Early Prediction: Below Normal Rainfall Most Likely for Antigua

21 04 2022

Dale C. S. Destin |

The year will most likely be another drier than usual one for Antigua. My early forecast calls for the rainfall total for 2022 to most likely be 1105 mm (43.50 in) with a 70 percent or high confidence of it being in the range of 811 to 1463 mm (31.93 to 57.60 in).

The main reason for the most likely below normal rainfall forecast is the current cooler than normal sea surface temperatures (SSTs) across the tropical North Atlantic (TNA), which should last, at least, into the second half of the year. Cooler than normal TNA SSTs favour suppressed rainfall conditions while the opposite enhances rainfall.  

The year started out with a severe drought brought forward. This drought started in the winter of 2020/2021 and continues through the present. January 2022 was wetter than January 2021, but it was still only 72 percent of the normal total. The last two months, February and March, have been wetter than normal resulting in the intensity of the meteorological drought easing to slight. This easing is likely to be a brief respite, given the forecast.  

The dry season, January to June, will likely be below normal with a 60 percent chance. The forecast is for 298 mm (11.73 in) with high confidence of it ranging between 182 to 459 mm (7.17 to 18.07 in). This dry season could also be one of the top 10 driest. There is a 33 percent chance of this happening with the possibility of the total falling below 254 mm (10 in). Currently, the total stands at less than 203 mm (8 in) with April running well below normal at less than 25.4 mm (1.0 in) and the forecast indicating a better than 70 percent chance of May-June being drier than normal.

WMO Lead Centre for Long-Range Forecast Multi-Model Ensemble is forecasting 70-80% likelihood of below normal rainfall for Antigua and Barbuda for May to July. Also, below normal rainfall is likely for much of the rest of the Eastern Caribbean.

A typical year, based on the new standard climate period 1991-2020, averages 1156.7 mm (45.54 in). The dry season averages 410 mm (16.14 in) and the wet season, July to December, averages 746.8 mm (29.40 in). The fall/autumn, September-November, accounts for 58 percent of the wet season total and 38 percent of the year’s total.

Rainfall-wise, last year–2021, will be most remembered for being the second driest on record with some parts of the country having record-breaking dry weather. There were likely significant socio-economic impacts but unfortunately, this has not been quantified.

This forecast will be updated monthly around the 21st of each month until August. The first update will be issued around May 21.

Regardless of the forecast, we all need to conserve water and be as efficient with its use as much as possible. Reducing our personal water footprint will literally redound to our individual and collective socio-economic benefit. Minimising your water footprint is also good for the climate and good for our environment.

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





June to November 2016 Climate Outlooks for Antigua and Barbuda

9 06 2016

Dale C. S. Destin |

The June to November 2016 (summer and autumn) climate outlooks are now available for Antigua and Barbuda. We are optimistic that some droughts will come to an end over this period. Meanwhile, uncomfortably warm temperatures are expected for the upcoming six months. June to November is also the Atlantic hurricane season; it is likely to be the most active since 2012.

Drought

May 2016 was wetter than last year’s; however, it was still a relatively dry May – the second driest in nine years. Hence, the droughts (meteorological, agricultural, hydrological and socioeconomic) continue across Antigua and Barbuda. We are now entering the 36th month of mostly moderate or worse rainfall deficits.

Looking forward – some droughts are likely to ease. At worst, slight meteorological and agricultural droughts will exist at the end of the March-August and December 2015-November 2016 periods. Meanwhile, a moderate drought or worse is possible at the end of the January-September 2016 period.

ProjectedRainfall_Mar-Aug2016

The warm phase of El Nino Southern Oscillation (ENSO) – El Nino, is expected to end in weeks and a transition to the cold phase of ENSO – La Nina, is expected during our wet season – July to December. This is good news for us in that La Nina, unlike El Nino, generally encourages rainfall across our area, mainly during the wet season. This is one of the main reasons why we are optimistic about the possibility of drought ending rainfall over the next six months, if not sooner.

However, there is some caution with our optimism as La Nina is not guaranteed nor are its normal positive impacts on our rainfall. Further, the strength of the La Nina is highly uncertain. A strong La Nina favours more rainfall, whereas a weak one favours less.

