Forecasters announced Thursday that El Niño has officially formed and with conditions expected to intensify by winter, making the event among the largest in over 70 years.
El Niño is a phenomenon that typically occurs every two to seven years and is characterized by unusually warm ocean temperatures in the Equatorial Pacific.
Conditions developed in the past month, forecasters at the National Oceanic and Atmospheric Administration (NOAA) said.
“El Niño conditions (are) already present at this point and expected to strengthen across the Northern Hemisphere into the wintertime over the next several months,” said Ariel Cohen, a lead meteorologist with NOAA’s National Weather Service.
For months, forecasters have anticipated an El Niño event, but their confidence in the likelihood of a powerful one just increased.
There’s now a 63% chance of “very strong” conditions, meaning that tropical Pacific waters may warm above 2 degrees Celsius between November and January, according to NOAA, up from a forecast of 37% issued last month and 25% in April.
That could rank this El Niño “amongst the largest El Niño events in the historical record going back to 1950,” Cohen said.
While the odds are tilted toward wet conditions, “by no means does a significant El Niño guarantee wet conditions,” Cohen said.
Over the past half-century, there have only been three “very strong” El Niño events. They occurred in 1982-1983, 1997-1998 and 2015-16. The first two were exceptionally wet for California, but the 2015-16 event brought drier-than-normal conditions across several southwest states.
