Calif. rain won’t be enough to ease severe drought
SACRAMENTO, Calif. – Moderate to heavy rain fell across Northern California on Friday, heading into a weekend expected bring increasingly stormy weather to the drought-stricken state while also raising concerns about flash flooding in vast areas scorched by wildfires.
A flood warning was posted in part of Siskiyou County bordering Oregon, where “law local law enforcement reported debris flow and flooding on roadway from excessive runoff,” according to the National Weather Service’s office in Medford, Oregon.
Californians rejoiced this week when big drops of water started falling from the sky for the first time in any measurable way since the spring, an annual soaking that heralds the start of the rainy season following some of the hottest and driest months on record.
But as the rain was beginning to fall Tuesday night, Gov. Gavin Newsom issued a statewide drought emergency and gave regulators permission to enact mandatory statewide water restrictions if they choose.
Newsom’s order might seem jarring, especially as forecasters predicted up to 7 inches rain could fall on parts of the Northern California mountains and Central Valley this week. But experts said it makes sense if you think of drought as something caused not by the weather, but by climate change.
For decades, California has relied on rain and snow in the winter to fill the state’s major rivers and streams in the spring, which then feed a massive system of lakes that store water for drinking, farming and energy production. But that annual runoff from the mountains is getting smaller, mostly because it’s getting hotter and drier, not just because it’s raining less.
In the spring, California’s snowpack in the Sierra Nevada mountains was 60% of its historical average. But the amount of water that made it to the reservoirs was similar to 2015, when the snowpack was just 5% of its historical average. Nearly all of the water state officials had expected to get this year either evaporated into the hotter air or was absorbed into the drier soil.
“You don’t get into the type of drought that we’re seeing in the American West right now just from … missing a few storms,” said Justin Mankin, a geography professor at Dartmouth College and co-lead of the Drought Task Force at the National Oceanic and Atmospheric Administration. “A warm atmosphere evaporates more water from the land surface (and) reduces (the) amount of water available for other uses, like people and hydropower and growing crops.”
Increasingly strong storms are expected to spread throughout California through the beginning of next week.
“By Saturday night, a rapidly intensifying Pacific cyclone directing a powerful atmospheric river squarely at the West Coast delivers a fire hose of rich subtropical moisture into California,” the National Weather Service said. “Snow levels will be low enough to blanket the Sierra Nevada in heavy snow on Sunday while prolonged periods of rain soak the coast and valleys of northern and central California.”
Precipitation will then spread into Southern California on Monday.
The rain has helped contain some of the nation’s largest wildfires this year, including a fire that threatened the Lake Tahoe resort region this summer.