been quiet and the overall season turned out active.

It’s also the first time since 2013 that January to August scored a duck for hurricanes. Usually, by August 26, there would be two hurricanes for the month; however, this was not the case for August of 2022, 2013, 2001, 1998 and 1984, based on reliable data dating back to 1971. There are other years with no hurricanes through August, but the data are questionable, especially prior to the satellite era.

The season got off to a flyer. By July 3, the number of tropical cyclones stood at three. From January through August, the number remains at three. This is low but it does not set any record. The year with the fewest number of tropical cyclones for January to August is 1977 with one, over the period 1971-2022. There are 15 other Augusts with nil tropical cyclones between 1928 and 1851; however, this data is not very reliable.

For years with below-normal ACE activity in August, the overall seasons usually also have a below-normal number of tropical cyclones. With 95 percent confidence, years with quiet Augusts average 6 to 10 named storms, 3 to 4 hurricanes and 0.5 to 1.5 major hurricanes. The max and min numbers of named storms for such seasons are 12 and 4 respectively. The max and min for hurricanes are 6 and 2 respectively and the max and min for major hurricanes are 2 and 0 respectively.

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Correction:

02 Sep 2022: A correction to the year was made in the first line of the first paragraph. It is 2022, not 2023. 08 Sep 2022: A correction to the climate normal for September was made in the fourth paragraph. It is named storms of 5.5, hurricanes of of 3.3 and major hurricanes of 1.6. and NOT named storms of 4.4, hurricanes of of 2.5 and major hurricanes of 1.2.

August Updated Forecast for the 2022 Atlantic Hurricane Season

Dale C. S. Destin |

My August updated forecast for the 2022 Atlantic Hurricane Season is out, and despite the July-August lull in tropical cyclone activity, it continues to call for a busy and active/above-normal season. This is because the existing and projected atmospheric and oceanic conditions are what usually favour such seasons. There is also still the possibility of it being super hyperactive. As of August 20, the forecast is for 19 named storms, 8 hurricanes and 5 major hurricanes. This includes Tropical Storms Alex, Bonnie and Colin.

Probabilistically, there is a 73 percent chance of an above-normal season; a 21 percent chance of a near-normal season and a 6 percent chance of a below-normal one, based on the accumulated cyclone energy index (ACE). If the forecast pans out, this season would be the 17th most active season, on record, in terms of ACE, dating back to 1851.

Recall that the ACE is the universally accepted metric used to classify the overall activity of a hurricane season. The ACE forecast for this year has been revised downwards by nearly 14 percent to 167. This is still 10 percent above the threshold for an active season, based on 1991-2020 data. The forecast number of hurricanes has also been revised downwards to 8, which represents a 27 percent decrease from the previous forecast.

A super hyperactive season like 2017 also remains possible, although with a slightly reduced probability. This is because there is a 39 percent chance of the ACE exceeding 223. Further, there is a 54 percent chance of more than 19 named storms; a 29 percent chance of more than 11 hurricanes and also a 40 percent chance of more than 6 major hurricanes.

Notwithstanding the forecast, there are notable uncertainties, mainly in relation to the unpredictable nature of the Saharan Dust, which is also known as the Saharan Air Layer. The dust suppresses tropical cyclone formation when present; however, it is not predictable beyond a week or two; hence, it cannot be factored into the hurricane season forecast, which covers months. This x-factor could make the difference between an active season and a quiet one.

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.

The Atlantic hurricane season officially goes until November 30. Regardless of the forecast, we all should get or remain prepared and ready to take action if a hurricane threatens our area. This includes developing a hurricane plan, securing property insurance and gathering hurricane supplies now, well in advance of any threat.

For a more detailed forecast click here.

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August Update: Below Normal Rainfall Still Most Likely for Antigua for 2022

Dale C. S. Destin |

The prediction for rainfall remains off-putting for Antigua for 2022. My latest updated forecast once again projected rainfall to be most likely below normal. The most likely forecast total for the year is 1091 mm (43.0 in), up just 2 mm (0.08 in) from the previous forecast. There is also a 70 percent or high confidence of the rainfall total falling in the range of 825 to 1410 mm (32.5 to 55.5 in).

