Since Christmas, an almost continuous stream of Pacific moisture has raced over Colorado and much of the West, dumping rain in the valleys and heavy snows in the mountains. The sun and crystalline blue skies I brag about to my non-Western friends and relatives have made only rare appearances in the narrow seams between storms.

Frankly, it’s been a little depressing. But water-watchers in the West are almost giddy with delight: Every week, our local papers run stories with cheerful quotes from forecasters, proclaiming that the drought that has gripped the region for the past five years may soon be broken.

"Every string of fantastic years has to start with one," Tom Pagano, a water-supply forecaster for the U.S. Department of Agriculture, recently told The Associated Press, "and we can only hope this is it."

Early January surveys of snowpack show that the Colorado River system, which gathers runoff from Wyoming to Southern California, is likely to receive 98 percent of "normal" precipitation this year. If the rest of the winter meets historic averages, Lake Mead and Lake Powell — which have shrunk over the past five years to 56 percent and 36 percent of capacity, respectively — will soon rise.

But I wouldn’t bet on the reservoirs overflowing just yet. As the scientists featured in this week’s cover story so ably articulate, drought is a regular visitor to the West, sometimes lasting many decades.

The basic aridity of the region is something that explorer John Wesley Powell (whose name graces the massive reservoir on the Utah-Arizona border) warned the nation about more than 100 years ago. Powell’s 1878 report to Congress — reprinted recently as The Arid Lands by the University of Nebraska Press — is "a sober and foresighted warning about the consequences of trying to impose on a dry country the habits that have been formed in a wet one," as Wallace Stegner wrote in the introduction to the book.

Powell and Stegner knew that droughts would ultimately define the development of the West. What they couldn’t know was that our rapid combustion of the planet’s fossil fuels could actually make the dry periods more lengthy and intense.

Over the past couple of years — years of warm temperatures, drought and wildfire — a new sobriety has fallen over the region. The realization is sinking in that the great system of dams and reservoirs built by the federal government might not see us through a major drought, especially not one amplified by global warming.

And so the West is once again on the cusp of confronting its basic aridity. Another dry year or two, and we might actually change our behavior. I hope it stops raining and snowing soon.