This animation shows the flows of total precipitable water in the atmosphere. A stream of atmospheric moisture can be seen emanating in the western Pacific and hosing down the west coast of the United States. (Source: Cooperative Institute for Meteorological Satellite Studies, http://tropic.ssec.wisc.edu/real-time/mimic-tpw/global2/main.html) As I write this late Saturday night, clouds are thickening over the Front Range of Colorado, where I live, and weather models are predicting more than a foot of snow in some places. And this is just the first of three storms that are predicted to blow through Colorado through Thursday. As the image above shows, we can thank a veritable atmospheric fire hose out in the Pacific that is spewing precipitable water at the West coast, and thereby helping to spawn storms. In the map below, I am roughly in the Colorado bullseye — the 'x' marking the spot where more than eight tenths of an inch of precipitation is expected to fall through Thursday.
The forecast for total precipitation, in inches of water, through Wednesday, from the National Weather Service. (Source: http://www.hpc.ncep.noaa.gov/qpf/day1-3.shtml) Meanwhile, to the east and south of me, in Nebraska and Kansas, even more precipitation is expected. And still more in the Southeast. As the U.S. Drought Monitor indicates, all of these regions can use every molecule of moisture they can get. In fact, when it comes to snowpack, the source of most of the West's water, we're verging on desperate in many places. How much of an impact will this have on widespread drought? Stay tuned...