Don't give up on La Niña just yet: Cooler February, March odds-on favorite for Northwest
SEATTLE -- If you were to give snow and storm fans a report card and ask them to grade this year's La Niña winter so far, judging from my social media feeds (which, admittedly, likely has a winter weather fan bias), I'm thinking a "C" might be the winner, maybe a "C-".
Granted we've had a little bit of snow -- the region's first official White Christmas in nine years was amazing. And the mountain snowpack is hanging in there at just a bit below normal in Washington (Oregon could use some help.)
"Washington’s snowpack is in relatively good shape, considering warmer temperatures," says the Washington Department of Ecology's Tyler Roberts. "We are getting precipitation, though not optimally timed or at the right temperature."
But usually La Niña winters are marked by chilly winter months with an overflowing snowpack.
Take out our little snow bout and it's been a generally benign late fall and winter. Seattle is on a stretch of eight consecutive days above 50 degrees in January with a five-day stretch over 55 degrees that just ended. If the month ended Friday, it'd be tied for the fourth-warmest. And there isn't much hope in the next two weeks of any kind of arctic blast or lowland snow (although the mountains are expected to start getting some decent snow next week.)
But there is hope for cold winter fans! The newest long range forecasts came out Thursday and Western Washington has the blues -- the good kind for snow fans.
The map for February gives a solid signal of expected below normal temperatures both for February and the February-April period, and a slight signal toward above normal rainfall for the 90 day forecast - both hallmarks of a good La Niña pattern.
That cooler/wetter signal holds into early spring then fades as we get into the heart of spring:
La Niña has been here as expected, it just has been overwhelmed by other weather patterns, including the chic-term polar vortex that has brought a few arctic events to the East Coast. On the other hand, the West Coast has been dominated by persistent (boring) ridges of high pressure.
Roberts says the ridging has kept Oregon dry and British Columbia flush with snow, "and you have Washington caught in the middle contending with a fits-and-starts variety snowpack we have had so far."
But signs of change are there.
For one, forecasters note that another oscillation that occurs in the Pacific, called the "Madden-Julien Oscillation" (nothing to do with football video games, sadly) or sometimes known as the "MJO" is expected to be active in our region early in the month. The MJO is, over-simply put, a cluster of weather activity that moves around the globe in 30-60 day time frames. (A bit more expanded explanation can be found here) and it's predicted to be in a phase in early February that makes it stormy in the Northwest.
Or, more officially from the NOAA forecaster Dan Collins' discussion: "The current MJO phase and forecast increase the likelihood of... below normal temperatures in the Northwest early in the month." They also are leaning wetter than normal in deference to La Niña finally exerting some influence around here.
Forecasters believe La Niña will fade during spring and head back toward neutral conditions, and as such, so do our odds of remaining cooler than normal. By the middle of spring, the Northwest is back in "equal chances" which means no signal either way on trying to predict overall temperature trends. (Looks like another warm summer again though...)
Does this mean we're in for a big snowstorm in Seattle this winter then? No. But the odds are at least a little better of some lowland snow with this overall weather pattern setup than it has been in January. And as mentioned earlier, next week's weather pattern is looking at least cool enough to bring some heavy snows to the mountains. And going forward?
"Traditionally February and March are also the months with the greatest snow accumulation, regardless of Niño status," Roberts said. "Hopefully this climatology bears out and we have abundant snow in the Cascades over the next 10 weeks."
How would you grade this La Nina winter?