WASHINGTON – What was already a strong El Niño event is getting stronger, and the odds of it reaching "historic" levels have increased for the winter, according to NOAA’s latest update on the El Niño-Southern Oscillation (ENSO) cycle.
Sea-surface temperature anomalies in the central tropical Pacific Ocean, where El Niño thresholds are calculated, reached 1.8 degrees Celsius (3.2 degrees Fahrenheit) above average in the October measurement, keeping this event squarely in the "strong" category. Other areas farther east in the Pacific have reached 2.2 degrees Celsius (4 degrees Fahrenheit) above average.
"The reason that's important is those sea-surface temperatures control where normally large thunderstorms are, what we would call deep convection is," Dave DeWitt, the director of NOAA's Climate Prediction Center, told FOX Weather. "And that deep convection actually has a large influence on the jet stream. And when you have an El Niño event, the jet stream tends to shift south and east of its normal pattern. And that's how it has major impacts over the U.S."
In addition, NOAA forecasters indicate there is now a 35% chance of reaching "historically strong" levels, also known as "super El Niño," deemed at 2 degrees Celsius (3.6 degrees Fahrenheit) above average.
El Niños have only reached those levels three times before since 1950.
"When we have a stronger El Niño event, those storms and circulation patterns are typically stronger, meaning that this can have a larger influence on the jet stream and a larger influence on weather in the United States," Marybeth Arcodia, a research scientist at Colorado State University, told FOX Weather during an interview in October.
Mixed signals on how strong El Nino impacts will be
Dozens of computer models are run with different variations to determine the status and predict future cycles of the ENSO, but these computer outputs are rather inconclusive in saying the 2023-24 El Niño event will ever reach the significant threshold.
Another sign the El Niño pattern is not following a typical playbook and may be more challenging to forecasters is the amount of tropical activity observed around the globe.
During previous events, at least one ocean has seen a decrease in activity, but that has not been the case in 2023 with above-average tropical cyclone formations in the Atlantic, Pacific and Indian oceans.
Forecasters say episodes of El Niño and La Niña typically last between nine and 12 months, but double- or even triple-dip episodes can prolong the status for years.
Looking back at "historic El Nino" events
Deadly 1997-98 El Niño
Over the winter of 1997-98, the West Coast suffered destructive storm after storm. California alone lost 17 people, and 27 homes were red-tagged, according to the California Coastal Commission. Los Angeles received a record 13.86 inches of rain in February, according to the National Weather Service.
The Los Angeles Times reported that damages totaled over a half-billion dollars.
Crippling 2015-16 El Niño
The city recorded the second-biggest snowstorm in history. A large area of 2 feet of snow fell across the Eastern Seaboard, crippling the Interstate 95 corridor.
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Again, the West Coast saw unimaginable erosion.
"The 2015/16 El Niño was one of the strongest of the last 145 years, with winter wave energy equal to or exceeding measured historic maxima all along the Western U.S. coast and anomalously large beach erosion across the region," wrote the commission.
How does 2023 El Nino compare to 2015?
Currently, se- surface temperatures are behind the three historic strong events. The red line shows the above-average subsurface temperatures compared to other El Niño years. So far, 2023 is falling behind the heat of 2015, 1982 and 1997, but don't rule "historic strength" out.
"While there is still a good amount of heat under the surface of the Pacific – this warmer water provides a source to the surface – it’s not quite at the level we’ve seen during previous historically strong El Niños like 1982-83, 1997-98 or 2015-16," Emily Becker, associate director of the University of Miami Cooperative Institute for Marine and Atmospheric Studies, wrote in October.
But, she says, the world has seen record global ocean warmth this year.