Thanks to everyone who logged on for the midsummer weather outlook webinar Tuesday June 29. Mike Palmerino and I found something to converse about for 50 minutes, and everyone who logged on stayed on. We appreciate that very much.

There has been a lot of commentary during the past month about La Nina developing in the Pacific. Following are details of how we see the situation at this point just ahead of July 1st.

We continue to look for La Nina conditions to develop by late summer--possibly as early as mid-August. If that's the case, we would dodge some drastic effects that Florida State research has shown are part of La Nina during summer. The Florida State study shows that La Nina during summer features warm to hot and dry conditions over the western and the northern Midwest. And, of course, the hallmark of that development was during the famous Midwest drought back in 1988--when a spring-early summer La Nina combined with a longer-term dry pattern to bring about the crippling pattern to the Corn Belt.

Of course, if La Nina shows up in late summer it would tend to bring a more favorable environment for tropical weather systems to develop and threaten the U.S.

The odds of a notable La Nina are higher than they were a month ago. Mike pegs the odds at 60-65 percent, versus 30-35 percent back in May.

Also, Argentina bears some comment regarding La Nina. After all, this is the crop region which has the strongest correlation--around 80 percent--to the Pacific Ocean trends. And, La Nina is a definite dry-weather producer for central Argentina.

For Argentina, as with other areas of the western hemisphere, the big question is whether what is going on now can be taken to the next level. There is a weak La Nina temperature pattern in the Pacific (cool, temps of -1 Celsius), but the SOI has been trending around neutral. Again--we think that there is a 60-65 percent chance that we could have significant La Nina conditions by mid to late August or early September based on the way the situation is evolving.

The most important feature right now is for the Southern Oscillation Index (SOI) to continue and truly evolve into a full-scale La Nina. The SOI had La Nina threshold values of greater than +8.0 for a 30-day reading back in April and May, but dropped off dramatically since.

To repeat--right now we are looking at a mid to late August time frame for the earliest onset of La Nina—that’s about as good as any estimate right now. The concern we have for Argentina is whether the sea temperatures and SOI evolve to where La Nina helps to re-establish the long-term drought that we have noted in the past few years.

Bryce

I can be found on Twitter at bryceadtnwx.