By Dale C. S. Destin |
It looks like we may have a repeat of last year’s hurricane season. Early forecasts for this year’s Atlantic hurricane season indicate that it could make it two seasons in a row of quiet conditions. That would be a relief to many residents of Antigua and the Caribbean.
According to the UK-based Tropical Storm Risk (TSR), the Weather Channel (WC) and Colorado State University (CSU), the consensus is for around 11 named storms of which four will become hurricanes and two major hurricanes – Category 3 or stronger – this hurricane season. Those numbers are pretty normal. Based on the period 1950-2012, the hurricane season usually generates 11 named storms, six hurricanes and three major hurricanes.
Notwithstanding, the consensus of TSR and CSU is that the accumulated cyclone energy (ACE) index going to be roughly 35% below average. The ACE index is the measurement that takes into account the strength and duration of each tropical cyclone. Summing together the ACE of each cyclone, provides a snapshot of how active the season was outside of just the number of storms.
If these forecasts pan out, the 2014 hurricane season would be the fourth quietest since 1995, when the hurricane season went from a quiet phase to an active one. The average ACE since 1995 is 134, whereas, the ACE for 2014 is predicted to be 65 by consensus. This would also make this the quietest two year period since 1995.
However, the TSR forecast, in particular, was quick to point out that there are large uncertainties as to how the season will actually play out and the forecast skill, for this time of the year, is very low. In fact, last year’s early season forecasts offer a cautionary tale. The main factors pointing to an inactive hurricane season are the likelihood of El Nino and cool tropical Atlantic sea surface temperatures (SSTs).
Last year was a major failure for hurricane season forecasters. Of the dozen or so forecasts issued, all were “a complete bust”. This came as a surprise as the tropical Pacific SSTs was average to slightly cool and the tropical Atlantic SSTs were warmer than normal. More often than not, this is a recipe for an active Atlantic hurricane season. Admittedly though, although not perfect, these forecasts normally perform much better.
2013 Hurricane Season Tracks
Overall, there were 14 named storms, but only two became hurricanes. Both were weak Category 1 hurricanes.
Despite the slightly above normal number of named storms, the 2013 season tied with 1982 for the record fewest hurricanes since 1950. And 2013 was the first time since 1994 that there were no major hurricanes, something that’s only happened three other seasons since 1950, (1968 1972 1986). Further, this was the first time since 1968 that an Atlantic hurricane season failed to produce a Category 2 hurricane. Also telling was the season’s ACE index score, which is just 30% of the 1950 – 2012 average.
The Blame for Last Year
The low activity in 2013 is being blamed on an “unpredictable atmospheric pattern that prevented the growth of storms by producing exceptionally dry, sinking air and strong vertical wind shear in much of the main hurricane formation region, which spans the tropical Atlantic Ocean and Caribbean Sea,” said Gerry Bell, lead seasonal hurricane forecaster at NOAA. Bell also said that “detrimental to some tropical cyclones this year  were strong outbreaks of dry and stable air that originated over Africa.”
Similar explanations for the notably quiet season have also come from other scientists such as Chris Landsea, a meteorologist at the US National Hurricane Center and Philip Klotzbach, a hurricane researcher and seasonal hurricane forecaster at CSU.
Klotzbach also said that recent research has led researchers to “attribute a sizeable portion” of the negative hurricane conditions to the springtime weakening of the Atlantic Ocean overturning circulation. He said that a strong circulation favours high activity and a weak circulation favours low activity. According to Klotzbach, the 2013 spring circulation dropped to the “weakest since 1950.” There is ongoing research by other organizations to better understand the factors that contributed to the almost hurrcaneless season.
Hurricane Drought Continues
TS Chantal moving through the Caribbean – 2013
The 2013 season marks the 14th consecutive year of our hurricane drought. Since Jose and Lenny both made landfall in Antigua in 1999, the island has been spared from hurricane-force winds.
TS Chantal’s Tornado
This is not to say that the island has not been affected by any tropical cyclones since 1999 but rather none has caused any winds in excess of 73 mph to affect the country. This was also the first time since 2005 that no storm passed within 120 miles of Antigua. But of course, winds are not the only threat from tropical cyclones. Last year, we experienced one of the rare threats in this part of the world. Although Tropical Storm Chantal passed about 178 miles to the south, it spawned a tornado which proved destructive to Camp Blizzard.
Consecutive quiet hurricane seasons are most welcome. And although some may have felt letdown by the failure of the forecasts last year, most of us were ecstatic that the season was very slow. Over the next days and months, other organizations will issue their take on the 2014 season, which runs from June 1 to November 30. We look forward with bated breath to similar or better (lower) numbers. However, it is important to remember that regardless of the number of storms forecast for the season, it only takes one to ruin our year, so be prepared. I will keep you posted.
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