Weather event also caused flooding, heavy rain and gusts of over 100mph this week

An unusually deep area of low pressure moved into California late on Tuesday. The low deepened quickly, reaching the threshold for “rapid cyclogenesis”, when a low deepens by at least 24 millibars (mb) in a 24-hour period (millibars measure the effective weight of the atmosphere pushing down on the Earth’s surface, due to gravity). A weather buoy in Monterey Bay reported a drop of 24mb in just 17 hours, with a minimum air pressure of 985mb recorded there.

A similar air pressure was recorded at San Francisco international airport, a March air pressure record for that site. The area of low pressure brought heavy rain to California, with some further flooding, along with strong winds. A gust of 102mph (164km/h) was recorded over higher ground to the north of Los Angeles. The strong winds resulted in power outages, and were potentially caused by a sting jet, although the details are uncertain until further research has been conducted. Additionally, the low also produced tornadoes on Tuesday and Wednesday. A tornado in Carpinteria, near Santa Barbara, damaged mobile homes on Tuesday. The following day, one person suffered minor injuries from a tornado in Montebello, south-east of Los Angeles. The tornado also damaged building roofs and cars during its path of over half a kilometre in length.