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Weather Wise

published: October 2nd 2020
by: Brian Bledsoe

La Niña status and an updated look at  analog years for the upcoming winter

We've been writing about La Niña for months now. It is established and is getting stronger. You can see the sea surface anomalies trend colder (bluer) during the past several weeks, not only at the surface:

    But beneath the surface too: 

    Most models continue to show La Niña prevailing for the next several months.

    Here is the current sea surface temperature anomaly map, showing the budding La Niña: 

    So, where does the current situation stack up in relation to past years?  Well, our analog list is as follows: 1995, 1998, 2005, 2007, 2010, 2013, 2016. The maps show the sea surface temperature anomalies for those years, at this time of year.

While we continue to sort out which analog years will mean more than others, here are a couple things to consider when looking at the maps. 1) The Pacific Ocean was cooler during some of those years, than it is now. 2) This La Niña isn't as strong (at least not yet) as some of the other episodes. These are two things we are weighing, as we eliminate analog years, in the next few weeks.
    Regardless of strength or duration, we still wanted to give you an idea of what the next several months (including winter) may have to offer us. The maps below show the temperature and precipitation anomalies for the analog years that we have selected.
October - December analog temperature composite 
    Warmth is expected to overwhelm the pattern for the near term, especially across the central United States, with little signal in the analogs for any areas seeing below average temperatures (on average) during the Oct-Dec time period: 

October - December Analog Precipitation Composite 
    The same period shows a stout dry signal across Texas and the greater Mississippi Valley:

January - March analog temperature composite 
    For the winter months, the analogs listed take on a very Niña look to be sure. A cooler northern tier, and warmer than average across the south and Eastern Seaboard: 

January - March analog precipitation composite 
    Similarly for precipitation, a rather classic Niña look if conditions hold as we head toward winter: 

    We don't see this changing much in the months ahead. We've been talking about this setup since last winter, and modeling continues to align pretty well with the analogs we have shown above. We'll see how things look as we head into October, and make any adjustments to this analog set if needed.