Images Show Scale of Sierra Nevada's Record-Breaking Snowpack

The spectacular snowpack that has coated the Sierra Nevada with a thick layer of white powder this year is visibly larger than it has been in previous years, even when seen from space.

Images taken by the Moderate Resolution Imaging Spectroradiometer on NASA's Terra satellite show the stark difference between the 2023 snow season and those in 2022, 2021 and 2020. The current year far surpasses the others in terms of the size of the snowy areas.

The Sierra Nevada, a mountain range that stretches from the Central Valley of California to the Great Basin, experienced historical record-breaking levels of snow in recent months.

Drag slider

compare photos

On March 13, California Department of Water Resources data showed that the Southern Sierra—between San Joaquin and Mono counties to Kern County—had a snowpack 257 percent greater than the average for that date and had more snow than in the previous record-holding season, in 1982-1983. The Central Sierra and Northern Sierra were at 218 percent and 168 percent of the average for the time of year, respectively.

"As of this weekend, the Southern Sierra now appears to have largest snowpack in recorded history (as measured by snow water equivalent, or SWE). Not just for the calendar date, but for *any* date!" tweeted Daniel Swain, a climate scientist at UCLA and the Nature Conservancy, on March 12.

These huge levels of snow resulted from numerous and powerful atmospheric river storms that hit the West Coast this winter. Eleven atmospheric rivers drenched the lower elevations with rain and coated the mountains with snow, which is twice the usual number of such storms to hit in a single winter.

Eventually, this thick snowpack will begin to melt and flow down the mountains into the state's reservoirs, where it will supplement nearly a third of California's total water supply.

Topography data from NASA's Shuttle Radar Topography Mission shows that the amount of water that would emerge if all of the snow in a given area melted at once, known as snow water equivalent, was especially high this year, with the Southern Sierra having an SWE 439 percent higher than the average for April 1.

In the wake of California's intense drought during the summer months last year, more snowmelt is a good thing, as it helps replenish low reservoirs. However, because of the dry and hardened ground, if all the snow melts at once, it can lead to flash flooding, where the water instead runs over the ground and eventually into the ocean.

"It's important to remember that timing and type of precipitation—rain versus snow—is crucial for staying out of drought," Jacob Petersen-Perlman, a water resources geography expert and assistant professor at East Carolina University, previously told Newsweek.

"Timing also matters. All the rain at once means that much of it will run off into the ocean instead of filling California's reservoirs," he said.

Additionally, while the huge amount of snow is a relatively good thing in the short term, it will not help end the megadrought that has been plaguing the Western states for over two decades.

"Megadroughts typically refer to droughts that are very severe and also span many years. They also typically have a large geographic spread," Antonia Hadjimichael, an assistant professor in geosciences at Penn State University, told Newsweek in February.

This has meant that the groundwater levels have been depleted over many years, so they will need a lot more water to be restored fully.

"Surface water levels are only part of the picture. Groundwater levels will likely still remain chronically low because, rain or no rain, we deplete more groundwater than is replenished," Aakash Ahamed, a hydrologist and co-founder of the Water Data Lab, previously told Newsweek.

Therefore, while this heavy snow year will help, the state might need a few more years like this one to fully recover from the megadrought.

"It's like we've spent down our bank accounts, and it will take quite a while to rebuild. One year of good snowpack helps a lot but is definitely not enough," Lara Fowler, an environmental and energy issues attorney and interim director of the Penn State Sustainability Institute at Penn State University, told Newsweek in February.

Do you have a tip on a science story that Newsweek should be covering? Do you have a question about the Sierra Nevada snowpack? Let us know via science@newsweek.com.