Wetter Than Normal November Eases Drought to Slight

31 12 2018

Dale C. S. Destin |

DroughtMeterNovember’s rainfall was higher than usual – 135% of the average for the month. The total of 204 mm (8.03 in) makes this November the 21 wettest on record. The very welcome rainfall has ease the meteorological drought to slight levels and have also eased or eliminated other droughts.

Over 95% of the rainfall for November fell during the first 15 days of the month, making it the second wettest such period on record. The rainfall was caused by a cold front and a series of troughs.

The last three-month period – September to November, upon which the assessment of the current intensity of the drought is based, was slight dry. Notwithstanding a wetter than normal November, the last three months, as a time interval, had below normal rainfall with 370.6 mm (14.59 in) recorded. This is the lowest since 2015 and the second lowest since 2009.

RainfallAccuForPast24Months

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

We remain in a severe meteorological drought, the worst category on our drought scale. However, at the moment, the current intensity is slight. 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. Last month the intensity was at serious levels.

Potworks Dam, with a billion-gallon capacity, has moved from near totally dry to being one-third full, two-third empty – depending on your perspective. The water levels have gone above extraction height and I am advised that the same is true for the other smaller catchments.

Potworks Dams Nov13_2018_KarenCarbin

Potworks Dam – Nov 13, 2018. Complements Karen Corbin of the Humane Society

Potable water has become more readily available and water rationing has apparently cease, for now. This is indicative of huge dent November’s rainfall made on the droughts.

The fourteen-month period – October 2017 to November 2018, the duration of the drought thus far, is deemed severely dry. The total for the last 14 months of 977.6 mm (38.49 in) is the second lowest since 2001 – only the similar period October 2014 to November 2015 was drier. October of one year to November of the next normally gets 1514.6 mm (59.63 in), which means that there is a large rainfall deficit of around 35% – more than one-third of the usual rain did not fall.

Based on the last set of rainfall forecasts from regional and especially international sources, the news is discouraging with respect to rainfall. Overall, below normal rainfall is most likely for the next six months – January to June 2019, with relatively high confidence that the period January to March 2019 will be drier than normal – possibly well below normal. Thus, there is every reason to believe that the droughts will continue and likely reintensify. The chance of the droughts ending is, at most 30% or low.

MultimodelEnsembleRainfall_JFM_2019

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Jan-Mar 2019, based on 12 global model

On average, our severe meteorological droughts last for around 16 months, but not continuously at severe intensity. At current, the drought is in its 15th month; the longest such drought on record lasted 38 months – Jul 2013 to August 2016.

I now expected 2018 to be among the top 10 direst years on record with the island-average total less than 900 mm or less than 35 inches. We normally get 1206.5 mm or 47.5 inches.

AccumulationJan_Dec2018

Keep following me for more on this developing story and all things weather and climate. If you find this article useful, please share it with your family and friends. I am also available to follow on TwitterFacebook and Instagram.

All the best for 2019!


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2 responses

31 12 2018
Julius Ross

New Year’s greetings Dale. Great stuff maybe an analysis of the wider implications for the agriculture community can make it even more beneficial to stakeholders. Julius. 

Sent from Yahoo Mail on Android

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31 12 2018
Dale C. S. Destin - 268Weather

Thanks, greetings to you also. I know of the theoretical implications; however, what is lacking are the ground truth implications that hopefully the ministry can share.

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