Tropical Storm Bret 2017: Firsts or Firsts in a Long Time

9 07 2017

Dale C. S. Destin |

Tropical Storm Bret making landfall on Trinidad during the early morning hours of June 20, 2017.

Tropical Storm Bret making landfall on Trinidad during the early morning hours of June 20, 2017.

The formation of Tropical Storm Bret, a few weeks ago, resulted in several firsts or firsts in a long time for the Atlantic hurricane season, for the Eastern Caribbean and for Trinidad. Here are some we have noted:

  • 1st named storm to pass south of La Brea, Trinidad.
  • 1st named storm to form between Africa and the Caribbean before summer (June 21).
  • 1st time there were two named storms (Bret and Cindy) in June alive at the same time – June 20, 2017.
  • 1st designated potential tropical cyclone ever by the U.S. National Hurricane Center.
  • 1st named storm to impact the Eastern Caribbean before summer, since an unnamed hurricane in March 1908 impacted Antigua and the northeast Caribbean – the only other such system to impact the area before June 21; it formed in the Caribbean Sea.
  • 1st named storm to impact Trinidad in June since an unnamed hurricane in 1933. There is no other June storm on record for Trinidad.
All named storm on record for June - 1851 to 2016

All named storm on record for June – 1851 to 2016. Only three storms have affected the Eastern Caribbean in June since 1851. Two seen above plus Bret.

  • 1st named storm to form between African and the Caribbean in June since Tropical Storm Anna of 1979. There has ONLY been one other in June – an unnamed hurricane of 1933. So, there have ONLY been three named storms to impact the Eastern Caribbean in June on record.
  • 1st named storm to make landfall (pass over land) in Trinidad since Tropical Storm Bret of 1993. This has ONLY happened three other times – Fran of 1990, Alma of 1974 and an unnamed storm of 1933.
  • 1st named storm to pass within 65 nuatical miles (nm) or 120 km of Port of Spain, Trinidad, since Joyce of 2000. There have ONLY been 11 named storms in history, dating back to 1851, to have passed within 65 nm of Port of Spain, Trinidad; ONLY four were hurricanes, the last one being Hurricane Flora of 1963.
All named storms to have passed within 65 nm of Port of Spain, Trinidad on Record - 1851 to 2016

All named storms to have passed within 65 nm of Port of Spain, Trinidad on Record – 1851 to 2016

  • 1st time two named storms (Bret and Cindy) formed in June since 1909. It has happened ONLY two other times – 1906 and 1886. Both 1906 and 1886 turned out to be very active years; 1909 had near normal activity.
  • 1st named storm in June since Barry of 2013.

This June was quite active, in terms of named storms. The average for the month is 0.5 or one every other year. So, the two named storms which formed in this past June amount to the total we normally get in four Junes.

Is the activity of June an omen for the rest of the season? Well, the sample  size – three, is way too small to so say anything remotely definitive; however, FYI, of the three Junes with two named storms, two were quite active. Further, of the 10 seasons with at least 3 named storms forming between January 1 and June 30, six have been near or below normal.

All named storms for Jan-Jun 1851 to 2016

All Jan-Jun named storms on record, 1851 to 2016

Our most recent forecast of the season calls for above normal activity with 16 named storms, 7 becoming hurricanes and 4 becoming major hurricanes.

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Our Inaugural Forecast of the Atlantic Hurricane Season

5 07 2017

Dale C. S. Destin |

We have just released our first inhouse-produced forecast of the Atlantic hurricane season. It calls for an above normal season with 16 named storms, 7 becoming hurricanes and 4 reaching major hurricane status.

The main reasons for the above normal forecast are the warmer than usual tropical North Atlantic and the unlikely development of an El Nino. This season could turn our similar to last year’s and be one of the most active since 2010.

We hope that you find this forecast to be a useful resource in your hurricane season preparations. Please feel free to share you feedback with us as usual.  Click here for the full forecast.

Become hurricane strong!

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The Advent of Potential Tropical Cyclones – What, When and Why?

