It's key information collected across 900 SNOTEL sites in the West where about up to 80% of the water comes from mountain snowmelt, Domonkos said.

Source: https://gazette.com/news/colorado-river-basin-sees-spectacular-snowpack-buying-time-for-big-decisions/article_841dae22-d4c9-11ed-98aa-a387189cb1c9.html

SNOTEL sites are remote backcountry weather stations that measure snow and transmit the data wirelessly, which help inform decisions about water management.

Source: https://gazette.com/news/colorado-river-basin-sees-spectacular-snowpack-buying-time-for-big-decisions/article_841dae22-d4c9-11ed-98aa-a387189cb1c9.html

The SNOTEL sites also monitor temperature, wind speed and snow depth, broadcasting their automated results back to scientists’ computers every 15 minutes.

Source: https://www.eastidahonews.com/2023/03/its-been-a-wet-and-cold-winter-in-idaho-what-does-that-mean-for-snowpack/