San Diego Gas & Electric says it expects to temporarily turn off power to some of its customers this week to help minimize the risk of wildfires when powerful Santa Ana winds whip through the region Tuesday through Thursday. The utility has yet to decide how many customers could be affected, but the number is potentially large. SDG&E shut off electricity to nearly 51,000 customers during a similar wind storm in early December. The latest round of Santa Anas will arrive in San Diego County’s backcountry late Tuesday night. They will appear one day before San Diego sets a new record for the driest start of the rainy season. Only 0.16 inches of precipitation has fallen at San Diego International Airport since Oct. 1. “The thing that concerns me about (this storm) is its long duration,” Brian D’Agostino, SDG&E’s vice president of wildfire and climate science, told The San Diego Union-Tribune on Sunday. “We’re kind of looking at multiple waves of wind.” The system will arrive from the northeast, dropping into Orange County early Tuesday, then spreading into San Diego County, peaking on Wednesday, the National Weather Service says. It appears that the winds will fall into a lull late Wednesday but could roar back on Thursday, possibly lasting into early Friday. Forecasters say the winds will be gone by Saturday, but a new round of Santa Anas could arrive next week. The new storm is expected to produce gusts upward of 50 mph in San Diego County’s mountains and inland valleys and foothills, and could reach as high as 75 mph in isolated areas, including Palomar Mountain. The winds also will be especially fierce along Interstate 8, east of Alpine. In December, gusty winds toppled at least five big rig trucks on I-8.