Thus far for the year, through the end of July, the rainfall total of 396.7 mm (15.62 in) is running 104.1 mm (4.1 in) below the average of 500.1 mm (19.69 in). In other words, the total is 79.3 percent of the average or a 20+ percent deficit in rainfall. The forecast rainfall for the year will likely range between 71 and 122 percent of average, with a skew to 71.

The main reason for the below normal rainfall forecast is seemingly the near normal sea surface temperatures (SSTs) across the tropical North Atlantic (TNA). This contributed largely to the first half of the year, the dry season – January to June, being drier than normal. Cooler than normal TNA SSTs favour suppressed rainfall conditions while the opposite enhances rainfall.

Saharan dust is also a factor in the below normal rainfall being experienced; however, there is no predictability of the dust beyond a week or two; hence, it cannot objectively be factored into the models. It remains an x-factor that we cannot give an account for, except in hindsight. The dust is a significant rainfall suppressant.

There is a La Nina underway, and this historically favours above normal rainfall for our area. Thus, the latter half of the year will most likely see near normal rainfall. However, because we are so deep in drought, normal rainfall is not going to cut it. Notwithstanding, below normal rainfall being most likely, there are relatively healthy probabilities for near or above normal totals – there is still hope, continue to think rain!    

Recall, a typical year, based on the new standard climate period 1991-2020, averages 1156.7 mm (45.54 in). The dry season averages 410 mm (16.14 in) and the wet season, July to December, averages 746.8 mm (29.40 in). Fall/autumn, September-November, accounts for 58 percent of the wet season total and 38 percent of the year’s total.

Regardless of the forecast, we all should make it our business to conserve water and be as efficient with its use as much as possible. Reducing our personal water footprint will literally redound to our individual and collective socio-economic benefit. Minimising your water footprint is also good for the climate, good for our environment and even good for rainfall.

This is the last update for the year. The first forecast for rainfall for 2023 will be in April.

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Record-breaking Dry 12 Months

Dale C. S. Destin |

The deficit in rainfall over the last 12 months ending July was record-breaking. August  2021 to July 2022 is now the driest such period on record, in a series dating back to 1928. The rainfall total of 727.2 mm (28.63 in) broke the previous record of 731.0 mm (28.78 in) measured over a similar period – August 1973 to July 1974, nearly 50 years ago.

During the last 12-month episode of drought, the six months ending January 2022 was the driest such half-year on record with 378.7 mm (14.91 in). Further, the last quarter of 2021, October to December (OND), had a record low rainfall of 127.3 mm (5.01 in). This displaced the previous OND record of 143.0 mm (5.63 in) observed in 1983, that fateful year in which we were forced to import water from Dominica, due to severe drought.

The rainfall total for the past 12 months was down an unprecedented 37 percent. This would have been much worse, if not for near normal rainfall in July of 99.3 mm (3.91 in), which is equivalent to 101 percent of the month’s average of  98.0 mm (3.86 in). The August-July year averages 1150.7 mm (45.3 in), which is similar to the annual average.

Since the deluge of November 2020, rainfall has been as scarce as gold. The rainfall for the past 20 months – December 2020 to July 2022, is the second lowest for such a period with 1082.8 mm (42.63 in). This is even less than the annual 12-month total and represents a deficit of over 38 percent. Only the 20-month period ending July 2016 was drier. Relative to all 20-month periods on record, the last 20 months rank seventh.

Happily, the impacts of the very harsh dry conditions continue to be masked by the adaptation measure of building more and more reverse osmosis (RO) plants to extract potable water from the ocean. If not for the plants, the socio-economic situation would be quite desperate. And to say that without the RO plants the country would have to be closed, leading to mass migration, is not hyperbolic.

According to the United Nations: “Water is at the core of sustainable development and is critical for socio-economic development, energy and food production, healthy ecosystems and for human survival itself. Water is also at the heart of adaptation to climate change, serving as the crucial link between society and the environment.”

Our poster child for droughts, Potworks Reservoir, remains dry land. Recall that in addition to meteorological droughts, there are also agricultural, hydrological, ecological and socio-economic droughts, which are currently, at varying intensities.

There is likely a number of factors responsible for the dryness; however, the main one seems to be the consistent stream of dry and dusty air from the Sahara Desert.

