Weekly Weather Event -Week of December 2December 6, 2019
A large winter storm system is set to arrive on the West coast this afternoon, bringing rain and snow to the Pacific Northwest and California. The heaviest rain is expected to impact portions of Northern California, with rainfall predictions ranging from .25 inches in the Bay Area to 2 inches in the northwest foothills.
In addition to the rain, winter weather advisories are in place along the Eastern Sierra Slopes, with elevations above 7,000 feet seeing between 5 to 10 inches and elevations above 8,500 feet likely to see up to a foot of snow. Wind advisories are in place along the coast, and a flash flood watch is in affect for parts of the San Francisco area that have been damaged by fire as burn zones carry an increased risk of mudslides.
Landslides are the movement of rocks, debris, or earth down a sloped incline. Almost all landslides have multiple causes and factors, including earthquakes loosening rocks and soil, rainfall, flooding, and human intervention. Mudslides are the more common term for debris flow, a type of landslide where the mass being moved is made of materials that can easily flow. These landslides typically contain mud, loose rocks, sand, soil, and water, as well as anything it happens to collect in its path.
Post-wildfire regions are particularly vulnerable to mudslides. Burned vegetation removes root systems holding soil in place, creating large swaths of loose soil that is easily disturbed by rainfall. Mudslides can happen quickly and with little warning, further stripping vegetation from a fire-torn region and damaging structures in its path. The United States Geological Survey recommends seeking higher ground in debris flow risk areas.