Near Normal Rainfall for September for Antigua, Droughts Eased Slightly

29 10 2018

Dale C. S. Destin |

SevereToSeriousThe rainfall for September was near normal for the second month in a row. The total of 107.2 mm (4.22 in) makes September the wettest month for the year, thus far; however, no month has yet had more than near normal. Notwithstanding, the consecutive months of near normal rainfall has led to the droughts easing slightly.

The total rainfall for the month – 107.2 mm was 74% of what normally falls – 144.0 mm (5.67 in). This was not very helpful, given the severe rainfall deficit we are experiencing.

The last three-month period – July to September, upon which the assessment of the current intensity of the drought is based, was seriously dry. In the last three months, only 249.7 mm (9.83 in) of rain fell. This is the 12th driest such period on record dating back to 1928.


Cumulatively, July, August and September normally yield 358.1 mm (14.1 in) of rain; however, a huge 30% of it did not fall. This means that we remain in a severe meteorological drought, the worst category on our drought scale.

So, overall, we remain in a severe drought that is currently at serious intensity. There has been a slight ease from last month – but nothing to shout about.  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, Sep 29, 2018. Courtesy Veronica Yearwood - APUA

Potworks Dam, Sep 29, 2018. Courtesy Veronica Yearwood – APUA

Potworks Dam, with a billion-gallon capacity, has been totally dry for a few months now; however, it got in some water toward the end of August. Notwithstanding, the water levels remains well below extraction level and I am advised that the same is true for the other smaller catchments. These are indicative of the fact that the droughts are at very impactful levels.

The full brunt of the droughts continues to be masked by the presence of the desalination plants, which are virtually still the only source for potable water in the country. Notwithstanding, many impacts are starting to break through. Potable water is still being rationed; places have been left without water for days to weeks, at a time, especially when the sea is stirred up by swells, which negatively impacts the desalination process.

The twelve-month period – October 2017 to September 2018, the duration of the drought thus far, is deemed severely dry. The total for the last eleven months of 714.2 mm (28.12 in) is the third lowest on record and the lowest since 2001. The period normally gets 1202.2 mm (47.33 in) – a little less than twice the amount that fell.


Based on the last set of rainfall forecasts from regional and especially international sources, the news remains discouraging. Overall, below normal rainfall is likely for the next six months – November 2018 to April 2019. Thus, there is every reason to believe that the droughts will continue and likely worsen. The chance of the droughts ending is, at most 30% or low.

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Nov 2018 - Jan 2019

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Nov 2018 – Jan 2019

On average, our severe meteorological droughts last for around 16 months, but not continuously at severe intensity. Will this one go for another four months? Very likely, given the climate signals.

I now expected 2018 to be a drier than normal year with a confidence level of 80%. The best forecast for the amount of rainfall for the year is 845 mm (33.3 in) with a 70% chance of the amount ranging between 623 mm (24.5 in) and 1118 mm (44.0 in). Normally, we get 1206.5 mm (47.5 in) annually,

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