Drought Continues

25 05 2021

Dale C. S. Destin |

With continued below normal rainfall through April, the meteorological drought continues for Antigua; however, it has eased to slight intensity as compared to serious at the end of March. Notwithstanding, we remain in a serious drought with significant cumulative rainfall deficits that are likely to have socio-economic impacts. Models continue to portray a dry scene for the upcoming months.

WMO Lead Centre for Long-Range Forecast Multi-Model Ensemble is forecasting 60-70% likelihood of below normal rainfall for Antigua and Barbuda. Also, below normal rainfall is likely for much of the Caribbean Basin.

We continue to witness the driest start to a year since 2015 and the eighth driest quadrimester for Antigua in a series that dates to 1928. The island-average rainfall of 131.8 mm (5.19 in) represents only 55 percent of the normal total for January to April; hence, 45 percent of the regular stream of water from the heaven was missed and is evident by our thirsty brownish landscape. Further, from the flooding rainfall in November to the end of April (December-April), only 64 percent of the normal rainfall has fallen. This is the 10th lowest on record.

The background is a picture of Potworks Dam, Antigua taken May 3, 2021 by Karen Corbin of the Humane Society.

The rainfall for this April of 38.9 mm (1.53 in) is more than twice the amount fell last April; however, it is the second lowest since 2006. The total was only 51 percent of the usual amount for mid-spring; hence, an unmissable deficit of 49 percent.

There is no discernible respite in the near future. The majority of models are forecasting deficit rainfall to be the order of, at least, the next three months. Thus, the drought is likely to continue. Our catchments could again revert to mud patches and or grasslands, which has virtually become an annual phenomenon.

Based on models which correlate our sea surface temperatures, across the tropics, with our rainfall, the medium and long term look brown. There is a 78 percent chance of the dry season, January to June, will suffer below normal rainfall. Further, there is a 52 percent chance of the dry season rainfall being in the bottom 10 percentile i.e. less than 10 inches, when the average is 16.14 inches. For the year, the forecast is for a 46 percent chance of it being drier than usual, with a non-trivial probability of 19 percent of well below usual, possibly with about a 24 percent deficit in the annual total.

Rainfall projection for Antigua in inches. A for chance of above normal; N for near normal and B for below normal. The background is a picture of Potworks Dam taken May 3, 2021 by Karen Corbin of the Humane Society.
Rainfall projection for Antigua in inches. A for chance of above normal; N for near normal and B for below normal. The background is a picture of Potworks Dam taken May 3, 2021 by Karen Corbin of the Humane Society.

Other droughts generally lag meteorological droughts; it is evident from our catchments that agricultural, hydrological and ecological droughts, to some degree, are also occurring or imminent. There is also the concern that this may precipitate a socio-economic drought. Our utilisation of the ocean around us for fresh water has made us resilient; however, there are still likely to be notable impacts, when the other droughts get underway in earnest.

Image from the Landsat satellite showing the contrasting green landscape of December 9, 2020, one month after the deluge of November 9-10, 2020, compared to the brown drought-ridden landscape of May 2, 2021

Potworks Dam is down to around a quarter. With the rainfall outlook bleak, we could virtually be out of surface water soon. Water rationing is imminent, if not already occurring.

Antigua continues not alone in experiencing significant rainfall shortages. Much of the Eastern Caribbean is having a similar thirst for rainfall, especially for December 2020 to April 2021. Short and long-term droughts continue to evolve across many places, and it is probable that the shortfall in precipitation will worsen and or spread to other islands, particularly the eastern ones, over the upcoming months, based on recent forecasts.

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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!

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