HomeScienceWe’re about to run out of Atlantic hurricane names—again

We’re about to run out of Atlantic hurricane names—again

Major Hurricane Sam is, fortunately, going to avoid landmasses as it churns away.
Enlarge / Major Hurricane Sam is, fortunately, going to avoid landmasses as it churns away.

NOAA

It has been another record-setting hurricane season in the Atlantic basin, with a total of 19 named storms so far. It has been so busy that, with still more than two months to go until the season’s end, the National Hurricane Season is probably going to run out of names for the second year in a row.

Currently in the Atlantic, Hurricane Sam is rampaging across open waters. Fortunately this major hurricane is unlikely to threaten any landmasses. Behind Sam, it’s possible that Victor and Wanda will form during the next few days. Neither of these storms, either, poses any immediate threat to land.

If they do form, these two storms would exhaust the allotment of “official” names the National Hurricane Season uses for tropical storms and hurricanes. (Because the letters Q, U, X, Y, and Z are not commonly used for names, they don’t appear on the list of Atlantic names). In years past, the Miami-based hurricane center would then start assigning Greek letters for excess named storms.

The hurricane center has only ever had to do this twice, during the 2005 and 2020 seasons. Last year’s season was so fierce late in the game that two of the storms with Greek names, Eta and Iota, had to be retired after they both struck the coast of Nicaragua.

Even before the retirement of these Greek names, however, forecasters were already expressing concern about the confusing nature of using Greek names during extremely busy seasons. “There can be too much focus on the use of Greek alphabet names and not the actual impacts from the storm,” the World Meteorological Organization noted. “This can greatly detract from the needed impact and safety messaging.”

And so after last season, the World Meteorological Organization—which is designated by the United Nations to handle weather issues—decided to create a supplemental list of names in lieu of the Greek alphabet. These storm names, beginning with Adria, Braylen, and Caridad, will come into play this year if more than two named storms form during the remainder of 2021. This seems likely given that about 25 percent of activity during any given Atlantic season occurs after October 1. One particular area of concern next month is the Western Caribbean Sea, which has sea surface temperatures several degrees above normal.

So why is the Atlantic Ocean seeing more named storms? Part of this is attributable to the fact that we now have excellent satellite coverage of the entire Atlantic Ocean, Caribbean Sea, and Gulf of Mexico. Because of this, forecasters can identify closed circulations even if they only form for 6 or 12 hours. 

Plenty of Atlantic tropical storms and hurricanes form after October 1, on average.
Enlarge / Plenty of Atlantic tropical storms and hurricanes form after October 1, on average.

National Hurricane Center

How much of this increase in activity is due to climate change, however, is an open question. Based upon the best available science, the number of named storms forming in the Atlantic has significantly increased since the 1970s. But scientists attribute this greater activity to decreases in aerosols from humans and volcanic forcing, as well as natural variability. Scientists are not sure these increases will continue, as some models project future decreases in storm frequency in response to increasing greenhouse gas concentrations.

However, this is not the panacea it may seem. There is mounting evidence that rainfall rates within tropical systems are increasing and that stronger storms could get as much as 10 percent more intense on average. Higher winds, of course, increase the destructive power of a storm both in terms of wind damage and storm surge.

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