The Relationship Between the Catalina Eddy and Mountain Lee Side Effects

A mesoscale marine layer cyclonic eddy forms in the Southern California Bight once or twice a month and lasts for a few days. The published hypothesis that this eddy is initiated by Santa Ynez mountain lee side effects fails. A June 1996 case is examined. Stations at the lee foot of the mountains and along the Santa Barbara channel do not have significant offshore winds nor temperature increases expected with lee side effects. A low pressure forms in the south central portion of the Bight separate from the Santa Barbara Channel and a day in advance of the eddy formation. The along coast pressure gradient is relatively large between San Diego and Los Angeles while it is weak or even reversed between Los Angeles and Santa Barbara during the formation stage. Southerly winds at San Diego began a day before the eddy initiation. There is no wind and pressure structure phase shift indicating a low forming in the Santa Barbara Channel and then moving southward.