Severe winds and fallen trees slowed power restoration to 400,000 customers as abnormally high Santa Ana winds blasted the Los Angeles area a third day Friday.The winds, gusting around 60 mph, were forecast to continue through midday in Los Angeles and Ventura counties after reaching 97 mph Thursday, the National Weather Service said.In many cities, schools were expected to be canceled for a second day Friday due to the fierce winds, which gusted to more than 80 mph overnight.It was unclear whether Los Angeles\' 4,310-acre Griffith Park, at the eastern end of the Santa Monica Mountains, would be reopened after being closed Thursday out of fear the strong, dry winds would whip up fires.Los Angeles County declared a state of emergency Thursday and officials urged residents to stay off the roads, for fear of being crushed by branches and debris. Many motorists ignored pleas and battled gridlock caused by broken traffic signals and blowing debris, the Los Angeles Times reported.The storm, which produced some of the strongest wind gusts in the region in more than a decade, was caused by a highly unusual weather system. In some places, winds suddenly shifted from 10 mph or 20 mph to more than 80 mph, making trees, power lines and roofs vulnerable, the Times said.A fallen tree sliced through an apartment building in Pasadena, forcing 40 residents to evacuate. Pasadena City officials said at least 40 buildings were so badly damaged they would have to be torn down.The desert winds, notorious for fanning regional wildfires, annually push their way west through Southern California and northern Baja California in late fall and winter. But this time, a clockwise high-pressure system parked over Northern California and the Great Basin was near a counter-clockwise low-pressure system hovering over Arizona.The blustery conditions extended across the Southwest, including Utah, Nevada, Wyoming, Arizona and New Mexico. In some places, wind gusts topped 100 mph.Bill Edwards, a meteorologist with AccuWeather.com, said the difference in pressure between the two systems -- high pressure to the north and low to the east -- added force to the winds.\"In some places we\'ve seen gusts over hurricane force, which for the Southwest part of the country is not something that usually happens,\" Edwards said. \"This is a one-every-10-years kind of thing.\"Wind speeds were expected to start dropping Friday.