September 2016 to February 2017 Climate Outlooks for Antigua and Barbuda

29 09 2016

Dale C. S. Destin |

The September 2016 to February 2017 climate outlooks are now available for Antigua and Barbuda. Over the long-term (September-February), above to near normal rainfall is expected. However, in the short-term – September to November (SON), below to near normal rainfall is expected. The droughts are more likely than not to remain as is or end over the short-term. Meanwhile, uncomfortably warm temperatures are expected for the upcoming six months, especially during the short-term.

Drought

August 2016 is the wettest since 2011 and the wettest of any month since November 2014. It was a wetter than normal August with an island-average of 130.3 mm (5.13 in). Notwithstanding, it was not wet enough to end the droughts, which have gone past 38 months.

Looking forward – there is a moderate chance (55%) of the droughts either not getting worse or ending during the period SON. Conversely, there is also a moderate chance of the SON period having below normal rainfall. Notwithstanding, over the long run, above to near normal rainfall is expected. Thus, drought watches are in effect instead of warnings.

jun-nov2016_rainfall

The warm phase of El Nino Southern Oscillation (ENSO) – El Nino, came to an end in May. At which time, the chance of a cold phase i.e. La Nina was in excess of 75%. However, as of this month, the probability of La Nina is at 55% and declining.

If you are in our part of the world – the Caribbean, a La Nina would be more than welcome. Unlike El Nino, La Nina often brings us more than usual rainfall. Hence, given our severe water crisis of the past three years, to not have a La Nina as “promised” would be a great disappointment.

The rains over the past weeks have put a huge dent into the droughts. We are experiencing one of our wettest, if not wettest September in over 20 years. There is optimism that a few of the droughts have ended. More will be said on this, after a full assessment, by the middle of October.

Precipitation and temperature

Year-to-date, Antigua, on average, has had more than twice the amount of rainfall than for the same period last year. Notwithstanding, we are still over three inches in the “red” relative to the long-term average for January-August of 647.7 mm (25.50 in).

This up-tick in rainfall has a reasonable chance of continuing over the long-term: September 2016 to February 2017, there is an 80% probability of above to near normal rainfall. However, the projected rainfall for 2016 is 657 to 1218.5 mm (25.9-48.0 in) or below to near normal.

For the seasons SON (autumn) and DJF (winter), there are equal chances of below, near or above normal mean temperatures. However, over the long-term, mean temperatures are likely to be above normal. Higher than usual night-time low temperatures are likely to continue through November, resulting in continued uncomfortable warmer nights.

The hurricane season

We are passed the peak days of the hurricane season for us and for the season overall. However, we are still very much in the most active period of the hurricane season – August to October. Thus far, the 2016 Atlantic hurricane season has produced, 12 named storms, four hurricanes and one major hurricane.

The 12 named storms are 50% more than the average of 8 to date [September 25]. However, the accumulated energy (ACE) index which matters most, is less than 50% of the average of 106. The relatively low ACE is indicative of the fact that the storms have been generally weak.

The forecast is for a near normal season with around 15 named storms, 7 becoming hurricanes and 3 major hurricanes; this includes those already formed.

Notwithstanding the forecast, we need to be fully prepared, as it only takes one hurricane to set our life and community back by decades. Be prudent: prepare for the worst and hope for the best!

See the following links for the full outlooks: September 2016, September-November 2016, December 2016-February 2017September 2016-February 2017Drought, 2016 Updated Hurricane Season Forecast.

The next set of outlooks will be available by October 5, 2016.





Antigua and Barbuda Battered by Torrential Rains

16 09 2016

Last week Monday, Antigua and Barbuda was battered by torrential rains from a tropical disturbance. This resulted in major flooding in many parts of the country, especially in low-lying and flood-prone areas. We had not seen such downpours in nearly a decade.

Satellte loop of the tropical disturbance

Satellite loop of the tropical disturbance

Many parts of Antigua got more than the average total rainfall for September in less than 24 hours. On average, Antigua got around 139.7 mm (5.5 in) in less than 24 hours, with many areas getting over 180 mm (over 7 in), which is much more than the island-average of 144.0 mm (5.67 in) for September.

