Midwinter dry spell, thin snowpack raise concerns about drought

Correction: This story was updated to add a graph showing snowpack. The wrong graph was included earlier.

If this winter has felt exceptionally dry, the data backs it up.

Weather stations across Lane County recorded some of their lowest precipitation totals for January since 2015, a year widely remembered for severe drought.

The weather station at Eugene Airport measured 3.59 inches of rain in January, placing it among the airport’s 10 driest Januaries on record.

Larry O’Neill, the state climatologist and an associate professor at Oregon State University, is tracking the conditions both professionally and as a Eugene resident. He described the pattern as a midwinter dry spell. The spell itself is not an unusual thing, he said, and it’s a pattern that usually lasts about a week or two, according to historical records. 

“But this one is especially long-lasting,” he said. “Now we’re over two weeks of really dry weather.” 

The dryness marks a sharp shift from conditions going into the winter. From October through December, warm atmospheric rivers — often described as waterways in the sky — delivered heavy rain across the region.

By January, that wet storm pattern stopped. A persistent high-pressure ridge settled over the region, deflecting storms north into Alaska and leaving western Oregon dry. 

Then inversions developed as cold air became trapped near the surface, leading to stagnant air, fog and worsening air quality. Pollution from vehicles, wood burning — and tear gas from protests — lingered near the ground, and there was a stretch of freezing temperatures.

Part of the reason is the Willamette Valley’s bowl-like geography, which traps dense, cold air.

While the cold has been noticeable, the lack of snow in the mountains may be more consequential. Oregon’s snowpack is currently less than 30 percent of normal, a level comparable to 2015.

The Cascade Summit measuring station is near the top of Willamette Pass.

Snowpack is a critical part of the state’s water system, acting as a natural reservoir that releases water slowly through spring and early summer. 

“Snowpack is a really key indicator for water supply for much of the state,” O’Neill said. 

Already, according to the U.S. Drought Monitor, about half of Lane County — primarily areas east of Interstate 5 — is classified as abnormally dry.

In 2015, the low snowpack foretold a harsh summer, prompting Lane County to issue a drought declaration and ask residents to conserve water.

Historically, here’s how drought has looked in Lane County over the past decade.

Looking ahead, O’Neill said drought conditions this year are unlikely to affect drinking water supplies as they did in 2015. However, rivers and streams are typically replenished by winter rain and snowmelt, and that recharge has not occurred.

That could mean areas relying on rivers and reservoirs for agriculture or recreation may face restrictions later in the year. A diminished snowpack also increases wildfire risk. Without sustained snowmelt to keep soils moist into summer, vegetation dries out earlier, prolonging and intensifying wildfire season.

Eyes are now on the remaining weeks of February, with climatologists and emergency managers hoping for precipitation.

O’Neill said he doesn’t expect snowpack to get back to normal levels this winter. “It’s possible, but it’s not likely at this point.”