Summary - The basic pattern consists of high pressure off the Pacific Northwest and the northern California coast, and troughing off central and southern California and Baja. Upper lows continue to develop over central California in the medium range through September 20th. These produce recurrent northeastern wind events in northern California and onshore flow at times in southern California. Sea surface temperature influence continues to favor weak east-west troughing along 30N from southwest of southern California and extending well west out into the central subtropical Pacific to north of Hawaii. Other tropical cyclones develop off southern Baja, but the usual pattern is for upper high pressure to build to the north of these systems, producing hot weather into California, and the possibility of more rain for Baja and western Mexico. After a hot dry period from September 20th-22nd, more rain develops for the southeastern U.S., culminating in a significant rain around September 27th-28th.
