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The La Niña weather phenomenon, which persisted for the past three years and contributed to extreme weather all over the world, has finally left the scene after an especially protracted stay.
The La Niña state, which is identified by the Pacific Sea surface temperature, has ended as the Pacific Ocean waters near the equator have warmed to near-average temperatures. The U.S. announced the information on Thursday. Climate Prediction Center, “Final La Niña Advisory.” Climatologists and meteorologists predict that some of the weather patterns that have become established over the past few years will change in tandem with the change in marine temperature.
Numerous global trends in precipitation and temperature are correlated with La Niña. In the southern and western U.S., it exacerbates drought. As it moves rain eastward across the Pacific, it also causes rainfall in South America. La Niña consequently typically results in heavy rains and flooding in Southeast Asia and parts of Australia, as it has over the last three years.
In other places in the U.S. La Niña frequently causes the northeastern states to receive more rain. Additionally, the severity of the Atlantic hurricane season is influenced by air currents that are determined by ocean temperatures in La Niña years. The effects of the phenomenon are also felt in East and Central Asia and in Africa.
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According to Michelle L’Heureux of the NOAA, this most recent La Niña event, which started in spring 2020, was one of the most intense “in the historical record dating back to 1950,” she told Axios last year. It caused a lot of trouble for the three years that it was around. A severe drought that had already killed crops and forests, reduced reservoir levels to record lows, forced water restrictions, and had other effects worsened in California and many other western states.
The eastern U.S. was impacted by two very active hurricane seasons in 2020 and 2021, which led to numerous billion-dollar disasters, including Hurricanes Ida and Laura. More than 30 storms developed in 2020, setting records. Even though the Atlantic hurricane season in 2022 was less active than usual, it still produced several extremely dangerous late-season storms, including Hurricane Ian and Hurricane Fiona.
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El Niño-Southern Oscillation, or ENSO, is a cyclical climate pattern that affects weather patterns all over the world. La Niña is one side of ENSO. It is known as an El Niño period when the tropical Pacific Ocean surface is unusually warm. It is La Niña season when the same waters are unusually cold. An “ENSO-neutral” situation is one in which tropical Pacific waters are comparable to the historical average.
We are currently in neutral territory, according to NOAA and the National Weather Service. The threshold for La Niña is -0.50 °C, according to a blog post by prediction center researchers. At the time of the most recent temperature check, the central Pacific’s sea surface temperature was only 0.20 °C (0.40 °F) below the long-term average. The expected global weather during ENSO-neutral conditions, whatever that means these days, will be essentially average. However, the NOAA/NWS forecasters noted that it is unclear how long we will remain in the neutral zone.
Before the summer, the U.S. would experience an El Niño could anticipate an unusually weak hurricane season. The Southwest would likely experience rainy weather during an El Niño event, some eastern states would experience dry weather, and many northern states would experience warm temperatures.
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According to the ENSO post, there is a 60% chance that the Pacific will warm up enough to trigger an El Niño by the fall. The forecasters did add, though, that springtime forecasts are infamously unreliable. An official El Niño watch has not yet been established by the Climate Prediction Center.
A variation that happens independently of climate change brought on by humans is the ENSO cycle. But that does not imply that the two are unconnected. According to research, climate change is altering ENSO patterns and resulting in more extreme La Niña and El Niño events. Additionally, ENSO-related weather patterns, such as heatwaves and storms, can become more intense due to climate change.