Record-Breaking Dry 19 Months for Antigua

13 07 2022

Dale C. S. Destin |

The past 19 months is the driest such period on record for Antigua, dating back to at least 1928. Since the deluge of November 2020, December 2020 to June 2022 has yielded only a meagre 983.5 mm (38.72 in), for the island-average rainfall. This broke the record set for a similar period, December 2014 to June 2016, of 994.4 mm (39.15 in), which was also the record lowest for any consecutive 19 months.

Usually, 19 months ending June averages 1656.3 mm (65.21 in). This means that since December 2020 only 59 percent of the normal amount of rain fell. The 19-month total of 983.5 mm is less than that for 17 full years. The rainfall total for the last 19 months was less than what usually falls in 12 months – annually.

Rainfall total for Dec 2020-Jun 2022 – 983.5 mm (38.72 in) vs the normal total for the same period – 1656.3 mm (65.21 in). December 2020 to June 2022 is the driest 19 months on record.

Such an extremely low rainfall total for the last 19 months has a less than a 1 percent chance of occurring – 0.8 percent.  This translates to the dryness for December 2020 to June 2022 having a return period of 1-in-125 years, on average. It is unlikely that anyone alive has seen this kind of scant rainfall before and there is a less than 10 percent chance of a repeat in the next 13 years.

The last time we saw such dryness we were in the midst of the Great Drought of 2013-2016. At no time during that dearth of rainfall was the dryness this intense for any successive 19 months.

A lot of the dryness seems largely due to dry and dusty air from the Sahara Desert and or cooler than normal sea surface temperatures across the tropical North Atlantic Ocean. The high number of tropical cyclones in 2021 likely contributed, by steering clear of the area and pulling moisture away from the islands.

The dryness has been quite robust. Not only records were set for the last 19 months but also for the last 18, 17, 16 and 15 months respectively. It is also likely that more records will fall in the coming months.

As forecast, it was a drier than normal dry season for Antigua. The period January to June was the 20th driest in a series going back to 1928. The continued below normal rainfall means that drought continues to reign with no predictable end in sight.

With the rainfall at or near record-low levels over the past 19 months, one can appreciate the absence of virtually ALL water from surface catchments and the significant drop in groundwater. Potworks Reservoir, our billion-gallon surface catchment, has been totally dry since late October 2021. If not for water from the increasing number of reverse osmosis plants, “crapo would be smoking our pipes”, at the very least. And for those who say he is smoking our pipes, without the plants, it would be exponentially worse, in unimaginable ways.

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Updated Prediction: Below Normal Rainfall Most Likely for Antigua for 2022

31 05 2022

Dale C. S. Destin |

The prediction for rainfall remains discouraging. My latest forecast continues to call for most likely below normal rainfall for Antigua. The most likely total for the year is 1080 (42.5 in), down 25 mm (1 in) from the previous forecast. There is also a 70 percent or high confidence of the rainfall total falling in the range of 590 to 1695 mm (23.2 to 66.7 in).

The main reason for the below normal rainfall forecast is the current trend of cooler than average sea surface temperatures (SSTs) across the tropical North Atlantic (TNA), which should last through summer (June-August). 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. This May has been wetter than the last one; notwithstanding, it will end with well below normal rainfall. Year-to-date is drier than normal. Further, since the deluge of November 2020, the start of the current drought, there has been 943.1 mm (37.13 in) of rainfall, for December 2020 to May 2022. This total is so far below normal that it is the second driest such period on record.

The dry season, January to June, is on track to be drier than usual. Summer, June to August, is also likely to be drier than normal. Further, the first three quarters of this year (January to September) is likely to see deficit rainfall with a most likely total of 645 mm (25.4 in) compared to the usual amount of  759 (29.9 in). There is also a 29 percent chance of January to September having top 10 dryness.

WMO Lead Centre for Long-Range Forecast Multi-Model Ensemble is forecasting 40-50% likelihood of below normal rainfall for Antigua and Barbuda for June to August. Also, below normal rainfall is likely for much of the rest of the 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.

This forecast will be updated monthly around the 25th of each month until August. The next update will be issued around June 25.

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, good for our environment and good for rainfall.

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Drier than Usual January for Antigua

23 02 2022

Dale C. S. Destin |

January 2022 was another drier than usual month for Antigua; the fourth in a row and the 10th since January 2021. The month registered just  48.3 mm (1.90 in), making it the fifth January of the last eight with below normal rainfall.

January usually clocks 67.3 mm (2.65 in) of rainfall annually (1991-2020); this means the month fell close to 28 percent below its usual total. This is an improvement over January 2021, when the deficit was close to 60 percent. Notwithstanding, it is another year with a bad start.

January’s rainfall anomaly (deviation from normal) in percentage (blue line) along with the long-term trend (grey broken line). The background is that of Potworks Dam, 3 February, 2022

The rainfall for January continues to trend negatively (downward); however, this trend is statistically insignificant. The trend is at a rate of just 0.16 mm (0.0064 in) per year or 16 mm (0.64 in) per hundred years. This also represents an insignificant rate of 0.24 percent per year or 24 percent in 100 years. No evidence of a changing climate with respect to rainfall in January.

In aggregate, the three-month period ending January is among the driest on record going back to 1928. The total of 141 mm (5.55 in) is the third lowest behind November-January of 1967/68 and 1947/48. The last four, five, six and seven-month periods ending January had record-breaking low rainfall. Further, the last year (February to January) ranks second driest, on record, with 621.5 mm (24.47 in). The record is 588 mm (23.15 in), February 2015-January 2016.

Clearly, we remain in the grips of a severe meteorological drought, which is also defined as exceptional by some other metrics. Also evident are agriculturalhydrologicalecological and socio-economic droughts, at varying intensities. Potworks Reservoir remains 100 percent empty, converted into a pasture for grazing animals. All other surface catchments are in a similar state or below extraction levels.

Antigua Public Utilities Authority (APUA), the country’s water resource manager, has just commissioned a new reverse osmosis plant to obtain more potable water from the sea. This should bring the daily total from this source to over 7 million and it should help to ease the water woes. However, the drought continues to be a very serious matter for many, who are forced to go days without potable water, as demand continues to outstrip production by hundreds of thousands of gallons.

The drier than usual start to the year was not confined to Antigua. Much of the Caribbean Basin experienced below normal rainfall with some islands or part thereof getting less than 25 percent of their usual total–75 percent rainfall deficit or more.

CMORPH 1-Month Percent of Normal Rainfall for January 2022

Drought conditions have worsened across a number of the other islands, including the rest of the Leeward Islands, the Virgin Islands and Puerto Rico, most of the Windward Islands and Barbados. The Caribbean Institute for Meteorology and Hydrology (CIMH) has recommended drought watches or warnings for most islands of the Caribbean.

