August 10, 2011

Fears of a Double Dip

Nothing terrifies Northwesteners more.  

Many of us have suffered greatly because of it. 

Folks are depressed over its effects.  

Supposed experts are not sure which way it will go. 

And the media can't seem to get enough of it, with headlines and articles describing its unpleasant effects all the time.

The nation's financial mess?   Political paralysis in Washington D.C.?


 I am talking about the threat of...dare I say it?...the return of La Nina next winter.  Or to use a technical term:  a double-dip La Nina.

I know, we suffered from La Nina last winter and this spring, and the forecasts were for an escape to a neutral year.  But the atmosphere is not following the script and the Climate Prediction Center has just put out a La Nina WATCH, which means it is not certain but possible.

So here is the situation.  Last winter we were in a fairly strong La Nina, one that weakened during the spring.   A primary measure of La Ninas (and El Ninos) are the anomalies (differences from climatology) of the sea surface temperatures (SST) in the tropical Pacific. The most well-known index is the SST anomaly in the Nino 3.4 region (see below).  The anomaly weakened to near zero by May, went slightly positive, and now is slightly negative.   Call it Neutral.

The trouble is that although the ocean say neutral the atmosphere has been holding to a La Nina-like configuration...including the troughing and cool weather along the West Coast.  And subsurface temperature sensors in the Pacific indicate cooling.  Ominous. 

The NOAA Climate Prediction Center has a number of models available that simulate the tropical sea surface temperatures.  As shown below, they are all over the place..some near zero, some indicating warming, but an equal number going for cooling.  Looks like a coin flip.
Even more worrisome, the NOAA Coupled Climate Model, their main simulation model for the atmosphere and ocean, is now turning more towards the La Nina (negative) side (see below)

 A look at the history of El Ninos/La Ninas (the ENSO Index) over the past 60 years shows that double dips do occur...such as in 2008/9 and during the mid 70s. (La Ninas correspond to the blue negative excursions).   In fact, double dips are not rare.

So the bottom line:  a double dip, with La Nina coming back is a real possibility, but no sure thing.  By late September, we should have a much better idea, but believe me, we have gotten this wrong plenty of times in the past.

So if I was Mayor McGinn I would kick the tires of those snowplows and be ready to order some more salt if needed.  My group is rushing to complete a powerful new aid for the City, a web-based application called SNOWWATCH. You will not believe what it is capable of!  With the new coastal radar in place, expect better snow forecasts if it does occur.  And KING TV's snowmaven Jim Forman should get his famous parka cleaned--he might need it.


  1. I made this little animation that helps explain how our marine layer forms:

  2. I dunno why, but for the first time, I clicked Climate 'SST Anomolies' on the UW website the other day. Very cool.

    But what stuck out, was an area of 4-6 C' of warm water in the north pacific. I thought it was a data error, but its been consistant. Wouldn't that have major implications on our weather whatever that may be?

  3. I thought I recalled a double El Niño sequence a few years ago - and the plot of the ENSO here seems to bear my memories out.

    So it can definitely happen... ugh.

  4. You know, I got some unique and beautiful photos last winter because of La Niña. E.G.:
    It's not all bad.

  5. More info by late September is perfect - just in time to sign the kids up for ski lessons. Save that warm January last year, it was a great ski season!

    I have no beef with real winters. It's this non-existent summer that kills me.

  6. Looking forward to Snowwatch if we wind up getting any snow. It is so patchy and difficult to predict around the Puget Sound, anything at all that helps us know where, when and how much will be a big help.

  7. Bring it on!!! Better skiing, fewer forest fires, greener countryside.

  8. What a shame : If there's anyplace that NEEDS some global warming it's the Northwest, but we're supposed to be the last place to get it.

    To echo TVN: I have no beef with real winters. It's weak summers I can't stand.


  9. Is the second winter of a double-dip La Nina usually more severe than the first? Maybe we'll finally get the cold, snowy winter that so many of us were looking forward to last fall when the La Nina hype machine was in full gear. A severe winter does not bother me in the least, as long as it doesn't overstay its welcome.

  10. So Cliff,

    What does this ENSO pattern tell us about the probability of big wet and windy storms this November and January?


  11. So what does this ENSO pattern suggest about the probability of big wet and windy storms this November and January?


  12. It's a CURSE!!! Notice that we get this report just after the fancy new radar is powered up?

  13. I can handle a La Nina November through April, but I sure wouldn't mind having it go away by May!
    Looking forward to more info in September.

  14. On the other hand, I "can't" handle a hard, snowy winter because this place isn't set-up to keep the roads clear. We have more problems with limited snow than the midwest has with feet of snow. I liked the way winter was confined to the mountains last year.

    A mild winter and summer are an ideal climate.

  15. Please say it isn't so! I was so dissapointed in last winters "La Nina"....It certainly didn't live up to the hyped up forcasts! I was looking forward to a "Nuetral" winter...they seem to be more snowy and windy.....Guess we'll have to wait and see. I do know one thing....I am not going to get all excited for a snowy stormy winter again!

  16. The full half of the glass is this: if the weather this summer was caused by a hangover from last winter's La Niña, then the weather this fall to early winter may be pretty normal due to hangover from the neutral ocean conditions this summer. I'm pretty confident that there WILL be a break from the troughy pattern some time in the next few months.

  17. Everyone complains about no summer, too cool, where's the sun, etc. The truth is if we even had the temps and climate of say, the Willamette Valley, we would be living in a jampacked Puget Sound the likes of the San Francisco and Bay Area. If you can't handle it plan a vacation... Otherwise stop complaining, move, and leave this wonderfully green, and gray, landscape to those who love it for what it is.

  18. I get so tired of people complaining about the summers here. This is the PNW. The rain and cooler temperatures are what gives us all our glorious green. If you don't like it...don't live here.

  19. Interesting. Congratulations. — I've enjoyed your video presentations, and so look forward to being able to hear you speak on different topics more current, either whether or both, weather and climate related. I don't live in the PNW, and so will be looking into just how to access the main station and program, more streaming, and via the net.


Please make sure your comments are civil. Name calling and personal attacks are not appropriate.

A Drier Than Normal Spring over the Pacific Northwest

I had to water some new plants today because the last few weeks have been relatively dry.   So I was dry has it been in our ...