This morning, NOAA released its long-range temperature and precipitation outlook for this winter and the verdict is that we’re on track for a strange season. Basically, El Niño’s gonna El Niño, with a decent chance of the stereotypical wintry disruptions one would expect in the U.S. during one of these events.
The latest forecast paints odds of above-normal precipitation in the southern half of the U.S.—from California to Florida—with drier-than-normal conditions in the northern part of the country. Possible temperature trends will mirror precipitation trends, with cooler down south and warmer (“warmer”) up north.
An El Niño occurs when sea surface temperatures in the eastern part of the equatorial Pacific Ocean are anomalously warm—at least 0.5°C above normal—for at least seven consecutive months. The strength of an El Niño is most commonly determined based on how abnormally warm the water is in a certain part of the ocean known as the “Niño 3.4” region.
According to the Climate Prediction Center’s latest update this past Monday (Oct. 12), the average temperature anomaly in that Niño 3.4 region was +2.4°C. That’s toasty. It doesn’t sound like much, but when you think about it, a fever in your body is also just a few degrees above normal.
While comparing a fever in a human to abnormally warm temperatures in the ocean is an extreme simplification, this warmer water can have a significant impact on global weather, as forecasters have predicted for many months now.
Pretty much, this NOAA news is no new news at all, but it’s big news to people because it’s from NOAA itself.
The biggest impact an El Niño has during the winter months in North America is that it can nudge the subtropical jet stream farther north, allowing it to more heavily influence the weather in places like California and the Gulf Coast. A subtropical jet that’s displaced to the north allows more disturbances to swing through the southern half of the United States, bringing the potential for above-normal precipitation and below-normal temperatures.
What does that mean for you? Here’s a look at the odds of above- or below-average temperatures...
Now, these are forecast trends. Just like it’s impossible to accurately forecast months ahead of time exactly how much rain or snow you’ll see, it’s hard to tell exactly how El Niño will affect our weather this winter. However, we have long-range models and a couple of similar setups in the past that tell us that the warmer ocean water will probably have a noticeable impact on our weather.
These forecasts depict the odds of a winter that sees above- or below-average temperatures and precipitation. You could still have one brutal week of cold and snow and the winter as a whole could easily come out normal or above normal. Likewise, the southern U.S. could see an extended period of dry, warmish weather, and the season there as a whole winds up coming in wetter and cooler than average.
If you’re pining for precip out in California, don’t take this forecast to mean that you’ll be drought-free come spring. It’s probable that you’ll see a wetter winter than you’re used to in even a normal year, but it doesn’t mean that this rain will put a huge dent in the drought. Historically, the heaviest rain stays in the southern part of the state, and it’ll take many months and years of sustained, decent rainfall across the whole state (the entire region, really) to enter recovery.
For those of you in colder parts of the country who are calmed at the thought of not having a repeat of the previous two winters, don’t take this forecast to mean you’re off the hook completely. Think of an El Niño winter like a quiet hurricane season in the Atlantic Ocean—it only takes one solid blast of cold air or one memorable thump from a powerful nor’easter to make it seem like a terrible winter. This has been a very quiet hurricane season overall, yet we saw a borderline category five hurricane pound the Bahamas as the strongest storm in five years. It could be a warmer/drier season overall up north, but at least a few storms and Arctic plunges will make it through. (Though hopefully not lasting as long as we’ve seen in recent years.)
Based on model solutions and previous winters where we saw a strong El Niño, the experts expect that this winter should be milder and drier up north, and it should be a little cooler and wetter down south. Any long-range outlook is one of more caveats and cautions than answers, and that doesn’t play well in a world where we demand instant gratification and total knowledge of forthcoming events.
As always, prepare for the worst, and hope it was all for naught.