Another storm set to slam Bay Area

The NWS says this storm will go north to south, soaking coastal mountains and potentially causing widespread flooding. Some meteorologists estimated this third atmospheric river since Dec. 26 could bring around between two inches and five inches of rain to the peninsula’s coastal mountains over the next three days. Mount Tamalpais and the Santa Cruz Mountains could see between six to 10 inches of rain. The heaviest rainfall is expected to be from late Wednesday through Thursday morning.

Unlike the New Year’s Eve storm, this pattern is accompanied by lots of wind, and some forecasts show gusts of 35 to 55 miles per hour. This has prompted concern as the wind could cause outages and topple waterlogged trees planted in saturated soils.

A forecast from the National Weather Service on Monday summarized it bluntly: “To put it simply, this will likely be one of the most impactful storm systems on a widespread scale that experts have seen in a long while. The impacts will include extensive flooding, roads washing out, hillsides collapsing, trees down (potentially full groves), large scale power outages, immediate disruption to commerce, and the worst of all, likely loss of human life. We are looking at a truly brutal system that needs to be taken seriously.”

The grim assessment is coupled with a flood watch and wind advisory spanning past Sacramento as far north as the Sonoma-Mendocino county line, and as far south as King City. The city of Half Moon Bay has declared a local state of emergency and will open its Emergency Operations Center adjacent to the San Mateo County Sheriff’s Office substation at Shoreline Station on Wednesday.

San Mateo County health officials are worried enough about sewage runoff that the county announced on Saturday it would close all beaches and recommended not swimming in the ocean “at least three days after rain conditions subside and waters can be tested for safe use,” the statement read. The county said it will post warning signs at beaches.

On Tuesday, San Mateo County Health Officer Dr. Scott Morrow issued a statement reminding people of the dangers of floods. “Floodwater can contain all kinds of dangerous materials, and it is obviously best to avoid any contact with the water,” he said. “Raw sewage, animal waste, toxic substances, chemical compounds, fungus, bacteria – things you would rather avoid – may be in the water, and you need to take precautions to avoid illness or injury.”

In response to the pending rains, the San Francisco Public Utilities Commission started releasing water from Pilarcitos Reservoir into Pilarcitos Creek on Monday. This will cause the water level to appear higher than usual, though officials say the releases will be timed with current rain forecasts and the tide to minimize overflow.