Southern California may have just experienced a historic amount of rainfall, but more extreme precipitation is headed toward the region. More than a month’s worth of rain fell in a span of three hours in San Diego on Monday, according to the National Weather Service.
Reporters who slog through a meadow near Lake Tahoe next week for California’s first manual snow survey of the season will find copious amounts of snow. The state Department of Water Resources’ electronic readings on Dec. 29 showed a statewide snowpack at 156% of normal as a persistent parade of storm clouds has pelted the West Coast in December.
Often in the winter, you’ll hear that “atmospheric rivers” are causing big weather problems along the West Coast. But what are they?
Made visible by clouds, these ribbons of water vapor extend thousands of miles from the tropics to the western U.S. At 250 to 375 miles wide, they provide the fuel for massive rain and snowstorms that can cause flooding along the West Coast.
In general, atmospheric rivers pick up water vapor from the warm, moist air of tropical regions and then drop the water over land in cooler regions as rain or snow.
I’ll keep this part pretty short and sweet: for the Water Year to date, most of California is in pretty good shape when it comes to precipitation. And that’s good news, given the historic severity of the regional drought as recently as late September.
Residents across the western United States who have drought relief on their holiday wish lists this season will be in luck over the next week. A series of storms will take aim at the West Coast and deliver needed rain and mountain snow from Southern California to the Pacific Northwest through Christmas Day.
Multiple storms are expected to march into the West Coast this week, bringing along a changeable mixture of rain, wind and snow for many places. While a dent in the ongoing drought is expected, it will come at a cost.
This week has already kicked off with a storm marching into the Pacific Northwest. The grey skies and spits of rain that are typical of autumn led to a dreary end to the weekend along the Interstate 5 corridor across western Washington, Oregon and even Northern California.
Trees are dying. Riverbeds are empty. Lake Mead’s water level dropped to its lowest point in history, and Utah’s governor asked residents to pray for rain. Water is increasingly scarce in the Western U.S. — where 72 percent of the region is in “severe” drought, 26 percent is in exceptional drought, and populations are booming. Insufficient monsoon rains last summer and low snowpacks over the winter left states like Arizona, Utah and Nevada without the typical amount of water they need, and forecasts for the rainy summer season don’t show promise.
There is dry, and then there is desiccated.
As any movie fan knows from the classic film Chinatown, California is an infamously thirsty place. But this year, even by its own standards, the state is shockingly, scarily parched. So far in 2021, the state has received half of its expected precipitation; that makes it the third driest year on record according to California’s Department of Water Resources.
This past week, as temperatures from Sacramento up to the Oregon border topped 100º Fahrenheit, the intense heat evaporated the remaining water at an astonishing pace, creating scenes more reminiscent of Hollywood-manufactured dystopias like Mad Max than the lush paradise Americans are used to envisioning on their West Coast.
Nearly half of the country — from the Pacific coast to the Great Plains and upper Midwest — is experiencing moderate to exceptional drought conditions. That’s expected to get worse throughout the summer. As William Brangham reports, it’s the western states in particular that are taking the hardest hit, and the possibilities for devastating wildfires are at an all-time high.
The Water News Network is San Diego County’s source for water news and information.
