San Francisco witnessed a rare incident in weather history when a high-powered atmospheric river pounded torrential rain and winds with intense fury on the West Coast. Early Saturday, more than 120,000 residents in and around the region were in the dark as the storm pummeled through Northern California and the Pacific Northwest.
In the San Francisco Bay Area, residents faced numerous hazards that included issuance of the city’s first-ever Tornado Warning. Doppler radar detected rotation in a severe thunderstorm moving through the region; this prompted a brief, but intense warning that covered over a million people, including the city’s bustling downtown area.
Although the tornado threat dissipated after approximately 20 minutes with no touchdowns reported, the storm caused significant impacts. San Francisco International Airport recorded an incredible wind gust of 83 mph during the event, underscoring the severity of the storm.
Flood Risks Heighten Across Northern California
Flood Watches were in effect across Northern California, with the North Bay and surrounding areas under a forecast of 2-3 inches of rain in the valleys and upwards of 5 inches in higher elevations. The Weather Prediction Center had the Bay Area under a Level 2 out of 4 flash flood risk, warning of hazardous conditions on roadways and in underpasses.
Saturated ground conditions from recent storms added to the flooding concerns. For instance, Livermore, California, reported some localized flooding that disrupted daily life and caused concern about further damage if heavy rains persisted.
Winter Storm Warnings remained in effect in the Sierra Nevada, where the storm dumped 8 to 20 inches of snow in higher elevations. The winds have been howling with gusts up to 120 mph along mountain ridges, creating near-blizzard conditions, making travel difficult, and increasing the danger of avalanches.
Pacific Northwest Faces Coastal Flooding
Meanwhile, the storm brought its force upon the Pacific Northwest, too, where the coastal communities fought the dual menace of heavy rains and high winds. The gusts reached as high as 62 mph along the coast of Washington at places like Forks and Hoquiam. High Wind Warnings remained in effect with the region getting ready for the potential damage.
Adding to the danger was the risk of significant coastal flooding, fueled by massive 20-23 foot waves, extreme spring tides, and low atmospheric pressure. The National Weather Service in Seattle issued warnings of floodwaters reaching depths of 2.5-3.5 feet in vulnerable low-lying areas during high tide.
A Brief Respite as Storm Moves Inland
The weather in Northern California and the Pacific Northwest was expected to be significantly improved later on Saturday, as the atmospheric river had already moved inland; yet the residual effects of such a storm, from flooded roadways to power outages, reminded one of an evolving sense of weather that affects this area.
As residents start recovering, meteorologists warn that this storm is but one symptom of the challenges posed by changing climate dynamics and call for preparedness for extreme weather events in the future.
