October 2016 to March 2017 Climate Outlooks for Antigua and Barbuda

24 10 2016

Dale C. S. Destin |

The October 2016 to March 2017 climate outlooks are now available for Antigua and Barbuda. Our worst meteorological (Met) drought on record has come to an end; however, other droughts continue. It is unclear what will happen with respect to rainfall over the next six months as there are equal chances of below, near or above normal rainfall for October-December and January-March. Meanwhile, warmer than normal night-time temperatures are likely to continue.

Potworks Dam, Aug242016 (L) v. Sep62016 (R)

Potworks Dam, Aug 24 2016 (L) v. Sep 6 2016 (R). Pictures courtesy Karen Corbin – Humane Society. 

Drought

After over three years, the rainfall for September 2016 has brought the Met and agrometeorological (AgMet) droughts to an end. However, it was not enough to end the hydrological (Hydro) and socioeconomic (SE) droughts, which continue at slight levels or worse. The island-average of 213.4 mm (8.40 in) for September 2016 is the most for a September since 1995. Further, it is the wettest of any month since October 2012.

Drought Meter

Looking forward – below to near normal rainfall is likely for October-March. Meanwhile, there are equal chances of below, near or above normal rainfall for both October-December (OND) and January-March (JFM). Given these and other forecasts, there is a moderate chance of the country going back into Met and AgMet droughts, and the Hydro and SE droughts re-intensifying in the medium to long-term. Drought watches are in effect.

Rainfall Projection for Jul-Dec2016

El Nino Southern Oscillation (ENSO) – El Nino, is happily becoming a distant memory. There is now a 65% chance of a cold phase i.e. La Nina developing over the next three months.

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. Given our severe water crisis of the past three years, a La Nina is being prayed for.

Precipitation and temperature

Year-to-date, the rainfall for Antigua is 1.3 times more than all the rainfall for 2015. Further, it is the wettest January-September since 2013. Notwithstanding, we are still over an inch in the “red” relative to the long-term average of 792.5 mm (31.2 in).

The recent up-tick in rainfall seems to have flattened-out. There is no clear signal as to rainfall for the upcoming seasons: OND, JFM and October-March. The best forecast is trending toward near to below normal rainfall for the next six months.

The projected rainfall for 2016 is 757.3 to 1336.8 mm (29.8 to 52.6 in) or near to below normal. This is at least 182.0 mm (7.0 in) more than last year’s total. There is only a slight chance of above normal rainfall for the year.

For the period October to March, above normal temperature is likely. Further, night-time lows are likely to continue above normal through OND resulting in continued uncomfortable warmer than usual nights.  Relatively cooler nights are likely for JFM.

The hurricane season

The 2016 hurricane season will go down as the first active season since 2012. Thus far, the current Atlantic hurricane season has produced 14 named storms, 6 hurricanes and 3 major hurricanes.

The accumulated energy (ACE) index which matters most, has shot up to 119% of the average of 106 in less than a month from less than 50%. More than half of this ACE is due to the strength and duration of Major Hurricanes Matthew and Nicole.

In terms of numbers, the forecast for the season is on point as it called for around 15 named storms, 7 becoming hurricanes and 3 major hurricanes.

Notwithstanding the end of the season drawing near, we have been seriously impacted by tropical cyclones in November, recall Hurricane Lenny of 1999. Thus, we need to remain fully prepared, as it only takes one hurricane to set our life and community back by decades. Be prudent: stay prepared for the worst and hope for the best!

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

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





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.





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.





Antigua’s Unenviable Record Worst Drought Continues

25 04 2016

Dale C. S. Destin |

Notwithstanding the significant rainfall of the past week, our unenviable record worst drought continues. However, the rains did bring some much-needed relief, as many residents got their cisterns and other catchments replenished. The precipitation also brought some relief to our farming community and landscape.

No sign of water in Potworks Dam, Antigua, April 22, 2016. Photo courtesy Karen Corbin – President of the Humane Society

No sign of water in Potworks Dam, Bethesda, Antigua; April 22, 2016. Photo courtesy Karen Corbin – President of the Humane Society

Recall that there are, at least, four types of droughts – meteorological, agricultural, hydrological and socioeconomic, which is the worst. Antigua has been in these droughts for around two months shy of three years. Of the mentioned droughts, the rains had the greatest impact on the meteorological and agricultural droughts.