Examination of recent models reveals that there is no sustainable end to this dry weather. At best, rainfall for the rest of the year will be near normal, which will not erase the massive, accumulated deficit.

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July Updated Forecast for the 2022 Atlantic Hurricane Season

Dale C. S. Destin |

My July updated forecast for the 2022 Atlantic Hurricane Season is out, and it continues to call for a very busy and active season with the possibility of being super hyperactive. As of July 20, the forecast is for 19 named storms, 11 hurricanes and 5 major hurricanes. This includes Tropical Storms Alex Bonnie and Colin.

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 193, 41 above the threshold for an active season, based on 1991-2020 data.

A super hyperactive season like 2017 also remains possible. There is a 41 percent chance of the ACE exceeding 223. Further, there is a 50 percent chance of more than 19 named storms; 43 percent chance of more than 11 hurricanes and also a 35 percent chance of more than 6 major hurricanes.

If the forecast pans out, this season would be the most active season since 2017 and the ninth most active, on record, in terms of ACE, dating back to 1851.  

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.

The Atlantic hurricane season officially goes until November 30.

For a more detailed forecast click here.

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Record-Breaking Dry 19 Months for Antigua

By Dale C. S. Destin – Published 13 July 2022, Updated 13 September 2022 |

The past 19 months is the driest such period on record for Antigua, dating back to at least 1928. Since the deluge of November 2020, December 2020 to June 2022 has yielded only a meagre 983.5 mm (38.72 in), for the island-average rainfall. This broke the record set for a similar period, December 2014 to June 2016, of 994.4 mm (39.15 in), which was also the record lowest for any consecutive 19 months.

Usually, 19 months ending June averages 1656.3 mm (65.21 in). This means that since December 2020 only 59 percent of the normal amount of rain fell. The 19-month total of 983.5 mm is less than that for 67 of the 94 years on record i.e. 71 percent of years have been wetter. In other words, the rainfall total for the last 19 months was much less than what usually falls in 12 months – annually.

Rainfall total for Dec 2020-Jun 2022 – 983.5 mm (38.72 in) vs the normal total for the same period – 1656.3 mm (65.21 in). December 2020 to June 2022 is the driest 19 months on record.

Such an extremely low rainfall total for the last 19 months has a less than a 1 percent chance of occurring – 0.8 percent.  This translates to the dryness for December 2020 to June 2022 having a return period of 1-in-125 years, on average. It is unlikely that anyone alive has seen this kind of scant rainfall before and there is a less than 10 percent chance of a repeat in the next 13 years.

The last time we saw such dryness we were in the midst of the Great Drought of 2013-2016. At no time during that dearth of rainfall was the dryness this intense for any successive 19 months.

A lot of the dryness seems largely due to dry and dusty air from the Sahara Desert and or cooler than normal sea surface temperatures across the tropical North Atlantic Ocean. The high number of tropical cyclones in 2021 likely contributed, by steering clear of the area and pulling moisture away from the islands.

The dryness has been quite robust. Not only records were set for the last 19 months but also for the last 18, 17, 16 and 15 months respectively. It is also likely that more records will fall in the coming months.

As forecast, it was a drier than normal dry season for Antigua. The period January to June was the 20^th driest in a series going back to 1928. The continued below normal rainfall means that drought continues to reign with no predictable end in sight.

With the rainfall at or near record-low levels over the past 19 months, one can appreciate the absence of virtually ALL water from surface catchments and the significant drop in groundwater. Potworks Reservoir, our billion-gallon surface catchment, has been totally dry since late October 2021. If not for water from the increasing number of reverse osmosis plants, “crapo would be smoking our pipes”, at the very least. And for those who say he is smoking our pipes, without the plants, it would be exponentially worse, in unimaginable ways.

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July Update: Below Normal Rainfall Still Most Likely for Antigua for 2022

Dale C. S. Destin |

The prediction for rainfall remains unpromising. My latest updated forecast continues to call for most likely below normal rainfall for Antigua. The most likely total for the year is 1089 (42.9 in), up 9 mm (0.4 in) from the previous forecast. There is also a 70 percent or high confidence of the rainfall total falling in the range of 827 to 1405 mm (32.6 to 55.3 in).

