Wednesday, December 24, 2008
On the edge
It is snowing now in much of the western interior, except for light rain around Tacoma, with rain on the coast. The temperatures aloft are right on the edge. Over Seattle, the temperature is 32 F for the first few thousand feet above the surface. In the business we call such a situation "isothermal" and that temperature is being dictated by the melting of snow falling from aloft.
You can see the incoming system in the satellite picture (image) and the precipitation in the radar picture to the right. The rainshadow(or in this case snowshadow) in the lee of the Olympics is clearly visible over Sequim and northern Whidbey Is. The lack of coastal and SW Olympic radar coverage are clear as well. Really frustrated we can't see what is coming in on the radar! The lack of a NWS coastal radar is similar to the city's lack of salt and snowplows...a reconsideration is needed.
The forecast from last night is still on track at this point...with snow for a few more hours and then change to rain as a stronger system comes in this afternoon. But the snow will be close...only a few thousand feet above us...and if our models and analyses are off....well, you know what could happen! In any case, the mountains will get large amounts of snow..which is good for our water supplies and those looking for some recreation over the holidays.
Posted by Cliff Mass at 7:12 AM