01-30-2017

Powerful storms pump up California’s snow-water deficit by 37%

Earth.com staff writer

While California’s long drought isn’t over, a pair of rainstorms that ripped down the West Coast may have gone a long way towards repairing the water shortage. Scientists believe powerful storms that swept California from December through January have likely refilled a whopping 37% of California’s snow-water deficit.

The team from the University of Colorado at Boulder analyzed rainfall totals from two recent storms over the Sierra Nevada region. The storms dropped nearly 17.5-million acre feet, or 21.6 cubic kilometers of water on the mountain range.

Scientists determined this amount by looking at data from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS), a device located on NASA’s Aqua and Terra satellites. They also looked at a computer model drawn up by the University of Colorado and the Jet Propulsion Laboratory at NASA, as well as data from California Department of Water Resources snow sensors.

These numbers are noteworthy because they total more than 120% of the average snow accumulation for the area in the pre-drought time before 2012. From 2012 to 2016, California began experiencing an average annual snow-water deficit of nearly 10.8 million acre feet (13.3 cubic kilometers). This added up to 54 million acre feet (67 cubic kilometers) over that period.

The storms that dumped large amounts of rain over California this winter are known as “atmospheric rivers.” These send huge amounts of moisture from the tropics to the west coast of the U.S., resulting in heavy rain and snowstorms. The Pineapple Express is an example of one of these atmospheric rivers.

Although the new numbers are promising, Noah Molotch, leader of the study, says that one rainy winter season won’t be enough to make up its water deficit.

“When the snow stopped falling five years ago, the state had to tap into its groundwater reserves to keep up,” he said. “One snowy winter won’t be able to entirely reverse that, but there is, at least, some cautious optimism.”