The main reason for the below normal rainfall forecast is the cooler than average sea surface temperatures (SSTs) across the tropical North Atlantic (TNA), during the first half of the year, which led to a drier than normal dry season – January to June. Cooler than normal TNA SSTs favour suppressed rainfall conditions while the opposite enhances rainfall.

There is a La Niña underway, and this historically favours above normal rainfall for our area. Thus, the latter half of the year will most likely see near normal rainfall. However, because we are so deep in drought, normal rainfall is not going to cut it. Notwithstanding, below normal rainfall being most likely, there are relatively healthy probabilities for near or above normal totals – there is hope, think rain.    

A typical year, based on the new standard climate period 1991-2020, averages 1156.7 mm (45.54 in). The dry season averages 410 mm (16.14 in) and the wet season, July to December, averages 746.8 mm (29.40 in). Fall/autumn, September-November, accounts for 58 percent of the wet season total and 38 percent of the year’s total.

Regardless of the forecast, we all need to conserve water and be as efficient with its use as much as possible. Reducing our personal water footprint will literally redound to our individual and collective socio-economic benefit. Minimising your water footprint is also good for the climate, good for our environment and good for rainfall.

This forecast will be updated during the first week of August.

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June Updated Forecast for the 2022 Atlantic Hurricane Season

Dale C. S. Destin |

My June 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 June 20, the forecast is for 20 named storms, 10 hurricanes and 4 major hurricanes.

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 186, 34 above the threshold for an active season, based on 1991-2020 data.

A super hyperactive season like 2017 also remains possible. There is a 37 percent chance of the ACE exceeding 223. Further, there is a 43 percent chance of more than 19 named storms; 24 percent chance of more than 11 hurricanes and also a 22 percent chance of more than 6 major hurricanes.

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

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.

The Atlantic hurricane season officially goes until November 30.

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Updated Prediction: Below Normal Rainfall Most Likely for Antigua for 2022

Dale C. S. Destin |

The prediction for rainfall remains discouraging. My latest forecast continues to call for most likely below normal rainfall for Antigua. The most likely total for the year is 1080 (42.5 in), down 25 mm (1 in) from the previous forecast. There is also a 70 percent or high confidence of the rainfall total falling in the range of 590 to 1695 mm (23.2 to 66.7 in).

The main reason for the below normal rainfall forecast is the current trend of cooler than average sea surface temperatures (SSTs) across the tropical North Atlantic (TNA), which should last through summer (June-August). Cooler than normal TNA SSTs favour suppressed rainfall conditions while the opposite enhances rainfall.  

The year started out with a severe drought brought forward. This drought started in the winter of 2020/2021 and continues through the present. This May has been wetter than the last one; notwithstanding, it will end with well below normal rainfall. Year-to-date is drier than normal. Further, since the deluge of November 2020, the start of the current drought, there has been 943.1 mm (37.13 in) of rainfall, for December 2020 to May 2022. This total is so far below normal that it is the second driest such period on record.

The dry season, January to June, is on track to be drier than usual. Summer, June to August, is also likely to be drier than normal. Further, the first three quarters of this year (January to September) is likely to see deficit rainfall with a most likely total of 645 mm (25.4 in) compared to the usual amount of  759 (29.9 in). There is also a 29 percent chance of January to September having top 10 dryness.

WMO Lead Centre for Long-Range Forecast Multi-Model Ensemble is forecasting 40-50% likelihood of below normal rainfall for Antigua and Barbuda for June to August. Also, below normal rainfall is likely for much of the rest of the Caribbean.

A typical year, based on the new standard climate period 1991-2020, averages 1156.7 mm (45.54 in). The dry season averages 410 mm (16.14 in) and the wet season, July to December, averages 746.8 mm (29.40 in). The fall/autumn, September-November, accounts for 58 percent of the wet season total and 38 percent of the year’s total.

This forecast will be updated monthly around the 25^th of each month until August. The next update will be issued around June 25.

Regardless of the forecast, we all need to conserve water and be as efficient with its use as much as possible. Reducing our personal water footprint will literally redound to our individual and collective socio-economic benefit. Minimising your water footprint is also good for the climate, good for our environment and good for rainfall.

