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.

Remember...this is a two-step event...and this is only the first part!

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.

A Monster Moisture Plume is About to Hit the Pacific Northwest

 The latest satellite imagery is stunning....and concerning.  A huge plume of water vapor, extending thousands of miles to the southwest, is about to hit our region, resulting in massive rainfall and localized flooding.  

Consider the water vapor imagery late this afternoon (below). Green and yellow are the highest values,

Look at a wider view, and you can see this atmospheric river of moisture extends many thousands of miles to the southwest.

We are now close enough in time to the event, and forecast models are similar enough, that we can have great confidence in the forecasts.  

The forecast totals through Wednesday morning are stunning, with over ten inches over the Cascades and coastal mountains. Some locations in SW Washington and NW Oregon will receive 15 inches.

Very concerning.

But it doesn't end there.  The next 24 hours will bring even more, particularly over the southern Cascades.  Major rivers in SW Washington (e.g., the Cowlitz) are going to flood.

Don't take my word for it:  here are the latest predictions from the NOAA NW River Forecast Center:

TEN Rivers are predicted to go into major flood, up from two predicted a few days ago.

Some rivers, like the Collitz, are predicted to approach all-time record levels (black line below).

Stunning.

I am more than surprised that the National Weather Service does not have flood warnings out for drainages in the central and southern Cascades (see below).  They should.