The Torrent Has Begun: The Philippine Connection

The predicted rain has begun.  Rain associated with a potent atmospheric river, with some of the water originating thousands of miles away near the Philippines! 

Consider the situation on Sunday afternoon, as shown by special satellites that observe atmospheric moisture from space (below).  

You can see the plume of atmospheric moisture extending from the western Pacific to the Northwest.

But it is not quite that simple.  There is substantial three-dimensionality to atmospheric rivers.

To prove this to you, below are air trajectories--the three-dimensional motion in space--of the air reaching the Cascades at 10,000, 5000, and 2000 meters above the surface.   At high altitudes, the moisture is coming from the western Pacific, but at lower elevations, the moisture is coming off the Pacific to our south.

Atmospheric rivers are like real rivers, with tributaries contributing moisture along the way.

The big precipitation has started.  Below are the precipitation totals for the past 24h.  

 A number of locations have already received 3-4.5 inches.   And more is on the way.

Our rivers are rising very rapidly.  For example, the levels of the Cowlitz River in SW Washington are zooming upward (see below).   Soon it will be at flood stage.

The Seattle NWS Forecast Office has FINALLY put out flooding warnings over large areas of western WA (see below).  Quite honestly, they waited way too long to do this.  

This is a serious event, and people need time to prepare.