![]() As always, there are key regional differences within the national averages – and those regional impacts may get reordered dramatically in the next few months, due to the major switch now underway from La Niña to El Niño. The tropical Atlantic has been running an astounding full degree Celsius or warmer above its long-term average, blistering warmth that in any other year would signal an active hurricane season ahead.” A warm, dry spring contributed to Canadian wildfiresĬonditions were a bit warmer and drier than usual when averaged across the contiguous United States during spring 2023, especially in May, according to the latest monthly climate update from the National Centers for Environmental Information. With sea surface temperatures at or near record-warm levels, that could tip the balance toward an active season, as discussed in our roundup of seasonal outlooks on June 1.Īs summarized on Friday by Yale Climate Connections contributor Michael Lowry in a Substack post: “Examining other recent episodes of El Niño coinciding with the peak months of hurricane season, Atlantic waters were generally much cooler than they are today. Met Office and the European Center for Medium-range Weather Forecasts has trended toward less wind shear in the Atlantic than usual for an El Niño hurricane season. The split jet stream fostered by El Niño tends to smooth out wintertime temperature contrasts across the U.S., leaving the northern states milder and drier than average and the southern states cooler and wetter than usual.Įl Niño may not deliver the hurricane-suppressing wind shear we’re used to seeing in the Atlantic. (Image credit: IRI/NOAA)Įl Niño events that develop in northern spring and summer typically persist through the following winter. Forecasts for the Oceanic Niño Index (ONI) compiled for May from an ensemble of dynamical and statistical models monitored by NOAA and the International Research Institute for Climate and Society. The statistics-based models, typically older and less sophisticated than the dynamical models, are less bullish, as shown below. The consensus of the dynamics-based seasonal climate models used to predict El Niño suggests the unfolding event will rank as a strong one, which would make it the most intense event since the record-level El Niño of 2015-16. (Image credit: National Drought Mitigation Center) Drought Monitor weekly summaries from Nov. That’s the most rapid such decrease in drought conditions since the monitor was founded in 2000, according to NOAA. ![]() Drought Monitor reported that the percentage of the country classified as being in drought (categories D1 to D4) dropped from 63% at the start of November 2022 to 19% by the end of May 2023 (see Figure 3 below). One vivid sign of the big transition underway: the U.S. (This winter’s welcome moisture there – which arrived in spite of La Niña’s tendency toward dry conditions over the Southwest – just goes to remind us that the tendencies fostered by El Niño and La Niña are probabilities, not guarantees.) The return of El Niño follows an unusually prolonged three-year period dominated by La Niña, which intensified the 23-year megadrought across the Southwest. Once El Niño or La Niña emerges, the odds reliably shift toward hotter, colder, wetter, or drier conditions for various parts of the globe. ![]() The natural phenomenon is part of a recurring ocean-and-atmosphere pattern that warms and cools the eastern tropical Pacific through El Niño and La Niña events that last from one to three years.
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