A temperature shift in the tropical Pacific Ocean, combined with climate model outlooks, suggest that she probably is.
In fact, if surface sea waters continue to cool, La Niña could emerge as early as this fall, say scientists with the National Oceanic and Atmospheric Administration and an increasing number of international forecasters.
Why is this significant?
Because La Niña – like her attention-grabbing brother El Niño – can disrupt normal weather patterns around the globe. But while El Niño is marked by a band of warmer-than-average sea water in the equatorial Pacific, La Niña represents cooler-than-average water in the same region.
Which means, if El Niño seesaws into a La Niña event, various parts of the world could get hit with very different weather in 2016-17.
The Pacific Northwest is no exception. In 2015, El Niño was a major driver behind the region’s unusually warm weather and lack of snowpack in the mountains. The emergence of a strong La Niña could do just the opposite, bringing greater precipitation and cooler temperatures.
It’s not unusual for these naturally occurring phenomena to run back to back. Most legendary is the double billing that took place in the late 1990s, when the strongest El Niño on record segued into a powerful La Niña.
Each ushered in its own stretch of intense weather conditions around the globe, ranging from heatwaves and severe droughts to heavy rains and flooding. If El Niño produced intense heat and less-than-average rain in a certain location, chances are, La Niña did the reverse.
Talk about the ultimate sibling rivalry.
If a La Niña episode is on the way, her impact in the U.S. would peak next winter, bringing cold and wet weather to the Pacific Northwest, warm and dry conditions across the southern states and cold, stormy weather patterns to the central and northern tier.
By Nic Loyd, WSU meteorologist, and Linda Weiford, WSU News
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