Another Santa Ana Wind Event

Offshore winds will impact some areas again beginning early Thursday before sunrise peaking around mid-morning.  Winds will be mostly from synoptic-scale dynamics as a shortwave trough dives down across the Great Basin and deepens the cut-off longwave trough residing to our south and east over the past couple of days.  Upper-level flow will be perpendicular to the transverse mountain ranges (San Gabriel and San Bernardino mtns) with strong wind gusts on the lee-side upper elevations of those ranges.  After midnight on Thursday, winds will pour through the Soledad Pass and impact areas in the Santa Clara River valley.  Due to the strong forward vertical wind shear, trapped lee waves are likely which could impact areas downwind from the lower elevation ridges and passes.  Wind gusts exceeding 65mph are possible in portions of Riverside downwind from the Cajon Pass including Fontana and Rialto.  Wind gusts near 75mph are possible in the Santa Ana mountains (Freemont Canyon).  Areas of Orange County against the Santa Ana mountains could experience wind gusts exceeding 50mph mid-morning through early afternoon Thursday.