Usual Rainfall for April, Droughts Eased

31 05 2018

Dale C. S. Destin |

The rainfall for April 2018 was near normal; however, is the driest April since 2015. The island-average total for the month was 71.6 mm (2.82 in). This represents 84% of the usual amount of 85.6 mm (3.37 in).

Potworks_Apr282018

The last three month period – February to April, upon which the assessment of the current intensity of the drought is based, had 126.2 mm (4.97 in), 65% of the normal total of 193.0 mm (7.60 in). This puts the meteorological droughts current intensity at slight, improving from moderate. With Potworks Dam about to go totally dry and the vegetation of the Island struggling, there is little doubt that most other droughts are at moderate levels or worse. Happily, the full impacts of the droughts are being masked by the presence of the desalination plants.  According to the Antigua Public Utilities Authority, around 85% of all potable water is coming from the sea via reverse osmosis and is expected to climb to near 90% in days.

The seven-month period – October 2017 to April 2018, the duration of the drought thus far, was seriously dry. The total for the period of 407.92 mm (16.06 in) is the lowest since 2001 and the eighth lowest on record dating back to 1928.

RainfallDeficitGraphic_April2018

Based on the last set of rainfall outlooks, the news is not good for rainfall. Overall, below normal rainfall is most likely for, at least, the next three months – June to August. Additionally, the projected rainfall for 2018 is below normal with a 60% confidence. Thus, there is every reason to believe that the droughts will continue and likely worsen.

Even if the rainfall total turns out to be near average, it will not be enough, especially with respect to the hydrological drought, as the monthly evaporation rates significantly exceeds rainfall totals for most of the upcoming months. The chance of the droughts ending is around 20% or slight.

Recall that the current drought started in October 2017 with the intensity at serious levels. On average, serious meteorological droughts last for close to a year, but not continuously at serious intensity. We have just passed the seven-month mark. Will it go another five months? The answer still looks more like to be yes than no.

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

 

Advertisements




February to July 2018 Climate Outlooks for Antigua and Barbuda

8 02 2018

Dale C. S. Destin |

Antigua and Barbuda is back in a meteorological drought again. The latest round of climate outlooks suggest that it is unlikely to worsen and could even end in a few months. However, with us entering the heart of the dry season, the prospects of real relief are not good. Beyond the next few months, it is very unclear as to how the rainfall will perform. Meanwhile, temperatures will vary over the upcoming six months.

Rainfall and drought

At least, a meteorological (Met) drought has returned to Antigua and Barbuda as of October 2017. The rainfall totals for our two wettest months – October and November, were below and well below normal respectively. Combined, it is the driest October-November period since 1983 – 34 year ago or in a generation.

Nov2017-Apr2018_Rainfall

Looking forward – the Met drought is likely to remain the same or perhaps come to an end in the next three months or so. Rainfall totals for December and January were near normal and the outlooks for February-April is for above to near normal rainfall.

Although the Met drought may not get any worse, we could still slip into a hydrological drought, if we are not already in one. Catchments are on the decline, as is normal for the dry season, and will unlikely be recharged by the rainfall of the upcoming three months.

Beyond April, rainfall performance is quite uncertain – the signals are all over the place. Hopefully, in a month’s time things will become relatively clear.

The cold phase of El Nino Southern Oscillation (ENSO) – La Nina is evident although an episode cannot yet be declared. La Nina is weak and expected to come to an end around April; hence, having very little impact on rainfall across our area.

If you are in our part of the world – the Caribbean, a moderate or strong La Nina is almost always welcome, particularly in the summer when it has a usual positive impact on rainfall. The opposite – El Nino, has a negative impact. Outside the wet season – July to December, ENSO has little or no effect on our rainfall.

Temperature

Temperatures were generally near normal for the October-December (OND) period. However, the mean minimum temperature was above normal – the second highest since 2002, based on preliminary data.

The warmer than normal mean minimum temperature for OND was due mainly November and December having above normal nighttime low temperatures. This was reflected in the mean maximum temperature, where November and December also experienced warmer than normal daytime high temperatures.

