The National Weather Service’s Climate Prediction Center is projecting that the El Niño weather pattern will dissipate around late summer, and that there are growing indications a La Niña pattern will develop going into winter. Both patterns are largely driven by Pacific Ocean water temperatures.
“Nearly all models predict further weakening of El Niño, with a transition to neutral likely during the late summer or early fall,” states the latest advisory issued by the Climate Prediction Center. “Then the chance of La Niña increases during the late summer or early fall.”
Tom Di Liberto, a meteorologist with the center in College Park, Md., said influences on local weather systems from El Niño and La Niña are difficult to detect in the summer rather than winter months. During the summer, other weather patterns can be the driving force for localized weather.
The center maintains a caveat that some regions like the Pacific Northwest can have varying effects from one basin to the next but the overall, average influences of an El Niño can be detected.
Di Liberto said the strongest “signal” for the declining El Niño in the Pacific Northwest indicates there will be warmer-than-average temperatures, with above-average precipitation in parts of the Columbia Basin.
“La Niña impacts, generally speaking, are the opposite of El Niño,” Di Liberto said. “If La Niña forms, a colder-than-average winter, and wetter than average winter” are generally expected for the Pacific Northwest. (This past winter’s El Niño was an exception to the general rule, sending many wet rainstorms crashing into the Pacific Northwest instead of sending them south, as usually happens.)
There are growing indications that La Niña will form.
“Our values show a 70 percent chance of La Niña forming by the end of summer and going into fall,” Di Liberto said.