RadarRainfallAccumulation-24hrs ending 2amSep62016

Radar rainfall accumulations for the 24 hrs ending 2 a.m. Sep 6, 2016

With the average rainfall total of 139.7 falling on 108 square miles (the size of Antigua), it means that about 8.6 billion imperial gallons (IG) of water fell on Antigua between 2 am, September 5 and 2 am September 6. As a reference, this amount of water could serve the country for three years. It’s also close to 100 times the 90 million IG collected by Potworks Dam.

Clearly, with all this water, it should come as no surprise the we had areas with major flooding. Notwithstanding the negative impacts of the flooding, it was rainfall to make most Antiguans and Barbudans, particularly water resources managers and farmers, smile from ear to ear. It resulted in significant recharging of catchments, many of which were dry or below extraction levels since early last year.

Potworks Dam: left – Aug 24, 2016, right – Sep 6, 2016

Potworks Dam, which was dry for over a year, was filled to around one-eighth, according to the Antigua Public Utilities Authority – APUA (the water authority) . It collected around 90 million IG of water, enough to augment water supplies for the next three to four months. APUA has since indicated an easing of water rationing, at least, for the short-term.

Monday September 5, 2016 was the wettest day for quite a while for many areas of Antigua. At the Airport it was the wettest day since Hurricane Earl’s unwelcome visit in 2010. It was also one of the wettest days since Hurricane Lenny in 1999. Only three other days have been wetter since Lenny – the “father” of all flooding for Antigua.

Although this type of rainfall has been rare for the past 15 years, it does occur fairly frequently at a rate of around once every four to five years, based on rainfall measured at the V. C. Bird International Airport – the home of the Antigua and Barbuda Meteorological Service. In other words, it has about a 20-25% chance of happening each year.

The rains caused major flooding of low-lying and flood-prone areas. This resulted in an unknown number of cars being stalled in flood waters and a number of homes came very close to being flooded. There were minor rock slides reported but damage, if any, is unknown. In the wake of the event, many roads were damage due to erosion.

Flooded road

Flooded road

Flooded road

Flooded yard

The event proved very challenging to forecast. Several days before the event, most models forecast up to five inches of rainfall to occur. However, as we got closer to September 5, the models shifted the rainfall to the south of Antigua. Up to the morning of the event, none of the models surveyed came remotely close to forecast the rainfall that eventually occurred.  

Can we get a repeat of last week Monday?  It is probable but highly unlikely. The chance of getting two such days in a given year is around seven percent. So whereas getting dowsed by such drenching rainfall is not unusual, especially at this time of the year, it is highly unusual for it to happen twice in a year.

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Potential Hurricane Scare Early Next Week

30 08 2016

Dale C.S. Destin |

A weather disturbance coming off West Africa will likely cause a scare to residents of the northeast Caribbean early next week. Two of the more reliable weather models are forecasting this disturbance to become tropical storm or hurricane later this week and track in the direction of the islands.

Tropical Disturbance Moving Off the West Coast of Africa - Aug 29, 2016

Tropical Disturbance Moving Off the West Coast of Africa – Aug 29, 2016

The preliminary forecast track has it moving on a westerly path, in line with the Leeward Islands, which includes Antigua and Barbuda. However, just before reaching the islands, it’s forecast to turn right or north away from the islands, which should spare us its wrath.

ECMWF IFS

ECMWF Integrated Forecast System Showing at least an 80% Chance of a Tropical Cyclone Near the Northeast Caribbean Between Sep 4 and 6

Twenty-one years ago from September 5, 2016, Antigua and Barbuda experienced one of the most powerful hurricanes in its history – Category 4 Hurricane Luis. It brought death and major destruction to the islands. It left in its wake three dead and around US$350 million dollars in damage. It is easily our costliest hurricane in history.

The system that could cause us some stress is not being forecast to be a Luis, God forbid! However, its potential path and timing are reminiscent of Luis. It could be nearest us around September 5, just that this time, it should turn away sooner than Luis did and spare us this time.

