May’s Showers Ended Droughts

24 07 2019

Dale C. S. Destin |

The mini deluge at the end of May ended the droughts that were being experienced by Antigua, most of which started back in October 2017, after hurricanes Irma and Maria. May 2019 was the second wettest since 2011 and the 15th wettest on record dating back to 1928, with an island-average rainfall of 183.9 mm (7.24 in).

Following a wetter than normal May, June was drier than normal, yielding a meagre 26.1 mm (1.03 in) – only 38 percent of the usual total for the month. Meanwhile, July thus far is running below average, which is not a good sign.

Based on the last set of rainfall forecasts from regional and especially international sources, droughts are likely to return in the upcoming few months – August to October. However, things are looking less challenging for rainfall, as ENSO has returned to neutral state from the rainfall suppressing effects of El Nino.

Probabilistic multi-model ensenble forecast of rainfall for June-August 2019, based on 12 global models – 50 to 60% chance of below normal rainfall for Antigua and Barbuda

Recent projection is for a 50 percent chance of 2019 being drier than normal. This has happily dropped from 65 percent in May, likely, at least in part, due to the dissipation of El Nino. Further, around 1024 mm (41.0 in) of rain is forecast for the year, with a 70% chance of it falling in the range 741 to 1371 mm (29.2 to 54.0 in). The average annual rainfall is 1206.5 mm (47.5 in).

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July’s Update: 2019 Atlantic Hurricane Season Forecast

15 07 2019

Dale C. S. Destin |

My updated forecast for the 2019 Atlantic Hurricane Season is out and it continues to call for above normal activity (an active season) being likely. The probability of this happening is up from the previous forecast from 45% to 54%. Thus, I am more confident of an above normal season.

It calls for an accumulated cyclone energy (ACE) index of 127 (up 13), 13 named storms, 6 hurricanes and 3 major hurricanes.

Forecast parameters with 70 percent confidence intervals in (parentheses), right

A typical season has 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), according to the Saffir Simpson Hurricane Wind Scale.

According to other forecasts surveyed, the consensus is for an ACE of 112, 13 named storms, 7 hurricanes and 3 major hurricanes – above to near normal season. Thus, my forecast is calling for more activity.  However, regardless of the forecast, you should always prepare the same each season, as it only takes one hurricane to ruin your year and or life.

The Atlantic hurricane season began on June 1 and will conclude November 30.

The next update will be issued around August 10.

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Hurricane Season History: June

29 06 2019

Dale C. S. Destin|

The first month of the Atlantic hurricane season is coming to a close and the month is yet to see a named storm (tropical storm or hurricane). And as it stands, we are unlikely to see any this June but this is not uncommon.

All 98 Atlantic Named Storms to Have Formed In June – 1851 to 2018

In total, the month has produced 98 named storms on record dating back to 1851; 38 were hurricanes and only 3 were major hurricanes – Category 3 or higher.  

On average, there is a 44% chance of a named Atlantic storm in June, 20% chance of a hurricane and 2% chance of a major hurricane.

In other words, there is a named storm every other June, and hurricane every 5 Junes and a major hurricane every 50 Junes, on average.

From 1851 to present, there have been 75 years with June storms and 93 years without. The June with the most named storms are 2012, 1968, 1936, 1909 and 1886 with three each.

The June with the most hurricanes is 1886. The strongest June hurricane is Alma of 1966 with 205 km/h (127 mph) winds; it did a “number” on Cuba and southeast United States.

The Eastern Caribbean Have Only Had Two Named Storms In June – 1851 to 2018

As the graphic above shows, only three times have we every experienced a named storm across the Eastern Caribbean in June – Tropical Storm Bret in 2017, Tropical Storm Ana in 1979 and an unnamed hurricane in 1933. Bret and the unnamed hurricane impacted Trinidad and Tobago and Ana impacted St. Lucia and Martinique.

Climatological Areas of Origin and Typical Hurricane Tracks for June

Clearly, when storms do form in June, they are likely to develop across the western Caribbean Seas and the Gulf of Mexico – there is very little to no action elsewhere across the basin.

No June Storm has Every Passed Within 120 Miles of Antigua on Record – 1851 to 2018

Quite evident also is that Antigua and Barbuda has never being impacted by a storm or hurricane in June. This may be surprising to many, but it is very much the case and this record is not about to come to an end this year.

This is the second consecutive year no named storm formed in June. The longest streak of no June storm is 7 years – 1947 to 1953. On the other hand, the longest streak of June storms is 8, 2010 to 2017.

Don’t be fouled by a quiet June – it says nothing about the rest of the hurricane season. The probability of an above normal season is similar with or without a named storm in June. Keep your guard up and get or stay prepared. It only takes one storm to ruin your year, if not life.





June’s Update: 2019 Atlantic Hurricane Season Forecast

12 06 2019

Dale C. S. Destin|

My updated forecast for the 2019 Atlantic Hurricane Season is out and it continues to call for above normal activity (an active season) being most likely. The probability of this happening is virtually unchanged from the previous forecast – 45%.

It calls for an accumulated cyclone energy (ACE) index of 114 (up 1), 13 named storms (up 1), 6 hurricanes (down 1) and 3 major hurricanes (up 1). Another way of interpreting my forecast is that it is calling for an above to near normal season – 80% probability.

Forecast parameters with 70 percent confidence intervals in (parentheses), right

A typical season has 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), according to the Saffir Simpson Hurricane Wind Scale.

