Oregon snowstorm: Meteorologists explain why Wednesday’s forecast was so wrong

Snow covers South Portland and downtown Milwaukie. Wednesday, Feb. 22, 2023

Kristian Foden-Vencil / OPB

As Oregonians dig out from heavy snows along the northern Willamette Valley and coast, they’re wondering how forecasts for a light dusting above 500, turned into more than 10 inches on the valley floor.

Forecasters knew there could be some snow on Wednesday because a low-pressure trough was headed in northwest Oregon's direction.

But rather than blowing over, the trough stalled just off the north coast, meaning snow conditions stayed in the same place all day and all night.

National Weather Service meteorologist Colby Newman said their models didn't do a good job of predicting the stall.

"We have a big data vacuum to our west," Newman said. "There are not many weather stations over the ocean. And we don't have a good way of getting a lot of weather observations, out over the ocean."

Caleigh Feeny, left, and Matthew Baumgartner walk their dog Whiskey in southwest Portland, Feb. 23, 2023. Heavy snowfall began on Wednesday afternoon, making it the second-snowiest day ever recorded in the city.

Kristyna Wentz-Graff / OPB

Myron Lee shovels the sidewalks in the Sylvan Hills area as Portland area digs out on Feb. 23, 2023. Heavy snowfall began on Wednesday afternoon, making it the second-snowiest day ever recorded in the city.

Kristyna Wentz-Graff / OPB

A driver gets a push after being stuck in the snow, in southwest Portland, Feb. 23, 2023. Heavy snowfall began on Wednesday afternoon, making it the second-snowiest day ever recorded in the city.

Kristyna Wentz-Graff / OPB

A pair of cross country skiers ski through Sellwood Park in Portland, Feb. 23, 2023.

Stephani Gordon / OPB

Rockaway Beach, Ore., on Thursday, Feb. 23, 2023. Heavy snow coated much of Northwest Oregon and Southwest Washington Wednesday afternoon and overnight into Thursday morning.

Courtesy of Doug Colling

A woman uses a blanket to stay warm as she battles the cold and snow on Feb. 23, 2023 in the far west side of Portland. Heavy snowfall began on Wednesday afternoon, making it the second-snowiest day ever recorded in the city.

Kristyna Wentz-Graff / OPB

Greg Palin shovels the sidewalk in front of his wife's business, a yarn shop called Close Knit on Northeast Alberta Street, in Portland on Thursday, Feb. 23, 2023. A snow storm covered the metro area in several inches of snow, making roads icy and leading to several school and business closures.

Rob Manning / OPB

TriMet buses pause on any icy patch of of road at Northeast Alberta Street and 15th Avenue Northeast in Portland on Thursday, Feb. 23, 2023. A snow storm covered the metro area in several inches of snow, making roads icy and leading to several school and business closures.

Rob Manning / OPB

Packed ice on Milwaukie Avenue in Sellwood, Feb. 23, 2023.

Stephani Gordon / OPB

Christopher Gorton carries home groceries after walking to the store in southwest Portland, Feb. 23, 2023. Heavy snowfall began on Wednesday afternoon, making it the second-snowiest day ever recorded in the city.

Kristyna Wentz-Graff / OPB

A smile is drawn onto the windshield on a snow-covered car in southwest Portland, Feb. 23, 2023. Heavy snowfall began on Wednesday afternoon, making it the second-snowiest day ever recorded in the city.

Kristyna Wentz-Graff / OPB

Portland area digs out on Feb. 23, 2023, after heavy snowfall began on Wednesday afternoon, making it the second-snowiest day ever recorded in the city.

Kristyna Wentz-Graff / OPB

Portland area digs out on Feb. 23, 2023, after heavy snowfall began on Wednesday afternoon, making it the second-snowiest day ever recorded in the city.

Kristyna Wentz-Graff / OPB

Portland area digs out on Feb. 23, 2023, after heavy snowfall began on Wednesday afternoon, making it the second-snowiest day ever recorded in the city. A person walks through deep snow in the Sylvan Hills area in SW Portland.

Kristyna Wentz-Graff / OPB

Portland area digs out on Feb. 23, 2023, after heavy snowfall began on Wednesday afternoon, making it the second-snowiest day ever recorded in the city.

