Droughts Remain Slight, Despite Scarce April Showers

31 05 2019

Dale C. S. Destin |

Less than normal April showers fell across Antigua this year. The observed total rainfall of 42.2 mm (1.66 in), makes this April the second driest since 2006. Only 49 percent of the usual April showers fell, the rest added to our rainfall deficit; hence, droughts continue.

The last three-month period – February to April, upon which the assessment of the current intensity of the drought is based, was below normal. The period had 129.5 mm (5.10 in), while the normal amount of rainfall is 193.0 mm (7.60 in).

We remain in a severe meteorological drought, the worst category on our drought scale. However, at the moment, the current intensity remains at 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. Severe intensities were observed May-July and June-August of last year.

Potworks Dam as of May 1, 2019 – drying up; picture courtesy Karen Corbin of the Humane Society

Potworks Dam, our billion-gallon surface catchment, has fallen below extraction levels – no 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.

The nineteen-month period – October 2017 to April 2019, the duration of the drought thus far, is deemed severely dry. The total for the period of 1213.1 mm (47.76 in) is the third lowest on record, for such a period, dating back to 1928. This interval normally gets 1866.9 mm (73.5 in), which means a rainfall deficit of near 35% – over 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 – June to November 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 June-August 2019, based on 12 global models – 70 to 80% chance of below normal rainfall for Antigua and Barbuda

Early projections have us with a 65 percent chance of being drier than normal for the year, with a 50% chance of the rainfall total being in the bottom 20th percentile of all years. Further, around 929 mm (36.6 in) of rain is forecast for 2019, with a 70% chance it falling in the range 664 to 1264 mm (26.1 to 49.8 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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