The rare ‘triple-dip’ La Niña appears to be coming to an end, according to the National Oceanic and Atmospheric Association (NOAA) and Australia’s Bureau of Meteorology (BOM). La Niña, the cool phase of the El Niño-Southern Oscillation (ENSO) climate pattern is expected to transition to neutral this spring as sea surface temperatures in the Pacific Ocean rise. Forecasters expected ENSO-neutral, which is neither La Niña nor El Niño, to persist throughout the spring and early summer in the Northern Hemisphere, fall and early winter in the Southern Hemisphere, in 2023 with a 50% chance that El Niño conditions develop in the second half of the year. After intense flooding in Eastern Australia and New Zealand, and drought across the Western U.S. during the summer months of 2022, will El Niño bring a welcome change or are additional climatic challenges on the horizon?
La Niña brought increased rainfall and cyclonic activity to eastern Australia and the North Island of New Zealand in recent months. In late 2022, Australia experienced one of the worst floods on record throughout most of the eastern provinces. Waterlogged fields and washed out roads led to a 2.8% decrease in agriculture gross value added product in Q4 2022. Meanwhile, Cyclone Gabrielle tore through Auckland and the North Island costing farmers more than $1 billion in estimated lost income, restoration, and infrastructure repair. Luckily, rainfall is expected to wane in the coming months as ENSO-neutral takes over according to New Zealand’s National Institute of Water and Atmospheric Research (NIWA). As the calendar turns to winter in the Southern Hemisphere, westerly winds will bring more typical cold fronts to the region and rainfall will gradually begin to lessen. If El Niño develops during the latter half of the year, hotter and drier conditions can be expected. High pressure airflows will reduce cloud cover, increasing surface temperatures as rainfall becomes more sparse. While there is a reduced risk for tropical cyclones, the warmer-than-average and drier-than-average conditions that come with El Niño poses additional drought risk during the summer months, particularly for Australia and New Zealand’s South Island.
Despite an onslaught of atmospheric rivers bringing record rainfall and flooding to California, ENSO-neutral conditions for the spring and early summer bring above-average temperatures throughout the Eastern and South-Central regions of the US with above-average rainfall throughout the Great Lakes and the Ohio River Valley, according to the NOAA. El Niño development would cause the Pacific jet stream to extend across the southern part of the country bringing wetter conditions to Southern California, Arizona, New Mexico and Texas, a much needed reprieve for the states who struggled with intense drought conditions in recent years. The Polar jet stream typically remains in the upper latitudes of the country and into Canada, allowing the Upper Midwest throughout the North-Central Plains to experience warmer-than-normal temperatures, particularly in the winter months. Ultimately, additional rainfall across the South could provide ideal growing conditions for crops in the late summer while warmer-than-average temperatures could benefit milk production in the Upper Midwest and Pacific Northwest throughout the early winter in 2023.
Charts Provided by the National Oceanic and Atmospheric Administration