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.

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The Most Active Atlantic Hurricane Season in Four Years Likely

4 06 2016

Dale C. S. Destin |

After a hat-trick of quiet Atlantic hurricane seasons, the latest round of forecasts is pointing to the most active season since 2012. However, notwithstanding the projected increase in activity over recent years, the forecast is for the 2016 hurricane season to be near normal.

Ensemble forecast

Our ensemble (mean) forecast calls for 14 named storms with 7 becoming hurricanes and 4 reaching major hurricane status. This represents an increase over the previous forecast for the season of one named storm and one hurricane.

MayJuneHurricaneSeasonForecast

In the tropical cyclone community, the accumulated cyclone energy (ACE) is the indicator used to determine the activity of a hurricane season. The ACE index is a measurement of the strength and duration of a named storm. Summing together the ACE of each named storm, provides a more comprehensive picture of the activity of the season, aside from just the number of storms.

This year, our ensemble forecast calls for an ACE index of 109, which is near normal. If this forecast pans out, the 2016 season would be around 200%, 63% and 73% more active than 2013, 2014 and 2015 respectively.

The ensemble (mean) forecast is based on predictions from Klotzbach of Colorado State University, the U.S. National Oceanic and Atmospheric Administration (NOAA), Saunders and Lea of Tropical Storm Risk.com (TSR), the Integrated Forecast System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF), UK Met Office, the Hurricane Genesis & Outlook (HUGO) Project of Coastal Carolina University and the Institute for Meteorology (INSMET) of Cuba.

Uncertainty

It must be noted though that the skill in forecasting the hurricane season (June to November) in May/June is moderate. However, it is the best available on earth, and it continues to improve.

Apart from the inherent limits to our skill in forecasting the season, this year, there is the huge uncertainty of the eventual strength of La Nina (the coolness of the tropical Pacific Ocean). A strong La Nina could result in a more active season than is forecast, with the converse being true.

Probability of Antigua and Barbuda being hit

According to Klotzbach, the likely best similar years to this hurricane season are 1973, 1978, 1983, 1992 and 2003. Of these years, we were only hit by Tropical Storm Christine of 1973. Thus, based ONLY on similar years, the probability of Antigua being hit this year by one or more named storms is around 18%, while the probability of one or more hurricanes is 0%.

In general, the probability of Antigua being hit by one or more named storms annually appears to vary according to the phase of the Atlantic. During the quiet phase of 1962 to 1994, the probability of one or more named storms was around 26%, while the probability of one or more hurricanes was around 14%. Meanwhile, for the active phase of 1995 to present, which may have come to an end, the probability of one or more named storms increased to around 55%, while the probability of one or more hurricanes is around 35%.

Overall, based on the climatological period of 1981-2010, the probability of being hit by one or more named storms is around 49% (every 2 years on average), while the probability of one or more hurricanes is around 31% (every 3 years on average). Barbuda has similar numbers.

Become hurricane strong

Notwithstanding the forecast, it only takes one hurricane to change your life and community, so the same comprehensive preparations are required every year. Become hurricane strong by taking actions today to become hurricane resilient. This includes:

  • Determining your risk from tropical cyclones;
  • Developing an evacuation plan;
  • Securing an insurance check-up;
  • Assembling disaster supplies;
  • Strengthening your home;
  • Identifying trusted sources of information for a hurricane event and
  • Having your written hurricane plan.

Recall – an ounce of prevention is better than pound of cure!

We will publish an undated ensemble forecast by early August, just before the traditional peak of the hurricane season. This forecast is generally the most skilful; it will have much reduced uncertainty.

2016 Atlantic Tropical Cyclone Names

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