It is unclear as to when there will be any notable respite from the drought. The latest set of models surveyed suggests an equal chance of below, near or above normal rainfall for March to May for Antigua and Barbuda and much of the rest of the Caribbean.

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Near Record-Breaking Dry Year, Drought Reigns

18 01 2022

Dale C. S. Destin |

It was a near-record-breaking dry year (2021) for Antigua. The year produced a measly island-average rainfall of 600.7 mm (23.65 in), the second lowest on record behind 2015 with 574.5 mm (22.62 in). Officially, 2021 was easily the second most parched year in a series from 1928 and unofficially, since, at least, 1871.

The yellow broken line represents the rainfall anomaly trend, which indicates no significant change to wet (positive) or dry (negative) anomaly.

It was a year reigned by drought from beginning to end, and the reign is likely to go on through the upcoming months. The drought has a firm grip on the weather, being at the most intense category: severe, exceptional by some other standards. The normal annual total is 1156.7 mm (45.54 in), nearly twice the amount measured for 2021.

The rainfall deficit amounts to a whopping 556.0 mm (21.89 in) or 48 percent of the usual total for the year. This is more than the average for the first seven months of a year. Every month accrued a shortfall with the usually wettest month of the year–November, accounting for over 22 percent of the overall rainfall shortage.

This level of waterlessness for a year is extremely rare. There is only a 0.5 percent chance of the island-average being 23.65 inches or lower. This translates to the kind of dryness that has a return period of once in 200 years (1-in-200 years), on average.

Alternatively, there is less than a 10 percent chance of such harsh weather reoccurring in the next 20 years. One is, at least, twice as likely to see a hat-trick in a cricket match than experience the likes of such lacklustre annual rainfall.

268Weather accurately predicted a drier than usual year was likely. As early as May 2021, we indicated a 46 percent chance of below normal rainfall. The chance rose to 58 percent in June and peaked at 61 percent in August. There was also a peak of 19 percent for the year to rank among the top 10 driest.

The usually wettest consecutive pair of months, October-November, almost literally produced a speck in the bucket. The frequently rainiest duo was the record driest with the trivial amount of 63.8 mm (2.51 in) with each month recording less than an inch-and-a-half of rainfall for the first time, on record. Combined, the shortfall for the months accounted for 45 percent of the year’s deficit. The previous lowest for this period was 89.7 mm (3.53 in), in 1983.  

The last quarter (October-December) was also the driest on record, dating back to 1928. The total of 127.3 mm (5.01 in) shattered the previous record of 143.0 mm (5.63 in), for the last three months of the year, set in 1983. Usually, this period precipitates 397.5 mm (15.65 in), over thrice what actually fell.

It was essentially a year without a wet season (July-December). The dry season pretty much went on and on, for the whole year, resulting in a record-breaking dry wet season. The season’s total of 396.0 mm (15.59 in) retired the previous driest wet season of 1983, which accumulated 405.6 mm (15.97 in). Cumulatively, the third and fourth quarter rainfall represented just 53% of the normal amount of 746.8 mm (29.40 in). A typical dry season (January-June) averages more rainfall than occurred for the 2021 wet season.

While the island on a whole had near-record-breaking low rainfall, parts of the country actually had record dryness. Coolidge, in northeast Antigua, had a record low rainfall of 469.6 mm (18.49 in), crushing the previous record of 554.0 mm (21.81 in) set in 2015. This represents only 47 percent of the normal annual total of 1000.8 mm (39.40 in). This kind of rainfall scarcity occurs only once every 333 years, on average, or a less than 10 percent chance of occurring in the next 35 years or the next generation.

It is unclear as to what was responsible for this nearly unprecedented dryness. The usual culprit: El Niño was not only absent but his sister: La Niña, usually the rainmaker, was present, yet to little avail. The dryness may have been mainly the result of a consistent stream of dry and dusty air from the Sahara Desert along with a cooler than usually tropical North Atlantic.

There is the saying: “If rain does not fill a [water] drum, dew is not going to fill it.” Meaning, if the wet season did not end the droughts, particularly the hydrological and socioeconomic ones, how can the dry season, which we are in, do so? It can’t; hence, the sufferation from insufficient rainfall could continue through the next six months.

The last 10 years have been the driest decade for Antigua. Five of the last 10 years have had below normal rainfall with 2015 and 2021 ranking one and two, on record. Only one year (2020) has had above normal rainfall since 2011.

Other Caribbean islands are having similar challenges with rainfall or lack thereof. For example, the Henry Rohlsen Airport in St. Croix was said to be on track, in December, to record its third driest year, on record dating back 58 years. A number of other parts of the Caribbean were also on the way to record rainfall ranking among the top 10 lowest.  

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Near Record Driest November for Antigua

7 12 2021

Dale C. S. Destin|

Most Antiguans alive have never endured a November like the just ended one. The month was second driest on record, dating back to 1928. It registered a near record breaking 29.2 mm (1.15 in) of rainfall, the lowest since 25.1 mm (0.99 in) in 1947, almost 75 years ago. This very rare November rainfall event has around a 0.7 percent chance annually or once every 143 years, on average.

November usually logs 152.1 mm (5.99 in) of rainfall annually (1991-2020); this means that only a little over 19 percent of the usual total fell this year. The deficit of 81 percent is the second worst for the year, behind May with 83 percent. November is usually the wettest month of the year.

The absentee rainfall for November has virtually ensured that 2021 will be among the top eight driest, on record. Although unlikely, this year could even break the record for the driest year set by 2015, when just 574.5 mm (22.62 in) rainfall was accumulated.

Thus far, the total for 2021, through November, stood at 537.2 mm (21.15 in). Normally, this period yields 1059.2 mm (41.7 in); hence, there is close to a 50 percent shortfall of rainfall. Less than 37.3 mm (1.47 in) of rainfall for December would see the record fall. Such low annual rainfall is extremely rare. The chance of this meagre annual total is less than 0.2 percent. This translates to a 500-year event or worse, an event with a return period of once every 500 years or more, on average.

November has also virtually sealed the fate of the wet season (July-December). It is certain to be among the driest, if not the driest, on record. The current record is 405.6 mm (15.97 in) for the 1983 wet season. Thus far, July-November, the total for the 2021 wet season is 332.5 mm (13.09 in).

While it is possible that the rainfall for the wet season will be at a record low, the rainfall for the last seven months ending November was in fact record breaking. No other May-November has been drier, on record going back to, at least, 1928. The total of 405.4 mm (15.96 in), for this year, eclipsed that of 406.4 mm (16.00 in) observed in 2015.

It goes without saying that serious meteorological drought continues, and it is highly likely to get worse, in the short-term. Also evident are agriculturalhydrologicalecological and socio-economic droughts, at varying intensities. Potworks Reservoir now has ZERO drop of water. All other surface catchments are in a similar state or below extraction levels.

