Tuesday, February 24, 2009
There has been some hyping of wind in some media outlets...it will get breezy as low pressure moves north of us this afternoon...perhaps 15-20 mph sustained for a few hours in well-exposed locations, but no windstorm. The showers we have been getting has produced significant snow in the mountains (see image), and this will continue the remainder of the week. FINALLY, we are starting to rebuild the snowpack...and I expected 1-2 feet snowfall at pass level and above by Friday. So grease your skis now.
But I did want to note the threat of snow showers in the lowlands on Thursday...something the National Weather Service hasn't mentioned yet. I cold front will move trough around dinner time on Wednesday, bringing in much colder air (see image, sea-level pressure--solid lines, colors are temperature, blue and purple are coldest). A upper trough will move through behind the cold front providing upward motion. A surface low associated with it, is heading towards the snow "sweet spot" off of SW Washington, and a Puget Sound convergence zone may for Thursday morning (graphic). There should be some cold air moving SW through the Fraser River Valley. Finally, this mornings high resolution run is showing snow reaching the surface Thursday morning (graphic--which shows 24-h snow ending 4 PM Thursday) . There is substantial uncertainty...and considering the time of the year and marginal temperatures, we are on the edge of this, but there is a significant chance (perhaps as high as 50-60%) that some snow showers with some accumulation could occur on Thursday AM. So I hope our friends in Metro and various DOTs are keeping a sharp eye on this!
Finally, let me note I will be at Town Hall tomorrow night (Wed) at 7:30 PM talking about the science of local weather prediction. And at the same time Knute Berger will be talking in another room at the same venue about his book "Pugetopolis"--which includes "weather wimps" in the title.
PS: There have been several snow events during the last few days of Feb, first week of March. But if we don't get it then, the probably drops precipitously the second week of the month.
Posted by Cliff Mass at 9:04 AM