A winter storm hit the desert a couple weeks ago, dropping enough snow that some roads in Joshua Tree National Park were closed for a day or so. The resulting picturesque photos of snow-laden Joshua trees, like the one here, prompted a bit of discussion in my circles about the seeming incongruity of snowfall in a desert landscape.
But snow isn't actually all that rare a thing in California's deserts, at least in the Mojave and northward. Snow is likely to cap a mountain or two in the desert each winter -- though the individual mountains may vary. And though it doesn't happen all the time, even the valley floors in the Mojave can suddenly look more like the North Pole than the burning desert.
Part of what drives the impression of incongruity is the popular assumption that deserts are hot places. Some of them are, to be sure, including the Mojave in summer: the US's record hot temperature of 134°F was set 99 years ago in Furnace Creek, Death Valley. But deserts are defined by dryness, not temperature. (Antarctica is a desert.) The water contained in a foot of snow is equivalent to a little bit over an inch of rain, well within the range for desert storms.
We don't even have to search too far back in time for a much greater snowstorm in the Mojave. In the week of December 15, 2008 storms spurred by a combination of moist air off the Pacific and a cold front advancing from the north dumped as much as a foot of snow even on the valley floors across the Mojave. The snow forced closure of 170 miles of Interstate 15 from below Cajon Pass to the Nevada line, and stranded workers and travelers across the desert.
Snowstorms in the desert aren't all catastrophic. Barstow, in San Bernardino County in the central Mojave, averages 1.3 inches of snow annually. To be sure that average includes snowless winters and large storms, but dustings of powder are by no means uncommon in that part of the desert. Even dry and dusty Needles, once a reliable source of the country's daily high temperature, averages a third of an inch a year. Some of that does arrive in relatively large amounts, as described for example in this account of a storm in the winter of 1949:
And sometimes even in the low elevations a snowstorm can be truly prodigious, as witness this note in a NOAA report on the 2008 storm:
It should be noted that while this storm officially stands as the greatest snowfall ever in the month of December in Las Vegas, a review of newspaper accounts and weather records kept by volunteers from the early days of Las Vegas show that a snow storm dropped 13.0 inches of snow in Las Vegas from December 20-21, 1909. This is the largest unofficial snow event ever documented in Las Vegas.
Above about 4,500 feet in elevation, desert snow is a routine thing. Taller peaks like Mount Charleston outside Las Vegas, or Telescope Peak in the Panamint Range, or Clark Mountain in the Mojave Preserve, are dusted with snow as often as not. Mountain Pass, in the shoulder between Clark Mountain and the Ivanpah Range just to the south, averages almost ten inches of snow a year. Camp at around 5,500 feet in the Mojave between January and March, and you're likely to have a morning wakeup call about like this one:
Substitute the expedition-grade tent for a cheap discount store version, and the junipers and pines outside for Joshua trees, and that's pretty much the experience my friend Matthew and I had one February morning a decade or so ago atop Cima Dome in the Mojave Preserve. The snow was melted by late afternoon and replaced by a bone-chilling melting sleet, but for a few hours we had a little bit of a winter wonderland there all to ourselves.
Unlike rain, which runs off when dumped on the desert in large amounts, snow provides a more slow-release source of moisture that trickles into the soil as it melts. Abundant desert snow often brings good spring bloom, which was certainly true over much of the desert in 2009. It's thought that Joshua trees might require a cold, wet February in order to flower profusely. Which means that not only is desert snow not an unusual thing, but at least one species may have staked its survival on it.
As the global climate warms, of course, that may change. Desert winters may grow warmer, decreasing snowfall, or storms may get more intense and increase it. Or both could happen, with a typical year being less snowy but with frequent devastatingly snowy storms in between. Most climate models predict that desert climate will become more erratic, with greater extremes in precipitation. We don't know yet. It's possible that snow in the Mojave may become more like snow in the Low Desert: something that never hits the valley floors but which you can see ringing the crowns of distant peaks, as in this camera phone image I took from Palm Springs of the snow in Joshua Tree National Park:
Chris Clarke is an environmental writer of two decades standing. Author of Walking With Zeke, he writes regularly at his acclaimed blog Coyote Crossing and comments on desert issues here every week. He lives in Palm Springs. Read his previous posts here.