Thursday Snow Set Up
This isn't the perfect situation for widespread valley snow, and the closer we get to Thursday morning the less impressed I am with the potential for heavy valley snow. The problem, as I see it, is the wind direction. Too much south wind, not enoough east or north wind. Yes, the pre-existing air mass is cold, Hillsboro has already been as low as 28°. But we can warm up rapidly when the south wind aloft gets going. I use the term "warm" a bit loosely here, I just mean warm enough so we get rain. Another wildcard is the precipitation rates. If it comes down really hard, there can be enough colling with the falling snow to lower the snow level and overcome any south wind warming. Bottom line is, south wind snow events are rare. Unless we get a good shot of offshore (east) winds, I think this is going to be more of a snow event for elevations just above the valley floor, with maybe an inch in the valley before it changes to rain.
Stay tuned!
Matt Zaffino
KGW Chief Meteorologist
Comments
Why does the national weather service have a heavy snow warning while you have a different snow ammount?
Posted by: Jason Sierakowski | December 27, 2007 2:55 AM
Snow heavy Ridgefield Wa
Posted by: Jacob | December 27, 2007 5:35 AM
Not a flake in the Portland area, so much for the "heavy snow" forecast!
Posted by: Ryan | December 27, 2007 10:22 AM
Well I'm at 750 feet in Oregon City and the slight dusting is melting quicker than it falls. Another disappointment. Looks like it'll turn to rain as its just too warm. My forecast is that it'll turn to rain by 1pm.
I think the best forecast for snow is looking outside.
Always remember the best snowfall always happens when it's not predicted.
Thanks for trying Matt. I know your job is hard.
Posted by: Bob Archibald | December 27, 2007 10:39 AM
Jason, I know I personally have a different snow amount from the National Weather Service simply based upon my interpretation of the computer models and other data I've looked at.
Jacob, glad to hear you're getting some snow up there! I'm jealous...
And Ryan, still looks like we'll get some snow in Portland today - may have to revise the forecast for our noon newscast, but the snow threat is not over yet.
Joe
Posted by: Joe Michaels | December 27, 2007 10:46 AM