One of the warmest winters in Willamette Valley history could tilt Oregon toward drought next summer.
Temperatures from November through January were the 12th warmest in Salem records stretching back to 1892.
The result has been most of the state’s precipitation falling as rain instead of snow in the Cascade Range, where snowpack is an anemic 35 to 40 percent of normal.
“The lack of snowpack is concerning, and without a cool, wet spring drought development is likely in parts of the state,” said Kathie Dello, climatologist with Oregon State University.
January’s average temperature of 45.7 degrees was 4.5 degrees warmer than normal in Salem, officials at the National Weather Service said. November was also warmer than normal, while December was a half degree cooler.
“We’ve had a high-pressure system over the West Coast or just off the coast for a good chunk of winter,” National Weather Service meteorologist Colby Neuman said. “That’s led to fewer storm systems than normal.”
Neuman pointed out that Oregon just missed a few cold storm systems that have blanketed Washington, Montana and Idaho in normal or above-normal snow.
“If the direction of the storms coming from the Gulf of Alaska changed just a little bit, a lot could change in February and March,” Neuman said.
But if things stay the way they are, a situation similar to 2014, ’15 and ’16 could play out, with summer drought conditions bringing issues for wildlife and forest health.
“Water managers will need to carefully evaluate water supplies this summer if snow and spring rains fail to bring relief,” said Julie Koeberle, Snow Survey hydrologist.
This winter follows a pattern that’s become familiar during Oregon’s recent winters, with plenty of rain but limited snow due to warm temperatures.
This year, for example, Oregon has gotten 88 percent of normal precipitation but 40 percent of normal snow, data shows.
The same trend — except more striking — was present during 2015 and 2014.
Dello says that trend is characteristic of what climate scientists have projected for Oregon’s future.
There will still be years with normal or big snowpack — such as 2016 and ’17 — but years with well-below average snowpack will be more common, she said.
“There’s certainly variability from year to year,” Dello said. “Last year was a big snow year. But years like 2015 and now 2018 are becoming more likely.”
Salem fall / winter temperatures
Average high: 54.2
Average low: 41.3
Average temp: 47.7
Normal average temp: 44.8
Takeaway: 2.2 degrees warmer than normal
Average high: 47.2
Average low: 32.0
Average temp: 39.6
Normal average temp: 40.1
Takeaway: 0.5 cooler than normal
Average high: 52.1
Average low: 39.4
Average temp: 45.7
Normal average temp: 41.2
Takeaway: 4.5 degrees warmer than normal
Source: National Weather Service