NOAA centers: 55-60% chance of a La Niña winter

NOAA is reporting the summer of 2017 was the third warmest on record globally, with the Pacific Northwest feeling the same heat, but the region may be in for another cold, wet fall and winter.

The NOAA Climate Prediction Center’s most recent El Niño Southern Oscillation outlook includes a “La Niña Watch” with a 55-60 percent chance of the pattern developing during the coming fall and winter. El Niño and La Niña weather patterns are driven by Pacific Ocean sea surface temperatures, and both patterns can be powerful influences on weather across the greater Columbia River Basin.

“Yes, we are expecting La Niña conditions,” said Dave Elson, a meteorologist with the National Weather Service in Portland. “They have a La Niña watch out right now, which means La Niña through fall is likely. We did have a La Niña last year.”

The last water year for the basin, starting in October of 2016, was marked by colder-than-average temperatures and higher-than-normal precipitation, resulting in record or near-record snowpacks covering mountain ranges across the region.

Starting in September 2016, Spokane recorded 23.47 inches of rain and snow through the following spring, short of the 1947-1948 record of 28.9 inches, but well above the historic average of 16 inches. Similar precipitation came to areas across the region.

“And it did lead to a big snowpack this spring,” Elson said. “It was a pretty impressive year as far as that goes.”

Elson cautioned that El Niño or La Niña patterns don’t necessarily cause warmer-drier or cooler-wetter weather, respectively.

“It’s hard to draw conclusions about what La Niña means for the Pacific Northwest,” he said. “It’s clear there’s a lot more that drives our winters here that goes beyond El Niño or La Niña.”

“Forecasters favor these predictions in part because of recent cooling of surface and sub-surface (ocean) temperature anomalies, and also because of the higher degree of forecast skill at this time of year,” the ENSO outlook states.

It could be a sharp turn from a summer that brought record-high heat and dryness in the region. Many counties in western Montana, northern Idaho and western Washington received no precipitation over a period lasting more than two months.

That mirrors global conditions.

“For the entire globe, both August and (the summer) season (June, July and August) each went down as the third warmest on record,” NOAA stated in a recent climate report. “But depending on where you live, the summer you experienced may have felt warmer or cooler than normal.”

August 2017 was 1.49 degrees above the 20th-century average of 60 degrees. This was the highest in the 1880-2017 record, behind 2016, the highest, and 2015, the second highest. The seasonal global temperature for June through August was 1.46 degrees above the average of 60 degrees — the third highest for this period in the record, trailing 2016 and 2015, the highest and second highest on record, respectively.

While the weather seemed to be baking dry to people throughout the Columbia Basin, temperatures across the Midwest were “much cooler than average” or “near average” during August and the summer season.