During periods of moderate to strong westerly flow at upper levels over the central part of the State, particularly during the winter and spring, the well-known “Sierra Wave” is created in the Bishop area.  Although this phenomenon is particularly useful to sail plane enthusiasts, it can also be a hazard to the unwary pilot.

TORNADOES – Tornadoes have been reported in California, but with a frequency of only one or two per year.  They are generally not severe, in many cases amounting to little more than damage to trees or light buildings.  In addition, pilots occasionally report seeing funnel clouds aloft, particularly off the southern California coast.

WAVES AND SURF – With the broad expanse of water to the west of California, the fetch of wind over hundreds of miles permits the buildup of seas and surf during much of the year.  The “Climatological and Oceanographic Atlas” for the North Pacific Ocean suggests that seas of five feet or higher are observed most frequently off the California coast during the spring season.  During these months they occur 30 percent to 40 percent of the time.  Seas of eight feet or more occur 10 percent to 20 percent of the time, and seas of 12 feet or more are observed between five percent and 10 percent of the time during the spring.