Recent rain and snow brought some relief to California’s historic drought. still not enough

CNN
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Winter in drought-stricken California is off to a fast start with a series of storms bringing a generous amount of rain and snow to the western states.

And it’s already starting to take its toll on California’s drought conditions, according to the latest US drought monitor released Thursday morning. The barrage of rain and snow brought a small glimmer of hope for drought-weary residents, who in the past three years have faced back-to-back historically dry years that led to unprecedented water shortages and landscape-altering wildfires.

Snowpack in California, as of Wednesday, is more than double the normal amount and is trending near December record levels, especially in the northern part of the state. But experts say they are “cautiously optimistic” about what this means for the coming months.

Andrew Schwartz, principal scientist and station manager for University of California, Berkeley Central Sierra Snow Laboratory, says they’re going to need more snow to fall at the lab, which is located on Donner Pass east of Sacramento. It’s where he and other researchers measure snowpack totals and how much water equivalent would be available to state residents.

“If we want to completely get rid of this drought, we basically need another year of rainfall. [at the lab] – We need 60 feet of total snow and an additional 30 feet of snow compared to what we would get on average,” Schwartz told CNN, noting that their average snowfall is 30 feet and that they would have to maintain momentum throughout the year. winter. , which is highly unlikely.

“The storm was fantastic, but it’s definitely not enough to end the drought,” he said.

The high-altitude snowpack serves as a natural reservoir that alleviates drought, storing water during the winter months and slowly releasing it during the spring melt season. The snow cover in the Sierra Nevada represents 30% of California’s fresh water supply in an average year, according to the California Department of Water Resources.

With the multi-year megadrought, snowpack in the Sierras had been at alarmingly low levels, while reservoirs, which are replenished by spring snowmelt, are still below the historical average.

However, this week’s storms provided some relief in drier areas of the state.

Daniel Swain, a climatologist at UCLA and the National Center for Atmospheric Research, says last week’s sequence of storms in the Sierra Nevada has been “honestly remarkable,” though he notes that it would have been considered “normal” just a few decades ago. if it weren’t for the climate crisis. For the past decade, California has been trending much drier than usual, so recent back-to-back precipitation events have been a significant change in pace.

“It was definitely a good news storm overall, as despite the short-term disruption, it did drop quite a bit of water on places that really need it due to long-term drought and aridification brought on by climate change,” he said. Swain told CNN. . “And, more importantly, it dropped that water as snow, which accumulates over weeks and months as snowpack, instead of warm rains that immediately turn into runoff.”

Exceptional Drought, the highest drought designation, nearly halved this week, covering only 7% of the state – the lowest California has seen since May. To put that in perspective, that number was over 28% a year ago. Per the latest update, exceptional drought continues to persist in the southern parts of the Central Valley, particularly Kern, Kings, Fresno, and Tulare counties.

While the storm didn’t break any long-standing records for snowfall last year, despite dropping several feet of snow in the higher elevations of the Sierra Nevada, Swain says the mountain’s snowpack is now well below above average for the calendar date and that overall precipitation is relatively close to average in most places.

“In the short term, California is in pretty decent shape from a water perspective,” Swain said.

Experts say it’s too early to say how recent storms will affect the drought, underscoring how last year snow record in december raised some early hopes, but later “flattened” for the rest of the winter months.

“It’s like a football game: we scored a touchdown in the first quarter, but there are three quarters left before we can really determine what the outcome of the game is going to be,” Schwartz said. “So if we get to March or April, and we’re sitting with above-average rainfall, then we can start to wind down. We can start celebrating a bit.”

Still, California is mired in years drought and continues to face an unprecedented long-term water crisis. More than 97% of the state remains in some level of drought. And on Wednesday, the Metropolitan Water District of Southern California declared a regional drought emergency as Southern California braces for the fourth consecutive dry year.

Swain says there are already signs of a potentially prolonged, multi-week dry spell in the coming weeks, right at the peak of the rainy season in California and the Southwest. If dry and relatively warm conditions develop over the next few weeks, he says that could substantially offset the gains brought by recent snow and rain in recent weeks.

A La Niña advisory is still in effect for the region, but according to the National Integrated Drought Information System (NIDIS), that is expected to change by spring, where a wetter pattern forecast to come through California. In the southwest, La Niña generally causes the jet stream (upper-level winds that carry storms around the world) to move northward. That means less rain for a region that desperately needs it.

Additionally, Swain says there has been a tilt in the seasonal outlook toward drier-than-average conditions in much of California and the lower Colorado River basin, which will see unprecedented additional water shutoffs in effect in the new year, from January to spring.

“That does not bode well for long-term drought relief, particularly in the Colorado River system, where the rapidly accelerating water crisis threatens to reach new heights in 2023 unless unexpected wet conditions occur in the coming months,” he said.

If anything, Schwartz said, this is the time “we need to conserve our water more and maybe even increase conservation efforts because this is not a guarantee of a deep, full winter.”