Updated Hurricane Season Forecast: Near to Above Normal Season is Now Likely

17 07 2018

Dale C. S. Destin |

Good news and bad news: Our July updated forecast for the 2018 Atlantic Hurricane Season is now available and it indicates that the hurricane season will likely be near to above normal. The prediction is for an accumulated cyclone energy (ACE) index of 99, 12 named storms, 5 becoming hurricanes and 3 becoming major hurricanes.

Jul2018HurricaneSeasonOutlook

The good news is that there is a 37 percent chance of there being a near normal season. The bad news is that there is also a 37 percent chance of there being an above normal/active season; hence, the near to above normal forecast for the season.

Recall that during a near normal season, there is a 33% chance of a named storm (tropical storm or hurricane) affecting, i.e. passing within 120 miles of Antigua and Barbuda. By comparison, during an above normal season, the chance soars to 75%.

With to hurricanes, the chance of us being affected during a near normal season – 18 percent, more than triples – 59 percent, for an above normal/active season. Further, we have never had a major hurricane during a near normal season. Clearly, an active season is least prefered.

Chance of Anu Being Affected By TS

These new numbers represent a marginal increase above those of the previous forecast. Previously, the forecast called for an ACE of 93, 11 named storms, 5 hurricanes and 2 major hurricanes. If the season turns out to be near normal, it would be due mainly to cooler than normal sea surface temperatures, across the tropical North Atlantic. If it turns out to be active, it would be mainly due to the absence or late development of El Nino.

Recall that the ACE is the overall predictor of a hurricane season, it is a measure that represent the total number of storms, their intensities and durations.

A typical season has an ACE index of 106, 12 named storms, 6 hurricanes, and 3 major hurricanes. Major hurricanes have sustained wind speeds of at least 178 km/h or 111 miles per hour (e.g., Category 3 or higher), based on the Saffir Simpson Hurricane Wind Scale.

If this forecast pans out, 2018 would be the least active since 2015. Notwithstanding, a season with activity second only to 2017, since 2005, cannot be ruled out.

According to other forecasts surveyed, the latest consensus is for an ACE of 89, 12 named storms, 5 hurricanes and 2 major hurricanes. Thus, our forecast is calling for slightly higher activity; however, regardless of the forecast, you should always prepare well each season, as it only takes one hurricane to ruin your year.

The Atlantic hurricane season started June 1 and will continue until November 30.

We will be updating this forecast by August 10.

If you found this article informative, I would be very grateful if you would help it spread by emailing it to a friend, or sharing it on Twitter or Facebook.

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Cooler Than Normal May for Antigua

30 06 2018

Dale Destin |

TempStmntGraphic_BelowNormalNotwithstanding being drier than usual, May was much cooler than normal, based on preliminary data record at the V.C. Bird International Airport (VCBIA), Antigua. The mean temperature of 26.4 °C (79.5 °F) was the lowest at VCBIA since 2012. Only six other Mays have been cooler on record dating back to 1969.

Further, at VCBIA, the mean daily minimum temperature (mean min) of 23.7 °C (74.7 °F), an indicator of night-time temperature, was well below normal. This is the lowest mean min for May since 1975 and only the third lowest on record dating back to 1969.

Additionally, the mean daily maximum temperature (mean max), an indicator of day-time temperature, was cooler than normal. The mean max of 29.3 °C (84.7 °F) tied with that of 2017 for the lowest temperature at VCBIA since 2014.

Looking deeper into the preliminary numbers at VCBIA, there was an above normal number of cold days (4) and cold nights (5). The most number of cold nights since 2008.

Clearly, the numbers indicated above, with respect to temperatures, differs from those recorded elsewhere across the island. We don’t have long enough datasets to speak definitively about temperatures for other areas of Antigua. However, it is believed that the rankings of temperatures are likely to be similar.

So, although other parts of Antigua had lower or higher temperatures, because temperatures are highly correlated, especially in a small island like ours, most if not all places had a cooler than normal May, relative to the given location. On average, some places across Antigua differ by as much as 5 °C (9 °F).

The reason for the cooler than normal temperatures is the same reason for the drought weather being experienced – cooler than normal sea surface temperatures across the tropical North Atlantic (TNA) Ocean. These temperatures are likely to remain cooler than normal for much of the rest of the year.

