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Weather Wise

published: April 29th 2022
by: Brian Bledsoe

Is there a triple dip La Niña ahead?
    While it is far from certain, I am growing more and more concerned about the possibility of another (continuation of) La Niña episode through this year and into winter 2022-23. While most of the modeling is still somewhat inaccurate this time of year, a lot of the models are advertising such. The fact that the PDO is cold/negative and staying quite negative, is something that lends credence to this thinking. Also, a La Niña usually weakens in the spring...this episode actually intensified in March, after weakening and almost going away in late January and February. 
    While the PDO has been warming a bit, it is still quite cold/negative.

    The images below show the latest model ensemble forecast when it comes to La Niña:

    The "blue bars" that remain around 50% or greater probability of La Niña hanging around through the rest of this year, are now pretty fixed. El Niño chances by the end of the year are essentially disappearing. I was talking about that recently, and this latest computer model forecast kind of confirms that line of thinking. Historically, if La Niña was going to disappear, it would have by now. It tried in January and February, but that March resurgence has really lingered...and likely has to do with the PDO still being so negative/cold.
    Whether we triple dip or not, here is a look at the rainfall anomalies when the PDO is negative from May - September:

    Both models and history suggest a continuation of the drought. We are also going to start getting warmer and that will only reinforce the drought positive feedback.
    As I've been saying for a long time now, areas that have been wet will likely remain that way...areas that have been dry will likely remain that way. The biggest change I saw in these longer range models today was the appearance of above average temperatures over the areas where drought is the worst-parts of Colorado, other Four Corners states, Western/Southern Plains, etc. This is a signal that the dry soil and the continued below average precipitation will likely start allowing the ground to heat up and add insult to injury in the positive drought feedback. Again, drought begets drought...
    Here is the latest IRI Multi-Model Forecast for May-July:
Temperature

Precipitation

    This model ensemble is also bullseyeing the areas that are dry right now, to continue to stay dry. The exception is the far northwest part of the country, as the dry signal essentially migrates that way, as the wet season winds down for California and the Pacific Northwest. You might ask why parts of Southern California, Arizona, and New Mexico are in the "white/average" for precipitation. That is likely due to the model forecasting a good monsoon season for the Desert Southwest. I don't see any reason to disagree with that setup either. That will likely setup later in June and really get going in July. Notice how some of Colorado is only in the yellow...that is also likely due to the monsoon element coming into play.