PORTLAND, Ore. (KOIN) — Snow, sleet, freezing rain and icy winds are forecast to create a trainwreck of nasty pre-Christmas weather in Northwest Oregon and Southwest Washington between Thursday afternoon and Christmas Eve.

KOIN 6 Meteorologist Kelley Bayern reports that after a cold and dry Wednesday, a blast of arctic air is expected to sink daytime temperatures into the low 20s on Thursday. Freezing temperatures, combined with wind chill, will likely bring subzero conditions to Portland, the Columbia River Gorge and the Hood River Valley into Friday morning.

The extreme weather conditions could cause a wave of downed trees, burst pipes, power outages and weather-related traffic collisions.

“We will likely see major citywide impacts from an incoming winter storm late this week,” Bayern said. “Models continue to advertise a wintry mix of snow, sleet and freezing rain arriving Thursday afternoon or evening. Then we transition to all freezing rain Friday morning and freezing rain showers continuing through Saturday morning.”

Forecast wind chill temperatures for Thursday. (KOIN)

These frigid temperatures could create blizzard conditions in the gorge by late Thursday, where freezing spray from the Columbia river will be possible. Current weather models forecast a quarter-inch to half-an-inch of ice in the Willamette Valley between Thursday and Friday. 

“When totals get that high, we’re talking downed tree branches and powerlines,” Bayern said. “Untreated roads will be an ice rink, flights out of PDX may be canceled or delayed. This could be a major setback for travelers.”

Cold arctic air will drop temperatures into the teens on Thursday. (KOIN)

In addition to poor driving conditions, the weather will also be generally hazardous to human health. The National Weather Service warns that anyone exposed to the elements on Thursday and Friday will have an increased risk of suffering from hypothermia and frostbite.

“This will significantly increase the threat of frostbite and hypothermia for anyone who is outdoors without proper winter gear,” the NWS said. “This will also increase the risk of pipe bursts if precautions are not taken. Lastly, don’t forget to keep your pets warm too.”