Blizzard may rescue Oregon's snowpack

After a bleak start to winter, Mother Nature hit Oregon mountain ranges with a foot of snow or greater last week — and much more could be on the way.

The National Weather Service issued rare blizzard warnings for the Cascades and Blue Mountains this week.

The storm could save Oregon’s snow season, said Larry O’Neill, state climatologist.

David Hill, Oregon State University engineering professor and water resources expert, said on Monday the forecast was “off the charts.”

“It looks like we’re going to play a little bit of catch-up, which is good,” he added.

More than 6.5 feet of snow was expected in the central Cascades in Oregon by Saturday at 5,000 feet of elevation, O’Neill said. Areas near some ski resorts may get as much as 10 feet of snow, he added.

The blizzards could boost Oregon’s snowpack to above normal for this time of the year, but much more snow will be needed before April, O’Neill said.

That leaves lingering concerns, especially as El Nino years tend to be warmer than usual, which could melt snow.

“Any additional snow is helpful, but we need that to stick around. We need to keep accumulating snow,” said Ryan Andrews, Oregon Water Resources Department hydrologist.

Hill said El Nino years haven’t been great for Oregon, but they haven’t generally been catastrophic either.

“On average, the La Nina years do better, but they’re not dramatically better,” he added.

More alarming to Hill is the dramatic dropoff since 2010 in maximum snow level at areas around 5,000 feet due to temperature.

O’Neill said extreme winter weather forecasts often turn out milder than predicted.

“The real worry is if this is going to be the only real storm that we get that builds up our snowpack,” he said.

Snowpack levels

Before the calendar flipped to 2024, Oregon faced a historically dire snow year .

As of Monday morning, Oregon’s snow-water-equivalent — the amount of water contained in snowpack — bounced up to average 64.6% of the median from 1991 to 2020, according to the USDA Natural Resources Conservation Service. Worst off were the areas around Mount Hood, the Sandy River and the lower Deschutes basin at 46%, followed by the Klamath region at 48%. The Willamette basin and the region containing the upper Deschutes and Crooked River were both at 51%.

Bright spots were the Owyhee region at 110% of normal, and Harney region at 97%.

Water Implications

Snowmelt runoff helps to fill streams and rivers for farms and fish.

In general, lower snowpack means earlier low summer flows, which could result in earlier water regulations. Low snowpack also contributes to drought. According to the U.S. Drought Monitor, less than a fifth of Oregon is in moderate to severe drought, Andrews said.

That includes the lower Deschutes River basin, the southern Willamette Valley and areas of Southwest Oregon.

Andrews said despite the rosy picture, conditions could quickly deteriorate into more severe drought conditions, especially considering how dependent Oregon is on snowpack.

Reservoir outlook

Reservoir storage is looking good in eastern Oregon, but below average in the Deschutes and Rogue basins, Andrews said.

Willamette basin reservoirs are on target, said Jeffrey Henson, U.S. Army Corps of Engineers spokesman.

“Barring an unforeseen event, there won’t be an issue having ample water for an authorized purpose such as irrigation, even for the dams that are operating under injunction measures,” Henson added, in an email.

Snowmelt, however, plays only a small role in refilling the Willamette basin’s dams, and wouldn’t make up for a lack of spring rainfall, Henson said.

Blizzard warnings

A blizzard warning in the Blue Mountains spanned 4 p.m. Monday until 10 a.m. Wednesday.

About 6 to 20 inches of snow was expected, with gusts of up to 60 mph.

The blizzard warning for Cascade Range passes in northern Oregon and Washington was from 4 p.m. Tuesday to 4 a.m. Wednesday.

The agency predicted that 1 to 4 feet of snow would fall. Combined with sustained high winds and gusts of up to 55 mph in the passes, whiteout conditions occasionally occur.

“By the time snow showers decrease Wednesday, elevations 3,000 feet and above will likely be measuring their snow in feet rather than inches,” reads a National Weather Service statement.

“In anything other than a true emergency, you should not be traveling (over Cascade passes),” said Jonathan Liu, a meteorologist at the National Weather Service’s Portland office.

O’Neill said that if blizzard conditions were to occur, highways could be closed over the Cascades.

The blizzard warnings come as Oregon has several unusual weather events underway, all of them associated with the same storm systems, Liu said.

Much of Southern Oregon and Northern California was under a winter storm warning.

High winds were forecast for much of the state.

The coast is under a high surf warning and flood warning.