Kristyna Wentz-Graff / OPB

Portland area digs out on Feb. 23, 2023, after heavy snowfall began on Wednesday afternoon, making it the second-snowiest day ever recorded in the city.

Kristyna Wentz-Graff / OPB

A bird is fluffed up for warmth, as Portland area digs out on Feb. 23, 2023. Heavy snowfall began on Wednesday afternoon, making it the second-snowiest day ever recorded in the city.

Kristyna Wentz-Graff / OPB

In this contributed photo, a view from Newport, Feb. 23, 2023. The snow postponed the city's seafood and wine festival. Organizers say it will kick off on Friday and run through Sunday.

Courtesy of Dean Sawyer

In the Outer Kerns area in Portland, Zephyr Anderson takes advantage of a snow day, Feb. 23, 2023. Heavy snowfall began on Wednesday afternoon, making it the second-snowiest day ever recorded in the city.

Heather Arndt Anderson / OPB

Snow covers South Portland and downtown Milwaukie. Wednesday, Feb. 22, 2023

Kristian Foden-Vencil / OPB

Drivers creep along NW Naito Parkway near Burnside Bridge in Portland, Feb. 22, 2023. Commutes throughout the Portland area were hampered by heavy snowfall, Feb. 22, 2023.

Prakruti Bhatt / OPB

A Catlin Gabel school bus was stranded near the Multnomah Athletic Club in Portland, Feb. 22, 2023.

Alexandria Hasenstab / OPB

Tanner Springs Park in the Pearl District, under a blanket of snow. Feb. 22, 2023.

Katie Alcantar / OPB

A TriMet bus is stuck in the roadway, facing south in the northbound lanes, near the intersection of NE 82nd and Sandy. Commutes throughout the Portland area were hampered by heavy snowfall, Feb. 22, 2023.

Kevin Kays / OPB

Traffic was inching along on Macadam Avenue in Portland, Feb. 22, 2023.

Courtney Sherwood / OPB

In the Sylvan Hills area of Southwest Portland, a driver receives some help getting up Barnes Road. Feb. 22, 2023.

Kristyna Wentz-Graff / OPB

At Hosford Middle School in SE Portland, there was enough snow for Mia, left, and Xander Livingston-Edwards to get started on making a snowman, Feb. 22, 2023.

Morgan McDonald / OPB

A truck sits in the middle of the roadway after attempting to climb NW Cornell Rd. near the intersection of NW Miller Rd. in Southwest Portland, Feb. 22, 2023.

Kristyna Wentz-Graff / OPB

People slip on the snow-covered sidewalks near Tanner Springs Park in the Pearl District, Feb. 22, 2023.

Katie Alcantar / OPB

As the snow fell around 3 p.m., Portland International Airport crews worked to clear the snow from the gates, Feb. 22, 2023.

Courtesy of Laura Britzius

Sellwood River Park, Feb. 23, 2023.

Stephani Gordon / OPB

In addition to that lack of ocean data, Newman said there was a combination of factors at play.

"We have satellites that the models are using to ingest that data and it has made these surprises a lot less frequent than they used to be," he said. "But there's definitely room for improvement."

He said the snow could have ended up as rain if the stall had happened elsewhere.

"If the low set up 30 miles off the coast," he said, "we probably would not have gotten any snow yesterday."

So a small shift in the location of where the low-pressure system settles makes a big difference in which area gets hit with snow and whether that snow falls as rain instead.

Without more research, it's not clear whether Wednesday's storm is linked to climate change. Every now and then, northwestern Oregon simply gets socked in with snow.

"We do get snowstorms on occasion of this magnitude," Newman said. "It's rare, but we do get them."

Rockaway Beach, Ore., on Thursday, Feb. 23, 2023. Heavy snow coated much of Northwest Oregon and Southwest Washington Wednesday afternoon and overnight into Thursday morning.

Courtesy of Doug Colling

We hear from officials and services providers from around the region about the impact of Wednesday's snowfall in Western Oregon.

Some areas of Portland saw more than a foot of snow as the region slowed to a crawl Wednesday night and will remain under a white blanket with a wind chill advisory in effect until noon Friday.

Heavy snow and high winds are causing blizzard conditions in the Upper Midwest. It's the latest stage of a three-day storm that's placed over half the country under winter weather warnings.

Smaller, faster-melting snowpack could deplete water supplies, increase wildfire risk and invite invasive species. The Cascades might reach that point earlier.