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May Updated Forecast for the 2022 Atlantic Hurricane Season

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 16^th 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 14^th 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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What does an Active Hurricane Season Mean for Antigua?

Dale C. S. Destin |

The early forecast is for the 2022 Atlantic hurricane season to be an active one or above normal. What could this mean for you? Will Antigua be affected by a named storm (tropical storm or hurricane)?

What is an active or above normal hurricane season? This is a season with the accumulated cyclone energy (ACE) index in the top third of the 1991-2020 dataset, or an ACE of 152 or higher. The ACE is a metric that takes into consideration not only the number of named tropical cyclones (subtropical storms, tropical storms or hurricanes) but also their strength and duration.

Given the forecast for an active hurricane season, there is a 43 percent chance/probability of a named storm passing within 105 nautical miles of Antigua or affecting (hitting of brushing) us. This translates into a named storm return period of 2 to 3 active years or a named storm affecting us every 2 to 3 active years, on average. Our last named storm during an active year was Tropical Storm Laura of 2020. This means statistically we are not due one this year, if the season turns out to be active, as forecast.

With an active season forecast, a named storm has a 28 percent probability of affecting us as a hurricane and an 18 percent probability of affecting us as a major hurricane (Category 3 or higher). On average, we get a hurricane passing within 105 nautical miles of Antigua every 3 to 4 active seasons and a major hurricane every 5 to 6 active seasons.

Our last hurricane during an active season, which was also a major hurricane, was Maria of 2017. It did not cause us hurricane winds, but it passed within 105 nautical miles to our southwest, affecting us with storm-force winds. Given we average a hurricane every 3 to 4 active years, and there has been only one active season since then, 2020; statistically, this means we are NOT due for a hurricane this year. Additionally, we are also NOT due a major hurricane this year.

What if a season is not active? For a near normal season, the chance of us being affected by a named storm drops to 23 percent and the chance of that named storm being a hurricane plummets to just 3 percent. If by some miracle, the season is below normal, the chance of a named storm passing within 105 nautical miles from Antigua is 21 percent with a 6 percent chance of it being a hurricane. For non-active seasons, near or below normal, we stand a zero percent chance of getting a major hurricane.

A tropical storm or hurricane not being due does not guarantee one will not occur. The fact that the probability of a named storm in any given year is not zero means that one could occur in any year, despite not being statistically due. An event with a given return period is said to be not due when the average return period has not yet elapsed. Because this is an average return period, the event can happen at any time before or after the return period.

Annually, based on the standard climate period of 1991 to 2020, taking all seasons into consideration, there is a 66 percent chance of a named storm affecting Antigua. Further, there is a 35 percent chance of the named storm being a hurricane and an 18 percent chance of it being a major hurricane.

Tracks of all 31 named storms to have passed within 105 nautical miles of Antigua, 1991 to 2020

Active hurricane seasons are generally not good for us, which may not come as a surprise to you. What may be new here are the relatively high chance of us being affected during such a season, which the forecast is calling for this year.

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Wet Weekend for the Northeast Caribbean

Dale C. S. Destin |

A trough system is poised to cause wet weather across the northeast Caribbean, including Antigua and Barbuda. Several of the more reliable weather models are forecasting the potential (10 percent chance) for rainfall totals exceeding 25 mm (over 1 in) to fall over the period Friday to Sunday of this weekend.

The potential total for over 25 mm in 72 hours is not in and of itself a high figure. However, relative to April and the fact that we are in a severe drought makes this worth “writing home about”.

Whereas all models consulted are forecasting rainfall for the weekend, the forecast totals differ, as can be expected. At the lower end of the potential rainfall scale some are projecting a 10 percent chance of over 25 mm (over an inch), while others are suggesting potentially higher totals, a 10 percent chance of over 75 mm (3 in) for the weekend.

GFS 24hr precipitation total exceedance forecast probabilities showing all areas with at least a 10 percent chance of getting over 50 mm (2 in) of rainfall from 2 am Saturday, 30 April to 2 am Sunday, 1 May 2022

The wet weather is expected from Dominica to Hispaniola. The highest totals are likely across Puerto Rico and the Virgin Islands Saturday/Sunday. Most of the rainfall for Antigua and the rest of the Leeward Islands is likely Friday/Saturday and for Hispaniola Sunday/Monday.

