Plumes of moisture stream across the entire Pacific basin and head toward the U.S. coastline. Over the first week of December 2012, over a foot of rain is expected to fall in parts of Northern California and up into British Columbia. This animation shows the total precipitable water in the atmosphere for November 28 - December 6, 2012 using the NOAA Global Forecast System model - one of the main weather models used by forecasters across the world. Dark blues are areas of high moisture content in the atmosphere. The large "tongues" of moisture can be seen extending thousands of miles across the ocean.
A River of Atmospheric Moisture Moves Across the Pacific
December 30, 2011