As November 2018 came to a close, extensive snow dropped over California’s Sierra Nevada, providing the first significant snowfall of the winter for much of the region.

The left image was acquired on November 20, 2018, while the right image was acquired on December 2. Both natural-color scenes were observed by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite.

Most mid-to-high elevation sites in the Western United States start to accumulate some snowpack around mid-November. Snow that falls on the mountains in winter melts and runs down into the valleys each summer and fall, providing water when rainfall is sparse. Mountain snowpack provides about 30 percent of the yearly fresh water supply for California.

This season has started slow for the western coastal states. As of November 15, 2018, California, Oregon, and Washington had below normal snow water equivalent, a measurement of how much water you would get if all of the snow melted at once.

On November 30, Yosemite National Park finally received its first major winter snow, totaling about 27 inches (69 centimeters) in some areas. Several ski resorts around Lake Tahoe reported more than a foot (30 centimeters) of snowfall on December 2. Some resorts were able to open a few days earlier than last year.

NASA Earth Observatory images by Joshua Stevens, using MODIS data from NASA EOSDIS/LANCE and GIBS/Worldview. Story by Kasha Patel.