Strong Santa Ana winds take an unusual path as they slam San Diego County

Dry Santa Ana winds took an unusual path through San Diego County on Monday, causing the offshore flow to roar down the western slopes of mountains with unusual force and speed, elevating the wildfire danger in a region where the soil is parched.

Gusts as high as 85 mph were recorded at Sill Hill, southwest of Julian, posing a threat to power lines. SDG&E shut off electricity to some communities out of concern that the winds would spark wildfires.

The phenomenon was part of larger meteorological conditions that led the National Weather Service to extend the red-flag fire weather warning along the coast until 5 p.m. Wednesday. A high-wind warning will be in effect across inland valleys, foothills and mountains until the same hour.

Forecasters said that wind-sheltered areas of San Diego County will become very cold Monday night, with temperatures dropping into the 40s in many areas.

Southern California has been experiencing strong and gusty Santa Ana winds that have generated deadly wildfires in Los Angeles and Ventura counties.

San Diego County has so far avoided such chaos, largely because its mountains are aligned in a roughly north-south direction. The Santa Anas usually arrive from the north or northeast, so the winds flow almost parallel to mountain ridges, taking away some of their punch.

But late Sunday and early Monday, the winds arrived from the east and struck San Diego’s mountains at a perpendicular angle, causing the winds to shoot up and then downward into the western foothills. The winds also accelerated as they dropped, making them even more dangerous.

Since midnight, the winds have gusted to 85 mph at Sill Hill, 77 mph in Ramona, 68 mph at Crestwood, 67 mph in Santa Ysabel, 63 mph at Boulder Creek and 62 mph in Alpine.

The weather service also record gusts of 52 mph in Campo, 51 mph in Descanso, 49 mph in Pine Hills, 46 mph on Palomar Mountain, 46 mph at Lake Moreno and 42 mph in Julian.

Schools in these districts will be closed because of the planned power shutoff:

• Julian Union School District
• Julian Union High School District
• Mountain Empire Unified School District
• Spencer Valley School District

Robbins writes for the San Diego Union-Tribune.