21 06 2017

Dale C. S. Destin |

History was made this past Sunday when for the first time ever the U.S. National Hurricane Center (NHC) issued tropical storm (TS) warnings for portions of the southern Caribbean, in the absence of a TS. This they were able to do by designating an approaching tropical disturbance a “potential tropical cyclone” (PTC).

PTC_Bret

In the past, it was the policy of the NHC to not issue tropical cyclone (the generic term for tropical depressions, TSs and hurricanes) watches and warnings UNLESS there EXISTS a threatening tropical cyclone (TC). This was the case even if there was a 100% certainty that one was going to form and impact land in a short space of time.

This policy served us well. However, just about every year, there would be, at least, that one tropical disturbance that would approach land, and everybody knew it was going to form into a TC just before impact. But the existing policy would get in the way of issuing watches and warnings that were needed to sprung persons into meaningful preparations.

A classic example of this was Hurricane Tomas of 2010. The system approach the southern Caribbean in late October and was not upgraded to a TS until it was less than 12 hours away from Barbados.

TOMASAsTropDisturbance2010

Tomas as a potential tropical cyclone on the “doorsteps” of Barbados, less than 9 hours before impact, with no warning issued

So instead of having 36-48 hours lead time to prepare, there was less than 9 hours. The bulletin announcing the warnings not only came late but also late in the day – 5 pm, which means any preparations that could be done, took place mainly after-dark, after it started to rain and after hardware stores were closed.

Tomas cause eight deaths and over US$500 million dollars in damage across the southern Caribbean. Some of the loss could have been avoided if many persons were not caught off guard due to the very short lead time between the formation of Tomas and its impact on the islands.

Hurricane Gonzalo of 2014 similarly caught many Antiguans off guard and unprepared. Many persons did not hear about the system until hours before it arrived. One person told me that she suffered damage to her property because she only found out what was happening when the winds started to pick up. By then, it was to late for her to go outside to close the shutters. Many boats were damage or sunk because of insufficient time to secure them.

Gonzalo_AsAPotentialTropCyclone

Gonzalo as a potential tropical cyclone less than 20 hours before it made landfall in Antigua as a hurricane with no warning issued

To solve this problem, the NHC has revised its policy and instead of just issuing watches and warnings for ONLY existing TCs, they have started this year to issue them for “PTCs”. By definition, according to NHC, a PTC is: ”…a disturbance that is not yet a TC, but which poses the threat of bringing TS or hurricane conditions to land areas within 48 hours.”

So, no longer is a disturbance, with a high chance of becoming a TC, allowed to march up to a country without 24-48 hours of watches and warnings being issued. Such systems can now be declared PTCs and the requisite watches and warnings will be issued, early.

It could be argued that an approaching tropical disturbance with a high chance of becoming a TC should be enough to spring persons into TS or hurricane preparations. However, studies have shown, a great number of persons just don’t prepare until watches or warnings are issued. Hence, the need for them to be issued early.

This policy change may be one of the most important ever by the NHC. Like the previous policy though, this one is not perfect; however, it plugs a huge loophole in the TC warning system. It has the distinct potential benefit of further reducing “surprised” attacks from TC, which translate into saving more lives, more properties and livelihoods.

Notwithstanding, it has the potential to create some unnecessary stress. This will be so when disturbances designated PTCs do not actually become cyclones. I expect, this be a rare occurrence. In any event, preparations for PTCs are deemed low-regret actions at worse.

Happily, we are off to a good start. The historic first PTC became TS Bret less than 6 hours before making landfall in Trinidad. Under the old policy, many persons would have been caught off guard and unprepared, not so this time around.

EarlAsATropDisturbanceAugust2016

Earl as a potential tropical cyclone forecast to be near or over Jamaica in a day or two with no watch or warning issued

This new policy may have been hastened into being by the actions of the Jamaica Meteorological Service (JMS) last year, as it related to TS Earl. Whereas the NHC made history by issuing its first TC warnings based on a PTC, they were not the first to do so. The JMS, quite bravely, “took the bull by the horn” and made the tough, unprecedented but right decision to issue TS warnings for Jamaica in the face of TS Earl of 2016, when it was what we are now calling a PTC, approaching the island.

So, well done to Jamaica for setting the stage for the first ever PTC bulletin by NHC – both are a success stories – mission accomplished, congratulations!





