Your way too early Christmas Forecast

I shamelessly admit that making a Christmas forecast right now is more of a crap shoot than anything, but I thought I might shed some light of the general idea that the Pacific Northwest is looking at here in two weeks. Before I start, though, take everything I say here with a grain of salt.

Long-range Forecast

Looking at data from the Climate Prediction Center, it looks like temperatures are going to get down right cold for the beginning of next week, especially east of the Cascades. These far below average temperatures will moderate the closer we get to Christmas, but temperatures will remain below average.

Those dreaming of a White Christmas in the lowlands look to be a tad bit dismayed. Where I live, I sit just below 5000′ in elevation. To give you an idea, that’s nearly 2000′ above Snoqualmie Pass and 500′ above White Pass. My White Christmas is all but guaranteed at this point, but looking at the probabilities for precipitation in the lowlands such as Seattle and Portland lead me to believe that the snow will just miss you. Sorry guys.

Precipitation will be slightly above average across most of the Northwest, so there is hope.

So what does this mean for me? It looks like it will be close to cold enough, and that there may be a storm, but if you want a White Christmas and you live below 2000 feet in elevation, now is probably the time to start hoping the storm does happen, that its timing is perfect, and that the snow levels drop like a rock.

Historical Probability
For your viewing pleasure, here’s the approximate historical probability for having 1 inch of snow or more on the ground Christmas Day in select locations around the Northwest:
Seattle – 7%
Portland* – 4%
Spokane – 70%
Boise – 30%
Eugene – 7%
Tri-Cities – 9%
Bend – 30%
Idaho Falls – 70%

Don’t live in one of those cities? Here’s a pretty map.

Note on Portland

It is hard to pin down the historical probability of a White Christmas in Portland for several reasons. First, official sources point from anywhere between a 0% chance and a 10% chance. I have marked down a 4% chance which I took from a specific study (archive) done in 2008 by the National Centers of Environmental Information.

This variation is possibly from my sources drawing from different years, or from different locations around the Portland Metro. I have spoken with longtime residents who have informed me of specific Christmases in the past that had snow. As always with Portland (and Seattle for that matter), the higher up you get the higher your chance of a White Christmas.

Merry Christmas!

Note: This post has been updated to reflect more accurate information that was pointed out to me after my original post.