Can one monster storm save California from drought?

After months of relatively dry weather in California, this winter’s biggest storm to date is set to deliver rain at lower elevations and feet of snow in the Sierra Nevada mountains. That’s good news for the precipitation-starved state, but will this storm be enough to mitigate the growing number of areas facing severe drought?

The National Weather Service reports that Los Angeles will see rain continuing into Saturday morning, with snow at elevations of 6,000 feet. Farther north, the forecast calls for up to seven feet of snow in Lake Tahoe and up to five feet along the Sierra Crest in Mammoth has skiers rejoicing and locals bracing for blizzard conditions.

Large amounts of snow and wind gusts up to 100 mph will make travel difficult across much of the state and will also raise the avalanche danger. The National Weather Service in Reno issued a blizzard that’s in effect this morning, advising people that “even a short walk could be deadly in these conditions.”

This week’s storm is a welcome break from the West’s abysmally dry winter that has revived concerns about water. Last winter, a record-breaking amount of snow lifted the state from a multi-year drought that caused Gov. Jerry Brown to declare a state of emergency.

At the end of January, Los Angeles had seen just 28 percent of its average precipitation since October, and the Bay Area is only at about 50 percent of average. The dry weather has been especially acute in the southern half of the state, and a lack of rain and high temperatures set the stage in early December for the largest fire in California history.

This winter’s lack of precipitation has plunged much of the state back into drought, with most of Southern California in moderate or severe drought and almost the entire state considered “abnormally dry.” Those assessments are made after considering the state’s precipitation totals, temperatures, moisture levels in soils, and water levels in streams and lakes. The recent lackluster numbers caused the Los Angeles Times to wonder whether Gov. Brown should have ever lifted the statewide water restrictions.

United States Drought Monitor

The big question remains: Is this upcoming storm—proclaimed to be the biggest of the winter so far—our last hope to potentially avoid more severe drought conditions this summer? Unfortunately, the answer is no.

While any moisture is better than no moisture, even a five- or seven-foot storm won’t be enough to return the Sierra Nevada—which is the source of about 30 percent of California’s water supply—to normal. A recent foot or two of snow was welcome news to snow-starved ski areas, but it only bumped up the snowpack by a few percentage points to 23 percent of average.

To put this in perspective, it takes about 10 inches of snow to deliver one inch of liquid water. To get to the average snowpack on March 1—which is about 25 inches of snow water equivalent—this week’s storm would need to drop over 16 feet of snow in the California mountains.

Of course, it’s rare for a single storm to end a drought. Last year, it took a successive number of large storms to make a difference in the snowpack and fill the state’s reservoirs. With forecasts of two to five feet of snow, the San Jose Mercury News reports that this week’s storm should take the snow pack from about 23 percent to about 40 percent of average. That’s better, but we’ll need several big storms in March to come close to ending the winter with an average snowpack.

Our advice: Start hoping for a March miracle.