SACRAMENTO, Calif. —
For the first time since 2019, ocean waters in the equatorial Pacific have reached 0.5 C above average, signaling the return of a potentially strong El Niño.
The El Niño Southern Oscillation (ENSO) recently returned to its neutral phase following three years of La Niña.
The pattern shifts back and forth irregularly every two to seven years, bringing predictable shifts in ocean surface temperature and disrupting the wind and rainfall patterns across the tropics, according to NOAA.
One-half a degree above normal represents the threshold needed to satisfy the presence of El Niño. Even though the reading has met the threshold, El Niño is not yet official as temperatures need to be 0.5 C above average in the east central equatorial pacific for at least three months.
ENSO typically does not play much of a role in summer weather here in California, but winter is another story. The phase of the oscillation typically helps shift the odds in favor of a drier (La Niña) or wetter (El Niño) year.
The latest update from NOAA placed the odds of El Niño materializing and persisting into the winter months at 90%.
“In summary, a transition from ENSO-neutral is expected in the next couple of months, with a greater than 90% chance of El Niño persisting into the Northern Hemisphere winter,” said the May 11 update.
El nino update
Not only is El Niño expected, but a strong El Niño is increasingly likely, according to model projections. NOAA indicates there is an 80% chance of moderate El Niño and a 55% chance of strong El Niño (at least 1.5 degree Celsius above average).
During strong El Niño years, there is a strong signal California is wetter than average. During a weak to moderate El Niño, California is typically wetter than average, although the signal is much weaker, especially north of Sacramento. During strong years, most areas of the state are much above-average in terms of precipitation.
This doesn’t mean California is guaranteed to have a wet winter, though. A strong El Niño was present in 2015-16 which was a drier year for the state and La Niña was present for this past, record-setting winter.
The developing El Niño is certainly worth keeping an eye on in the upcoming months.