What Is A Double-Dip La Niña And How Will Affect Your Winter?

The National Oceanic and Atmospheric Administration (NOAA) recently declared that La Niña has re-developed. La Niña is part of a larger cycle called the El Niño Southern Oscillation (ENSO). By now you are likely familiar with El Niño and La Niña. However, the term “double-dip La Niña” may not be household terminology. Here is an explanation of what it means as well as a look at how it could affect winter in the United States.

According to NOAA’s press release, “La Niña is a natural ocean-atmospheric phenomenon marked by cooler-than-average sea surface temperatures across the central and eastern Pacific Ocean near the equator and is translated from Spanish as little girl.” Its warm climatological brother is El Niño, which is characterized by warmer-than-average sea surface temperatures. Both phases of the cycle can modify weather patterns, including Atlantic season hurricanes, around the world through teleconnection patterns. According to a NASA Fact Sheet website, the following conditions are typically associated with La Niña in the United States:

• Below normal precipitation – central to southern Rockies, Great Plains, Florida, and the Southwest (first three months).
• Above normal precipitation – Pacific Northwest, upper Southeast, northern Intermountain West, and parts of the Ohio Valley/north-central states.
• Cooler than normal temperatures – Pacific Northwest, north-central states, and the northern Intermountain west.
• Warmer than normal temperatures – Great Plains, southern Rockies, the Ohio Valley, mid-Atlantic, and the Southeast.

The above-average 2021 hurricane season is likely tied to La Niña conditions which, according to NOAA, developed in August (2020) and weakened by April (2021). I should caution the reader that such conditions are based on climatological analyses of previous La Nina conditions but can vary in any particular cycle.

NOAA’s press release notes, “Consecutive La Niña following a transition through ENSO neutral conditions are not uncommon and can be referred to as a “double-dip.” The current La Niña will likely extend into the spring of 2022. Seasonal outlooks for the fall and early winter season (graphics below) have been issued by the Climate Prediction Center and the influence of La Niña is clearly evident (and I am loving the projected warmer than normal conditions here in the Southeast). Let’ see what happens.