Potworks Reservoir with zero drop of water – December 2, 2021. Picture courtesy Karen Corbin, Humane Society

Antigua Public Utilities Authority (APUA), the countries water resource manager, informed the public yesterday that 95 percent of all potable water, being produced by the organization, is desalinated water from the sea. We were also informed that the total water production of six million gallons per day is, at least,  a million gallons below the country’s daily requirement; hence, water is being rationed.

With such lean rainfall figures and with the recent conclusion of COP26, the obvious question would be: Was this caused by anthropogenic (human induced) climate change? From my reading of the latest IPCC report and other papers, the answer is no. According to the report, there is a low confidence in the change in agricultural and ecological droughts in the Caribbean, thus far. However, the long-term projection is for an increase in the intensity and frequency of droughts, but this will not be for all regions. Unfortunately ,the Caribbean is likely to be among the regions to bear the negative changes.

Whereas climate change is unlikely to have been a factor in November’s rainfall, or lack thereof; it was noted that suppressing rainfall conditions prevailed across the area for much of the month. Strong positive velocity potential anomalies caused sinking air, which is prohibitive to cloud growth and hence rainfall. The velocity potential is associated with the Madden-Julian Oscillation (MJO) with positive values being indicative of the dry portion of it.

Three-day centred average animation of daily IR and 200-hPa velocity potential anomalies (base period 1991-2020). Velocity potential anomalies are proportional to divergence with green (brown) contours corresponding to regions in which convection tends to be enhanced (suppressed).

This extreme dryness for November was not endured by Antigua only. The unusually low or near record breaking rainfall was observed across much of the Eastern Caribbean. For example, reports out of Trinidad and Tobago indicate that much of the country had its second driest November, on record.

November was the last hope for the replenishment of national surface catchments, this year. With the very disappointing rainfall, the next possible time for replenishing precipitation is May. The issue with insufficient potable water is likely to get worse before getting better.

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Near Normal Rainfall for September, Drought Continues

27 10 2021

Dale C. S. Destin |

September joins June as the only two months of the year, thus far, to register near normal rainfall, all others had below normal figures. The month produced 122.2 mm (4.81 in) of rainfall, the highest total for any month since December 2020; notwithstanding, drought continues through September. The rainfall for the last nine months ranks among the worst on record, and it is still unclear as to when there will be significant respite.

The rainfall for September is the second lowest since 2015. However, the total for the month was a decent 90 percent of the normal value of 136.4 mm (5.37 in), only a deficit of 10 percent.

The period July-September was also drier than usual. The total of 268.7 mm (10.58 in) was the 18th lowest on record starting 1928. The last time this period was drier was 2015 with 168.1 mm (6.62 in).

We continue to witness one of the driest years on record. Thus far, this January to September is the sixth driest on record and the driest since 2015. The first three-quarters of the year has only a meagre 473.5 mm (18.64 in), only a little over 62 percent of the usual rainfall of 759.0 mm (29.88 in). The five drier January to September are 2015, 2003, 2001, 1939 and 1930. The year is on track to be among the top 10 driest or worst, on record.  

Since the 2020 November’s deluge, the last ten months, December-September, is the seventh driest on record and the lowest since 2015. The period has only returned 65 percent of normal rainfall.

The upcoming three months, November to January, has equal chance of below, near or above normal rainfall. Meanwhile, some of the more reliable models are still forecasting the continuation of below usual rainfall being most likely. Looking at the glass half full, near to above normal rainfall is more likely than not.

WMO Lead Centre for Long-Range Forecast Multi-Model Ensemble is forecasting equal chance of below, near or above normal rainfall for Antigua and Barbuda.

As the meteorological drought goes, so go the other droughts: agricultural, hydrological and ecological. There is the continuing concern that this may precipitate a socio-economic drought, if it has not already done so. However, the rainfall of September did stabilise or eased the droughts a bit.

Our conversion of sea water to fresh water has built drought resilience; however, obtaining potable water from this source is several time more expensive than from surface and underground catchments. Also, it has negative climate and environmental consequences, further adding to the overall expense of using the sea as a source for fresh water. Unfortunately, these “evils” are virtually unavoidable, for the foreseeable future.

Potworks Reservoir remains below extraction levels, along with most other surface catchments, according to the Antigua Public Utilities Authority (APUA), the country’s water authority. Water rationing continues and with the rainfall outlook unclear, an end is unforecastable, at this time. Daily water use continues to outstrip production by about one million gallons.

Potworks Reservoir, Bethesda, Antigua, still on the verge of becoming totally dry – Oct 2, 2021. Picture courtesy Karen Corbin of the Humane Society

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Drier than Usual August, Drought Continues

27 09 2021

Dale C. S. Destin |

Like every month of the year, except June, August was drier than usual. The month yielded only 81.0 mm (3.19 in) of rainfall. With continued below normal rainfall, drought continues. The rainfall for the last eight months ranks among the worst on record and there is still not much respite in sight.

The rainfall for August is the second lowest since 2015. The total for the month represents only 71 percent of the normal value of 114.8 mm (4.52 in), a deficit of 29 percent.

The period June-August was also drier than usual. The total of 202.2 mm (7.96 in) was the 18th lowest on record starting 1928. The last time this period was drier was 2015 with 95.0 mm (3.74 in).

We continue to witness one of the driest years on record. The last eight months is the fourth driest on record and the driest since 2015. January to August produced only a meagre 351.3 mm (13.83 in), only a little above half of the usual rainfall of 622.0 mm (24.51 in). Just three years have been drier through August: 2015, 2001 and 1939.  

Since the 2020 November’s deluge, the last nine months, December-August, is the fifth driest on record and the lowest since 2015. The period has only returned 61 percent of normal rainfall.

The upcoming three months, October to December, is likely to see further misery from lower than usual rainfall. Majority of models are forecasting the continuation of drier than normal weather. Hence, more rainfall deficits likely.

WMO Lead Centre for Long-Range Forecast Multi-Model Ensemble is forecasting 50-60% likelihood of below normal rainfall for Antigua and Barbuda. Also, below normal rainfall is likely for much of the rest of the northeast Caribbean.

As the meteorological drought goes, so go the other droughts: agricultural, hydrological and ecological. There is the continuing concern that this may precipitate a socio-economic drought, if it has not already done so. Our utilisation of the ocean for fresh water has made us drought resilient; however, obtaining potable water from this source is several time more expensive than from surface and underground catchments. Also, it has negative climate and environmental consequences, further adding to the overall expense of using the sea as a source for fresh water.  

Potworks Reservoir remains below extraction levels, along with most other surface catchments, according to the Antigua Public Utilities Authority (APUA), the country’s water authority. Water rationing is officially into its second month and with the rainfall outlook being gloomy, it is likely to continue for the foreseeable future.