Dangerous Surfs to Threaten Beachgoers in Antigua and Barbuda Easter Monday

17 04 2017

Dale C. S. Destin |

Those heading to the beaches in Antigua and Barbuda should be wary of the threat of strong rip currents Easter Monday through Wednesday.

Seas Forecast Apr 17, 2017

Beaches on the northern and eastern sides of the islands will be at greatest risk for stronger and more frequent rip currents through midweek, due to large swells. Seas are on the rise and will peak on Tuesday with a combination of wind waves and swells nearing 3.0 metres (10 ft) occasionally reaching 3.8 metres (13 ft).

A huge low pressure system near the centre of the North Atlantic is pushing large swells to the region. Meanwhile, the winds in the area are on the increase, which will cause a rise in the wind waves.

Low pressure systems

Rip currents are not new to our shores. They are always present in situations like this and are characterised by water flowing away from the shore. The strength of the current is usually proportional the height of the swells.

Vacationers and residents should take precautions while at the beach. It would be prudent to seek out only beaches under the watch of lifeguards, if possible, and heed all warnings issued. The west facing beasches should be least affected.

Should you ever get caught in a rip current, never attempt to swim directly back to shore as you will be swimming against the current. Instead, swim parallel to the beach to escape the current’s grip before swimming ashore.

Small craft should use caution and heed all advisories, as seas will also be rough.

Similar sea conditions are forecast for most of the rest of the Leeward Islands, the Virgin Islands, Puerto Rico, Hispaniola, the eastern parts of the Bahamas, the Winward Islands and Barbados. The swells will also eventually reach Trinidad and Tobago and the Guyanas late Tuesday.

It is also likely to be a somewhat wet Easter Monday as the same low pressure system mentioned above is pulling a lot of moisture across the islands. The range of the possible rainfall total is wide – 0 to 12 mm (0 to 0.48 in).

The increasing wind will peak late Easter Monday at around 16 knots (18 mph) over open waters and 13 knots (15 mph) over land. Frequent higher gusts will take place.

Seas will return to near normal levels on Thursday.





The 2017 Atlantic Hurricane Season Early Forecast

7 04 2017

Dale C. S. Destin |

Good news! The early forecasts just issued for the upcoming 2017 Atlantic hurricane season (AHS) indicate a below normal season is most likely. This is forecast to be most evident in the number of hurricanes that forms (see graphic below). It could be as quiet as the 2014 and 2015 seasons. Nevertheless, the usual complete preparations are still very much required.

Ensemble forecast

The ensemble (mean) forecast, based on predictions from Klotzbach of Colorado State University, Saunders and Lea of Tropical Storm Risk.com (TSR) and AccuWeather.com, is for 11 named storms, 4 becoming hurricanes and 2 becoming major hurricanes.

2017HurricaneSeason

A better indicator of the activity for the season is the accumulated cyclone energy (ACE) index which is a measurement of the strength and duration of each tropical cyclone. Summing together the ACE of each cyclone, provides a more complete picture of how active the season is likely to be outside of just the number of storms.

This year, the ensemble forecast calls for an ACE index of 71. If this forecast pans out, the 2016 season would be around 30% less active than normal.

It must be noted though that there is very low skill in forecasting the AHS (June to November) in April. However, this is the best available forecast for the season, from this vantage point, and can be used as a guide for what is possible. A more skilful forecast will be available around June 1.

El Nino

 The development of an El Nino is the main climate factor that is forecasts to cause the hurricane season to be quieter than normal. El Nino is virtually synonymous with inactive AHSs, as it causes unfavourable conditions for tropical cyclones (tropical depressions, tropical storms and hurricanes). The main one being the creation of strong winds aloft that inhibits or rips tropical cyclones apart.

However, regardless of the above probabilities and forecasts, this is not a licence to do anything differently for this hurricane season. The same comprehensive preparations are required to deal successfully with any eventuality. It only takes one tropical cyclone to set you back for years. Recall – Gonzalo struck us in a quiet year – 2014.

