Wednesday, December 24, 2008
Christmas Eve Update
I think we will see some more snow tonight...particularly at higher elevations. Temperatures warmed a great deal during the day, and lower elevations (less than 500 ft) generally switched to rain. Some of you at higher elevations did have snow most of the day...although it was generally the wet, sloppy variety. Anyway, the freezing level is starting to drop due to cooler air moving in from the NW and normal nighttime cooling. Right now the snow level is between 500 and 1000 ft and will drop during the night and during intense showers--so even the lower elevations will see snow showers by morning.
Looking at the satellite picture, another disturbance is making landfall...associated with an upper level trough and cool, unstable marine air (see image). You will note that the clouds are not continuous like the system earlier...because it is made up of convective showers. The radar shows the showery nature well (see radar). Because the winds in the lower atmosphere are from the SW, there is a clear rainshadow north of Seattle and extending towards Everett...greater amounts of snow will be north and south of shadow, of course.
Anyway, the snow will not be uniform....because of the showery, hit or miss nature of the precipitation...so some of you will get a few inches and others nothing. This should be the final snow chapter of this week. And most of us will be happy to be able to get around again--my family is running out of groceries! And I hope all of you have a good holiday season and a good new year.
Posted by Cliff Mass at 8:01 PM