Amid the relentless rain brought by an atmospheric river soaking Northern California, a flash flood warning was issued Friday afternoon for San Francisco and parts of San Mateo County where instances of flooding deemed "life-threatening" were occurring.

The National Weather Service on Friday issued several flash flood warnings in parts of the Bay Area as heavy rain saturated the region.

A powerful atmospheric river storm that drenched the North Bay for two days in a row and set rainfall records moved south Friday, bringing steady rain starting around mid-day that was expected to soak the entire Bay Area until Saturday morning.