New and improved products

As is the case annually, there are new and improved products that will be on show. The most significant of which will be the issuing of watches, warnings and advisories for potential tropical cyclones.  A potential tropical cyclone is being defined as a disturbance that has the potential to produce tropical storm or hurricane conditions to land areas within 48 hours.

This new product is expected to be a game-changer as it will eliminate surprise storms and hurricanes and increase the lead time for preparations for rapidly developing disturbances approaching land. If such a product were in place for Gonzalo of 2014, Antigua would have likely fared much better.

Click here for other new and improved products.

2016 hurricane season summary

The 2016 AHS was active – the first active (above normal) season since 2012 and the most active since 2010, based on the ACE index. It produced 15 named storms. Of the 15, 7 became hurricanes and 4 reached major hurricane status – at least Category 3 on the Saffir-Simpson Hurricane Wind Scale. The strongest tropical cyclone for the season was Major Hurricane (MH) Matthew with peak winds of 160 mph and minimum pressure of 934 millibars.

Hurricane Matthew caused the most devastation. In total, up to 600 deaths have been attributed to the storm, including over 500 in Haiti, making it the deadliest Atlantic hurricane since Stan in 2005.

The 2016 season is the first year since 2008 no tropical cyclone passed within 121 miles of Antigua. It was likely the least stressful AHS for the island in, at least, eight years.

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A Severely Dry February for Antigua

22 03 2017

Dale C. S. Destin |

February 2017 was a severely dry month for Antigua. It is the fourth driest February on record, dating back to, at least, 1928. Only one other February has been drier since 1983 – that of 2013.

Top4DriestFebForAntigua

On average, such an extremely low rainfall only occurs once in around every 33 years for February. In other words, there is only a 3% chance of such little rainfall taking place for the month.

The island-average for the February was just 14.0 mm (0.55 in). This makes it the driest and first below normal rainfall month since October 2016.

One month of dryness does not say anything about the rainfall for the upcoming months. However, with the probability of an El Nino rising, this dryness may be a sign of unwelcome things to come.

Recall the El Nino reduces rainfall activity across our area, mainly during the wet season, while the opposite – La Nina has reverse effect. It is still early days as to whether El Nino will develop but not too early for us to start to put contingency plans in place.

On average, February is our second driest month on, with an island-average of 55.9 mm (2.20 in).

Based on rain gauge measurement and satellite estimates, Barbuda fared slightly better with a total in the range of 12.7 to 38.0 mm (0.5-1.5 in).

Thus far, March is on track for, at least, near normal rainfall.

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Storm-Force Wind Gusts and Hazardous Seas Are Returning to the Area

7 03 2017

Storm-force wind gusts and hazardous seas are returning to the area. The weather will be generally good but the increased winds will cause the lower atmosphere to become somewhat unsettled, giving rise to occasional showers.

The Met Office has already issued a small craft warning and this is expected to continue in place through, at least, Friday. Given the expected conditions, small craft operators should not venture far from port, especially on the windward side of the islands. Beachgoers should avoid the waters of the north and east facing beaches.

The expected strong gusts will also make some outdoor activities very uncomfortable if not dangerous. At least, light objects should be secured, as minimal storm conditions are possible. Please be guided accordingly.

The wind speed will steadily rise to 28 to 44 km/h (17 to 28 mph) by late Tuesday and continue in that range until Thursday; thereafter, subsiding. Wind gusts as high as 67 km/h (41 mph) are possible in showers. The prevailing winds will be east-northeast.

The major concern about the winds is the impact on the seas. They will cause the seas to become very hazardous, with heights reaching 4 metres (13 ft), occasionally reaching 5 metres (17 ft) late Tuesday and staying at those heights until Friday, when they will start to subside.

These conditions, especially the seas, will not be dissimilar to what would obtain during the passage of a tropical storm through the area. However, no such system will be around.

The brunt of this windy weather will be felt mainly over open waters on the windward side of the islands, windward coastlines and elevated places.

The gale-force or storm-force wind gusts and associated strong winds will be as a result of a very steep pressure gradient across the area. Recall that winds blow due to pressure differences or pressure gradients, and the greater the gradients the stronger the winds and vice versa.

The last episode of similarly strong winds and rough seas was a recent as last week.

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