Weaker La Nina Trends May Portend Colder Winter: Could Energy Bulls Benefit?

With the new month, more climate models are beginning to print out their late fall/winter forecasts. The climate model consensus has generally been one that is quite warm, though there is a decent range. The NMME climate model, which just had its July run come out very recently, is forecasting widespread warmth across the country for December/January/February, as seen below. This also fits with recent runs of the other American CFSv2 climate model.

There are reasons to be skeptical. The model does show a weak/moderate La Nina through the winter, as seen below.

In such a scenario, we could see widespread warmth across the country. However, it is far from a guarantee. In fact, recently we have seen confidence decreasing on just how much of a La Nina we will have come winter, and some aspects of the upper level pattern on this model do not fit what we would expect with a weaker La Nina. The Australian Bureau of Meteorology shows either neutral or very weak La Nina conditions through the winter, but recently the ensemble climate members have been skewed higher, with some trending neutral through the winter.

The American CFSv2 has a similarly wide spread. In blue we see the 8 most recent runs of the model, and it shows everything from a moderate La Nina to almost entirely neutral ENSO conditions for the winter. The ensemble mean now favors a very weak La Nina, potentially not even reaching technical La Nina classification if it unable to persist for the 5-month minimum.

Both dynamic and statistical models were favoring a stronger La Nina a couple months ago, but this more recent chart from the CPC has not been updated since June 16th; we are expecting the new one in the next week or so and expect some of these models will back off their stronger La Nina forecasts even more as we have not seen quite as rapid a transition to La Nina conditions as expected.

In fact, just today the Southern Oscillation Index (SOI) flipped back weakly negative, indicating no significant short-term transition to a more La Nina-dominated atmosphere. As can be seen, April had a strongly negative SOI and since then we had been trending positive, though not in any very significant or convincing way.