Continued Below Normal Rainfall; Droughts Loom Large for Antigua

1 03 2019

Dale C. S. Destin |


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

Antigua has had a drier than normal start to the year and the second consecutive drier than normal month. The rainfall for January was the driest since 2015 and the 14th driest on record dating back to 1928. Nearly half of the normal rainfall did not take place; the rainfall total of 40.4 mm (1.59 in) is only 59% of the average for the month. The near record rainfall of the first half of November 2018, is becoming a distant memory and the reintensification of the droughts looms large.

CurrentDroughtIntensityThe last three-month period – November to January, upon which the assessment of the current intensity of the drought is based, was slightly dry. However, the rainfall total fell in the near normal category. The three-month period had 310.1 mm (12.21 in), while the normal amount of rainfall is 422.7 mm (16.64 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, for the third month in a row. 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, is relatively close to falling below extraction levels. Water rationing is imminent or already occurring. This is indicative of the continued drought, which has no end in sight, at the moment.

The sixteen-month period – October 2017 to January 2019, the duration of the drought thus far, is deemed severely dry. The total for the period of 1083.8 mm (42.67 in) is the third lowest on record, for such a period, dating back to 1928. This interval normally gets 1673.9 mm (65.90 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 remains discouraging for rainfall. Overall, below normal rainfall is most likely for the next three months – March to May 2019. Beyond this period, there is notable uncertainty; however, the ECMWF IFS model, one of the more reliable models is forecasting continued drier than normal conditions being most likely for June to August 2019. Thus, there is every reason to believe that the droughts will reintensify. The chance of the droughts ending is, at most 25% or low.

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Mar-May 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 17th month; the longest such drought on record lasted 38 months – July 2013 to August 2016.

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