LOS ANGELES, CA – Atmospheric rivers hitting California since late last year have blanketed mountains with a winter full of snow and begun to raise reservoir levels – but experts say it will take much more precipitation to reverse the effects of years of drought .
The US Drought Monitor’s weekly update released on Thursday showed that “extreme” drought has all but been eliminated a week after the worst category – “exceptional” – was washed off the map. Two weeks ago extreme drought covered 35% of California.
The Drought Monitor characterized the improvement as a significant reduction in drought intensity but warned that large parts of the state have moisture deficits that have been entrenched for two to three years.
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Most of the state is now in the “severe” or “moderate” categories of drought, with small areas in the far northwest and far southeast in a status described as “abnormally dry,” which is the lowest level.
After significant damage to some communities and at least 18 deaths, California was in a lull between storms on Thursday, but more precipitation was expected to arrive on Friday and last through the weekend. Flooding remained a concern, especially along the Salinas River in Monterey County, due to so much rain falling.
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Downtown San Francisco, for example, received nearly 13.6 inches (34.5 centimeters) of rain from December 26 to January 10. The snowfall so far this season on the summit of the Mammoth Mountain resort in the Eastern Sierra has hit 444 inches (11.3 meter).
In the Sierra Nevada and other mountains, the water content of the snowpack is more than 200% of normal so far and more than 100% of the April 1 average, when it is historically at its peak, according to the Department of Water Resources the state.
“The automated sensors are registering what they would consider a full seasonal snowpack, about what we would expect on April 1,” state climatologist Michael Anderson told reporters this week .
The snowpack supplies about a third of California’s water when it melts and runs into rivers and reservoirs.
Locally, some reservoirs have seen a significant increase in water levels but there are still significant deficiencies to be overcome.
Across the country, reservoir storage is only 82% of average for this time of year. Only 44% of the capacity of the largest reservoir, Shasta. That is only 70% of the average to date. Oroville’s massive reservoir is closer to average but only 49% of capacity.
“The good news is they’re not off historic lows,” Anderson said of the large reservoirs. “The challenge is that they still have a lot of recovery to do before they would be back to normal operating conditions.”
And there is concern that the rain could stop suddenly. Significant storms marked the end of 2021, but the beginning of 2022 saw months of bone dry weather.
There are some hints of a drier pattern developing around January 20, said Daniel Swain, a climate scientist at the University of California, Los Angeles, during an online briefing this week.
