More stormy times ahead? Saul Loeb/AFP/Getty
Following a barrage of storms 鈥 such as Harvey, Irma and Maria 鈥 it seems like this year鈥檚 hurricane season may be one for the record books. But the Atlantic Ocean may be roiling even more strongly next year, if the La Ni帽a that looks likely to arrive in the coming months persists into next summer.
There is a 55 to 65 per cent chance that La Ni帽a will make an appearance before the US winter sets in, according to the released last week by the US National Oceanic and Atmospheric Administration.
La Ni帽a is one of two phases of the El Ni帽o Southern Oscillation (ENSO), a repeating change in surface ocean temperatures near the equatorial Pacific that affects climate patterns from the Pacific to the Atlantic.
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The two ENSO phases act like a seesaw between the two oceans, intensifying hurricane activity in one while weakening it in the other. La Ni帽a conditions tend to enhance such activity in the Atlantic and reduce it in the central and eastern Pacific, whereas El Ni帽o does the opposite.
These effects occur as a result of different wind patterns. During an El Ni帽o, a subtropical jet stream creates high-speed westerly winds that can cleave a developing Atlantic hurricane in two, or even prevent it from forming, says climatologist聽 at the Union of Concerned 精东传媒s in Oakland, California. This does not happen during La Ni帽as.
Windy again
La Ni帽a conditions typically last about 9 to 12 months, and some cycles can persist for up to two years. That means Florida, Texas and the Caribbean may be staring down the barrel of another severe hurricane season.
However, this is not a certainty. 鈥淭wo La Ni帽as are never alike, and they don鈥檛 happen in a vacuum,鈥 says at the NOAA Climate Prediction Center in Washington DC. He says other factors such as the Arctic Oscillation, a southward shift in arctic air masses, could also impact on Atlantic hurricanes.
The Climate Prediction Center does consider ENSO forecasts when it issues its outlooks, says Di Liberto. But when it comes to hurricanes, he says it’s better to wait and look at what the ocean conditions will be during the summer than in winter.
NOAA鈥檚 next La Ni帽a update will be on 9 November.
Read more: La Ni帽a to give some relief from warming after hottest April yet
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