This slide deck here provides the main El Nino/La Nina data since 1950, and the basic correlations of this climate condition index with US corn yields.
In the past 65 years, there have been 15 "bad" corn yield years, with yields down at least 4% from trend. Of these 15, 8 "bad" years can be considered "connected" (or as climatologists say, "teleconnected") with La Nina conditions, and 6 of these occurred in the year immediately following a strong El Nino--when the El Nino (warm) phase of Pacific ocean temperature changed rapidly to a La Nina (cool) phase.
Climatologists generally agree that it is the RATE of CHANGE from a peak El Nino downward toward a La Nina coolness, along with the TIME of the YEAR this occurs--relative to the crop season--that matters most.
We issued this deck last September, showing that the stage was set with a very high El Nino in the 15-16 winter for transition toward La Nina during Jun-Jul-Aug of 2016, and we began monitoring the weekly forecasts of El Nino/La Nina by the NOAA. The Jan-18 forecast is included in the deck.
Let me say this as forcefully as I can: I have followed this data carefully since 1983, and it is very fluky! One reason is that the "equatorial temperature of the Pacific Ocean" is a very difficult thing to measure--which part of the Pacific do you try to measure, and how many thermometers do you need to do it? What if there's a "blob" of very warm water somewhere else, like now off the coast of the American northwest and Canada? (This "blob," by the way is now said to be cooling a bit, but who knows how it may all play together with longer term conditions, like the Pacific Decadal Oscillation, etc.?)
One thing I'm sure of is that the potential La Nina and its potential effects this Spring-Summer will get a lot of talk among traders. Another thing I'm sure of is that you won't know it's going to happen until it happens. Sure, sure, the cornbelt soil moisture is good now, just as it was in the winter of 82-83. But what will it be next August?
Our climate consultant Roy Spencer will focus on this critical question at our Seminar March 21-22. Don't miss it! (Someone will ask him, "What are the odds, 1 in 2 or 1 in 3?" You'll want to hear the tone in his voice when he answers!)
