With the formation of Hurricane Alex – the first named storm of 2016 – in the Atlantic, MORECAST takes a look at just how unusual out-of-season tropical activity really is.
What made Hurricane Alex so rare is that hurricane season is between June and the end of November. Conditions do not favor tropical storms outside of the season, with the exception of a handful of storms that formed in May and December in past century. The strongest recorded storm outside of a regular season was Hurricane Able in December 1951, which was a category one hurricane with peak winds of 90 mph.
The reason for such limitation in strength during the winter is that hurricanes and tropical storms require immense amounts of energy to develop and strengthen. Such energy must be taken from the ocean in the form of heat, specifically sea surface temperatures of 79ºF (26ºC) or higher. Seas are at their warmest (in the Northern Hemisphere) during the usual hurricane season. Outside of that time frame, ocean waters are often too cold, and even if they are warm enough, winter and spring weather patterns push energy farther south, preventing tropical development. Because of the huge limitations to environments that storms need to form, out of season tropical activity is almost exclusively limited to southern portions of the Caribbean and off the coast of West Africa. As such, hurricanes have never posed a threat to the U.S. in the off-season. According to the NOAA Hurricane Research Division, there has never been a hurricane landfall in the U.S. between December 1 and May 31 as far back as records go (1851), with only 12 total hurricanes in the Atlantic Basin overall during the winter and spring months.
Nevertheless, weather always throw curveballs to go against the expected patterns from time to time. Hurricane Alex, which became a hurricane on January 14 south of the Azores, intensified from a subtropical storm in water temperatures of 73ºF, far colder than normally required. It is the first hurricane to form in the Atlantic during the month of January since 1938. The only other January hurricane on record was Hurricane Alice in 1955, though that storm actually formed in the final days of 1954.
As for Hurricane Alex, the storm only remained at hurricane strength for less than 24 hours. According to Reuters, the storm only caused minor damage on the Azores, as the strongest winds up to 85 mph stayed offshore of the tiny island chain. There were no reports of any injuries.
The unique conditions in which this hurricane formed will likely provide researchers with unique data that will help them improve hurricane forecasting methods and better understand the complex science of tropical storms.
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