Snow is expected to arrive across Oregon’s mountains in the coming days, but the most dangerous system is targeting the state’s southern half.

High winds and heavy snow could make travel difficult across the mountains, particularly on Tuesday south of Willamette Pass and even on Interstate 5 south of Roseburg.

Overall, it could be a difficult travel time in advance of Thanksgiving, said meteorologists.

“If you were planning to travel down to Medford on Tuesday, or especially into California, you might want to rethink those plans,” said Shad Keene, meteorologist with the National Weather Service in Medford.

High winds on the Oregon Coast also have brought weather warnings.

Here’s a roundup of what’s expected in the coming days.

Snow hits mountains Monday into Tuesday

Snow is expected to hit most of Oregon’s mountain passes and roads above 3,500 feet late Sunday night, Monday and Tuesday, meteorologists said.

Between 5 to 9 inches is forecast for Government Camp (U.S. Highway 26) and Santiam Pass (U.S. Highway 20).

Further south, Willamette Pass could see 9 to 16 inches between Monday and Tuesday, according to the National Weather Service in Portland.

That would impact travel from the Willamette Valley to Bend and Central Oregon.

“Even a few inches of snow are possible in the higher Coast Range Tuesday into early Wednesday,” the National Weather Service said.

On Tuesday, storm slams Southern Oregon

Keene said that beginning Tuesday morning, a windy, snowy storm is headed for Southern Oregon’s coast, valleys and mountains.

“It’s a system where the pressure drops sharply as it approaches the coastline, and yes, we call it a ‘bomb cyclone,’” Keene said. “The main result is wind and snow.”

Winds on the Oregon Coast could reach 60 mph, Keene said, making it difficult to drive tall vehicles and bringing very high seas to the coast.

How much snow will hit I-5, mountain roads?

The big question in Southern Oregon is where the snow level will set up, Keene said.

Right now, 6 to 16 inches of snow and winds up to 50 mph are forecast everywhere above 2,500 feet in southwest Oregon.

That means numerous roads, including the highest parts of I-5, could get hit by whiteout conditions.

“It could be snow showers, high winds, and really poor visibility — basically a mess,” Keene said.

The biggest mess is expected for the Siskiyou Summit pass — the highest point on I-5 located on the Oregon and California border. Around 9 inches are forecast for Tuesday, Keene said.

Major impacts also are forecast for southern Oregon Cascade passes near Highway 97 at Chemult (8-12 inches of snow), around Crater Lake and Diamond Lake (12-18 inches) and on Highway 140 between Medford and Klamath Falls.

In other words, travel around Southern Oregon and into California on Tuesday could be very difficult.

“This isn’t written in stone, and could change, but Tuesday looks like a bad day to travel as of now,” Keene said. “We could even have some snow on the valley floors.”

He said the forecast improves slowly, likely staying messy into Wednesday morning before clearing up late Wednesday and into Thursday.

“It gets better Wednesday and into Thursday,” he said.

What about around the valleys?

It’s unclear how low the snow will come in the Willamette Valley, but it doesn’t appear likely to accumulate on the valley floor as of now, meteorologists said.

“Now, while lowest elevations of interior northwest Oregon may see some light snow or a mix of rain/snow later Tuesday night into Wednesday, little or no accumulation is expected,” National Weather Service said.