La Niña Persists in Pacific
Most La Niñas and El Niños peak in December or early January. In fact, El Niño was first called “El Niño de Navidad” (translated from Spanish to “the Christ Child”) by Peruvian fisherman in the 1600s due to its tendency to peak right around Christmas. Like most El Niños and La Niñas, the 2021–2022 La Niña peaked around Christmas and declined through late January and early February, but it unexpectedly and significantly re-strengthened in late February/early March as the Walker Circulation–the atmospheric circulation in the Tropical Pacific that drives the evolution of El Niño and La Niña–intensified. Our La Niña has since resumed a slow weakening trend, but because we are now starting from a cooler baseline, it will take longer than initially forecast for the tropical Pacific to return to Neutral conditions. The official forecast from the Climate Prediction Center is for La Niña conditions to continue into the Northern Hemisphere summer (53% chance during June–August 2022), with a 40–50% chance of La Niña or ENSO-neutral after.
For the Pacific Northwest, La Niña has a similar impact during the spring as it does during the winter, with odds slightly favoring cooler and wetter-than-average weather compared to normal due to enhanced troughing in the Northeast Pacific. However, spring in the Pacific Northwest is, in many ways, just a calmer, warmer, and less depressing version of winter. Spring doesn't have any common weather features that are *notably* distinct from winter, so it’s only natural that La Niña would impact the winter and spring climates in a similar fashion.
Other parts of the country have far more pronounced seasonal swings in climate, and as a result, La Niñas have different impacts to climate depending on the time of year they occur in. For example, La Niñas often bring more tornadoes to the US during the spring than Neutral or El Niño years due to the tendency for La Niñas to create a more robust storm track from the Southern Plains northeast to the Ohio River Valley. In the spring, systems that develop along this storm track tap into increasingly warm, moist air from the Gulf of Mexico to create thunderstorms, and the wind shear at different levels of the atmosphere between the southerly winds at the surface from the Gulf of Mexico and the westerly jet stream aloft causes these thunderstorms to rotate, occasionally spawning tornadoes in the process.
Right now, most forecasts show us transitioning back to a “Neutral” phase next winter, but long-range forecasts are generally quite poor this time of the year, as the atmosphere is in flux due to the change in seasons. By June, we should have a clearer idea of what next winter may hold. A third consecutive La Niña would not be unprecedented, but it is unlikely – since 1950, we’ve only had two instances of “three-peat” La Niña winters, and both occurred after major El Niño events (our current string of La Niñas did not). In the meantime, our odds favor a cool and cloudy spring, so be sure to get out and enjoy the sunshine when it makes an appearance!