Record Breaking Dry Year for Antigua

28 01 2016

Dale C. S. Destin |

2015 will go down in meteorological history as the driest year on record for Antigua in nearly 150 years. The island-average rainfall was a paltry 574.5 mm (22.62 in), the lowest in a series from, at least, 1871. 2015 has shattered the previous record driest year – 1983 – by some distance, when we had 681.5 mm (26.83 in).

RainfallAccu

Never before on record has a year’s rainfall deficit or the rain that did not fall (rain-not-fall) was greater than the rain that did fall (rainfall). So the rain-not-fall, 628.6 mm(24.75 in), was greater than the rainfall – 574.5 mm. Of course, the rainfall deficit is the difference between what we got and what we usually get.

Avgvs2015Rain

Looking at the deficit another way, the rain-not-fall is roughly equivalent to the rainfall we would normally get from the first seven months of a year.

Such a dry year, as 2015, is extremely rare. It happens only once every 500 years on average. That translates to a 0.2% chance of a given year getting so little rainfall. It is quite possible that the last time it was this dry Christopher Columbus was still sailing the Caribbean.

If we were still in the pre-desalination-era, it would not be a stretch to say that the Antigua and Barbuda’s economy would have collapsed due to lack of sufficient potable water. As has been the case for months now, over 90% of potable water is coming from the ocean via desalination.

Interestingly, no month had record low rainfall. So, the record low rainfall for 2015 came about due to persistent low rainfall throughout most of the year. Five of the 12 months not only had below normal, but well below normal rainfall. Further, all months had below normal rainfall except September and November, which had near normal rainfall.

MonthlyRain

Most areas of the country had record or near record low number of wet days – WDs – (days with at least one mm) for the year. At the V. C. Bird International Airport (VCBIA), there were 97 WDs, the third lowest behind 2001 with 94 and 1983 with 93. However, the total rainfall from WDs of 495.8 mm (19.52 in) was at a record low for 2015. Normally, WDs yield around 1019.3 mm (40.13 in).

Heavy rainfall days – HRDs –  (days with at least 10 mm) was also at record low numbers at many places during 2015. At the VCBIA, they were at a record low total of 12, tying 1983 and 1973. Normally, there are 26 HRDs annually. Meanwhile, the rainfall total from HRDs of 217.1 mm (8.55 in) was the second lowest behind 207.4 (8.16 in) measured in 1983. Usually, it’s around 665.5 mm (26.20 in).

The dismal rainfall for the year was due largely to two factors. Firstly, dry and dusty air from the Sahara Desert which hampered rainfall mainly during the first half of the year. Secondly, a record strong El Nino, which suppressed rainfall mainly over the latter half of 2015.

Follow us on twitterfacebookinstagramtumblrflickrgoogle+, and youtube as we provide you with further analyses of the historic rainfall year for Antigua. We will also provide you with observed and forecast rainfall totals for 2016, as we keep close eyes on our climate.

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4 responses

9 02 2016
Frank Goodwill

Has there been a greater prevalence of the Saharan Air Layer (SAL) over the Caribbean during 2015? I understand that the dry air/dust reduces the amount of moisture in the air and therefore reduces rainfall.

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10 02 2016
Dale C. S. Destin - Antigua Met Service

It’s up there as one of the dustiest on record; I will look into where on record it actually ranks. It does a number of things, which makes it difficult to rain, including the reduction of moisture.

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14 02 2016
Frank Goodwill

It has been looking pretty ‘dusty’ over the last week or so as well. It would be interesting to see how 2015 measured up regarding SAL.

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14 02 2016
Dale C. S. Destin - Antigua Met Service

Yes, it has been.

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