According to other forecasts surveyed, the consensus is for an ACE of 114, 13 named storms, 7 hurricanes and 3 major hurricanes – above to near normal season, which is now almost identical to my forecast. However, regardless of the forecast, you should always prepare the same each season, as it only takes one hurricane to ruin your year and or life.

The Atlantic hurricane season begins on June 1 and concludes November 30.

The next update will be issued around July 10.

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Droughts Remain Slight, Despite Scarce April Showers

31 05 2019

Dale C. S. Destin |

Less than normal April showers fell across Antigua this year. The observed total rainfall of 42.2 mm (1.66 in), makes this April the second driest since 2006. Only 49 percent of the usual April showers fell, the rest added to our rainfall deficit; hence, droughts continue.

The last three-month period – February to April, upon which the assessment of the current intensity of the drought is based, was below normal. The period had 129.5 mm (5.10 in), while the normal amount of rainfall is 193.0 mm (7.60 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. 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 as of May 1, 2019 – drying up; picture courtesy Karen Corbin of the Humane Society

Potworks Dam, our billion-gallon surface catchment, has fallen below extraction levels – no 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.

The nineteen-month period – October 2017 to April 2019, the duration of the drought thus far, is deemed severely dry. The total for the period of 1213.1 mm (47.76 in) is the third lowest on record, for such a period, dating back to 1928. This interval normally gets 1866.9 mm (73.5 in), which means a rainfall deficit of near 35% – over 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 – June to November 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 June-August 2019, based on 12 global models – 70 to 80% chance of below normal rainfall for Antigua and Barbuda

Early projections have us with a 65 percent chance of being drier than normal for the year, with a 50% chance of the rainfall total being in the bottom 20th percentile of all years. Further, around 929 mm (36.6 in) of rain is forecast for 2019, with a 70% chance it falling in the range 664 to 1264 mm (26.1 to 49.8 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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May’s Update: 2019 Atlantic Hurricane Season Forecast

16 05 2019

Dale C. S. Destin |

Our updated forecast for the 2019 Atlantic Hurricane Season is out and it continues to call for above normal activity (an active season) being most likely. However, the probability of this happening has dropped a bit from 49% to 45% – previous forecast. It calls for an accumulated energy (ACE) index of 113 (down 11), 12 named storms (down 1), 7 hurricanes and 2 major hurricanes (down 1).

May's Update: 2019 Hurricane Season Forecast

A typical season has 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), according to the Saffir Simpson Hurricane Wind Scale.

According to other forecasts surveyed, the consensus is for an ACE of 102, 12 named storms, 5 hurricanes and 3 major hurricanes – near to above normal season. This is consistent with my forecast. However, regardless of the forecast, you should always prepare the same each season as it only takes one hurricane to ruin your year and or life.

The Atlantic hurricane season begins on June 1 and concludes November 30.

The next update will be issued around June 10.

Please share this blog, if you found it useful and follow me for more on the upcoming hurricane season and all things weather and climate – TwitterFacebook and Instagram.





Tropical Storm in May? Uncommon but not Unheard Of

5 05 2019

Dale C. S. Destin |

The first tropical disturbance for the year has formed and is currently over the Western Atlantic, near the southeast United States. Although this system is unlikely to form, it is not unheard of for tropical storms to develop in May, but it is relatively uncommon.

Looking back at the history, there have been 26 tropical storms in May, 4 of which became hurricanes – all category ones. This means, on average, one tropical storm forms every 6 to 7 years, based on data for the period 1981-2010, upon which the current climate is based.

All Tropical Storms in May on Record, 1851 to 2018

All May Tropical Storms, on Record – 1851 to 2018

The probability of a tropical storm forming in May is 15% (a slight chance), which means storms seldom form in May. The last time this happened was back in 2016 – Tropical Storm Bonnie.

Hurricanes in May are even more uncommon, if not rare. The probability of one forming in May is less than 3%, based on the full history – 1851 to 2018. This means there is a hurricane in May, on average, once every 42 years – once in a generation plus. The last one was Hurricane Alma of 1970.

One may be tempted to think that a tropical storm in May is an omen for an active (above normal) hurricane season. In a (small) poll done by me on twitter, 61% of persons said that a storm in May means an active or hyperactive season; however, this is false. The record shows the following w.r.t. seasons whenever there has been a storm in May:

  • 3 hyperactive;
  • 4 active (above Normal);
  • 11 normal and
  • 5 quiet (below normal).

In other words, whenever there was a storm in May:

  • 4% of the time the seasons were hyperactive;
  • 17% were active;
  • 48% were normal and
  • 22% were quiet.

Hence, a storm in May seems to portend a normal hurricane season, as opposed to an active or hyperactive season. So, we may, perhaps, want to wish for a storm in May.

With all the talk about climate change and tropical cyclones, one may be tempted to think that we are having more storms in May than before. However, the record does not bear that out. In the 38 years from 1981 to 2018, there have been nine tropical storms, no hurricane. By comparison, during the previous 38 years, there were eight tropical storms, two of which became hurricanes.

While tropical storms are not unheard of for the Atlantic Basin, they are unheard of for our neck of the woods – Antigua and Barbuda. We have never been impacted by a tropical cyclone (tropical depression, tropical storm or hurricane) in May.

The fortune of never having a tropical cyclone in May extends to the rest of the Eastern Caribbean. As a matter of fact, none has ever formed east of Hispaniola. Further, no hurricane has ever impacted/affected any Caribbean island in May. Clearly May is not a month to be worried about tropical storms.

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