A monster El Nino churning in the Pacific Ocean appears to be the strongest in nearly two decades, and could have a big impact on the country’s weather this winter, climatologists said Thursday.
For the Northwest, the climate phenomenon often means warmer, drier-than-normal conditions. That could be bad news for a region already reeling from drought conditions. It’s also a recipe for a meager mountain snowpack — one of the major factors that drove this year’s drought in Washington.
The National Oceanic and Atmospheric Administration says there’s a 95 percent chance El Nino will linger at least through the winter. But that doesn’t mean the typical weather patterns associated with El Nino are a sure thing, said Mike Halpert, deputy director of NOAA’s Climate Prediction Center.
“The climate system is far more complicated than just El Nino,” Halpert said in a conference call with reporters. “Just because something is favored doesn’t guarantee it will happen.”
El Nino is characterized by warmer-than-average water temperatures in much of the Pacific Ocean, among other factors. Its counterpart, La Nina, comes with cooler ocean temperatures. (And in the Northwest, cooler winter conditions.)
The strongest El Nino on record occurred in the winter of 1997-98. That year, the Portland-Vancouver area indeed saw “much warmer” temperatures and drier conditions in the later part of the season, said Dave Elson, a meteorologist with the National Weather Service in Portland. Generally, El Nino has a stronger correlation with warmer temperatures in the Northwest than it does with precipitation, Elson said.
Even with normal precipitation in the region, a mild winter could be enough to cause problems into next spring and summer. That’s exactly what happened this year, when warm temperatures produced a dismal mountain snowpack despite near-normal rainfall. The resulting deficit set the stage for this year’s drought.
Elsewhere in the country, El Nino could actually be good news, Halpert said. The pattern has “without a doubt” contributed to a relatively calm hurricane season in the Atlantic this year, he said. Other places may save on their heating bills this winter due to less harsh conditions, he added.
El Nino often brings more rainfall to the southern United States, which could provide relief to some drought-stricken areas in the West, including Southern California. But it will take more than that for the region to recover entirely, said Kevin Werner, director of NOAA’s western region climate services.
“A single El Nino event is unlikely to erase four years of drought,” Werner said.
Whatever the effects, officials are confident this year’s El Nino will linger for a while, Halpert said. The question is how strong it is. But he cautioned that long-range outlooks are probabilistic in nature. They’re not guarantees.
“We could be surprised,” Halpert said. “It wouldn’t be the first time.”
