Thursday, February 9, 2023

El Nino conditions on track to return after early summer

 There continue to be good odds that oceanic conditions will return to an El Nino state by mid-year, and that could portend a more active hurricane season for the Hawaiian Islands.

The U.S. Climate Prediction Center, in a paper issued today (February 9, 2023), said that the current La Nina is weak and continuing to weaken in the Pacific Ocean near the equator. Warmer waters are appearing in the western Pacific and moving east.

The El Nino phenomenon is often called ENSO, for El Nino Southern Oscillation. It is associated with movement of heat in ocean waters, changes in winds, alterations in rainfall patterns and much more. It seems to cycle every three to five years between El Nino, the warm phase, and La Nina, the cool phase, which we’ve been for the last couple of years.

Within a couple of months, we are expected to transition out of La Nina to ENSO neutral. That should continue until early summer. 

After that, not sure, but it’s starting to look like El Nino is in the cards, according to the latest forecast:

 “There are increasing chances of El Niño at longer forecast horizons, though uncertainty remains high because of the spring prediction barrier, which typically is associated with lower forecast accuracy.” 

Here is a National Weather Service report on the specific impacts of El Nino in Hawai’i. 

Here is the progression of the El Nino/La Nina condition, as reported on this blog: This from December 2022. And this from January 2023.

© Jan TenBruggencate

1 comment:

Anonymous said...

Jan,

According to “February 2023 ENSO update: the ENSO Blog investigates, part 3” by Emily Becker (https://www.climate.gov/news-features/blogs/february-2023-enso-update-enso-blog-investigates-part-3):

“This is the second month in a row that the Niño-3.4 anomaly (anomaly = ”difference from the long-term average”) has weakened, but it still exceeds the La Niña threshold of -0.5 °C. The most recent weekly Niño-3.4 anomaly, which comes from the OISST dataset, was just at that threshold, measuring -0.5 °C.”
“…. we won’t declare La Niña is over the moment the weekly value crosses the threshold—we’ll wait to be sure that the monthly average anomaly is in the neutral range (between -0.5 °C and 0.5 °C). The last time neutral conditions were present was summer of 2021.”
“…La Niña is still here. But forecasters expect that a change is imminent, with an 85% chance that the February–April period will be neutral. This is based on the consensus of our computer models and bolstered by some physical observations, including the weakening oceanic anomalies at the surface and subsurface.”

” But will the neutral conditions we expect for spring precede an El Niño?? Tell us what we really want to know! Currently, El Niño has odds of about 60% for next fall—and after three La Niña winters in a row, it might seem inevitable—but there are some factors that provide uncertainty. There’s our old friend, the spring predictability barrier. Forecasts made in the spring tend to have lower accuracy, at least in part because spring is a time of transition for ENSO (other possible factors are still being explored), making it harder for models to get a grip on what direction things are going.”

“In summary: La Niña is waning, and confidence is high that neutral conditions will be in place soon and will last through the spring and early summer. Chances for El Niño next fall are increasing, but we’ll have a better picture as we progress through and past the spring predictability barrier.”

So, it may be a bit early to start proclaiming “good odds”.