Very Dry Start to 2021

16 02 2021

Dale C. S. Destin |

Antiguans have just witnessed the driest start to the year in over a generation. January 2021 was the driest January since 1977 for Antigua, with an island average of 27.4 mm (1.08 in).

Usually January yields 67.3 mm (2.65 in) of rain; however, this time, the total was down by 59%. This puts the rainfall for the month in the well below normal category – the bottom 10 percentile of the most recent climate period – 1991 to 2020.

Such low rainfall is rare for January. How rare? Once in every 27 years, on average, which translates to a 3.7 percent chance of such a low total annually. Usually, there is over a 96 percent chance of the month producing more rainfall.

From a historical standpoint, this is the third driest January on record dating back to 1928. Only January 1977 and 1931 have been drier. January 1931 is the driest on record with 16.3 mm (0.64 in) and January 2006 is the wettest with 2017.7 mm (8.57 in).

Despite the trickle of rainfall for January 2021, the rainfall for the month is usually the most reliable of all months with the lowest variability index of 0.83 or moderate, for the climate period 1991-2020. All other months have a variability index of 1 to 2.37 or moderate to extreme. The variability is obtained by dividing the difference in rainfall of the 90th percentile and the 10th percentile by the median.

Notwithstanding the drier than normal January 2021, the rainfall for January remains without any significant (statistical) trend. The mean rainfall over the past seven climates has not changed significantly, ranging between 65.8 to 79.5 mm (2.59 to 3.13 in), over the period 1928 to 2020.

As we look forward, the rainfall for February is lagging average by about 38 percent, and even if the averaged is reached, there is the high likelihood for rainfall to drop to drought levels by the end of February. About another 35 mm (1.38 in) of rain is needed to stave off drought. This or more rainfall for February 17-28 has only occurred 10 times in the last 55 years – 18 percent of the time.

January is unlikely to be this dry again under the next 27 years. By then, we will be at the middle of the 21st Century – millennials would have reach senior citizen age.

Please continue to follow me for more on what looks likely to be the start of a drought and all things weather and climate via TwitterFacebook and Instagram. Also, share this blog, if you found it useful. 



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