If the models prove right, and the upper end of the rainfall potential materialises, some places across the northeast Caribbean could see the average total for April falling in one weekend, if not one day. The possible rainfall total for the area is 25 to 100 mm (1 to 4 in). With this kind of rainfall possible, depending on the intensity and duration, flash flooding and associated impacts are of concern.

Deterministic rainfall accumulation forecast by the GFS model from Thursday, 28 April to Sunday, 1 May 2022

The rainfall of this weekend could, at least, put a dent or further dent in the droughts across the area, particularly the Virgin Islands and Puerto Rico. It will certainly have a big impact on domestic catchments, temporarily easing the stress and demand on water resources authorities.

There is no doubt that these showers will be welcome by all; however, they could prove disruptive to weekend plans leading up to Labour Day Monday celebrations. Good news though: The weather should just about be back to normal by Monday.

The system has already caused wet weather across the southern Caribbean with some areas receiving over 75 mm (3 in). The trough also prompted flash flood warnings for some islands.

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Early Prediction: Below Normal Rainfall Most Likely for Antigua

Dale C. S. Destin |

The year will most likely be another drier than usual one for Antigua. My early forecast calls for the rainfall total for 2022 to most likely be 1105 mm (43.50 in) with a 70 percent or high confidence of it being in the range of 811 to 1463 mm (31.93 to 57.60 in).

The main reason for the most likely below normal rainfall forecast is the current cooler than normal sea surface temperatures (SSTs) across the tropical North Atlantic (TNA), which should last, at least, into the second half of the year. Cooler than normal TNA SSTs favour suppressed rainfall conditions while the opposite enhances rainfall.  

The year started out with a severe drought brought forward. This drought started in the winter of 2020/2021 and continues through the present. January 2022 was wetter than January 2021, but it was still only 72 percent of the normal total. The last two months, February and March, have been wetter than normal resulting in the intensity of the meteorological drought easing to slight. This easing is likely to be a brief respite, given the forecast.  

The dry season, January to June, will likely be below normal with a 60 percent chance. The forecast is for 298 mm (11.73 in) with high confidence of it ranging between 182 to 459 mm (7.17 to 18.07 in). This dry season could also be one of the top 10 driest. There is a 33 percent chance of this happening with the possibility of the total falling below 254 mm (10 in). Currently, the total stands at less than 203 mm (8 in) with April running well below normal at less than 25.4 mm (1.0 in) and the forecast indicating a better than 70 percent chance of May-June being drier than normal.

WMO Lead Centre for Long-Range Forecast Multi-Model Ensemble is forecasting 70-80% likelihood of below normal rainfall for Antigua and Barbuda for May to July. Also, below normal rainfall is likely for much of the rest of the Eastern Caribbean.

A typical year, based on the new standard climate period 1991-2020, averages 1156.7 mm (45.54 in). The dry season averages 410 mm (16.14 in) and the wet season, July to December, averages 746.8 mm (29.40 in). The fall/autumn, September-November, accounts for 58 percent of the wet season total and 38 percent of the year’s total.

Rainfall-wise, last year–2021, will be most remembered for being the second driest on record with some parts of the country having record-breaking dry weather. There were likely significant socio-economic impacts but unfortunately, this has not been quantified.

This forecast will be updated monthly around the 21^st of each month until August. The first update will be issued around May 21.

Regardless of the forecast, we all need to conserve water and be as efficient with its use as much as possible. Reducing our personal water footprint will literally redound to our individual and collective socio-economic benefit. Minimising your water footprint is also good for the climate and good for our environment.

Please share this blog, if you found it useful, and follow me for more on the evolving drought and for all things weather and climate – Twitter, Facebook and Instagram.

Early Prediction: Very Busy 2022 Atlantic Hurricane Season Forecast

Dale C. S. Destin |

This hurricane season will likely be another very busy one, exhausting the primary list of named storms, once again. My early forecast for the 2022 Season is out, and it calls for 21 named storms, 9 hurricanes and 4 major hurricanes.

In addition to being a very busy season, it is most likely to be an active season. 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 182, 30 above the threshold for an active season, based on 1991-2020 data.

