Atmospheric river from bomb cyclone drenches peninsula

An atmospheric river driven by a powerful bomb cyclone doused the Tiburon Peninsula with more than 6 inches of rain over three days last week, knocking out power to more than 1,000 homes and businesses when it first struck Nov. 20.

After a mostly dry weekend, bouts of wet weather resumed early Nov. 25 and were expected to continue through Tuesday afternoon, Nov. 26, after The Ark’s press deadline, with partly cloudy skies and chances of rain falling to 15% or lower through the Thanksgiving holiday weekend.

Massive back-to-back storms had initially moved in Nov. 20 as a triple bomb cyclone centered on the Pacific Northwest and British Columbia. The term refers to explosive cyclogenesis, or bombogenesis, where warm and cold air masses collide — typically in winter and over the ocean — causing rapid 24-hour intensification from an extreme drop in air pressure. Pressure for this storm dropped at three times the qualifying rate, causing gusts of more than 100 mph near Vancouver Island and cutting power to more than 700,000 homes and businesses in Washington, with falling trees killing two people in separate incidents there.

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