PORTLAND, Ore. (KOIN) – December is showing up with colder air and mountain snow. It only took a few weeks but we made it here.

The views from Government Camp and US26/ORE35 are quite snowy Monday afternoon. Drivers will have to take their time if they are doing some mountain driving. These are the views of a successful batch of snow. The base of the ski resorts is now approaching 40 inches and the slopes are starting to look right. A burst of snow here or there Monday afternoon is not out of the question as we have scattered showers in the forecast until early Tuesday.

The Winter Weather Advisory for the coast and the Cascades is still in place. It will expire first to the west, as the moisture tapers off Monday evening. The Winter Weather Advisory will remain in effect until midnight for the Oregon Cascades. Multiple inches of snow through the evening hours is likely.

With temperatures hovering in the 40s Monday afternoon, the thought about snow to the valley floor is limited. There have been a few pockets of heavy showers that have allowed for some snow to mix in down south today in Corvallis. Most locations should steer away from snow to the floor at this time.

Showers are still going to move across the valley around the time of the commute home. Anything late Monday that finds a place passing over the Portland Metro Area could also be enough to show off some flakes or a wintry mix. A sticking winter scene is not expected.

The west hills will be in the position to pick up some snow, mostly above 500 feet. If you swipe through the Futurecast graphics, you can see the areas of mixed precipitation coming through late Monday.

We do have some cold winter air over the top of us, but we haven’t quite tapped into the arctic air from the north. The temperatures aloft have been plenty cold for mountain snow and cold showers. We’ve even had a few bouts of small ice pellets recently.

The graphic below represents the air around 4500 to 5000 feet. That blue is plenty below freezing. What we need for the valley floor is colder air to come pulling in for the Gorge or for an even colder air mass to find a place over the Pacific Northwest (PNW).


What are the chances we find a white valley floor around Rose City in the next few days? Although it is cooling down, the timing and moisture is not syncing up completely.

Tuesday will dry out, leaving a cold morning with little moisture to use for snow. We will focus more on Wednesday morning as our next system arrives. This will bring in more moisture and it will encourage a snow and rain mix for the Portland metro area. It is likely we do see some snow mixing in, but I wouldn’t count on it sticking. The locations will be better suited for that will be up in the higher elevated areas, the West Hills and all the points stretching south closer to the foothills of the coast range — above 500 feet at this time. If you’re commuting down from the hills, you may have to deal with some minor accumulation.

The probability for snow is low this week. Although we can’t fully rule out Tuesday for a mix of rain and snow, it should be a nice dry day.

Wednesday we are looking at close to a 5% chance of snow around Portland. By Wednesday morning, the wind will tell the story for our temperatures in Portland. It is likely that we have more of a southerly wind kick in to warm us up out of snow as the morning continues. Weather models aren’t projecting measurable snow at this time for Portland and the surrounding communities (this is for the valley floor).

Anyone with some elevation to their place of residence will be vulnerable to snow on Wednesday morning. I would even say we could have up to about an inch or so if you get an active pocket of moisture come in. For now we are not expecting to change the city nickname to “Snow City”. We are still waiting for the cold arctic air and the moisture to match up for downtown.