Outside of the Northern Rockies and Washington State, the U.S. is desperately seeking snow. Hot, dry weather has been the norm for much of this winter in the West, setting the region up for a summer of water woes.
The snow drought is most severe in California and the Southwest. California’s Sierra Nevada are averaging just 19 percent of their normal snowpack, trending in record-low territory. At the start of the water year, which began Oct. 1, there was nary a hint of drought to be seen in the Southwest. Now, nearly the entire region is in drought. The epicenter is right at the Four Corners, where extreme drought expanded this week to engulf 10 percent of the region, according to the U.S. Drought Monitor.
A powerful ridge has blocked storms from entering the region. It’s also locked in hot weather, which has melted out what precious little snow has fallen. California, Nevada, and the Four Corners states have all had their hottest winter-to-date on record. Oregon, Idaho, and Wyoming are also have one of their 10 warmest winters in 123 years of record keeping.
While La Niña is likely playing somewhat of a role, it’s impossible to ignore that climate change is also a factor driving up temperatures.
“What’s driving the snow drought is heat,” Kathie Dello, a climate researcher at Oregon State University, told Earther about the dry conditions in Oregon and Northern California. “This is climate change. It’s here. We’re expecting more years like this in the future.”
New NASA Earth Observatory maps show just how much snow is missing in the region, comparing the end of January this year to January 2016, when conditions were close to average for much of the West. They paint a picture of just how dire 2018 has been, with large parts of the Southern Rockies completely barren. The map below shows 2016 on the left and this year on the right.
While cold weather has returned this week, snow continues to be in short supply. Many out West are praying for a March miracle, but forecasts released last week by the National Oceanic and Atmospheric Administration indicate that March could warm back up and dry out from Southern California to New Mexico.
Heat-driven snow droughts are expected to become more common with climate change. More winter precipitation is already falling as rain across the West (and the whole U.S. for that matter). That means the natural snow reservoirs in the mountains aren’t as full as they used to be when the dry season hits in May, which can have a host of knock on impacts. Add in a growing population and you have a recipe for more competition for less water.
“The conversation (about what to do) is definitely happening about future water supply even before climate change became part of the planning process because of population growth,” Dello said.