Tuesday, February 10, 2009
We are going to see snow today in the western Washington lowlands. The Pacific warm front is now moving in and precipitation is now entering the western Puget Sound lowlands (see radar). Central and north coast stations are now reporting snow as is Shelton. The air mass in place is cold enough to support snow, as indicated by the latest profiler data (see graphic). Offshore flow has not developed yet, and without it, the drying and warming that would have lessened the snow threat over the eastern Sound will not be in place. However, SE flow should develop as the system approaches, producing a large E-W snow gradient across the Sound..lighter on the Cascade western slopes and heavier towards the Olympics. Between now and 9 AM the snow shield should progressively move into area. SW Washington will also see light snow (up to a few inches).
The big question is how fast the temperatures will warm up aloft and whether the precipitation will be heavy enough to delay the transition to rain into the afternoon.
Posted by Cliff Mass at 6:33 AM