The 24-h precipitation totals (ending 5 AM Friday) show over nine inches at one SW Olympics location and around six at nearby stations. One research rain gauge has received over 11 inches. The Olympics are getting hammered. The North Cascades have peaks around 3 inches so far.
The storm total from the Langley Hill radar near Hoquiam paints out the localized maximum precipitation on the lower windward slopes and the extraordinary lack of rain offshore. You can see why the new radar is so valuable.
The regional radar shows the same thing....offshore the rain is not impressive. And a distinct rain shadow is apparent northeast of the Olympics.
This is a good example of a major characteristic of many atmospheric rivers. This moist airflow does not produce heavy amounts offshore but release their moisture as the air ascends our terrain.
The OLYMPEX experiment is going on now and there is a huge armada of observation assets in place, including research aircraft that are flying this morning. We will gain huge insights into precipitation processes over this terrain feature during the next month.
There is going to be serious flooding on western Washington rivers, particularly those draining off the Olympics and north/central Cascades. The latest Northwest River Forecast Center maps shows their forecasts (see one below). Several rivers will hit moderate flood stage (blue dots). Don't even think about driving through flood waters...can be a fatal mistake.
And big news....looks like lots of snow in the mountains on Sunday....more later.
I will talk more about this situation on KPLU FM (and streaming) at 9 AM in my usual segment with Bellamy Pailthorp.