Precipitation and temperature

Over the coming three months – June to August (JJA), above to near normal rainfall is expected. This could result in the meteorological and agricultural droughts coming to an end or at worse be at slight levels at the end of the period. Unfortunately, these rains are unlikely to end the more serious hydrological and socioeconomic droughts; these will likely continue at moderate or worse levels.

September to November (SON) is also expected to have above to near normal rainfall. SON is on average our wettest “season”, accounting for nearly 40% of our yearly rainfall. Thus, if this forecast pans out, all droughts would be significantly eased, if not end. This is especially true if the JJA forecast holds true also.

So far, 2016 is about 70% wetter that last year, but it’s still much drier than normal. It is now almost certain that the dry season (January-June) will be drier than usual for the third consecutive year.

The summer heat is likely to be on, as warmer than usual temperatures are forecast for June to August. With high confidence of warmer than usual weather, there is also the potential for extreme temperatures. The heat could be very distressing for many especially since night-time temperatures are likely to be higher than usual. This has negative implications for health especially among older adults, infants and young children.

The hurricane season

Relative to the last three years, we are likely to have the most active Atlantic hurricane season since 2012. Notwithstanding, the forecast is for the season to fall in the near normal range with around 14 named storms, 7 becoming hurricanes and 4 major hurricanes.

MayJuneHurricaneSeasonForecast

Like our wet season, the great determinant of the hurricane season is ENSO. El Nino tends to suppress tropical cyclone (depression, tropical storm, hurricane) activity, while its sister-phenomenon – La Nina, does the opposite. Hence, the eventual activity of the season is largely dependent on the strength of La Nina which is quite uncertain, at this time. Stronger La Ninas tend to favour more active seasons than weaker ones.

For Antigua and Barbuda, the probability of a named storm (tropical storm or hurricane) affecting the islands during an active season is quite high (around 74%) and much higher than during a normal or quiet season, with around 59% and 26% probabilities respectively. Meanwhile, the probability of us being affected by a hurricane during an active season is around 49% as opposed to 18% in a normal one and 10% in a quiet one.

Irrespective the kind of Atlantic hurricane season that occurs, we need to be fully prepared, as it only takes one hurricane to set our life and community back by decades. Prepare for the worst and hope for the best!

See the following links for the full outlooks and more: JuneJune-August, September-NovemberJune-November 2016Drought, 2016 Hurricane Season Forecast.

The next set of outlooks will be available by July 3, 2016.





April to September 2016 Climate Outlooks for Antigua

1 04 2016

Dale C. S. Destin |

The latest climate outlooks are now available for Antigua. Unhappily, the news remains bleak. Below normal rainfall and above normal temperature are expected/likely for the upcoming six months – April-September 2016.

Drought

Antigua remains in drought, which has been ongoing for a record 33 months, based on record dating back to 1928.

Currently, a moderate drought or worse is evolving over the periods – January to June 2016, November 2015 to July 2016 and October 2015 to September 2016. All three periods are likely to see below normal rainfall. Drought warnings remain in place and will likely continue through the third quarter of the year.

https://268weather.files.wordpress.com/2016/04/jan-junrainfall2.png

The best rainfall forecast for Jan-Jun is around 271.8 mm (10.7 in); however, there is a 70% chance of it ranging between 152.7-443.6 mm  (6.0 to 17.5 in)

It is expected that El Nino will transition to a neutral state around the middle of the year and possibly to La Nina in the last third. La Nina, unlike El Nino, generally encourages rainfall across our area mainly during the wet season. Thus, there is light at the end of the tunnel but, at the moment, it’s a bit distant.

Precipitation and Temperature

Over the upcoming three months – April to June, near normal rainfall could ease the drought; however, an end to it is not anticipated.

Meanwhile, July to September is expected to see below normal rainfall. Thus, even if the drought eases during April to June, the following three months will see it reintensifying.

In the short-term, there are hopes of this dry season (January-June) being wetter than last year’s; however, it is likely to be drier than usual when compared to 1981-2010 average.

All forecast timescales (April, April-June, July-September, April-September) are likely/expected to have warmer than normal temperatures.

See the following links for the outlooks: April 2016, April-June 2016, July-September 2016, April-September 2016, Drought.

The next set of outlooks will be available by May 3, 2016.








%d bloggers like this: