Drier Than Normal December; Drought to Reintensify

30 01 2019

Dale C. S. Destin |

DCurrentDroughtIntensityecember was drier than normal for Antigua. The rainfall total of 65.8 mm (2.59 in) was below normal – 65% of the average for the month. This was the driest December since 2015. The month had very little positive impact on the droughts; hence, they will likely reintensify in the upcoming months.

The last three-month period – October to December, upon which the assessment of the current intensity of the drought is based, was slight dry. However, the rainfall total fell in the near normal category. The three-month period had 329.2 mm (12.96 in), while the normal amount of rainfall is 413.5 mm (16.28 in).

Rainfall for the past 24 months

Rainfall for the past 24 months for varying time intervals compared to the normal/average 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, for the second month in a row. Recall that the overall description of the drought is based on the worst intensity achieve during its lifetime; however, over time, the intensity will fluctuate.

Potworks Dam, our billion-gallon surface catchment, is again returning to critically low levels. The Authorities will be cutting back on extraction from the Dam and water rationing is imminent, if not already started. This is indicative of the continued drought; notwithstanding the ample rainfall of November.

The fifteen-month period – October 2017 to December 2018, the duration of the drought thus far, is deemed severely dry. The total for the last 15 months of 1043.4 mm (41.08 in) is the second lowest since 1969 and the fourth lowest on record, for such a period, dating back to 1928. This particular interval normally gets 1615.7 mm (63.61 in), which means a rainfall deficit of 35% – more than one-third of the usual rain was absent.

Based on the last set of rainfall forecasts from regional and especially international sources, the news is discouraging with respect to rainfall. Overall, below normal rainfall is likely for the next six months – February to July 2019, with moderate confidence that the period February to April – 2019 having well below normal rainfall. Thus, there is every reason to believe that the droughts will reintensify. The chance of the droughts ending is, at most 20% or slight.

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Jan-Mar 2019, based on 12 global model

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Jan-Mar 2019, based on 12 global models

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

Last year – 2018, was the eighth driest on record, dating back to 1928. It was also the second driest since 1983; only 2015 has been drier since 1983 – 35 years ago.

accumulation_december2018

It is too early to say with any confidence whether the rainfall for 2019 will be below, near or above normal. However, early indicators suggest it could be another tough drought year for Antigua and Barbuda.

Keep following me for more on this story and all things weather and climate.


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