The status of whether the world is being impacted by an El Nino or a La Nina is determined by water temperatures in the central and eastern Pacific. (NOAA)
SILVER SPRING, Md. — La Niña is running a little bit behind, but the hurricane-fueling weather pattern is still expected to arrive just in time for the heart of the Atlantic hurricane season, according to NOAA’s latest monthly update.
Current conditions in the tropical Pacific Ocean, where sea surface temperatures determine whether we’re in an El Niño, La Niña or the “neutral” phase of neither, still indicate a neutral status, but on a downward trend.
The latest reading shows water temperatures just slightly above average (+0.3 degrees C, or +0.5 degrees F). While the atmosphere in the Pacific currently agrees, with trade winds operating in typical fashion during neutral phases, computer guidance and indications of cooler water at greater depths working its way toward the surface suggest a continued cooling trend.
However, the speed of the cooling trend isn’t quite as robust as earlier predictions had suggested. What was looking like perhaps a La Niña arrival as early as July is now pushing back to late summer or early fall.
Still, NOAA gives a 70% chance La Niña will arrive by then and that would be right on time to coincide with the peak of the hurricane season, which is typically September and October.
This hurricane season is already off to an intense start, fueled by widespread and enduring record ocean water temperatures across the Atlantic and Gulf of Mexico basins. That on its own would concern forecasters that it would be an active year.
La Niña’s typical effects on the tropical trade winds work to lessen wind shear over the Atlantic basin, adding more fuel to the fire and making conditions ripe for tropical development.
This comes as Colorado State University’s updated hurricane forecast says Hurricane Beryl’s record nearly 2-week-long trek through the Atlantic basin is a likely “harbinger of a hyperactive season.”
Yet even when hurricane season ends on Nov. 1, La Niña is expected to hang around through the winter. La Niña winters tend to bring a drier and milder winter to the southern half of the nation while the northern half tends to be cooler and wetter/snowier.