By UW News Staff

NOAA

Ocean temperatures and their connections to weather trends have been making news. Five University of Washington experts offer their perspectives on the current El Niño — a climate pattern in the tropical Pacific Ocean that affects weather worldwide. UW researchers comment on the current El Niño, its effect on weather in the Pacific Northwest, as well as on regional and global ocean temperature trends.

Aaron Levine, a UW research scientist at the Cooperative Institute for Climate, Ocean and Ecosystem Studies, comments on the developing El Niño:

“This El Niño has evolved in a really interesting way. Since spring, the dynamical models have very confidently predicted an El Niño event. But while the key region of the tropical Pacific has warmed quickly, the typical atmospheric response has lagged. The atmosphere in the tropical Pacific is only now becoming more typical of an El Niño event, although it is still not fully matching the ocean surface. That’s unusual, because the tropical ocean and atmosphere tend to evolve together.

“It will be interesting to see how this El Niño continues to evolve over the next few months, which will help determine the extent of impacts on our upcoming winter weather. Remote impacts in places like Seattle tend to be stronger for stronger El Niño events. While sea surface temperature has typically been the main measure, the impacts might very well depend more on the atmospheric response. So the evolution of the system over the next few months will be key to the eventual local impacts in places like Seattle.”

Dennis Hartmann, professor of atmospheric sciences at the UW, on El Niño and its effects:

“The impact of El Niño on the Pacific Northwest varies a lot from one event to the other, depending on the spatial structure and size of the sea surface temperature changes in the tropics, and on the state of the atmosphere between the tropics and the Pacific Northwest. For that reason, the predictions of Pacific Northwest impacts based upon El Niño events that happened in the past are quite uncertain.

“In addition, the climate has warmed significantly in both the tropics and outside the tropics since some of the prior big El Niño events, in the 1970s and 1980s. That may add an additional complication to making an accurate forecast of how this winter will be different because of the current El Niño event.”

Nick Bond, a research scientist at CICOES and Washington’s state climatologist, on El Niño and its effects on Washington’s weather:

“El Niño conditions are present now in the tropical Pacific Ocean, and they are very likely to persist through the coming winter. The effects on Washington’s weather are expected to feature relatively warm, and perhaps drier, weather than usual after Jan. 1, and ultimately a lower-than-normal snowpack in our mountains at the end of winter. El Niño’s impacts on the weather in Washington state tend to be more consistent in the middle to latter part of the winter.

“But this is not written in stone — there has been variability among past El Niños in terms of effects on Washington’s winter weather.”