Santa is bringing the gift of another atmospheric river event to the parched US West Coast this week, with heavy snow and rain and windy conditions predicted in spots from Canada to Mexico. The first, warmer storm system will unfold Wednesday into Thursday, keeping snow to the highest elevations. Then, a much colder and more significant weekend storm could deliver snow closer to sea level in places like Washington and Oregon.
That would bring a chance of a white Christmas to cities like Seattle and Portland, where the climatological odds of such romantic -- or irritating, depending on your perspective -- holiday weather is just 1% to 3%. Check your climatological chance of a white Christmas Meantime in the Sierra Nevada mountains, isolated snow could pile high enough to reach the second story of a building -- up to 10 feet, according to meteorologists at the Sacramento National Weather Service office.