La Niña is predicted by Pacific Ocean temperatures off the coast of South America. That fat blue arrow in the sketch above is an "averaged" polar jet stream. Of course, week by week, that jet stream wobbles. It's predictability and stability depend on temperatures in the Arctic. The colder the arctic winter, the more snugly that blue rubber band remains toward the north. The warmer the arctic winter, the sloppier the arctic jet stream becomes, like an overstretch, worn out rubber band. Perhaps another analogy would be that the polar jet stream is the ice cream in your arctic freezer.
These long-range forecasts are not an assurance of the weather in your personal front yard. They are assertions of probabilities in general. The less that the baseline conditions of the documented past (e.g. arctic winter temperatures) resemble today's reality, the less predictive the models.
Feel free to continue to rage against whichever temperature and precipitation pattern you don't like.
Bob
www.npr.org
