4th Consecutive Drier Than Normal October for Antigua, Droughts Remain Serious

12 11 2018

Dale C. S. Destin |

The rainfall for October was below normal, for the fourth time in a row and the seventh time since 2009. The total of 59.4 mm (2.34 in) makes this October the second driest since 2001. Never have the rains failed for four consecutive Octobers. Long-term droughts continue at serious intensity, up to the end of October.

Oct2018

The total rainfall for the month – 59.4 mm was paltry 37% of the normally for October – 161.0 mm (6.34 in). Over 60% of the normal rainfall did not occur, for the third consecutive October and for the fourth consecutive October over 40% did not fall.

The last three-month period – August to October, upon which the assessment of the current intensity of the drought is based, was seriously dry. In the last three months, only 269.5 mm (10.61in) of rain fell. This is the 10th driest such period on record dating back to 1928. Only one other October (2015) has been drier since 1993.

Cumulatively, August, September and October normally yield 419.1 mm (16.5 in) of rain; however, a huge 36% 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 virtually been no change from last month – September. 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, with a billion-gallon capacity, has gotten some water but the water levels remain below extraction level, up to the end of October, 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.

Accumulation_Oct2018

The thirteen-month period – October 2017 to October 2018, the duration of the drought thus far, is deemed severely dry. The total for the last thirteen months of 773.7 mm (30.46 in) is the second lowest on record; only the similar period October 2000 to October 2001 was drier. The period normally gets 1363.2 mm (53.67 in), which means that there is a huge rainfall deficit for the period of 43%.

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, 

The month of November has been very wet, thus far. With 125 to 255 mm (5 to 10 in) already fallen across Antigua and Barbuda, the drought has eased to moderate levels or better. With further rains to come, the drought could come to a sudden end by the end of the month.

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


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