The drought in the U.S. West is unlikely to end any time soon, and that makes the coming winter one of the most crucial in recent years.
How the West gets its water is a delicate balancing act between what nature provides, mostly in the form of snow, and what humans can capture in reservoirs.
"All eyes will be turned to the winter because it is a really critical winter, not just for California but the rest of the West and the lower Great Plains as well," said Mark Svoboda of the National Drought Mitigation Center in Lincoln, Nebraska.
Exceptional drought, the worst category on a five-step scale, covered 19.88 percent of 11 Western states, including California, Nevada and Arizona, last week, according to the U.S. Drought Monitor, also based in Lincoln. Across the region, 70.26 percent of the land is at least "abnormally dry."
That affects almost 51.2 million people, or 16 percent of the U.S. population, the Drought Monitor said on its website.
Parts of the Southwest have a monsoon season in the summer, when rainfall increases. However, for a large part of the region, the equation is simpler: Ending the drought before the start of the next dry period would require more than twice the normal amount of snow.
"For the majority of the West, the lifeline is the snow that falls in the Rockies, the snow that falls in the Cascades and the snow that falls in the Sierra," Svoboda said in a telephone interview.
Arizona and New Mexico got some relief this year from their annual monsoon, as well as buckets of rain that hurricanes Norbert and Odile sent into the area, said Kevin Werner, western regional climate services director with the National Climatic Data Center.
None of that rain got far enough north to have a regional impact, said Werner. That brings the conversation back to snow.
"Most of our water, from 80 to 90 percent of it, falls in the form of snow in the winter time," he said.
With the West now in its third year of drought, "the reservoirs are all very low and the soils are pretty heavily dried out," said Rob Hartman, a hydrologist in charge of the California Nevada River Forecast Center in Sacramento.
"It’s going to take far more than an average snow pack to fully recover," he said.
A good winter would be one where 2 1/2 times the normal amount of snow fell, said Hartman. That would also have to be followed by several more years of above-average snowfall.
In the past three years, the mountains in Nevada, for instance, received only about 60 percent of the snow they normally would, said Douglas Boyle, the state’s climatologist, in Reno.
"We have essentially lost an entire year of snowpack over the last three years," Boyle said by telephone.
Across the Truckee River Basin that straddles California and Nevada, the average snow-water equivalent for a winter is between 28 and 30 inches (71 to 76 centimeters), Boyle said.
How many inches of snow it will take to actually get that depends on how moist the flakes are when they fall. For instance, if 10 feet of snow fell and only 30 percent of that was liquid, the snow-water equivalent would be 3 feet.
It will be March or April before solid figures on the season’s snow-water equivalent are available, Boyle said.
Until then, the West will have to wait.