Scott Swanson
Weather conditions in Sweet Home are drier and warmer than normal. That’s not news.
But the National Oceanic and Atmospheric Administration last week issued its forecast for the winter, stating that this year’s El Niño condition is “the strongest on record” and is expected to impact the position of the Pacific jet stream, meaning the clouds may not be here when and where they normally are at this time of year.
“We’re definitely looking at above-normal temperatures,” said Will Ahue, a meteorologist at the National Weather Service in Portland.
NOAA predicts drier-than-average conditions for much of the Pacific Northwest, as well as above-average temperatures. But for the central Willamette Valley, it’s a crapshoot, Ahue said. It could be wetter, drier or just normal.
“The way they break it down, it’s not 50-50 chance,” he said. “There’s an equal, 33 percent chance that precipitation will be normal, above normal, or below.
There’s no question that Sweet Home is currently dry. The rainfall thus far in 2015, recorded at Foster Dam, was 16.07 inches through Monday, Oct. 19. Last year it was 42.6 inches as of Oct. 20.
Average for Sweet Home is 54.73 per year.
According to the National Integrated Drought Information System, a computerized archive created through the collaborative activities of a number of government agencies, which maps drought in the U.S. and provides an early warning system for it, Sweet Home is in a “severe” drought condition.
The NOAA forecast cautions that El Niño can’t be blamed for all that happens this winter. Other factors that may impact winter weather include the Madden-Julian Oscillation, which can impact the number of heavy rain storms in the Pacific Northwest.
“A strong El Niño is in place and should exert a strong influence over our weather this winter,” said Mike Halpert, deputy director of NOAA’s Climate Prediction Center. “While temperature and precipitation impacts associated with El Niño are favored, El Niño is not the only player.
“Cold-air outbreaks and snow storms will likely occur at times this winter. However, the frequency, number and intensity of these events cannot be predicted on a seasonal timescale.”
Ahue said the current El Niño condition “is real comparable” to the El Niño of 1997-98, which produced precipitation “that was closer to normal, as opposed to a moderate El Niño.”
“It’s kind of weird, the way it breaks down,” he said. “The climate signals for precipitation can go either way.”
What likely will be impacted, he said, is the snowpack.
“We’re definitely looking at above-normal temperatures,” Ahue said. “We already have a pretty low snowpack to start the season out, compared to previous years. (The El Niño) could have an impact on our snowpack, which would have impacts on water.”
Currently, Green Peter Lake, the primary water storage reservoir for the Sweet Home area, is near its typical winter level, according to the U.S. Army Corps of Engineers.
Green Peter is “a little bit” below its normal winter elevation, said Mary Karen Scullion, a Portland-based Corps hydraulic engineer, last Friday. She said the lake level has “another two or three weeks” to go before the dam can no longer generate power.
“We have quite a bit of stored water left,” Scullion said. “Just because we’re below normal low elevation doesn’t mean we’re out of water. We still have lower-level outlets (in the dam). We’re watching what water we have left.”
Foster, she said, is still at “full generation capacity.”
The drought has affected the water levels, but the upside is “we’re in a great position for flood control – empty lakes,” Scullion said. “If we have any kind of normal winter, it will be just fine.”