ENSO, or El Niño Southern Oscillation, is an ocean-atmospheric climate pattern comprising of La Niña, El Niño and a neutral phase. La Niña is a cooling of the equatorial Pacific water, while El Niño is a warming of the equatorial Pacific water. The warming and cooling of this part of the ocean can have an influence in jet stream patterns that affect the United States and the Atlantic hurricane season.
La Niña has recently ended after a couple of months and has transitioned into the neutral phase. This means that the Niño-3.4 index was nearly the same as the long-term average (1991-2020). The ocean wasn’t cooling or warming compared to average. The Climate Prediction Center has an ENSO-neutral pattern forecast to continue through the summer with a greater than 50 percent chance of it continuing through the fall season.
La Niña typically leads to warmer-than-average temperatures across the Tennessee Valley. During El Niño, much of southern Alabama tends to be cooler than average, with drier conditions favored as you travel north.
La Niña also plays a role in the Atlantic hurricane season in that it reduces the amount of wind shear in the Atlantic Basin, which can lead to better ingredients for tropical cyclone development. However, just because La Niña has ended doesn’t mean that the hurricane season will be quiet. ENSO-neutral conditions have been known to bring both active and quiet hurricane seasons, as there are other factors involved. Sea-surface temperatures, ocean heat content and wind shear are just some of the variables that play a role in what we see during a season. Colorado State University releases a hurricane forecast each spring, along with the National Oceanic and Atmospheric Administration. The university recently released its forecast and is calling for an above-average season. The average number of hurricanes in an Atlantic season is 14, seven of which become hurricanes on average, and three major hurricanes.
NOAA will release its forecast in May.
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