Why localized snow? Because of cool air jetting out of the Fraser River Valley northeast of Bellingham, as illustrated by this surface map at 10 AM today (Wednesday). The Fraser River Valley acts as a conduit of colder air from the interior of British Columbia and the approaching low pressure increased the pressure difference across the gap.
The warm southwesterly flow was associated with an atmospheric river, a current of large moisture values out of the tropics (see map of moisture values at 10 PM)
But it doesn't stop there. Here is the precipitation total forecast for the next 48h from the UW WRF model. Wow....5-10 inches over the coastal mountains and the higher Cascades. California shares the fire hose of water as well.
Did I mention the potential for strong winds mid-day Friday as a strong trough of low pressure moves through our region?
The Northwest Weather Workshop, the big annual weather gathering in the Northwest, will take place on March 3-4, 2017 in Seattle (NOAA Sand Point Facility). Everyone is welcome. For more information and to register, go to https://www.atmos.washington.edu/pnww/