Potworks Reservoir, Bethesda, Antigua, still on the verge of becoming totally dry – Sep 2, 2021. Picture courtesy Karen Corbin of the Humane Society

APUA water manager, Ian Lewis, told the media on August 31, that the Authority is only able to produce six million of the seven-and-a-half million gallons required to serve the country daily. There is not enough water to go around for everyone each day; hence, the rationing.

Antigua is not alone in experiencing significant rainfall shortages. The countries around us remain  thirsty for rainfall also. Deficit rainfall is occurring across the rest of the Leeward Islands, the northern Windward Islands, Hispaniola, Cuba and the Bahamas. And it is probable that it will worsen, over the upcoming months.

CMORPH 180-Day Total Rainfall Anomaly (mm) for the period 26 Mar to 21 Sep 2021

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Drier than Usual July, Drought Continues

27 08 2021

Dale C. S. Destin |

July was drier than usual like the first five months of the year. The month yielded only 65.5 mm (2.58 in) of rainfall. Although July took over from June as being the wettest month for the current year; it barely made a dent in the ongoing droughts. July has become the only month of the year, thus far, to clock over two-and-half inches of rain. The rainfall for the last seven months ranks among the worst on record and there is not much respite in sight.

Potworks Reservoir, Bethesda, Antigua, on the verge of becoming totally dry – July 7, 2021. Picture courtesy Karen Corbin of the Humane Society

The rainfall for July is the lowest since 2018, when the country had 39.6 mm (1.56 in). The total for the month represents only 67 percent of the normal value of 98.0 mm (3.86 in), a deficit of 33 percent.

The period May-July was also drier than usual. The total of 138.4 mm (5.45 in) was the 13th driest on record starting 1928. The last time this period was drier was 2015 with 74.4 mm (2.96 in).

We continue to witness one of the driest years on record. The last seven months is the fifth driest on record and the driest since 2015. January to July produced only a meagre 270.3 mm (10.64 in), only a little above half of the usual rainfall of 500.1 mm (19.69 in). Again, just four other years have been drier through July: 2015, 2001, 1977 and 1939.

Since the 2020 November’s deluge, the last eight months, December-July, is the seventh driest on record and the lowest since 2015. The period has only yielded 58 percent of normal rainfall. Our starving landscape and parched grounds continue to bear witness to the below normal rainfall.

The upcoming autumn, September to November, is likely to see us continue to suffer from a scarcity of rainfall. The majority of models are forecasting the continuation of lower-than-normal rainfall. Hence, the drought is likely to continue. Our largest catchment, Potworks Reservoir, along with others, are transitioning to dry land, again.

WMO Lead Centre for Long-Range Forecast Multi-Model Ensemble is forecasting 50-60% likelihood of below normal rainfall for Antigua and Barbuda. Also, below normal rainfall is likely for much of the rest of the northeast Caribbean.

Based on models which correlate our sea surface temperatures, across the tropics, with our rainfall, the medium and long term continue to look brown. The year will most likely remain drier than usual with a 61 percent chance of below normal rainfall; this is up 11 percent from last month.

As the meteorological drought goes, so go the other droughts: agricultural, hydrological and ecological. There is also the growing concern that this may precipitate a socio-economic drought, if it has not already done so. Our utilisation of the ocean around us for fresh water has made us resilient; however, this is expensive water, over seven times the cost of that from surface and ground water.  

Potworks Reservoir remain below extraction levels, along with most other surface catchments, according the Antigua Public Utilities Authority (APUA), the country’s water authority. Water rationing has officially started and with the rainfall outlook being gloomy, it is likely to continue for the foreseeable future.

Antigua is not alone in experiencing significant rainfall shortages. The countries around us remain  thirsty for rainfall. Deficit rainfall is occurring across the rest of the Leeward Islands, and it is probable that it will worsen, over the upcoming months.  

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Drought Continues

25 05 2021

Dale C. S. Destin |

With continued below normal rainfall through April, the meteorological drought continues for Antigua; however, it has eased to slight intensity as compared to serious at the end of March. Notwithstanding, we remain in a serious drought with significant cumulative rainfall deficits that are likely to have socio-economic impacts. Models continue to portray a dry scene for the upcoming months.

WMO Lead Centre for Long-Range Forecast Multi-Model Ensemble is forecasting 60-70% likelihood of below normal rainfall for Antigua and Barbuda. Also, below normal rainfall is likely for much of the Caribbean Basin.

We continue to witness the driest start to a year since 2015 and the eighth driest quadrimester for Antigua in a series that dates to 1928. The island-average rainfall of 131.8 mm (5.19 in) represents only 55 percent of the normal total for January to April; hence, 45 percent of the regular stream of water from the heaven was missed and is evident by our thirsty brownish landscape. Further, from the flooding rainfall in November to the end of April (December-April), only 64 percent of the normal rainfall has fallen. This is the 10th lowest on record.

The background is a picture of Potworks Dam, Antigua taken May 3, 2021 by Karen Corbin of the Humane Society.

The rainfall for this April of 38.9 mm (1.53 in) is more than twice the amount fell last April; however, it is the second lowest since 2006. The total was only 51 percent of the usual amount for mid-spring; hence, an unmissable deficit of 49 percent.

There is no discernible respite in the near future. The majority of models are forecasting deficit rainfall to be the order of, at least, the next three months. Thus, the drought is likely to continue. Our catchments could again revert to mud patches and or grasslands, which has virtually become an annual phenomenon.

Based on models which correlate our sea surface temperatures, across the tropics, with our rainfall, the medium and long term look brown. There is a 78 percent chance of the dry season, January to June, will suffer below normal rainfall. Further, there is a 52 percent chance of the dry season rainfall being in the bottom 10 percentile i.e. less than 10 inches, when the average is 16.14 inches. For the year, the forecast is for a 46 percent chance of it being drier than usual, with a non-trivial probability of 19 percent of well below usual, possibly with about a 24 percent deficit in the annual total.

Rainfall projection for Antigua in inches. A for chance of above normal; N for near normal and B for below normal. The background is a picture of Potworks Dam taken May 3, 2021 by Karen Corbin of the Humane Society.
Rainfall projection for Antigua in inches. A for chance of above normal; N for near normal and B for below normal. The background is a picture of Potworks Dam taken May 3, 2021 by Karen Corbin of the Humane Society.

Other droughts generally lag meteorological droughts; it is evident from our catchments that agricultural, hydrological and ecological droughts, to some degree, are also occurring or imminent. There is also the concern that this may precipitate a socio-economic drought. Our utilisation of the ocean around us for fresh water has made us resilient; however, there are still likely to be notable impacts, when the other droughts get underway in earnest.

Image from the Landsat satellite showing the contrasting green landscape of December 9, 2020, one month after the deluge of November 9-10, 2020, compared to the brown drought-ridden landscape of May 2, 2021

Potworks Dam is down to around a quarter. With the rainfall outlook bleak, we could virtually be out of surface water soon. Water rationing is imminent, if not already occurring.

