SEATTLE - The lowland snows are back. Temperatures have dropped. After three unusually warm winters, does the current winter's cold mark a return to a "normal" winter for western Washington?
"It's not just normal, it's below normal," said Washington state Climatologist Nick Bond.
In fact, there's a big swing between the warmest recent winter in 2014-15 that saw record low snow pack and average December through January temperatures 4 degrees above normal to what's happening now.
"It's going to be something like 4 to 5 degrees below normal," said Bond.
The numbers are still being crunched for January, but Bond said most days in December, January, and so far in February have been below normal. Overall that's an average temperature swing of 8 degrees or more in two years.
Ok, it's cold, but why?
Bond said there are several influencing factors. First, high pressure has moved to the western portion of the Gulf of Alaska. That combined with a pattern of lows over the northwestern states has set up a pattern of pulling cold air from the interior of Canada.
And what about La Nina? La Nina is lower than average temperatures on the surface of the tropical Pacific Ocean. A La Nina typically causes cooler and wetter conditions in the northwest.
"It's never been that strong," said Bond of this La Nina, pointing to a relatively small patch of cool water near the middle of the ocean along the equator. "But it's had a really big impact. That's really interesting, and we don't really understand that."
What helped bring us warmer weather year round by about 5 degrees since 2013 is known as "The Blob," a giant patch of much warmer than normal ocean. It is believed to contribute not only to warm winters but two record summer fire seasons. The effects of the Blob were made worse by a series of warm El Ninos, which is warmer than normal sea surface temperatures in the central and eastern Pacific that can have a large effect on weather around the country.
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