Canicula, Mar de Fondo, and other weather phenomena

By Julie Etra

Canicula, canicular period, canicular days or the season of canicula refers to the hottest part of the year. My neighbor Larry Woelfel and I were chatting about the lack of rain and heat this summer in Huatulco and he exclaimed, “Canicula! Look it up, Julie!” Easy assignment for this lover of language and etymology. The Latin root of the word is canis, or dog and is a 14th century Old English word pertaining to the dogstar Sirius. It also pertains to dog days, or the dog days of summer, common in English-lingo. The canicular period lasts four to six weeks, depending on precise location relative to the equator and declination of the sun. Technically it begins when at midday or noon the sun is at its maximum height over the horizon.

Mar de Fondo roughly translated as sea from the depth or sea from the deep, it is also known in Spanish as oleaje or surf.

This phenomenon has occurred several times this year along our southern Pacific coast. The first event took place on May 2 and impacted the coastal populations of Mazunte, Zipolite, and to a lesser extent Huatulco with its protected bays. Damage in Acapulco, in the adjacent state of Guerrero to the west of Oaxaca, was extensive, with flooding along the bay and resorts.

What is a Mar de Fondo? These massive wave ‘events’ are not caused at depth by tectonic activity like tsunamis. Although they come from the South Pacific, they are also not generated by currents.

On the surface, so to speak, it is a large wave or series of waves. They occur along the southern coast of Mexico, and can extend as far as Chile. They are characterized by their regular intervals and soft peaks, with wavelengths much greater than wave heights. They never break at sea. Oleajes are wind generated, but originate over the sea and at a great distance from their shoreline destination, where depths are great; they are not formed below the surface.

The intensity of the Mar de Fondo depends on the size of the storm and its orientation. They can travel thousands of kilometers with almost no dissipation and then reach the shores of the Mexican Pacific.

Waves generated in the South Pacific reach more than 10 meters, but decrease in amplitude as they travel, ending up around six meters offshore. Of course, there is variability depending on the coastline, which can cause an increase or decrease in size and frequency.

This phenomenon happens during the summer in the northern hemisphere since the southern hemisphere is in its autumn winter season when the winds are generated.

Screen Shot 2015-10-28 at 7.02.19 AMAnother rare weather event occurred in late August along the Oaxacan coast, where residents of Mazunte, Ventanilla, San Agustinillo, and Zipolite reported a tornado about a kilometer off the beach. There was some minor damage to structures, but, fortunately, no one was hurt. Authorities and locals indicated it was the first time they had heard of such a phenomenon in the area.

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