Weather Blog

OMG! It's La Nina!

OMG! It's La Nina!

Have you built your igloo yet?

It seems there's some ominous sounding story about the "impending doom" of the La Nina winter every week, if not more frequently.

Here is a sampling of headlines from the past month or so from the various local media outlets (yes, including KOMO):

  • Brace yourself, La Nina threatens wetter, colder NW winter
  • Are we prepared for another 'Snowmageddon?'
  • Plan now for bad Puget Sound winter
  • Winter could be a whopper, forecasters say
  • Seattle snow plows already practicing for La Nina
  • Powerful La Nina Means Cold, Wet Winter Likely
  • NOAA: Get ready now for a La Nina winter
  • Don't get complacent about this winter, government warns
  • Strong La Nina Could Mean Harsh 2010 Winter
  • Seattle Braces for Unusually Cold, Wet Winter
  • Big snow this year? La Niña could bring it*
  • Winter May Bring Heavy Rain, Strong Winds, Lowland Snow*

    Oh, and of course, who could forget:
  • "OMG! It's La Nina!" :)

What began as a heads up that La Nina typically means a cooler and wetter winter and to be prepared as always I think has "snowballed" into this assumption that this winter is going to be December 2008 all over again, only this time with 30 foot drifts, wind chills of 30 below, and a new lane added to I-5 for those traveling via polar bear or Tauntaun.

I think some of the hyperbole is due to that this is one of the stronger La Ninas -- at this time of year -- since the mid 1950s. Note that does not mean this is the strongest La Nina since then, just at this point -- typically La Nina's peak in the heart of winter. Since this La Nina is getting stronger, it is conceivable that it will end up as a good, strong La Nina.

But even then, does this mean this winter is doomed to be "Snowmaggedon", part 2? (Or should that be "Episode 2: The Attack of the Snowmen"?)

In a word, no. It's not like La Ninas are a rare event. In fact, they occur every few winters, as part of the typical 3-6 year see-saw with El Nino -- the last official La Nina winter coming in 2007-08. (As a trick question, the last two asterisked headlines from above were actually from a story in September 2007 and September 2008, respectively -- and September 2008 wasn't even a La Nina winter! More on that in a moment.)

And Seattle obviously hasn't experienced "2008" every few winters, or else 2008 would not be so special or memorable and Arizona would be completely overrun with snowbirds. (Oh, wait...)

In fact, technically, 2008 wasn't even a La Nina winter. It was officially a "neutral" winter which was neither La Nina nor El Nino -- although it was just barely under the minimum threshold to being classified as a La Nina winter, so you could consider it a very, very weak La Nina. (Go back in Seattle weather history, and you'll find it's the neutral years that have really been the king of the snow storm and other major winter events.)

Here is what La Nina likely spells for us: Possibly more frequent snow events, but not necessarily a slam dunk of *big* snow events. Since La Ninas typically bring cooler-than-normal conditions, I think what we'll see is what usually would be fringe snow events where we'd play the "snow levels at 500-700 feet; snow showers in Cascade foothills/Convergence Zone" game -- perhaps this winter those events will bring snow closer to, or down to the surface.

And snow events that typically were 1,000-1,200 feet (as in the "Snow at Tiger/Cougar Mountains) may instead bring snow down to 500-700 feet. And the ski resorts should be licking their chops because traditionally, La Nina winters are big mountain snowpack generators. (The 1999 Mt. Baker national snow record? That was a La Nina winter.)

Overall, I expect we probably will have a higher frequency of 1-3" snow events in the lowlands. Sure, 1-3" is cause enough for panic and problems in snow-frightened Seattle and the call to be prepared is sound advice, but the point I want to get across is it certainly doesn't mean we'll see days and days on end of snow with 20" drifts.

That said, of course it's possible *any* year, La Nina, neutral, or even El Nino, to get a big snow storm, so this is not by any means a declaration that there will not be a big snow event this year. Only that La Nina doesn't guarantee one, as I think a lot of people are being led to believe or choosing to believe. And comparing this upcoming winter to 2008, while easy to do since it is fresh in everyone's mind, is really not a good idea because there is no meteorological connection between the two.

Should you be prepared for snow? Of course. That's good advice every winter. Some of THE best sites to read and follow is, and this site from Puget Sound Energy. Should you be getting ready to move to Florida to escape a rapid transition to Greenland? Nah. Besides, it's humid there. (And you'll never sell your home in time.)

And as I mentioned, it's the neutral years that have the most "storm trophies" -- for snow, wind and rain events. So save a bookmark spot for my upcoming blog in October, 2011: "OMG! It's a Neutral Year!"