California storm will bring rain and snow to mountains but drought persists

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Mountain rain and snow returned to California after the state’s driest start to the calendar year on record.

Meteorologists are delighted with the influx of precipitation. “We may not have had a miracle in March, but April was awesome!” tweeted the National Weather Service office serving the San Francisco Bay Area on Tuesday.

The welcome wet pattern will likely delay what would have been a very early start to the fire season. But that won’t be enough to make up for the missed rainfall this winter, and not enough to recover from more than two years of persistent drought.

Nearly half of California is experiencing extreme or exceptional drought, the two most severe categories. The rest is largely subject to severe drought.

California’s snowpack has shrunk significantly after a record dry start to the year

Although probably too little too late, a recent pattern shift directed a series of Pacific storms to the northern part of the state.

More than three feet of snow fell in some places, and another big storm is expected to hit the area Wednesday through Friday. The weather service issued a winter storm warning for elevations above 5,000 feet in the Sierra Nevada and southern Cascades, where one to two feet of snowfall and locally higher amounts are expected. “Mountain travel is strongly discouraged,” he warned.

At lower elevations, rain will be widespread and heavy, with up to 3 inches in foothill areas and up to an inch in the Sacramento Valley, Bay Area and Central Coast.

“Thursday looks like the rainy day we’ve been waiting for since January with much of the Bay Area expected to see steady and heavy rain,” San Francisco’s National Weather Service wrote in a forecast discussion.

Wildfire risk increases this spring in the western half of the United States due to drought

The weather service notes that from April 11 to 22, the amounts of precipitation may exceed what fell in the previous 3 months and more.

While the renewed storm may seem like a deluge compared to this winter’s dry spell, precipitation so far has not been extraordinary by April standards, and Southern California has remained mostly dry.

“We’re still below normal for most Bay Area locations for the month of April,” said Roger Gass, a meteorologist with the Bay Area office. “Additional rainfall later this week could put us above average for April – that would certainly be good news.”

Downtown San Francisco averages 1.6 inches of rain in April; so far this month it has registered 0.72 inches. Since January 1, it has seen only 13% of its normal rainfall. But for the year of water, which began on October 1, the picture is clearer: 2021-22 is not in the top 50 driest record for the city, thanks to early season storms.

“The reason we’re sitting where we are is because we had a very wet October and December,” Gass said. “We went from record rainfall in October and December across the region to record dry conditions in January, February and March.”

The state’s mountain snowpack has improved and this month’s snow will likely boost water supplies. But statewide snowpack is still only 30% of normal for the date, almost exactly what it was at this time in 2021, and not enough to reverse the current drought. .

“The amount of snow we have on the ground is way below what we would need,” said Andrew Schwartz, station manager and principal investigator at the Central Sierra Snow Lab, located in Donner Pass.

At this particular station, snow received from recent April storms eclipsed what fell in January, February and March combined. The lab recorded 45 inches in April, down from 41 inches from January through March.

But these amounts are far from records for April, so far.

“Really, at this point we’re not breaking any records yet,” he said. “It’s basically an average April, maybe slightly above.”

Schwartz estimates the site would need an additional five feet of snow to break the April record. That could be within reach if this week’s storm adds a few feet and the current wet regime continues. However, the latest forecasts indicate a return to dry weather next week.

And considering the hydrological year as a whole, the drastic swings between record wetness and record dryness are unusual even for California, a state accustomed to a variable climate.

“Unfortunately, it’s certainly up to those extreme weather conditions that we’re expecting more of,” Schwartz said. “Anthropogenic climate change is certainly exacerbating this and making this natural variability more severe.”

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