Drought Almost Everywhere

9 03 2019

Dale C. S. Destin |

Red is a beautiful colour but not when it is on a rainfall map. On such a map, red is bad news – it is a warning that something very unwelcome is happening – severe drought.

According to data from the Caribbean Climate Outlook Newsletter, over the past three months – November to January, rainfall deficits have resulted in severe drought across many parts of the Caribbean. This includes, parts or the whole of Barbados, Cuba, Hispaniola, St. Vincent and Trinidad and Tobago.  

Beyond the last three months – longer term drought is seen across Antigua and Barbuda and much of the rest of the northeast Caribbean, the Cayman Islands, parts of the Dominican Republic, northeast Guyana, much of the Windward Islands, Trinidad and Tobago.

El Nino, warmer than usual sea surface temperatures across the eastern tropical Pacific Ocean, is likely to have been the main cause of the deficit in rainfall over the past six months.

Regression analysis shows that El Nino normally causes negative rainfall anomalies – below normal rainfall, cross much of the region, especially across the Eastern Caribbean during September to November (SON) and December to February (DJF).

El Nino and rainfall – It normally results in negative (-) rainfall anomalies or below normal rainfall across the Caribbean during SON. Graphic courtesy U.S. Climate Predicttion Centre.

El Nino and rainfall – It normally results in negative (-) rainfall anomalies across the Eastern Caribbean and positive anomalies across the Western Caribbean during DJF.
Graphic courtesy U.S. Climate Predicttion Centre

The Newsletter indicates that there is just a little bit of distant light at the end of the tunnel for most of the Caribbean with respect to the end of the drought. How distant is this light? Three to six months down the road for the northeast Caribbean, including Antigua and Barbuda, at which time, the forecast is for rainfall to be most likely above normal. However, this light could go dark, if El Nino continues, as is most likely from this vantage point.

Usual rainfall totals for the Caribbean for March to May

The exceptions to the rule are Cuba and Jamaica, which are most likely to have above normal rainfall during the upcoming three months.

Unfortunately, we will continue to see mostly red for the rest of the next three months with a glimmer of hope for friendly, calming colours – blues, thereafter.

Please share this blog, if you found it useful and follow me for all things weather and climate – TwitterFacebook and Instagram.





Continued Below Normal Rainfall; Droughts Loom Large for Antigua

1 03 2019

Dale C. S. Destin |

Rainfall

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.

Keep following me for more on this story and all things weather and climate.








%d bloggers like this: