Since waterspouts and tornadoes do not occur very often in the Bay Area here is a little refresher:

• Waterspout: In general, a tornado occurring over water. Specifically, it normally refers to a small, relatively weak rotating column of air over water beneath a Cb or towering cumulus cloud. Waterspouts are most common over tropical or subtropical waters. The exact definition of waterspout is debatable. In most cases the term is reserved for small vortices over water that are not associated with storm-scale rotation (i.e., they are the water-based equivalent of landspouts). But there is sufficient justification for calling virtually any rotating column of air a waterspout if it is in contact with a water surface.
• Tornado: A violently rotating column of air, usually pendant to a cumulonimbus, with circulation reaching the ground. It nearly always starts as a funnel cloud and may be accompanied by a loud roaring noise. On a local scale, it is the most destructive of all atmospheric phenomena.

Even though tornadoes and waterspouts are somewhat rare in the San Francisco Bay Area they do occur. Over the past 20 years 24 tornadoes have been reported in the Monterey WFO County Warning Area (CWA). The vast majority of these tornadoes were ranked EF0 to EF1 on the Enhanced Fujita Scale. However, on May 15, 1998, a F2 (original Fujita Scale) occurred in Sunnyvale, CA causing and estimated 3.8 million dollars in damage. Generally speaking, unlike 'Tornado Alley', most tornadoes in the Monterey WFO CWA are associated with low topped/mini supercells (<~15k feet) or along narrow cold frontal rainbands. Given the shallow nature of these storms, it should be noted that in some cases tornadic storms cells can be hard to detect on WSR-88D KMUX, which is at an elevation of 3,469 feet MSL. That is why the general public and trained storm spotters are invaluable in relaying severe weather reports to the National Weather Service.

For a climatology of tornadoes in the state of California from 1950-2012 visit here

A vigorous cold front swept through California on January 5, 2019, bringing rain and wind to the region. The airmass became increasingly unstable behind the frontal passage leading to scattered convective showers. A second impulse took aim at the Bay Area on January 6, 2019, and was on track to bring more widespread rainfall to the region. The Oakland upper air sounding on the morning of January 6, 2019, indicated weak instability with weak low level shear. WSR-88D KMUX quickly revealed the instability and low level shear was sufficient as scattered low topped thunderstorms developed, some of them rotating, over the coastal waters. A group of cells ultimately developed off the Monterey Bay Coast tracking northeast toward Santa Cruz (see radar below). These fast moving cells held steady and a Significant Weather Advisory was issued for the Santa Cruz Coast prior to making landfall highlighting potential impacts. Two waterspouts developed (see video below) and made landfall as tornadoes: the first near West Cliff Drive and the second on the Santa Cruz Wharf. A National Weather Service Damage Survey Team analyzed the damage at both locations and determined these tornadoes were EF-0 strength. Damage included: broken trees, broken tree limbs, roof damage, and damage to agave cacti. A third area of damage was surveyed north of Santa Cruz, but later determined to be straight-line winds and not a tornado. The full Damage Survey Report can be found below.

Radar Animation (L: Velocity R: Reflectivity) Green = Flow toward radar Red = Flow away from radar	Overview of Tornado Locations
Waterspout off Santa Cruz - Video By : DropAndTurnShow	Tornado #1 - Tree Damage near W Cliff Drive. Several large branches broken off.
Tornado #2 - Tornado struck at the peak of lunch hour. Witnesses said it felt like an earthquake and pealed off ~35% of the roof cover. The tornado also moved some lunch tables.	Radar Imagery of cell that produced straight line wind damage.
Overview of straight line wind location	Straightline wind damage on a cliff along Cabrillo Hwy just north of Waddell Creek Beach.