The hurricane season runs until November 30. The forecast calls for 15 named storms, 7 hurricanes and 3 major hurricanes. Thus far, there have been seven named storms and three hurricanes, the last one being Gaston. The peak of the hurricane season is around September 10; however, for us, it’s around August 20 and September 3. Become hurricane strong by being prepared!

Follow us via our social media platform and stay updated on the 2016 Atlantic hurricane season. We are available on twitter, facebook, wordpress, instagram, tumblr, and google+. Follow us also for all things weather and climate.





August 2016 to January 2017 Climate Outlooks for Antigua and Barbuda

16 08 2016

Dale C.S. Destin |

The August 2016 to January 2017 climate outlooks are now available for Antigua and Barbuda. Over the short, medium and long-term the rainfall is likely to be above to near normal.  Thus, there is a moderate chance of, at least, a temporary end to some droughts over the upcoming six months. Meanwhile, uncomfortably warm temperatures are expected for the upcoming six months. August-October (ASO) is the most active part of the hurricane season and is likely to be the most active since 2012.

Drought

July 2016 was wetter than the last three Julys and wetter than the last two combined; however, it was not wet enough to end the droughts (meteorological, agricultural, hydrological and socioeconomic). We have now entered the 38th month of mostly moderate or worse rainfall deficits; however, since April, the meteorological and agricultural droughts have been at slight levels.

May-Oct2016 Rainfall Outlook

Looking forward – the meteorological and agricultural droughts could ease further or perhaps come to, at least, a temporary end as August has a 60% chance of being wetter than usual, and there is a 40% chance of the ASO period getting above normal rainfall. Over the long run, above  to near normal rainfall is likely. Notwithstanding, drought warnings and watches are in effect for various periods through January 2017.

The warm phase of El Nino Southern Oscillation (ENSO) – El Nino, came to an end in May leaving in its wake significant adverse impacts. There is now around a 60% chance of the cold phase of ENSO i.e. La Nina developing during the last third of the year or the latter half of our wet season. A few months, ago the chance of La Nina was in excess of 75%, so its chance of develop is on the decline; nevertheless, it is still more likely than not.

If you are in our part of the world – the Caribbean, a La Nina would be more than welcome. Unlike El Nino, La Nina often brings us more than usual rainfall, and with the record drought we are still experiencing, water is more precious than gold at the moment.

Unlikely, but a much wetter than normal wet season (July-December) is desperately needed to end our severe multi-year droughts.

Precipitation and temperature

Year-to-date, Antigua, on average, has had more than twice the amount of rainfall than for the same period last year. Nevertheless, we are still over 100 mm (four inches) in the “red” relative to the long-term average of 534.9 mm (21.06 in).

This up-tick in rainfall is likely to generally continue over the long-term – August 2016 to January 2017, there is a 75% probability of above to near normal rainfall. However, the projected rainfall for 2016 is 657 to 1218.5 mm (25.9-48.0 in) or below to near normal.

The summer heat is likely to continue through October with the ASO “season” likely to be warmer than usual. With a 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 both night-time and day-time temperatures are likely to be higher than usual. High than usual night-time temperatures are likely to continue through January 2017. This has negative implications for health, especially among older adults, infants and young children.

The hurricane season

Thus far for the 2016 Atlantic hurricane season, there have been five named storms and two hurricanes (Alex and Earl). The number of storms is considered above normal relative to the long-term average of three. However, the ACE, which matters most, is near normal.

Recently issued hurricane season forecasts have reasserted that the 2016 season is likely to be the most active since 2012. Notwithstanding, the forecast is for the season to fall in the near normal range with around 15 named storms, 7 becoming hurricanes and 3 major hurricanes; this includes those already formed.

Notwithstanding the forecast, we need to be fully prepared, as it only takes one hurricane to set our life and community back by decades. Be prudent: prepare for the worst and hope for the best!

See the following links for the full outlooks: August 2016, August-October 2016, November 2016-January 2017, August 2016-January 2017, Drought, 2016 Updated Hurricane Season Forecast.

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

Correction, August 19, 2016: An earlier version of this article incorrectly stated the rainfall forecast for August 2016 to January 2017. The forecast is for above to near normal rainfall rather than below to near normal.





