Lets examine plots of snow depth at Stevens, Snoqualmie, Crystal, and Baker (ignore the spikes on Baker, these are data glitches) for November 29th (last Saturday) through today.
A big week for snow lovers, with huge gains at all locations. But look closely at the last day: there has been a huge increase at Stevens, from roughly 63 to 90 inches! That increase is due to the localized enhancement of mountain-forced convergence zones, or more correctly perhaps, the Olympic Mountains/Vancouver island convergence zones.
Lets look at some recent radar images from the Camano Island radar to see these convergence zones in action!
10:50 PM Friday night: Nice enhanced band--looks like it is downstream of Vancouver Island.
First, the precipitation forecast for the three hours ending 1 AM Saturday. It has the band...looks good.
PS: I got some of the data above from the Northwest Weather and Avalanche Center, a group deserving of your support. They include highly trained mountain weather and avalanche specialists and their web site is a treasure trove of mountain weather data.