Antigua continues not alone in experiencing significant rainfall shortages. Much of the Eastern Caribbean is having a similar thirst for rainfall, especially for December 2020 to April 2021. Short and long-term droughts continue to evolve across many places, and it is probable that the shortfall in precipitation will worsen and or spread to other islands, particularly the eastern ones, over the upcoming months, based on recent forecasts.

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Drought Worsens to Serious Levels

20 04 2021

Dale C. S. Destin |

With continued below normal rainfall through March, the meteorological drought has worsened to serious levels for Antigua. That is the “good” news, the bad news is that the drought is likely to get worse over the next few months, as below normal rainfall is forecast by most models.

WMO Lead Centre for Long-Range Forecast Multi-Model Ensemble is forecasting 60-70% likelihood of below normal rainfall for Antigua and Barbuda; only two of the 12 models forecast near normal rainfall. Also, below normal rainfall is likely for much of the Caribbean Basin.

This is the driest start to a year since 2015 and the ninth driest first-quarter for Antigua in a series that dates to 1928. The island-average rainfall of 93.0 mm (3.66 in) represents only 57 percent of the normal total for January to March (JFM); hence, 43 percent of the regular flow of water from our skies was missed by our plants, catchments, economy and ecosystems.

The rainfall for March of 29.2 mm (1.15 in) is the worst for the month since 2015. The total was only 63 percent of the usual amount for the first month of spring; hence, a significant deficit of 37 percent.

There is no discernible respite in the foreseeable future. The vast majority of models are forecasting deficit rainfall to be the order of the next six months. Thus, the drought is likely to get worse. Our catchments could again revert to mud patches and or grasslands, which has virtually become an annual phenomenon.

Other droughts generally lag a meteorological drought; however, it is evident from our catchments that agricultural, hydrological and ecological droughts, to some degree, are occurring or imminent. There is also the concern that this may precipitate a socio-economic drought. Our utilisation of the ocean around us for fresh water has made us resilient; notwithstanding, there are still likely to be notable impacts, direct and indirect, when the other droughts get underway in earnest.

The water authority, the Antigua Public Utilities Authority (APUA), has already signal an end to surface water to occur in a few months, that is even more likely than when it was said over a month ago, as rainfall for April has been virtually absent, thus far. Water rationing is imminent, if not already occurring.

Antigua is not alone in experiencing significant first-quarter rainfall deficits. Much of the Eastern Caribbean is having a similar thirst for rainfall. Short and long-term droughts continue to evolve across many places, and it is probable that the shortfall is precipitation will worsen and or spread to most of the Basin over the upcoming months.

Exert from the Caribbean Climate Outlook Forum (CariCOF) Drought Outlook for March 2021

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Drought is Back

14 03 2021

Dale C. S. Destin |

Drought is back for Antigua. A slight meteorological drought is present as of the end of February. It is most likely to get worse over the next three months, as below normal rainfall is forecast by most models.

The rainfall for winter – December to February (DJF) 2020-2021, was 149.1 mm (5.87 in). This total is deemed below normal and beneath the drought threshold. Usually, DJF yields 225.8 mm (8.89 in) of rainfall, on average; hence, there is over a 75 mm (over 3 in) deficit or a 34 percent shortfall.

Rainfall for Antigua for the period December 2020 to February 2021. Picture in the background is Potworks Dam as of March 3, 2021 courtesy Karen Corbin of the Humane Society.
Rainfall for DJF is well below the slight or worse drought threshold, nearly at moderate drought. Rainfall for this period for Antigua shows no significant trend (black dashed line). Excess rainfall tends to be more extreme than drought rainfall.

The month that is mainly responsible for the scarcity in precipitation is January, which got only 41 percent of the normal amount of 67.3 mm (2.65 in). The rainfall for February was also lower than usual, accounting for 73 percent of the normal amount of 50.0 mm (1.97 in). The rainfall for December was near normal.

The two-month rainfall for January-February (JF) of 63.8 mm (2.51 in) is the lowest since 2001. Thus, the very dry start to the year continues. With this JF ranking the eighth driest on record, only seven other years have had a drier start on record dating back to 1928.

It normally takes a few months for the effects of a meteorological drought to descend to a hydrological drought and cause potable water issues. However, the effects are already manifesting themselves in the lowering of water in catchments. Yesterday, the APUA Business Unit Water Manager – Ian Lewis, said on Observer Radio News that the country has about three to four months of surface water remaining, at current extraction rate.  

We were last in a drought April to October last year. This was a severe drought that was more than meteorological; it resulted in surface catchments transforming into mud patches and then to grass lands. It is unclear, at this stage, whether there will be a repeat of similar rainfall absence this year.

The dry conditions last year, resulted in water rationing and almost a 100 percent reliance on desalinated water. Ian Lewis has already indicated that the absence of notable rainfall over the coming months would usher in return of the water conservation schedule better known as water rationing.

Antigua is not alone in experiencing notable rainfall deficits in the wake of winter. Much of the Caribbean is suffering a similar fate, from a drier than usual dry season, thus far. Short and long-term droughts are evolving across a number of islands and there is the potential of several others joining this drought-list.

Rainfall anomaly (departure form average) in mm for the Caribbean, based on CMORPH data

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Very Dry Start to 2021

16 02 2021

Dale C. S. Destin |

Antiguans have just witnessed the driest start to the year in over a generation. January 2021 was the driest January since 1977 for Antigua, with an island average of 27.4 mm (1.08 in).

Usually January yields 67.3 mm (2.65 in) of rain; however, this time, the total was down by 59%. This puts the rainfall for the month in the well below normal category – the bottom 10 percentile of the most recent climate period – 1991 to 2020.

Such low rainfall is rare for January. How rare? Once in every 27 years, on average, which translates to a 3.7 percent chance of such a low total annually. Usually, there is over a 96 percent chance of the month producing more rainfall.

From a historical standpoint, this is the third driest January on record dating back to 1928. Only January 1977 and 1931 have been drier. January 1931 is the driest on record with 16.3 mm (0.64 in) and January 2006 is the wettest with 2017.7 mm (8.57 in).

Despite the trickle of rainfall for January 2021, the rainfall for the month is usually the most reliable of all months with the lowest variability index of 0.83 or moderate, for the climate period 1991-2020. All other months have a variability index of 1 to 2.37 or moderate to extreme. The variability is obtained by dividing the difference in rainfall of the 90th percentile and the 10th percentile by the median.

Notwithstanding the drier than normal January 2021, the rainfall for January remains without any significant (statistical) trend. The mean rainfall over the past seven climates has not changed significantly, ranging between 65.8 to 79.5 mm (2.59 to 3.13 in), over the period 1928 to 2020.

As we look forward, the rainfall for February is lagging average by about 38 percent, and even if the averaged is reached, there is the high likelihood for rainfall to drop to drought levels by the end of February. About another 35 mm (1.38 in) of rain is needed to stave off drought. This or more rainfall for February 17-28 has only occurred 10 times in the last 55 years – 18 percent of the time.