For the week ending April 23, the island-average rainfall for Antigua was 63.3 mm (2.49 in). To have ended at least the meteorological drought, we needed over 100 mm (4 in); much more was need to end the other droughts.

Based on a mixture of rain gauge measurements and radar estimates, the rainfall across the island was quite variable, ranging from 25 mm (1 in) in the west to 152 mm (6 in) in the northeast. Notwithstanding, most areas got 40-100 mm (1.5-4 in).

24-hr Estimated Rainfall, From 8 pm April 17, 2016 to 8 pm April 18, 2016

24-hr Estimated Rainfall: From 8 pm April 17, 2016 to 8 pm April 18, 2016

At the V. C. Bird International Airport (VCBIA), the 42 mm that fell on April 18 makes it the wettest day since October 28, 2014. It was also the wettest April 18 at VCBIA since 1992 and 15th wettest of 1620 April days on record since 1962.

VCBIA also had a near record wet spell for April – six consecutive days with at least 1 mm (0.04 in), second only to the seven recorded in 1970. The six-day (April 17-22) total of 70.4 mm (2.77 in) at VCBIA, is now the fourth wettest for the month. With respect to a week, it’s the wettest for April since 2010 and the wettest for all weeks since October 23-29, 2014.

As of Sunday morning, April 24, the island-average rainfall for Antigua for the month was 80.5 mm (3.17 in). Thus far, this is the wettest April since 2013, when we had 132.1 mm (5.20 in). It is also our fourth wettest month since December 2014. On average, April is the fifth driest month with 85.6 mm (3.37 in).

The wet week was all due to a cold front preceded by an associated trough. Both systems have since been replaced by high pressure.

The wet weather has eased the meteorological drought to slight levels; however, not much has changed regarding the more serious hydrological and socioeconomic droughts. Follow us as we continue to monitor our rainfall closely.





The Worst Drought on Record for Antigua

25 03 2016

Dale C. S. Destin |

Antigua is witnessing the worst drought in recent history, dating back to, at least, 1928. The current drought is now over 32 months in length, similar to the drought of 1964-67. However, to date, the record rainfall deficit of 1143 mm (45 in) caused by the current drought, exceeds that of 1964-67 by 254 mm (10 in) or around 29%.

RainfallDeficitGraphic

While we don’t have observed monthly rainfall totals beyond 1928, we do have annual totals going back to 1871. Based on this record, 2015 is now the driest year in the series. This translates to 2015 rainfall total occurring once per 500 years, on average. Thus, it’s perhaps the most intense drought since the arrival of Christopher Columbus.

Not only the last year has been the driest on record, but so to have the last two years (24 months). Further, the last 32 months – July 2013 to February 2016, is the driest such period on record. We are missing about a year’s worth of rainfall.

Surface water contributes to around 30% of our potable water mix. However, since the drought started, the country has been completely out of surface water twice with an aggregate duration of around 14 months. We were out of surface water April to September 2014 and again from August 2015 to present.

The drought was caused by a number of climate actors not necessarily all acting at the same time. These include mainly an abundance of the dry and dusty Saharan air layer (SAL) from Africa, positive North Atlantic Oscillation (NAO), negative Tropical North Atlantic (TNA) Index and El Nino. It is fairly well established that these phenomena, in the mentioned phases, cause less than normal rainfall across our area with the converse being true.

The drought got kicked off by the SAL along with unpredictably strong vertical wind shear, sinking air and the weakening of the Atlantic Ocean overturning circulation. Happily, this resulted in a failed hurricane season in 2013, but unfortunately it also plunged us into what has become our worst rainfall deficit on record.

Contributing to the persistent drought, the NAO has been predominantly positive over the duration of the drought with only nine of the last 32 months having negative (rain-favoured) values. Meanwhile, the TNA was negative (unfavourable rainfall values) for most of January 2014 to June 2015. In 2015, El Nino developed and reach super (record) strength during the latter half of the year.

Droughts are expensive, and severe droughts are severely expensive. It’s believed that the drought has cost the country hundreds of millions of dollars, directly and indirectly. I will address this matter more in a subsequent blog.

The current drought is anticipated to become the longest on record – a further very unwelcome new record. Initial predictions had the drought easing significantly or ending around mid-year. However, our last set of forecasts has it continuing into the second half of the year.





