Last year’s El Niño event has been replaced, in a short period of time, by a La Niña, or “cool event.” That means that the cool water in the tropics west of South America has become even cooler than normal, and the warm water in the western Pacific has warmed considerably. For us, though, it heralds an upcoming fall-winter-spring with very different weather than last year.
In the Northwest, our coolest and wettest winters usually occur during La Niña events. Mind you, not every La Niña affects us that way, but most of them do. Wind storms, flooding, deep snowpacks — all of these are characteristic of La Niñas.
Joe Bastardi of AccuWeather has just released his winter forecast for the US, and his prediction pretty much follows classic La Niña patterns. Here’s some of what he said:
“The areas hit worst by winter last year, south of the Mason-Dixon Line, Ohio River and the southern Plains and Southeast, will have less winter to worry about this year, though the northern parts of these areas will be in the battle zone between what will be a severe winter over the northwestern U.S. that will try to extend through the northern Plains and Great Lakes, perhaps even into the Northeast. I use the word ‘severe’ because of the threat of extreme cold and enhanced snow and ice this year in the winter forecast, but northwest of where it was last year.
“Winter’s worst, in a sense that where one stands back and says, “there is where it was harshest,” is probably in the Northwest to the northern Plains and western Great Lakes. The rapid cooling of the globe with the La Niña will produce severe cold for Alaska and northwestern Canada, and in fact the Canadian winter will be as harsh as last year’s was gentle. The large expanse of this cold from northeastern Siberia through Alaska then southeast into the Northwest and North Central states means well-above-normal snowfalls in the Northwest in winter, opposite last year (recall my forecast from last year about the Olympics being plagued by warm, dry conditions… not this year), then into the Great Lakes.
“The snowpack in the Pacific Northwest should do great this year, making three out of four years for that. Conversely, the pattern will be very dry from Southern California through the Southwest and southern U.S. to the South and mid-Atlantic coasts.”
Last winter was pretty mild here (thank you, El Niño!), with the exception of the Arctic outbreak in December. We also had a very active fall and a wet, cool spring. Those will almost certainly be different this year.
Meanwhile, the NOAA Climate Prediction Center is predicting a winter similar to Bastardi’s: wetter and cooler than average in the Northwest.
I will issue my fall-winter-spring forecast this month, and describe it in this column the first Sunday in September.
For now, enjoy the remaining summer weather. Tuesday is the 29th anniversary of Corvallis’ record high temperature: 108 degrees in 1981. On the 9th through 11th, the highs were 104, 108 and 105. Now THAT’S a heat wave!