January is unlikely to be this dry again under the next 27 years. By then, we will be at the middle of the 21st Century – millennials would have reach senior citizen age.

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Driest April-May for Over 80 Years

6 06 2020

Dale C. S. Destin|

The combined rainfall total for April and May is near record-breaking low levels for Antigua. The total for this Apr-May: 36.8 mm (1.45 in), is the second lowest on record, dating back to 1928. Only Apr-May 1939, 81 years ago, had less rain – 27.9 mm (1.10 in).

Normally, these months would produce a combined rainfall of 189.2 mm (7.45 in). This means that the rainfall for Apr-May is less than 20% of the normal total, a deficit of over 80%.

Such low precipitation for Apr-May only happens once every 67 years, on average. In other words, there is only a 1.5% chance of this happening per year. Most Antiguans alive today have never witnessed such dryness before, for these months, and are very unlikely to witness it again.

Usually, Apr-May would account for 52% of the rainfall for Jan-May but instead it only accounted for less than 14%. Both April and May had similar extreme deficits. There have been only three other occasions when both months registered less than an inch of rain in the same year – 1973, 1939 and 1928.

It was not long ago that we were enjoying ample rainfall. First quarter rainfall, Jan-Mar, was above normal. However, this wonderful start to the year came to a screeching halt.

The horizontal (flat line) from Apr 1 to May 31 is indicative of the rapid downturn in rainfall as compared to the previous three months.

The difference in rainfall between Jan-Mar and Apr-May is the second greatest on record, indicative of the extremely sharp downturn in precipitation. We went from 237.7 mm (9.36 in) for Jan-Mar to 36.8 mm (1.45 in) for Apr-May, a decline of 200.9 mm (7.91 in). Normally, Jan-Mar and Apr-May produce 176.0 mm (6.93 in) and 189.2 mm (7.45 in) respectively.

Few of us alive today have ever seen this kind of change of rainfall, in Antigua. This kind sharp decline in rainfall from Jan-Mar to Apr-May only happens once every 100 years, on average. Only 1967 has had a greater decline, 240 mm (9.45 in), over the similar month periods.

This Apr-May is also the driest two-month period since May-Jun of 2001. It is also the 12th driest combined consecutive two months on record.

This past April and May were clearly extremely dry, and this dryness was magnified by the preceding wetter than normal first quarter.

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Temporary Interruption to Dry Weather; Droughts Eased

29 04 2019

Dale C. S. Destin |

Drought Level is Slight

A drier than normal start to the year continues across Antigua; however, there was a temporary interruption – March turned out wet, relatively. The month had 59.6 mm (2.35 in), the most for March since 2013. Most of the rain fell on the 29 March – over 52%, otherwise the story for the month would have been quite different. The rainfall for March was 15% more that usual; notwithstanding, droughts continue, although eased a bit.

The last three-month period – January to March, upon which the assessment of the current intensity of the drought is based, was below normal. The period had 127.5 mm (5.02 in), while the normal amount of rainfall is 176.0 mm (6.93 in).

Rainfall totals for the past 24 months plus normals, anomalies and records

We remain in a severe meteorological drought, the worst category on our drought scale. However, at the moment, the current intensity is slight, down from moderate. Recall that the overall description of the drought is based on the worst intensity achieved during its lifetime; however, over time, the intensity will fluctuate. Severe intensities were observed May-July and June-August of last year.

Potworks Dam, our billion-gallon surface catchment, has fallen below extraction levels – not potable water is currently available from the Dam. Water rationing is imminent but has been delayed by the presence of a number of desal plants operating in the country.  

Potworks Dam as of April 2, 2019 – drying up; picture courtesy Karen Corbin of the Humane Society

The eighteen-month period – October 2017 to March 2019, the duration of the drought thus far, is deemed severely dry. The total for the period of 1170.9 mm (46.10 in) is the fourth lowest on record, for such a period, dating back to 1928. This interval normally gets 1781.3 mm (70.13 in), which means a rainfall deficit of near 34% – close to one-third of the usual rain was absent.

Based on the last set of rainfall forecasts from regional and especially international sources, the news remains discouraging for rainfall. Overall, below normal rainfall is likely for the next six months – May to October 2019. Thus, there is every reason to believe that the droughts will not only continue but reintensify. The chance of the droughts ending is, at the very most, 30% or low.

Probabilistic multi-model ensemble forecast of rainfall for May-July 2019, based on 12 global models – 70 to 80% chance of below normal rainfall for Antigua and Barbuda

Early projections have us with a 60 chance of being drier than normal for the year, with a 45% chance of the rainfall total being in the bottom 20th percentile of all years. Further, around 977 mm (38.5 in) of rain is forecast for 2019, with a 70% chance it falling in the range 699 to 1321 mm (27.5 to 52.0 in).  

On average, our severe meteorological droughts last for around 16 months, but not continuously at severe intensity. At current, the drought is in its 19th month; the longest such drought on record lasted 38 months – Jul 2013 to August 2016.

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Continued Below Normal Rainfall; Droughts Loom Large for Antigua

1 03 2019

Dale C. S. Destin |

Rainfall

Rainfall for the past 24 months for varying time intervals compared to the normal/average and records

Antigua has had a drier than normal start to the year and the second consecutive drier than normal month. The rainfall for January was the driest since 2015 and the 14th driest on record dating back to 1928. Nearly half of the normal rainfall did not take place; the rainfall total of 40.4 mm (1.59 in) is only 59% of the average for the month. The near record rainfall of the first half of November 2018, is becoming a distant memory and the reintensification of the droughts looms large.

CurrentDroughtIntensityThe last three-month period – November to January, upon which the assessment of the current intensity of the drought is based, was slightly dry. However, the rainfall total fell in the near normal category. The three-month period had 310.1 mm (12.21 in), while the normal amount of rainfall is 422.7 mm (16.64 in).

We remain in a severe meteorological drought, the worst category on our drought scale. However, at the moment, the current intensity remains at slight, for the third month in a row. Recall that the overall description of the drought is based on the worst intensity achieved during its lifetime; however, over time, the intensity will fluctuate.

Potworks Dam, our billion-gallon surface catchment, is relatively close to falling below extraction levels. Water rationing is imminent or already occurring. This is indicative of the continued drought, which has no end in sight, at the moment.

The sixteen-month period – October 2017 to January 2019, the duration of the drought thus far, is deemed severely dry. The total for the period of 1083.8 mm (42.67 in) is the third lowest on record, for such a period, dating back to 1928. This interval normally gets 1673.9 mm (65.90 in), which means a rainfall deficit of 35% – more than one-third of the usual rain was absent.

Based on the last set of rainfall forecasts from regional and especially international sources, the news remains discouraging for rainfall. Overall, below normal rainfall is most likely for the next three months – March to May 2019. Beyond this period, there is notable uncertainty; however, the ECMWF IFS model, one of the more reliable models is forecasting continued drier than normal conditions being most likely for June to August 2019. Thus, there is every reason to believe that the droughts will reintensify. The chance of the droughts ending is, at most 25% or low.

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Mar-May 2019, Based on 12 Global Models

On average, our severe meteorological droughts last for around 16 months, but not continuously at severe intensity. At current, the drought is in its 17th month; the longest such drought on record lasted 38 months – July 2013 to August 2016.

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Relief Unlikely for Drought Stricken Areas of the Eastern Caribbean

1 02 2019

Dale C. S. Destin |

According to the latest Caribbean Climate Outlook Newsletter (CCON), Anguilla south to Trinidad, including Barbados will most likely experience below normal rainfall for the upcoming season – February to April (FMA). This means that any drought occurring in these islands will likely get worse or remain unchanged.

Over the period October-December, severe droughts have developed or are ongoing across parts of a number of islands to include:

  • Hispaniola;
  • Guadeloupe;
  • Martinique and
  • Barbados.

A scarcity of rainfall in 2018 and mostly likely lower than usual rainfall through April 2019 have led to long-term droughts or concern of long-term droughts in many islands, according to the February to April Newsletter. These include:

  • Antigua and Barbuda
  • Cayman;
  • NW Cuba;
  • Northern Dominican Republic;
  •  Grenada;
  • Martinique;
  • Northeast Puerto Rico and
  • Tobago.

CCON blames the likelihood of below normal rainfall for FMA on a weak El Nino, which is forecast to last through the period.

El Nino could last through the wet season, which is bad news, as it normally causes reduced rainfall and or droughts across most of the Caribbean – particularly in the wet season. 

El Nino refers to the unusual warming of the central and eastern tropical parts of the Pacific Ocean, which historically occurs every 2 to 7 years and lasting for 9-12 months, sometimes longer. It generally has the effect of causing drier than usual weather across the Eastern Caribbean.

We are in the dry months of the year. Traditionally, not a lot of rain fall across the Caribbean during FMA. It is a part of the heart of the dry season for the vast majority of the region, with only January-March being drier, as a whole.

The usual rainfall totals: February to April

The dryness of the season is normally especially evident across Aruba, Curacao and Bonaire – the ABC Islands, who have average rainfall for this period of below 75 mm (less than 3 in). It is not unusual for these islands to see zero rainfall during these months, in some years.  

Click here or the graphic above to read the full Newsletter

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Drier Than Normal December; Drought to Reintensify

30 01 2019

Dale C. S. Destin |

DCurrentDroughtIntensityecember was drier than normal for Antigua. The rainfall total of 65.8 mm (2.59 in) was below normal – 65% of the average for the month. This was the driest December since 2015. The month had very little positive impact on the droughts; hence, they will likely reintensify in the upcoming months.

The last three-month period – October to December, upon which the assessment of the current intensity of the drought is based, was slight dry. However, the rainfall total fell in the near normal category. The three-month period had 329.2 mm (12.96 in), while the normal amount of rainfall is 413.5 mm (16.28 in).

Rainfall for the past 24 months

Rainfall for the past 24 months for varying time intervals compared to the normal/average and records

We remain in a severe meteorological drought, the worst category on our drought scale. However, at the moment, the current intensity is slight, for the second month in a row. Recall that the overall description of the drought is based on the worst intensity achieve during its lifetime; however, over time, the intensity will fluctuate.

Potworks Dam, our billion-gallon surface catchment, is again returning to critically low levels. The Authorities will be cutting back on extraction from the Dam and water rationing is imminent, if not already started. This is indicative of the continued drought; notwithstanding the ample rainfall of November.

The fifteen-month period – October 2017 to December 2018, the duration of the drought thus far, is deemed severely dry. The total for the last 15 months of 1043.4 mm (41.08 in) is the second lowest since 1969 and the fourth lowest on record, for such a period, dating back to 1928. This particular interval normally gets 1615.7 mm (63.61 in), which means a rainfall deficit of 35% – more than one-third of the usual rain was absent.

Based on the last set of rainfall forecasts from regional and especially international sources, the news is discouraging with respect to rainfall. Overall, below normal rainfall is likely for the next six months – February to July 2019, with moderate confidence that the period February to April – 2019 having well below normal rainfall. Thus, there is every reason to believe that the droughts will reintensify. The chance of the droughts ending is, at most 20% or slight.

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Jan-Mar 2019, based on 12 global model

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Jan-Mar 2019, based on 12 global models

On average, our severe meteorological droughts last for around 16 months, but not continuously at severe intensity. At current, the drought is in its 16th month; the longest such drought on record lasted 38 months – Jul 2013 to August 2016.

Last year – 2018, was the eighth driest on record, dating back to 1928. It was also the second driest since 1983; only 2015 has been drier since 1983 – 35 years ago.

accumulation_december2018

It is too early to say with any confidence whether the rainfall for 2019 will be below, near or above normal. However, early indicators suggest it could be another tough drought year for Antigua and Barbuda.

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9th Driest July on Record for Antigua, Droughts Continue

26 08 2018

Dale C. S. Destin |

July 2018 was the ninth driest on record for Antigua dating back to 1928. The last time we had a drier July was 2015, when we recorded our driest year in, at least, 145 years.

July2018

The total rainfall for the month of 39.6 mm (1.56 in) was a meagre 39% of what normally falls – 100.3 mm (3.95 in). Hence, there was a painful 61% rainfall deficit for the month.

From_mod_to_severe_droughtThis was also the third driest July or the third driest start to the wet season since 1977. Only 2015 and 2014 Julys were drier, with 33.3 mm (1.31 in) and 19.3 mm (0.76 in) respectively, in recent times.

The last three-month period – May to July, upon which the assessment of the current intensity of the drought is based, was severely dry. In that time, only 96.3 mm (3.79 in) of rain fell. This is the fourth driest such period on record and the second driest since 1977.

Cumulatively, May, June and July normally yield 273.1 mm (10.75 in) of rain; however, a massive 65% of it did not fall. This means that we are now in a severe meteorological drought, the worst category on our scale. Other droughts are believed to be at similar severity. Recall that there are, at least, five types of droughts.

RainfallForPast24Months_July2018

Rainfall (in) for the past 2 yrs. All periods showing well below or below normal rainfall.

So, overall, we are now in a severe drought that is currently at severe intensity. Last month, it was assessed to be a serious drought that was at moderate intensity. Recall that the overall description of the drought is based on the worst intensity achieved since it started; however, over time, the intensity will fluctuate.

Potworks Dam, with a billion-gallon capacity, has been totally dry for a few months now. The vegetation of the Island continues to struggle badly – grass has ceased growing in some locations. Many fields are bare, with some having large and dangerous cracks. Some animals are said to have perished due to insufficient food and water. These are indicative of the fact that the droughts, not just meteorological, are at severe levels.

