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Matt Zaffino blog: Evaluating the snow threat

by Matt Zaffino

Bio | Email | Follow: @Zaffino

Posted on February 21, 2011 at 10:08 PM

Updated Tuesday, Oct 29 at 9:23 PM


It's not the classic Portland snow set up, but it's about as good as it gets without being that. Here's what I'm thinking: colder and colder air is poised to drop into Oregon Wednesday. Check out the forecast map below:



A couple things jump out at me. The light blue color over Portland means it'll be cold enough for snow. The winds however, have gone from southerly to westerly, which usually works against valley snow. But the air should be cold enough to overcome the wind direction. The other thing that's notable is the low pressure area (storm) forming in the lee of Vancouver Island, off the Washington coast. This is the second storm to form there, the first appears to be weakening in central Washington.

As the coastal low moves southward, it should send bands of snowfall inland. The map below is 24-hour snowfall, from 4 pm Wednesday to 4 pm Thursday.

Virtually all of western Oregon has snow, with about 1-3" in the Portland area. Basically all of our computer guidance shows the same thing.

Again, it's not the classic Portland snow set up, where a storm moves up from the south throwing moisture over cold air that's being replenished by a strong east wind. But it's about as good as chance of valley snow as we'll see without an east wind.

The potential record snowfall Wednesday and Thursday will be followed by record cold temperatures Friday and possible Saturday. But we should begin to see a lot of sun Friday, and temperatures in the 40s Sunday.

Oh, and this may not be our last snow threat of the winter. Stay tuned.

Matt Zaffino

Chief Meteorologist

KGW NewsChannel 8