Temporary Interruption to Dry Weather; Droughts Eased

29 04 2019

Dale C. S. Destin |

Drought Level is Slight

A drier than normal start to the year continues across Antigua; however, there was a temporary interruption – March turned out wet, relatively. The month had 59.6 mm (2.35 in), the most for March since 2013. Most of the rain fell on the 29 March – over 52%, otherwise the story for the month would have been quite different. The rainfall for March was 15% more that usual; notwithstanding, droughts continue, although eased a bit.

The last three-month period – January to March, upon which the assessment of the current intensity of the drought is based, was below normal. The period had 127.5 mm (5.02 in), while the normal amount of rainfall is 176.0 mm (6.93 in).

Rainfall totals for the past 24 months plus normals, anomalies and records

We remain in a severe meteorological drought, the worst category on our drought scale. However, at the moment, the current intensity is slight, down from moderate. Recall that the overall description of the drought is based on the worst intensity achieved during its lifetime; however, over time, the intensity will fluctuate. Severe intensities were observed May-July and June-August of last year.

Potworks Dam, our billion-gallon surface catchment, has fallen below extraction levels – not potable water is currently available from the Dam. Water rationing is imminent but has been delayed by the presence of a number of desal plants operating in the country.  

Potworks Dam as of April 2, 2019 – drying up; picture courtesy Karen Corbin of the Humane Society

The eighteen-month period – October 2017 to March 2019, the duration of the drought thus far, is deemed severely dry. The total for the period of 1170.9 mm (46.10 in) is the fourth lowest on record, for such a period, dating back to 1928. This interval normally gets 1781.3 mm (70.13 in), which means a rainfall deficit of near 34% – close to one-third of the usual rain was absent.

Based on the last set of rainfall forecasts from regional and especially international sources, the news remains discouraging for rainfall. Overall, below normal rainfall is likely for the next six months – May to October 2019. Thus, there is every reason to believe that the droughts will not only continue but reintensify. The chance of the droughts ending is, at the very most, 30% or low.

Probabilistic multi-model ensemble forecast of rainfall for May-July 2019, based on 12 global models – 70 to 80% chance of below normal rainfall for Antigua and Barbuda

Early projections have us with a 60 chance of being drier than normal for the year, with a 45% chance of the rainfall total being in the bottom 20th percentile of all years. Further, around 977 mm (38.5 in) of rain is forecast for 2019, with a 70% chance it falling in the range 699 to 1321 mm (27.5 to 52.0 in).  

On average, our severe meteorological droughts last for around 16 months, but not continuously at severe intensity. At current, the drought is in its 19th month; the longest such drought on record lasted 38 months – Jul 2013 to August 2016.

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Sailing Time Again

27 04 2019

Dale C. S. Destin |

The 2019 Antigua Sailing Week (ASW) is off – it started today and will sail until May 3. Over 90 boats will be seeking to take home the top prize; will the weather cooperate?

I am told that the ideal wind speeds for sailing are winds of 15 to 20 knots. And what is the forecast – 10 to 18 knots. This means that the speeds will be a little less than ideal but not by much. Hence racers in ASW should be generally happy with the wind speeds.

What about the wind direction? This is expected to be east-by-north. And since most of the races will be along the south coast, this is a good direction, as they will either get a tail or head wind, which again is preferred.

Sky and precipitation conditions are not very important for sailing boat racing; however, dry and sunny weather are most desirable and are indeed what are expected, at least until Lay Day – Wednesday. The exception is Sunday when showers are likely; thereafter, showers will be very unlikely.

Sea surface and air temperature will be seasonal – 25 to 28 °C (77 to 82 °F) for the seas and a minimum of around 23 °C during the night and a maximum of around 32 °C (90 °F) during the day. The sea surface temperature is deemed comfortable while the air temperature is on the warm side, but there will be more than enough seawater to take care of the heat.

Of course, sailing week is not just about sailing. For many, it is an excuse to fete at the many after parties. And just like the weather will be conducive for the races, it will also be conducive for the fetes.

Happy and safe sailing and feting!





Drought Continues Almost Everywhere

20 04 2019

Dale C. S. Destin |

We continue to see red almost everywhere across the Caribbean region – indicative of drought, severe in some places. The red has spread from the last blog on the subject, suggestive of the drought spreading, one may say, like a wild-fire.

Dec 2018 – Feb 2019 SPI index, characterising rainfall across the Caribbean. More red seen above than below – the last three months drier than the previous three.

Nov – Dec 2018 SPI index, characterising rainfall across the Caribbean

According to data from the latest Caribbean Climate Outlook Newsletter, over the past three months – December to February, rainfall deficits have resulted in the development or continuation of drought across many parts of the Caribbean. The few exceptions include the Bahamas, the Cayman Islands and the western parts of Cuba.

El Nino, warmer than usual sea surface temperature across the eastern tropical Pacific Ocean, is likely to have been the main cause of the deficit in rainfall over the past three months. Regression analysis shows that El Nino normally causes negative rainfall anomalies – below normal rainfall, across much of the region, especially across the Eastern Caribbean during December to February (DJF).

Rainfall and El Nino – The gray areas indicate the places that receive below normal rainfall during an El Nino during the period December-February.

For much of the region, the Newsletter indicates just a low chance of drought-busting rainfall over the period April-June. Beyond June, there is just a slight chance of drought-busting rainfall over the period July-September. Rainfall will most likely be the scarcest across the Eastern Caribbean.

So, unfortunately, we will continue to see mostly red across the area – it is going to be another tough year for rainfall, with eastern area getting the driest end of the atmosphere.

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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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Dry Weather Continues; Droughts Reintensified

1 04 2019

Dale C. S. Destin |

This image has an empty alt attribute; its file name is slight_to_moderate1.png

Antigua continues to have a drier than normal start to the year. February marks the second consecutive drier than normal month, the third in a row. The rainfall for February was the second driest since 2013 and the 18th driest on record dating back to 1928. Over half of the normal rainfall did not take place; the rainfall total of 27.7 mm (1.09 in) is less than 50% of the average for the month. The near record rainfall of the first half of November 2018, is now a distant memory, the droughts have reintensified to, at least, moderate levels.

Rainfall for the past 24 months for varying time intervals compared to the normal/average and records

The last three-month period – December to February, upon which the assessment of the current intensity of the drought is based, was well below normal. The three-month period had paltry 133.6 mm (5.26 in), while the normal amount of rainfall is 225.8 mm (8.89 in).

We remain in a severe meteorological drought, the worst category on our drought scale. However, at the moment, the current intensity is at moderate, declined from slight. Recall that the overall description of the drought is based on the worst intensity achieved during its lifetime; however, over time, the intensity will fluctuate.

Potworks Dam, our billion-gallon surface catchment, continues to approach critical levels. Water rationing is imminent. This is indicative of the continued drought, which has no end in sight, at the moment.  

The seventeen-month period – October 2017 to February 2019, the duration of the drought thus far, is deemed severely dry. The total for the period of 1111.3 mm (43.75 in) is the third lowest on record, for such a period, dating back to 1928. This interval normally gets 1729.7 mm (68.10 in), which means a rainfall deficit of 36% – more than one-third of the usual rain was absent.

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Apr-Jun 2019, Based on 12 Global Models – 50-60% chance of below normal rainfall for Antigua and Barbuda

Based on the last set of rainfall forecasts from regional and especially international sources, the news remains discouraging for rainfall. Overall, below normal rainfall is likely for the next six months – April to September 2019. Thus, there is every reason to believe that the droughts will further reintensify. The chance of the droughts ending is, at the very most, 30% or low.








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