Potworks_Dam_Aug22018

Potworks Dam – August 2, 2018. Picture courtesy Karen Corbin – Humane Society

Happily, the full brunt of the droughts continues to be held at bay by the presence of the desalination plants, which are virtually the only source for potable water in the country. Notwithstanding, many impacts are starting to break through. Potable water is being rationed, places have been left without water for days to weeks, at a time, notwithstanding a schedule issued by APUA – the water authority, to provide water to everyone, at least, three times per week.

The ten-month period – October 2017 to July 2018, the duration of the drought thus far, is deemed severely dry. The total for the last ten months of 504.2 mm (19.85 in) is the third lowest on record and the lowest since 2001. The period normally gets 945.1 mm (37.21 in) – nearly twice the amount that fell.

Based on the last set of rainfall forecasts from regional and especially international sources, the news remains discouraging. Overall, below normal rainfall is likely, if not expected, for the next six months – September 2018 to February 2019. Thus, there is every reason to believe that the droughts will continue and likely worsen. The chance of the droughts ending is, at most 30% or low.

SON_Aug2018

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Sep-Nov 2018

On average, our severe meteorological droughts last for around 16 months, but not continuously at severe intensity. Will this one continue for another six months? Very likely, given the climate signals.

The probability of 2018 being a drier than normal year remains high – 75%. The best forecast for rainfall amount for the year is 872 mm (34.3 in) with a 70% confidence of the amount ranging between 658 mm (25.9 in) and 1130 mm (44.5 in). Normally, we get 1206.5 mm (47.5 in) annually.

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Driest June in Over a Generation for Antigua, Droughts Continue

23 07 2018

Dale C. S. Destin |

June 2018 was the driest for Antigua in 33 years – over a generation. With the median age of the Antiguan population being around 31, most Antiguans have never seen a drier June. Not since 1985 has Antigua experienced a drier start to summer.

Potworks_Dam_Jul6_2018

The total rainfall for the month of 12.7 mm (0.50 in) was a parched 18% of what normally falls – 69.3 mm (2.73 in). Thus, there was an excruciating 82% rainfall deficit for the month.

This was the third driest June on record dating back to 1928. Only 1985 and 1974 Junes were drier with 12.4 mm (0.49 in) and 8.1 mm (0.32 in) respectively. The 12.7 mm for this June has a return period of 34 years i.e. such severe dryness for the month only occurs once in every 34 years, on average.

ModerateMetDroughtUnchangedThe last three-month period – April to June, upon which the assessment of the current intensity of the drought is based, had 128.3 mm (5.05 in), only around half of the normal total of 258.6 mm (10.18 in). This puts the meteorological drought current intensity at moderate, unchanged the previous assessment.

Overall, we are in a serious meteorological drought, but currently it is at moderate intensity. The overall description of the drought is based on the worst intensity achieved since it started; however, over time, the intensity will fluctuate.

Potworks Dam, with a billion-gallon capacity, has been totally dry for a couple of months now. The vegetation of the Island is struggling – grass has virtually ceased growing in some locations. Many fields are bare, with some having large cracks. These are indicative of the fact that the droughts not just meteorological, are at moderate levels or worse.

Happily, the full impacts of the droughts continue to be masked by the presence of the desalination plants; however, impacts are starting to break through. Potable water is being rationed, some places have been left without water for many hours to weeks, at a time. There will be a big press conference this morning by APUA – the water authority, to provide answers to the water problem.

The dry season – January to June, had well below normal rainfall. On a scale of 1 to 100, with 100 being best rainfall situation and 1 being the worst, the rainfall was less than a 10. Only 254.3 mm (10.01 in) or 59% of the normal total of 434.6 mm (17.11 in) fell. It was the 10th driest dry season on record dating back to 1928. Only dry season 2015 was drier since 2004.

RainfallForPast24Months_June2018

Rainfall (in) for the past 2 yrs. All periods showing well below or below normal rainfall.

The nine-month period – October 2017 to June 2018, the duration of the drought thus far, is deemed severely dry. This means that the total is in the bottom 5% of the historical data. Such dryness happens around once every 20 years, on average.

The total for the last nine months of 464.6 mm (18.29 in) is the lowest since 2001 and the third lowest on record dating back to 1928. The period normally gets 845.1 mm (33.27 in).

Based on the last set of rainfall outlooks from regional and especially international sources, the news remains bad for rainfall. Below normal rainfall is most likely for the next six months – August 2018 to January 2019. Thus, there is every reason to believe that the droughts will continue and likely worsen. The chance of the droughts ending is at most 20% or slight.

Prob Multi-Model Ensemble Forecast For ASO_Jul2018

Probabilistic Multi-Model Ensemble Forecast of Rainfall For Aug-Oct 2018

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. Will it go for another three months? Yes, it is now almost certain that this drought will last for a year or more.

Our confidence of 2018 being a drier than normal year is growing. It has increased from 60% to 75% confidence. The best forecast for the amount of rain for the year is around 855 mm (33.7 in) with a 70% chance of the amount ranging between 625 mm (24.6 in) and 1139 mm (44.8 in). Normally, we get 1206.5 mm (47.5 in) annually.

Accumulations_June2018
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Drier Than Normal May for Antigua, Droughts Reintensify

28 06 2018

Dale C. S. Destin |

The rainfall for May 2018 was below normal for Antigua. The total of 43.9 mm (1.73 in) was only 42% of what normally falls – 103.6 mm (4.08 in). Thus, there was a 58% deficit of rainfall for the month.

DroughtDial-Slight_to_ModerateThe last three-month period – March to May, upon which the assessment of the current intensity of the drought is based, had 135.1 mm (5.32 in), only 56% of the normal total of 240.8 mm (9.48 in). This puts the meteorological droughts current intensity at moderate, declining from slight.

With Potworks Dam 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 continue to be masked by the presence of the desalination plants.

The eight-month period – October 2017 to May 2018, the duration of the drought thus far, is deemed severely dry. This means that the total is in the bottom 5% of the historical data; such dryness is unusual – it happens, at most, once every 20 years, on average. The total for the period of 451.9 mm (17.79 in) is the lowest since 2001 and the fourth lowest on record dating back to 1928. The period normally gets 775.7 mm (30.54 in).

TemporalRainfall

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 – July to September. Further, recent outlooks from global models indicate that the next six months will see below normal rainfall. Thus, there is every reason to believe that the droughts will continue and likely worsen.

The rainfall total for the year thus far – January to May, is well below normal. The 365.3 mm (14.38 in) is only 66% of what normally falls. Of the 91 years on record, only 17 have been drier to this point.

RainfallAccumulations_May2018

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 will significantly exceed 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 eight-month mark. Will it go another four months? The answer still looks more like to be yes than no.

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