PORTLAND, Ore. — A blizzard warning is in effect through Wednesday at 4 p.m. over the Cascades, with the potential for 20 to 40 inches of snow to fall on the mountain passes, KGW Meteorologist Rod Hill reports.
The rare blizzard warning is for areas higher than 3,000 feet. With west wind gusts of up to 55 mph expected at pass level, visibility will be near zero at times, Hill said. People should avoid traveling over the mountain passes on Tuesday and Wednesday unless absolutely necessary.
"Travel over the Cascades Tuesday through Wednesday morning should be avoided if possible," Hill said. "Snow levels Tuesday through Friday will range from 1,500 to 2,000 feet, on average, but may lower at times. Snow amounts Thursday and Friday may be higher than this current forecast."
According to the National Weather Service (NWS), this is the first blizzard warning for the Cascades since 2012. A blizzard means blowing snow, winds of 35 mph or higher and less than a quarter-mile visibility lasting longer than three hours, the NWS reports.
PHOTOS: Government Camp snow
High winds are expected in the valley Monday night into Tuesday morning, with the potential for power outages and tree damage
A valley wind advisory will be in effect Monday afternoon through 10 a.m. Tuesday for the Portland metro area, central Willamette Valley and greater Vancouver area. Hill said south wind gusts could reach 40-55 mph.
"The strongest winds will arrive shortly before midnight as a cold front arrives," Hill said.
Valley wind gusts from the west of up to 40 mph will be possible into Tuesday morning. Hill said the wind could cause power outages and tree damage. The cold front will also bring heavy rain through Tuesday, with the potential for hail and thunder.
"Futurecast shows heavy rain [Monday] at midnight as the strong front arrives," Hill said. "Valley rain totals may near an inch Monday night through Tuesday evening."
Below 1,500 feet, the gorge will see all rain. Winds in the gorge will pick up early Tuesday with west wind gusts of 50-60 mph possible, Hill said.
An arctic air mass arrives later this week. How cold will it get and will there be valley snow?
As if that's not enough, an arctic air mass is expected to arrive Friday in Oregon. The graphic in this section shows the arctic air in purple.
Hill said weather models show growing confidence of moisture Friday night with temperatures potentially dropping below freezing. He warned though that the exact forecast remains uncertain, as of Monday.
"While the forecast continues to show great uncertainty, accumulating snow at lowest elevations [on Friday night and Saturday morning], including Portland is a possibility," Hill said. "Snow amounts of 2-8 inches are possible, depending on the position of a low center arriving from the west. The snow forecast will become more clear as the week progresses."
Though temperatures could drop below freezing, it doesn't seem like the arctic air mass will bring extreme cold to western Oregon and southwest Washington. The air mass is expected to brush past this region briefly before it heads east and drops south over the midwest, Hill said.
We spoke with a transportation operator with ODOT who told us they're going to have extra crews working to clear the roads along Highway 26 along Government Camp the next couple of days. Shane Jansen said that he's more worried about the high winds than the snow. He said there's a chance some parts of the passes could close because of trees not being able to withstand the high winds over the next couple of days.
KGW WEATHER RESOURCES