Tropical North Atlantic  (TNA) Index - Much Cooler Than Normal

Tropical North Atlantic (TNA) Index – a measure of the sea surface temperature between Africa and the Caribbean – much cooler than normal.

Based on record dating back to 1948, this past May was the coolest the TNA has been for the said month since 1989 and the sixth coolest on record.

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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.

If you found this article informative, I would be very grateful if you would help it spread by emailing it to a friend, or sharing it on Twitter or Facebook.

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No End in Sight for Drought-Hit Antigua

22 06 2018

Dale C. S. Destin |

There is no end in sight for the current drought affecting Antigua. Not only there is no end in sight but it is expected to get worse, perhaps much worse.

Potworks Dam, a Billion Gallon Dam - Jun 5, 2018.

Potworks Dam, our billion gallon dam, is empty. Pic taken Jun 5, 2018, courtesy Karen Corbin – Humane Society.

Analyses done for the upcoming months, for as far as the (forecasting) eyes can see – through December 2018, suggest a moderate drought or worse will continue. For the drought to end, we need a very wet month or a few months of above normal rainfall – it’s possible but highly unlikely, based on projected climate signals.

LikelihoodOfRainfallForAntigua

The period with the highest likelihood of getting less than usual rainfall is July to September. It is near 100% certain that this period will be, at least, moderately dry i.e. rainfall in the bottom 20% of the historical record. This means that such dryness occurs no more than once every five years.

Already, June 1-20 is tied for the second driest across some parts of the island in over a generation. Further, the year, thus far, is the driest since 2015 and the second driest since 2003.

Meanwhile, the rainfall for the year has a 60% chance of being below normal. The projection is for the year to get around 965 mm (38 in) with a 70% likelihood of it being in the range 686 to 1295 mm (27 to 51 in).  On average, Antigua gets 1194 mm (47 in).

Rainfall For Anu 2018

Ongoing or potential impacts of the drought include the following:

  • Crop or pasture damage or losses
  • Decreased food production and crop scarcities
  • Financial losses primarily to farmers and related sectors
  • Water shortages and restrictions
  • Higher than usual grass and bush fires
  • Environmental degradations

The current and projected dry weather is largely due to the ongoing cooler than normal tropical North Atlantic, which is projected to remain this way through much of the rest of the year. The dryness could be intensified by El Nino, which is now likely to develop by October.

Recall that drought is not the absence of rainfall but rather lower than usual rainfall or a deficit in rainfall. Thus, relatively dry weather conditions will prevail for the drought period.

If you found this article informative, I would be very grateful if you would help it spread by emailing it to a friend, or sharing it on Twitter or Facebook.

Follow us for all you need to know about the current drought and all things weather and climate. Follow us on twitterfacebookinstagramtumblrflickrgoogle+, and youtube. Thank you!





Updated Hurricane Season Forecast: Near Normal Season is Now Most Likely

12 06 2018

Dale C. S. Destin |

Good news: Our June updated forecast for the 2018 Atlantic Hurricane Season is now available and it indicates that the hurricane season will most likely be near normal. The prediction is for an accumulated cyclone energy (ACE) index of 93, 11 named storms, 5 becoming hurricanes and 2 becoming major hurricanes.

Jun2018HurrucaneSeasonForecast

This forecast is relatively good news for us because, during a near normal season, there is a 33% chance of a named storm (tropical storm or hurricane) affecting, i.e. passing within 120 miles of, Antigua and Barbuda. By comparison, during an active season, the chance soars to 75%. Further, we have never had a major hurricane during a near normal season.

Chance of Anu Being Affected By TS

These new numbers represent notable decrease below those of the previous forecast. Previously, the forecast called for an ACE of 119, 13 named storms, 6 hurricanes and 3 major hurricanes. Current and projected cooler than normal sea surface temperatures, across the tropical North Atlantic, are mainly responsible for the downward trend in this year’s forecast hurricane season activity.

Recall that the ACE is the overall predictor of a hurricane season, it is a measure that is based on the total number of storms, their intensities and durations.