The Latest Round of Seasonal Forecasts for Antigua – Mar to Aug 2016

3 03 2016

Dale C. S. Destin |

Our latest round of seasonal forecasts for Antigua is indicating that the current record longest drought will likely continue into the second half of the year. Both the spring and summer rainfall forecasts are calling for below to near normal rainfall.

SeasonalOutlook_Mar-Aug2016.png

The previous round of forecasts had indicated a high chance of the drought easing to slight levels or ending around the middle of the year. However, the latest round of forecasts is backing away from the optimism of significant showers over the period May-July.

Notwithstanding our forecasts for the upcoming seasons, the prospects for drought busting rainfall is still possible. A number of the global models are forecasting above normal rainfall for the mentioned seasons. However, our downscaled forecasts, which we believe have better skill for our region, are predicting drier than normal weather will persist.

Our drought outlook is also in support of the drought continuing beyond the middle of the year. The periods December 2015-May 2016, October 2015 to June 2016 and September 2015 to August 2016 are projected to see moderate to major rainfall deficits.

Temperatures for the upcoming six months are generally expected to be above normal. Hence, this spring and summer are anticipated to be warmer than normal. This could further exacerbate the scarcity of water.

The next round of forecasts, which will cover April to September 2016, will be available by April 3. Hopefully, we will have better news then. All of our outlooks can be found here





Record Breaking Dry Year for Antigua

28 01 2016

Dale C. S. Destin |

2015 will go down in meteorological history as the driest year on record for Antigua in nearly 150 years. The island-average rainfall was a paltry 574.5 mm (22.62 in), the lowest in a series from, at least, 1871. 2015 has shattered the previous record driest year – 1983 – by some distance, when we had 681.5 mm (26.83 in).

RainfallAccu

Never before on record has a year’s rainfall deficit or the rain that did not fall (rain-not-fall) was greater than the rain that did fall (rainfall). So the rain-not-fall, 628.6 mm(24.75 in), was greater than the rainfall – 574.5 mm. Of course, the rainfall deficit is the difference between what we got and what we usually get.

Avgvs2015Rain

Looking at the deficit another way, the rain-not-fall is roughly equivalent to the rainfall we would normally get from the first seven months of a year.

Such a dry year, as 2015, is extremely rare. It happens only once every 500 years on average. That translates to a 0.2% chance of a given year getting so little rainfall. It is quite possible that the last time it was this dry Christopher Columbus was still sailing the Caribbean.

If we were still in the pre-desalination-era, it would not be a stretch to say that the Antigua and Barbuda’s economy would have collapsed due to lack of sufficient potable water. As has been the case for months now, over 90% of potable water is coming from the ocean via desalination.

Interestingly, no month had record low rainfall. So, the record low rainfall for 2015 came about due to persistent low rainfall throughout most of the year. Five of the 12 months not only had below normal, but well below normal rainfall. Further, all months had below normal rainfall except September and November, which had near normal rainfall.

MonthlyRain

Most areas of the country had record or near record low number of wet days – WDs – (days with at least one mm) for the year. At the V. C. Bird International Airport (VCBIA), there were 97 WDs, the third lowest behind 2001 with 94 and 1983 with 93. However, the total rainfall from WDs of 495.8 mm (19.52 in) was at a record low for 2015. Normally, WDs yield around 1019.3 mm (40.13 in).

Heavy rainfall days – HRDs –  (days with at least 10 mm) was also at record low numbers at many places during 2015. At the VCBIA, they were at a record low total of 12, tying 1983 and 1973. Normally, there are 26 HRDs annually. Meanwhile, the rainfall total from HRDs of 217.1 mm (8.55 in) was the second lowest behind 207.4 (8.16 in) measured in 1983. Usually, it’s around 665.5 mm (26.20 in).

The dismal rainfall for the year was due largely to two factors. Firstly, dry and dusty air from the Sahara Desert which hampered rainfall mainly during the first half of the year. Secondly, a record strong El Nino, which suppressed rainfall mainly over the latter half of 2015.

Follow us on twitterfacebookinstagramtumblrflickrgoogle+, and youtube as we provide you with further analyses of the historic rainfall year for Antigua. We will also provide you with observed and forecast rainfall totals for 2016, as we keep close eyes on our climate.








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