Hurricane and tornado season 2021 in the USA above average expected, thanks to La nina

La nina such a main predictor of hurricanes and tornadoes in the USA, both will be still here until Autumn 2021, what means above average hurricane and tornado season for Americans.

While hurricanes are during La nina pattern strongly associated with a wind shear (when there is less wind shear in the atmosphere, storms can develop with less obstruction), tornado risk is higher thanks to position of jet-strem, flowing from northwest to southeast across Midwest, with a higher probability of Arctic cold blasts on the back side of Rossby waves and tropical air advections on their front side.

Tornado season 2021 already has started above parts of USA in March, when 207 tornado reports were reported and 64 of them in Alabama, what is regionally unprecedented event.

Tornadoes came in 3 outbreaks, around 17., 25. and 31. March 2021.

A peak of tornado season however only coming, from April to June 2021 inhabitants of central and eastern USA should be prepared for explosive season with deadly tornadoes.

Hurricane season is officially beginning in June 2021, but the first tropical depressions or tropical storms should appear earlier.

According to Accuweather, 16-20 tropical storms, 7-10 hurricanes an 3-5 major hurricanes are expected above Atlantic in 2021 season. Many of them will threat the USA.

Every year watched ACE parameter will have values around 120 – 160, while average is 123.

If La nina will be in the second half of the season stronger, it should be the third year, with 22 or more Atlantic tropical storms, after 2005 and 2020.

Unprecedented 2 years in a row with using of Greek alphabet is still possible, what should signalize, that not only La nina, but too climate change warmer surface ocean waters and warmer atmosphere, should play crucial role in increasing trend of extreme events, such as hurricanes (and atmospheric blocking and meandering of Rossby waves in tornado occurrence).

Illustration photos:, Tropical cyclone – Wikipedia

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Author: marekkucera
Writer about weather since 2007. The goal of this project is to inform a wide audience about extremes of weather, atmospheric circulation, and climate change around the world. If you like our work, you can support us on Patreon or donate.