A typical season has an ACE index of 106, 12 named storms, 6 hurricanes, and 3 major hurricanes. Major hurricanes have sustained wind speeds of at least 178 km/h or 111 miles per hour (e.g., Category 3 or higher), based on the Saffir Simpson Hurricane Wind Scale.

If this forecast pans out, 2018 would be the least active since 2015. Notwithstanding, a season with activity second only to 2017, since 2005, cannot be ruled out.

According to other forecasts surveyed, the latest consensus is for an ACE of 96, 12 named storms, 6 hurricanes and 3 major hurricanes. Thus, our forecast is calling for similar activity; however, regardless of the forecast, you should always prepare well each season, as it only takes one hurricane to ruin your year.

The Atlantic hurricane season started June 1 and will continue until November 30.

We will be updating this forecast by July 10.

If you found this article informative, I would be very grateful if you would help it spread by emailing it to a friend, or sharing it on Twitter or Facebook.

Follow us for all you need to know about the upcoming hurricane season and all things weather and climate. Follow us on twitterfacebookinstagramtumblrflickrgoogle+, and youtube. Thank you!





Very Dry March; Droughts Reintensify

26 04 2018

Dale C. S. Destin |

March 2018 was the driest since 2014 and the 12th driest March on record dating back to 1928. The island-average total for the month was 17.8 mm (0.70 in). This represents only 34% of the usual amount of 51.8 mm (2.04 in).

D&P_RainfallGraphic_Mar2018

Rainfall in inches for the past 24 months. Multiply by 25.4 to get mm.

The last three-month period – January to March, upon which the assessment of the current intensity of the drought is based, had 116.1 mm (4.57 in), only 66% of the normal total of 176.0 mm (6.93 in). This puts the meteorological droughts current intensity at moderate, down from slight.

DroughtGraphic: Slight_to_Moderate

With Potworks Dam about to go totally dry and the vegetation of the Island struggling, there is little doubt that other droughts are at moderate levels or worse. Thankfully, the full impacts of the droughts are being masked by the presence of the desalination plants.

Rainfall_Accu_Anu

Interestingly, in a negative way, the rainfall accumulation for the year, thus far, is not very dissimilar to that of 2015 and 1983 – the driest and second driest years on record, respectively. We make no conclusions here but it may be an ominous sign.

The six-month period – October 2017 to March 2018, the duration of the drought thus far, was seriously dry. The total for the period of 326.4 mm (12.85 in) is the fifth lowest on record dating back to 1928. It is also the lowest total for the given period since 2001. The rainfall deficit since the drought started is at 260.1 mm (10.24 in).

Based on the last set of rainfall outlooks, the news is not good for rainfall. Overall, below normal rainfall is most likely for the six-month period April to September. 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 slight – less than 30%.

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

Keep following us for more on this developing story and all things weather and climate. Follow us here on wordpress and also via twitterfacebookinstagramtumblrflickrgoogle+, and youtube.





2nd Wettest February In Years, Yet Less Than Usual Rainfall

1 04 2018

Dale C. S. Destin|

February 2018 was the second wettest since 2011, yet the rainfall total for the month was below the usual.  The island-average total was 35.8 mm (1.41 in); however, the usual amount for the month is 55.9 mm (2.20 in). Clearly, with only 64% of February’s rains falling, there was no positive impact on the drought situation being experienced.

Slight Meteorological Drought

Rainfall in inches for the past 24 months. Multiply by 25.4 to get mm. For records, the year given marks the start of the period.

The three-month period – December to February, upon which the assessment of the current intensity of the drought is based, had 198.6 mm (7.82 in). This puts the meteorological droughts at slight. However, with Potworks Dam about to go totally dry and the vegetation of the Island struggling, there is little doubt that other droughts are at moderate levels or worse. Of course, and thankfully, the full impact of the droughts is being masked by the presence of the desalination plants.

Drought Level is Slight

Based on the last set of rainfall outlooks, the news is not good for rainfall. Overall, below normal rainfall is most likely for the six-month period March to August. Thus, there is every reason to believe that the droughts will 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 slight – less than 30%.

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 six-month mark in the drought. Will it go another six months? Unfortunately, the answer looks more like yes than no.

Keep following us for more on this developing story and things weather and climate. We are available on twitterfacebookinstagramtumblrflickrgoogle+, and youtube








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