What's the hype about El Niño?
There’s been a lot of chatter in the media about the developing El Niño in the equatorial Pacific Ocean. This week’s Climate Watch cuts through some of the hype and digs into what this means in the coming months for the Bering Strait region.
El Niño refers to a set of conditions in the equatorial Pacific Ocean south and southeast of Hawai'i that include higher than average sea surface temperatures, weaker than normal trade winds and increasing thunderstorm activity. It’s through these big tropical thunderstorms that the jet stream farther north is modified.
While the most widespread effects of El Niño on seasonal climate in the northern hemisphere are in the winter, Alaska and adjacent areas in Chukotka to the west and northwest Canada to the east also seem to see impacts in summer.
However, El Niño is just one factor, so while warm and drier summers and mild and stormy winters are more frequent in El Niño, some seasons can be quite different.
First up: El Niño conditions are not yet present. In fact, La Niña has just wound down. The April outlook from NOAA's Climate Prediction Center estimates a 79 percent chance that El Niño conditions will develop by summer but with a negligible chance of strong or very strong El Niño for June through August.
The odds of a “Super El Niño” increase to about a one-in-four by early next winter, but that's a long way out.
So, what about summer? Since it's quite likely that El Niño will be in place by then, let's look at past summers when there was El Niño.
Since 1970 there have been 13 summers El Niño conditions present, though only four have been in the 21st century. This week’s graphic shows how the June through August average temperature differed from normal in each El Niño summer. As you can see, there have been a number of very warm summers. In fact, five of the ten warmest have happened during El Niño since 1970.
However, there have been several summers when temperatures averaged close to or slightly below normal. As you might expect, warm summers often means less rain than usual, and that is the case here, and only one (1994) of the 13 summers had excessive rainfall.
Assuming the outlooks are correct and El Niño is in place for the summer, the odds for a warm and not rainy summer for Nome go way up, but as always with weather and climate, there are no guarantees.