‘Snow drought’ darkening California’s water outlook

Natalie Hanson

SACRAMENTO, Calif. (CN) — Despite a spate of recent storms, scientists say California needs more winterlike weather to bolster its water supply and avoid another drought.

Daniel McEvoy of the Western Regional Climate Center at the Desert Research Institute said in a panel Monday that much of California and Nevada have seen below average rainfall since the water year began on Oct. 1. Both are still reeling from severe drought, particularly in Nevada’s Colorado River basin.

“We have a snow drought underway across the Sierra Nevada," McEvoy said. Much-needed large winter storms haven't materialized, particularly in the northern Sierra, which was at 66% of average as of Jan. 18, and the southern Sierra, sitting at 40% of average.

It's also been the eighth warmest water year on record so far, with temperatures averaging around two to three degrees higher than normal across the state. And California climatologist Michael Anderson said a high pressure system off the coast has been consistently disrupting or slowing down atmospheric river events.

Statewide precipitation stands at about 71% of average, with much of Southern California “really, really dry still” after missing out on the bulk of recent rainfall events, Anderson said.

Despite the unusually dry and warm start, the U.S. Drought Monitor shows very little measurable drought in the state thus far. Most of the reservoirs in the region have plenty of water and are above average for this time of year, at about 114% — other than a few like Shasta and Trinity. And soil moisture, which is helpful to hold onto stored water, is measuring around average.

Both of these benefits are due to a very wet prior winter, McEvoy said.

“We have to consider that the monitor does have memory, there is a big focus on water supply and we have to think about what happened last year, with how wet and cold and snowy it was and how good that was for our resources,” McEvoy said. He said that nearly one year ago the monitor showed nearly every part of the state in drought, highlighting the importance of a prior year’s water storage.

The state has seen multiple welcome rainy events within the last month, with the National Weather Service reporting around 1 to 4 inches of rain across the north state in the last three days. Ski resorts in the Sierra received between 8 to 32 inches of snow within the last two days, and the region remains under a winter storm warning.

More rain arrives in the north state Wednesday and again next week. Julie Kalansky of the Scripps Institute of Oceanography in San Diego said it’s another good sign that, under current projections, “we’re in for active weather from the end of this week into, potentially, early February.”

She said the state is 100% likely to meet at least 50% of its average rainfall for the season, and has about an 80% chance of reaching 75% average of normal. However, the current models, while always uncertain, show a likelihood of increased warm and dry conditions from February through April.

McEvoy said that despite those recent storms, the snowpack is around the same as in February in 2021, sitting at around 30% of that year’s median peak. And, 36% of wells being monitored are already reporting at below average levels.

“We’ll take it,” he said, but the state needs to see strong storms in February and March to make good headway on the coming year and avoid drought — and it remains unclear if that will happen.