A super hyperactive season is also possible. There is a 36 percent chance of the ACE exceeding 223. Further, there is a 49 percent chance of more than 19 named storms; 30 percent chance of more than 11 hurricanes and 29 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 tied with 1998 for the 10^th most active on record dating back to 1851. It would also tie 2021 for the third highest number of named storms.  

According to other forecasts surveyed, the consensus is for an ACE of 161, 19 named storms, 8 hurricanes and 4 major hurricanes, a busy and active season. This is generally consistent with my forecast but with a notable 21 less ACE. 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 main reason for the above normal forecasts is the current La Niña, which should last into the first half of the hurricane season and maintain favourable conditions for tropical cyclone formation even beyond August, into the peak of the hurricane season.

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.

The last Atlantic hurricane season–2021, will be most remembered for being a very busy season with 21 named storms. Collectively, the season caused 103 deaths and over US$80 billion in damage. Major Hurricane Ida alone caused 55 deaths and over US$75 billion in damage.

This forecast will be updated monthly around the 14^th of each month until August. The first update will be issued around May 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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Drier than Usual January for Antigua

Dale C. S. Destin |

January 2022 was another drier than usual month for Antigua; the fourth in a row and the 10^th since January 2021. The month registered just  48.3 mm (1.90 in), making it the fifth January of the last eight with below normal rainfall.

January usually clocks 67.3 mm (2.65 in) of rainfall annually (1991-2020); this means the month fell close to 28 percent below its usual total. This is an improvement over January 2021, when the deficit was close to 60 percent. Notwithstanding, it is another year with a bad start.

January’s rainfall anomaly (deviation from normal) in percentage (blue line) along with the long-term trend (grey broken line). The background is that of Potworks Dam, 3 February, 2022

The rainfall for January continues to trend negatively (downward); however, this trend is statistically insignificant. The trend is at a rate of just 0.16 mm (0.0064 in) per year or 16 mm (0.64 in) per hundred years. This also represents an insignificant rate of 0.24 percent per year or 24 percent in 100 years. No evidence of a changing climate with respect to rainfall in January.

In aggregate, the three-month period ending January is among the driest on record going back to 1928. The total of 141 mm (5.55 in) is the third lowest behind November-January of 1967/68 and 1947/48. The last four, five, six and seven-month periods ending January had record-breaking low rainfall. Further, the last year (February to January) ranks second driest, on record, with 621.5 mm (24.47 in). The record is 588 mm (23.15 in), February 2015-January 2016.

Clearly, we remain in the grips of a severe meteorological drought, which is also defined as exceptional by some other metrics. Also evident are agricultural, hydrological, ecological and socio-economic droughts, at varying intensities. Potworks Reservoir remains 100 percent empty, converted into a pasture for grazing animals. All other surface catchments are in a similar state or below extraction levels.

Antigua Public Utilities Authority (APUA), the country’s water resource manager, has just commissioned a new reverse osmosis plant to obtain more potable water from the sea. This should bring the daily total from this source to over 7 million and it should help to ease the water woes. However, the drought continues to be a very serious matter for many, who are forced to go days without potable water, as demand continues to outstrip production by hundreds of thousands of gallons.

The drier than usual start to the year was not confined to Antigua. Much of the Caribbean Basin experienced below normal rainfall with some islands or part thereof getting less than 25 percent of their usual total–75 percent rainfall deficit or more.

CMORPH 1-Month Percent of Normal Rainfall for January 2022

Drought conditions have worsened across a number of the other islands, including the rest of the Leeward Islands, the Virgin Islands and Puerto Rico, most of the Windward Islands and Barbados. The Caribbean Institute for Meteorology and Hydrology (CIMH) has recommended drought watches or warnings for most islands of the Caribbean.

It is unclear as to when there will be any notable respite from the drought. The latest set of models surveyed suggests an equal chance of below, near or above normal rainfall for March to May for Antigua and Barbuda and much of the rest of the Caribbean.

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The Northern Caribbean Set to Experience its Worst Swell Event for the Season

Dale C. S. Destin |

Strong winds from a low-pressure system, some distance away, are pushing relatively large swells toward the northern Caribbean and the Bahamas, including Antigua and Barbuda and the rest of the Leeward Islands. Swells have started to arrive and will reach warning levels tonight through much of Saturday night.

