Honestly, Open Mind should just be ported over to 538.

The whole central valley is in a rain shadow from the coast range — the north is naturally a prairie, and seasonal wetland from river flows (not direct rainfall!) and the south is very, very dry. I’m shocked, shocked I say, that the data here is muddled.

That data table he spent time making is utterly useless. Why the heck would he pick central valley rainfall as some sort of reference?

The reality is that there’s a huge pool of very hot water moving East in the equatorial pacific, under the surface — the very edge of it is just starting to come up to the surface now in the East Pacific. This is measurable, we have these measurements. And it’s really very strongly warm — probably warmer than we’ve ever seen, and certainly at least as strong as the 97/98 event.

Now, that in itself doesn’t guarantee the strength of the El Nino over time, or even necessarily that we’ll have one, there are plenty of factors and we don’t necessarily know them all.

The 50% is a little out of date at this point, they don’t update those predictions but once a month, so that 50% is from mid march — meanwhile, it’s actually, like, surfacing now, so unless it just suddenly sort of fizzles out for… unknown reasons… I’d say it’s a pretty sure bet that some kind of El Nino is about to try to get going. That pool of incredibly warm subsurface water isn’t just going to disappear, at any rate.

There’s more data to look at here than doing some very basic statistical glancing at some historical data and referencing a model spread that has been strongly trending more and more “El Nino-y” for the last several months.

As for CA rainfall and the like, there aren’t guarantees, and CA really only sees much change from strong events, but we’re not totally in the dark when it comes to how these effects tend to shift the jet stream, etc. We have plenty to learn, but the sum of what we do know goes well beyond “gosh, we only have these few historical data points, so we have absolutely no idea!”

Some data for anybody interested: http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml

Since most years one does not develop, a 50 percent chance is high. But again I have seen no one saying moderate to mild. I only hear people saying two things: a) it could happen this year and b) it looks like a big one.

This is technically correct, but semantically meaningless.

What’s the probability range encompassed by the phrase “may develop”? Say a 20%-80% chance of development? So this just says that the models agree that the range of probability of an El Nino is somewhere in that range.