Saturday, August 8, 2020

Upcoming La Nina Winter: Cooler and Wetter than Normal

Note:  I will be providing my viewpoints on the KNKX situation, Cancel Culture, Seattle Police defunding and other matters in future blogs this week.  

Note2:  I am teaching atmospheric sciences 101 online this fall quarter and anyone can sign up!  This class is a good introduction to weather, including weather observations and forecasting.   I give a weather discussion every day. You can sign up as a non-matriculated student.  And if you are over 60, you can get the very, very inexpensive rate given to Access students.  I am really excited about serving a larger community with this class
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There comes a point during mid-summer when the veil of uncertainty lifts regarding the nature of the upcoming winter season and we are at that point now.

The key tool for seasonal forecasting in our region is the correlation between El Nino (warmer than normal water in the tropical Pacific) and La Nina (the opposite) and the large-scale weather circulation over our region.    El Nino years tend to bring our region warm/drier conditions with a lower than normal snowpack. La Nina years tend to be cooler/wetter and are the periods skiers dream of.

Interestingly, there is a spring predictability barrier for such forecasts, with forecast skill increasingly greatly during the summer (see figure below and NOAA discussion of this effect).  As you can see in the figure (which shows the skill in predicting El Nino/La Nina) by August, NOAA has almost achieved skill at the 80% level.    Good enough to share with all of you on this blog!


Let's begin by looking at what is happening right now, viewing the key sea surface temperatures in the central tropical Pacific (showing the difference from normal, known as the SST anomaly).  The areas we use is called the Nino3.4 region.  

Wow...a big change occurred in May, going from warmer than normal ( El Nino) to cooler than normal (La Nina) conditions.



Model forecasts for this winter are highly suggestive of  strengthening of La Nina, which will continue into mid-winter.
As a result, the National Weather Service Climate Prediction Center (CPC) is now suggesting a better than 50% chance of La Nina and very little chance of El Nino this winter (see below).


But what about the best extended forecasts in the world?  Those by the European Center?  As expected during a La Nina year, it is going for a wetter than normal winter (Dec-Feb)--see below.  Good for fish and water resources.


But what about temperature?  In La Nina years, the strongest correlations with our weather occurs after January 1st, so let's look at the temperature anomaly (again, difference from normal) for January (see below).  Cooler than over British Columbia and near normal over the Washington Cascades.

This implies good very snow accumulations in January over BC and a bit above normal over Washington State's mountains.


Now I don't know whether the ski areas will be operating in January due to COVID-19 (if people stay outdoors in the fresh air, it might be safe enough, as long as no indoor eating/drinking/congregation areas are open).  But if they are open, this might be the year to take a chance on a season's pass.

But no guarantees, of course.  The El Nino/La Nina influence weights the "meteorological dice" but does not guarantee a perfect forecast of the upcoming winter's weather.

10 comments:

  1. You say, "I am teaching atmospheric sciences 101 online this fall quarter and anyone can sign up!"

    When I go to the link, "atmospheric sciences 101 online" it goes to a web page that gives you a course outline, no online information.

    How does anyone sign up and register for this ONLINE class?

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  2. Hello Cliff, I fully support your right of free speech. As for la nina or the opposite, what about heating bills ?

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  3. That ECMWF January map looks rather odd,with cold temperatures extending well south into the Great Basin.In a typical La Nina,the greatest temperature departures are found from Montana east into the Dakotas.That map is indicating near normal temps for those areas,which is a bit hard to believe.

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  4. Wish it could just be spring forever, hey Cliff, just wanted you to know that I think you are great and it's sad that such reasonable comments by a reasonable man such as yourself have drawn such ire, I'll keep reading and hopefully listening to you as long as you are doing your thing, thanks

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  5. I'd be delighted to take the online 101 class. That's a real treat for me.

    And yes, please, the best of us (all of us) must speak now with conviction.

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  6. I was out for the weekend though I noted you were not on the radio. I assumed you were just on vacation.

    When I found out what happened, I sent KNKX a brief statement of my dismay and told them: No more contributions unless Cliff's weather segment is restored.

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  7. Cliff,

    You have so many people who admire your efforts. Keep up the good work!

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  8. "I will be providing my viewpoints on the KNKX situation, Cancel Culture, Seattle Police defunding and other matters in future blogs this week."

    Oh dear God please don't.

    When one has dug themselves into a hole the 1st thing to do is stop digging.

    You have been fired twice from public radio. Perhaps the problem is not them.

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    Replies
    1. Sound like you're not interested in hearing both sides. Killing dialogue makes truth-seeking impossible and democratic government a farce.

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  9. La Nina will be hard on the throngs of unemployed people caused by the Trump Virus who'll have trouble with their energy bills. Time to finally tax billionaires in our state. We're a rich state but can't capture it in revenue. Time for a change. People are mad as hell.

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