Monday, February 9, 2009
Surprise Convergence Zone snow
Last night a convergence zone formed in the wake of the passing front and was sufficiently intense to drive the snow level down to the surface (see radar image at 2 AM and now). There are reports of a trace to 1-2 inches. It is over now. The Seattle profiler shows the event clearly..with the low-level windshift and the cooling of the air due to evaporation and melting. "Surprise" convergence zone snow showers are a traditional here in Puget Sound country....rarely a year passes without one. To get a handle on such events a coastal radar would be very useful...allowing us to secure much better forecasts 3-9 hr ahead.
The next snow threat includes snowshowers today...which will be brief... and then this evening when the convergence zone should reestablish itself according to the latest high resolution model runs. The air is cold enough that heavy showers can bring wet snow down to the surface.
Tuesday looks as before....incoming weather system that will bring snow to the Kitsap and SE Olympics slopes...as well as the Chehalis River Valley. Near the Olympics the snow could be heavy...6-12 inches are possible. Tonight I will analyze this threat in some detail.
Posted by Cliff Mass at 6:57 AM