A Hyperactive 2017 Atlantic Hurricane Season Thus Far

1 09 2017

Dale C. S. Destin |

We are at the halfway mark of the 2017 Atlantic hurricane season and it has been a hyperactive one with respect to named storms. On average, the first half of the season produces four named storms; however, this year it produced nine – more than doubled the amount. The last time there were 9 named storms by the end of August was 2012. Also this has only happened 5 times in the last 82 years.

2017HurricaneNames_Sep2017

Ensemble forecast

Most of the forecasts for the season are on track. The ensemble (mean) forecast, based on predictions from yours truly, the Integrated Forecast System of the ECMWF, the National Oceanic and Atmospheric Administration (NOAA), Klotzbach of Colorado State University and Saunders and Lea of Tropical Storm Risk.com (TSR) is for 17 named storms, 7 becoming hurricanes and 4 becoming major hurricanes.

Hurricane Season Forecast 2017

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 or likely to be outside of just the number of storms.

Thus far, the ACE is 29. This is relatively low and is indicative of the weak and short-live nature of the storms so far. The forecast is for a further 108 ACE over second half of the season. For the whole season, the ensemble forecast calls for an ACE index of 136. If this forecast pans out, the 2017 season would be around 30% more active than normal and the highest in seven years.

Tropical North Atlantic

The tropical North Atlantic is almost catching fire. It is the warmest June to August since 2010 and the third warmest on record dating back to 1948. The very warm sea surface temperatures are the main reason for the more than doubling of the number of named storms normal for up to this time of the year.

Probability of Antigua being hit by a hurricane

According to Klotzbach, the likely best similar years to the upcoming 2017 AHS are 1953, 1969, 1979, 2001 and 2004. Over these year, we were affected by four named storms with one being a major hurricane. Thus, based ONLY on similar years, the probability of Antigua being affected by one or more named storms is around 54%, up 5% fro the average. However, the probability for one or more hurricanes is around 2%, down by 20% from the average. Notwithstanding, as I write, there is Category 3 Hurricane Irma tracking towards the island, causing a great scare.

We are in the peak of the hurricane season – keep monitoring and complete your hurricane plan, just in case you need to use it.

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The Atlantic Hurricane Season Consensus Forecast – Aug 14, 2013

14 08 2013

| Dale C. S. Destin

The general consensus among tropical cyclone experts continues to be for an above normal Atlantic Hurricane Season for 2013. The consensus forecast calls for 17 named storms, 8 hurricanes and 4 major hurricanes. A normal season averages of 12.1 named storms, 6.4 hurricanes and 2.7 major hurricanes (See table 1).  Much of the science behind the outlook is rooted in the analysis and prediction of current and future global climate patterns as compared to previous seasons with similar conditions. For this season, the experts are citing a warmer than normal Tropical North Atlantic as the main reason for an above normal season prediction.

Hurricane Season Outlook

What does this mean for Antigua and Barbuda?

 Although there have been great advancements in the science of tropical cyclone (depression, tropical storm and hurricane), the science has not yet reached the stage where accurate predictions can be made of how many cyclones will form in a given year. Also, the science cannot accurately predict when and where these systems will move or make landfall months in advance. The details of the large-scale weather patterns that direct the path of these cyclones cannot be predicted more than a few days into the future. However, for the current active era (1995 – present), there is around a 32% chance or 3 in 10 chances of one or more hurricanes affecting Antigua (directly or indirectly) over the period August – October; this is 4% above the long term chance (1981 – 2010).

The 2013 Hurricane Season

The 2013 Atlantic Hurricane Season, thus far, have produced four (4) named storms. The strongest tropical cyclone for the season has been Tropical Storm Andrea with peak winds of 65 mph and minimum pressure of 992 mb. There has been no hurricane, thus far. Relative to Antigua and Barbuda, Chantal, during it passage through the Eastern Caribbean, spawned a destructive water spout, which impacted Camp Blizzard, Antigua. The hurricane season officially runs from June 1 through November 30 each year; however, tropical cyclones can and have occurred outside the season. The peak of the hurricane season is mid August to late October while the peak of the hurricane season for Antigua is mid August to late September (graph 1).

It Only Takes One

Regardless of the numbers, we should always approach the hurricane season in the same manner each year: be aware and be prepared. The prevention of the loss of life and property from tropical cyclones is a responsibility that should be shared by all. As a reminder, recall our lesson from Hurricane George of 1998: it only takes one hurricane to make it a bad season. Accordingly, the Meteorological Service will play its usual role in alerting the public of any tropical cyclone that may form and threaten Antigua and Barbuda, the Leeward Islands and the British Virgin Islands. We endeavour to provide weather and climate information for the protect life, property, livelihood and the enhancement of the economy – be prepared!

AnuStorms

Graph 1: Antiguan Tropical Cyclones – distribution of tropical cyclones within 120 statute miles of Antiguan (1851 – 2012)

For more information see the links below or email me at dale_destin@yahoo.com. You are also welcome to follow us via twitter facebook youtube and blog .

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References

Accuweather.com, State College, Atlantic Hurricane Season: Three US Landfalls Predicted [online]
<http://www.accuweather.com/en/weather-news/atlantic-hurricane-forecast-2013/12116274>
[Accessed 3 June, 2013]

Colorado State University, Fort Collins, Forecast of Atlantic Seasonal Hurricane Activity and Landfall Strike Probability for 2013 [online].
<http://typhoon.atmos.colostate.edu/Forecasts/2013/aug2013/aug2013.pdf>
[Accessed 12 August, 2013]

Florida State University, Raleigh, FSU COAP Atlantic Hurricane Season Forecast [online]. Available from:
<http://coaps.fsu.edu/hurricanes>
[Accessed 3 June, 2013]

National Oceanic and Atmospheric Administration, Silver Spring, NOAA: Atlantic hurricane season on track to be above-normal [online]. Available from: <http://www.noaanews.noaa.gov/stories2013/20130808_atlantichurricaneupdate.html>
[Accessed 12 Aug, 2013]

North Carolina State University, Raleigh, 2013 Atlantic Tropical Cyclone Outlook [online]. Available from: <http://cfdl.meas.ncsu.edu/research/TCoutlook_2013.html>%5BAccessed 28 May, 2013]

Tropical Storm Risk, London, August Forecast Update for Atlantic and U.S. Hurricane Activity in 2013 [online]. Available from: <http://www.tropicalstormrisk.com/docs/TSRATLForecastAug2013.pdf>
[Accessed 12 Aug, 2013]

United Kingdom Met Office, Exeter, Seasonal Forecasting of Storms [online]. Available from:
< http://www.metoffice.gov.uk/weather/tropicalcyclone/seasonal/forecasting-method&gt;
[Accessed 3 June, 2013]








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