The Most Active Atlantic Hurricane Season in Four Years Remains Likely

15 08 2016

Dale C. S. Destin |

The latest round of forecasts has reaffirmed that the 2016 Atlantic hurricane season is likely to be the most active since 2012. However, notwithstanding the predicted increase in activity over recent years, the forecast continues to call for a near normal 2016 hurricane season.

Ensemble forecast

Our ensemble (mean) forecast calls for 15 named storms with 7 becoming hurricanes and 3 reaching major hurricane status. This represents a slight difference from the previous forecast, which called for one less named storm but one more major hurricane.

Updated Hurricane Season Forecast

In meteorological community, the accumulated cyclone energy (ACE) index is deemed the best “yard-stick” to measure 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 a season, aside from just the number of storms.

This year, our ensemble forecast calls for an ACE index of 102. This is seven less than the previous forecast ACE but still well within the near normal range. If this forecast pans out, the 2016 season would be around 183%, 52% and 62% more active than 2013, 2014 and 2015 respectively.

The ensemble (mean) forecast is based on predictions from seven organizations: 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), Weather Channel, the Institute for Meteorology (INSMET) of Cuba and Truchelut of WeatherTiger.

The season so far

So far, there have been five named storms: Hurricanes Alex and Earl and Tropical Storms Bonnie, Collin and Danielle. None impacted Antigua and Barbuda, but the disturbance that became Earl brought us some welcome showers. The season officially began June 1 and runs until November 30. However, no one told that to Alex and Bonnie – the former developed in January and the latter in May. With five named storms gone, around 10 more are likely.

Uncertainty

The skill in forecasting the hurricane season in August is quite high – up to 50% better than guessing or using the average activity of a season as the forecast, which would be correct around 33% of the time. This translates to the August forecast being right around 83% of the time.

Notwithstanding the high skill, there is and always will be some level of uncertainty. It is still uncertain as to if and when will La Nina (cooler than usual Pacific Ocean) develop. Also, there are uncertainties regarding it strength, if it does develop. A strong La Nina during August to November could result in an active/above normal season as opposed to a near normal one. NOAA has put the probability of an active season at 35% and the probability of a near normal one at 50%.

Probability of Antigua and Barbuda being hit

According to Klotzbach, the likely best similar years to this hurricane season are 1958, 1959, 1966, 1978, 1992 and 1998. Of these years, six named storms passed within 121 miles of Antigua; of them, there were three hurricanes and one tropical storm that hit the island. Of them, Major Hurricane Georges of 1998 is the most notable. Thus, based ONLY on similar years, probabilistically Antigua has a

  • 63% chance of being affected by one or more named storms (passing within 121 miles), usually it’s 62%;
  • 49% chance of being hit by one or more named storms (passing within 17 to 75 miles), usually it’s 49% and
  • 39% chance of being hit by one or more hurricanes (passing within 17 miles), usually its 31%.

 Barbuda’s numbers, based on five named storms passing within 75 miles:

  • 57% chance of being affected by one or more named storms (normally it’s 52%);
  • 57% chance of being hit by one or more named storms (normally it’s 32%) and
  • 39% chance of being hit by one or more hurricanes (normally it’s 23%).

The hit forecast probabilities for Barbuda are significantly higher than usual. The numbers suggest that Barbuda is more likely than not to be hit by a named storm. The other forecast probabilities are similar to what is usual. However, it must be noted that our usual numbers are generally higher than most places.

Become hurricane strong

Notwithstanding the forecast, active or inactive season, it only takes one hurricane to turn your life upside-down, so the same comprehensive preparations are required to mitigate or reduce the impacts a tropical cyclone. Take actions today and become hurricane strong/resilient. Actions include:

  • 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!

A summary of the hurricane season will be available by December. Follow us via our social media platform and stay updated on the current hurricane season. We are available on twitter, facebook, wordpress, instagram, tumblr, and google+. Follow us also for all things weather and climate.





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.





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

Follow us via our social media platform and stay updated on the 2016 Atlantic hurricane season. We are available on twitter, facebook, wordpress, instagram, tumblr, and google+. Follow us also for all things weather and climate.








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