NOAA Station 41044 – NE ST MARTIN – 330 NM NE St Martin Is showing relatively tall swells heading toward the northern Caribbean

This will be no Swellmageddon but it will be the worst swell event of the swell season: December to April. This event will see swell waves coming from the north-northeast at 2 to 3 metres (7 to 10 ft). Occasionally, they will reach 4 metres (near 13 ft). Though it will be no Swellmageddon, it will not be your garden variety swell event, as surf warnings are required.

Video by Windy.com showing swell heights

The possibility of significant wave heights (SWH) equaling or exceeding 3 metres or 10 feet. This is likely to expected in the northern coastal waters, according to the ECMWF IFS Model.

These swells will be virtually harmless in open waters, but they will be a very different “kettle of fish” when they run up on reefs and exposed northern and eastern coastlines which are relatively shallow and gentle to moderately sloping. In these environs, surfs (breaking swells) could be as much as twice the height of swells, as they crash onto shorelines.

Surfs at Fort James during a past swell/surf event

Such high swells and surfs will produce a high threat to life and property in the surf zone. There is the potential for extensive impacts. High surfs will result in beach closures, as swimming conditions will be extremely dangerous for beachgoers. Not entering the waters of affected areas would be a great safety idea and best advice.

The event will likely cause major beach erosion; possibly flooding of low-lying coastal roads; disruptions to marine recreation and businesses; financial losses and damage to coral reefs.

Although relatively small, this swell episode may also cause disruptions to potable water from desalination, as turbulent seas, will increase the turbidity of the water above tolerable levels for the desalting plants.

A high surf warning has been issued by the Met Office for Antigua and much of the rest of the northeast Caribbean. Other offices, as far west as the Bahamas, are expected to issue requisite marine alerts, if they have not done so already.

Precautionary actions: No one should enter the waters of the main warning areas: northern and eastern coastlines. All are also urged to stay away from rocky and or coastal structures along affected coastlines.

The impact on shorelines will not be the same everywhere. Depending on the depth, size, shape and the natural shelter of the coastal waters, the impact will be different. Shallow north-facing shorelines are expected to see the highest swells and surfs.

Seas are to return to safe levels by Monday morning.

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Relatively Very Wet Weekend Possible for Parts of the Northeast Caribbean

Dale C. S. Destin |

A cold front looks poised to cause a relatively very wet weekend across much of the northeast Caribbean, including Antigua and Barbuda. Several reliable models are forecasting possible rainfall totals of 25 to 76 mm (1 to 2 in) to fall over the period Friday to Sunday.

Proxy visible satellite image

The potential total of 76 mm in 48 to 72 hours is not in and of itself a high figure. However, relative to February, this is a lot of water. The average rainfall for the second month of the year is 50.0 mm (1.97 in). This means we could welcome more than the average for the month, in a few days.

After this weekend, this February could be the wettest since 2004, ranking among the top 10, on record. Only seven Februarys, on record dating back to 1928, had more than 76 mm (3 in) of rainfall.

GFS model indicating 30-40% chance of more than 25 mm in 24 hours ending 8 am (12 UTC) Saturday, 5 Feb, 2022

If the models prove right, this weekend would easily be the wettest in, at least, 16 weeks and the wettest month in four months. Some parts of the country could see a record wet first week of February. The record for February 1-7, at the Airport, is 54.8 mm (2.16 in), which occurred in 2002. We could also see the 24-hour rainfall accumulation, across some parts of the island, exceed 25.4 mm or one inch, for the first time since 2004 and the fourth time on record.

Notwithstanding the potential for a relatively very wet weekend, this will have minimal impact on the droughts. It will likely have a big impact on domestic catchments but virtually no impact on the island’s catchments.

There is no doubt that these showers would be welcome by all; however, they could prove very disruptive to the ongoing ICC Under-19 Cricket World Cup, which climaxes this weekend, with the final and third-place position. It will likely also be disruptive to other outdoor events.

The system has already caused wet weather across Hispaniola and Puerto Rico with isolated totals of up to 203 mm (8 in). If this amount were to reach us, it would cause absolutely wet conditions and place a dent in the drought, but it is very unlikely that we will get this lucky.

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