Looking down the road – there is equal chance of the mean and maximum temperatures for the next three months – February to April, being below, near or above normal. However, the minimum temperature is likely to be above to near normal.

For the period May-July, the mean temperature is expected to be above to near normal. There is equal chance of the maximum and minimum being below, near or above normal.

See the following links for the full outlooks: CariCOF Newsletter – summary and outlooks for the region; precipitation outlooks and temperature outlooks.





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.





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.





Drought Expected to Continue

30 11 2015

Dale C. S. Destin |

The main news coming out of the Caribbean Climate Outlook Forum (CariCOF), held at the Marriott Resort, St. Kitts, November 26-27, is that below to near normal rainfall is expected to continue for most of the Caribbean. This means that it is highly likely that drought will continue, worsen or develop across most of the region.

DroughtOutlookForTheCaribbean2015-2016

Over the last twenty-four months, many parts of the Caribbean have had record or near record low rainfall over various periods. The red in the standard precipitation index (SPI) map below shows severely dry weather across most islands. This has been mainly due to El Nino and Saharan Dust.

May-Oct_SPI_2015

The forecast also calls for higher than normal temperatures for the upcoming six months. All things being equal, these unseasonal temperatures will worsen the impacts of the drought by causing more than normal evaporation.

The 2015 Dry Season CariCOF brought together representatives from the region’s weather and climate services and climate sensitive sectors to discuss the next season’s forecasts and its potential socio-economy implications on the region.

Of course, having looked at the potential implications of the forecasts, it is anticipated that the sector-leaders would implement plans to mitigate possible negative impacts and maximise potential opportunities.

The actual forecasts were produced during the pre-CariCOF training workshop for meteorologists and climatologists, November 23-25, at the above mentioned venue.

During the workshop, the Caribbean Institute for Meteorology and Hydrology (CIMH) unveiled the Caribbean Outlook Generator (CAROGEN).  CAROGEN is a potential game changing tool. It is expected to significantly reduce the time and stress linked with the production of climate forecasts for the region.

Another highlight of the pre-CariCOF workshop was the media training. This is a part of the World Meteorological Organization (WMO) efforts to promote the value of climate services to island nations, such as ours.

The training was conducted by David Eades – world renowned journalist and celebrity with the British Broadcasting Corporation (BBC).  He shared with us some of the “tricks of the trade” including understanding what journalists are looking for and framing effective messages.

In the short-term, water conservation and efficiency measures should be ramped up, to cope with the ongoing shortage of rainfall. For the medium to long-term, strategies, including those to increase water storage capacity and improve drought management plans, are required to build resilience to drought.

Congratulations to Adrian Trotman and his CIMH team for organizing another very successful CariCOF! The next CariCOF is schedule for May/June 2016 in Dominica. It is expected to have a special focus on the link between climate and health.





How dry has this September been?

19 09 2012

By Dale C. S. Destin

Antigua is currently experiencing a meteorological drought, which started in February of this year. Notwithstanding the active hurricane season, so far, September has been especially dry. The first half of the month only yielded 1.3 mm / 0.05 inch of rainfall at the V. C. Bird International Airport. This tied with September of 1986 for the lowest total at the Airport on record (1971-2012). Below normal rainfall was anticipated for the month so this does not come as a surprise. This sort of rainfall is consistent with a warm Pacific Ocean (El Nino) and a lukewarm/cold tropical north Atlantic (TNA) Ocean. The lowest total rainfall for the month of September on record at the Airport is 27.2 mm or 1.07 inches (1978, at the start of a strong El Nino and cold TNA), while the highest is 410.2mm or 16.15 inches (1995, during a moderate La Nina Episode and warm TNA). Thus, based on record, there has never been a sub-inch total for the month; only two other month has never experienced sub-inch rainfall – August and December. However, at the current rate, and based of the outlook, sub-inch rainfall is quite possible and would obviously make it a record dry September. Further, it would make the drought become severe.








%d bloggers like this: