A strong upper level trough swept through the Rockies on the 3rd of December, ushering a strong surface high into the Great Basin. The high peaked at 1048 mb on the 7th and brought a prolonged period of strong Santa Ana Winds and very dry weather to Southern California. The most intense winds occurred on the 7th. The Lilac Fire began on the 7th near Interstate 15, and spread rapidly through the San Luis Rey River Basin near Bonsall. Damage to trees and power lines also occurred, along with some road closures.

High Wind in SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS - THE INLAND EMPIRE, CALIFORNIA
From 05-DEC-17 01:00:00 to 05-DEC-17 20:00:00 (PST-8)
Magnitude: 56.00 EG
Property damage: 500.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Strong winds below the Cajon Pass downed numerous trees and power lines, toppled 8-12 big rigs and lofted debris onto highways. Most of the toppled big rigs occurred near the Interstate 15-210 interchange. Two small wildfires also occurred along the 215.

High Wind in SAN BERNARDINO COUNTY MOUNTAINS, CALIFORNIA
From 07-DEC-17 09:00:00 to 08-DEC-17 02:00:00 (PST-8)
Magnitude: 56.00 MG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Mesonet

The Heaps Peak mesonet station reported wind gusts above 50 mph for 10 hours with a peak gust of 64 mph. A large tree fell along state route 38 near Barton Flats.

High Wind in SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS - THE INLAND EMPIRE, CALIFORNIA
From 07-DEC-17 09:00:00 to 07-DEC-17 21:00:00 (PST-8)
Magnitude: 56.00 MG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Mesonet

Peak wind gusts across the Inland Empire were mostly in the 30-40 mph range. Stronger gusts occurred below the Cajon Pass (with peak a gust of 55 mph at Ontario International) and the San Gorgonio Pass with a peak gust of 65 mph at Highland Springs Raws. The peak gust at Highland Springs occurred between 1316 and 1416 PST. Some tree damage occurred in Hemet. Small brush fires occurred near Murrieta and Mira Loma.

High Wind in SANTA ANA MOUNTAINS AND FOOTHILLS, CALIFORNIA
From 07-DEC-17 14:51:00 to 07-DEC-17 17:51:00 (PST-8)
Magnitude: 67.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Fremont Canyon reported wind gusts above 70 mph for 3 hours. Sustained winds were as high as 63 mph.

Strong Wind in SAN DIEGO COUNTY COASTAL AREAS, CALIFORNIA
From 07-DEC-17 10:00:00 to 07-DEC-17 14:00:00 (PST-8)
Magnitude: 43.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Winds downed several large trees in Carlsbad, La Mesa and National City. A man was killed in Carlsbad when a large tree branch fell on him. Light poles were also knocked down in Carlsbad and Tierrasanta.

High Wind in SAN DIEGO COUNTY VALLEYS, CALIFORNIA
From 07-DEC-17 06:00:00 to 08-DEC-17 01:00:00 (PST-8)
Magnitude: 61.00 MG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Mesonet

Three mesonet stations near the Pala Indian Reservation reported peak gusts between 64 and 69 mph, with the peak gust occurring at Palomar Launch between 1015 and 1030 PST. Similar gusts impacted southern San Diego County with a peak of 70 mph at an SDG&E gauge along East Willows Rd. Tree damage was reported in El Cajon, with both trees and power lines down in Ramona.

High Wind in SAN DIEGO COUNTY MOUNTAINS, CALIFORNIA
From 07-DEC-17 06:00:00 to 08-DEC-17 06:00:00 (PST-8)
Magnitude: 76.00 MG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Mesonet

Winds gusts in the 50-70 mph range were reported throughout the San Diego County Mountains. The strongest winds were at Sill Hill where winds gusted over 70 mph for 12 hours (0600 to 1900 PST), with a peak gust of 88 mph. A section of Interstate 8 through the Cleveland National Forest was closed to High profile vehicles. A big rig and trailer were blown over near the intersection of Interstate 8 and Hwy 79.

Wildfire in SAN DIEGO COUNTY VALLEYS, CALIFORNIA
From 07-DEC-17 11:15:00 to 09-DEC-17 00:00:00 (PST-8)
Property damage: 30.00M
Crop damage: 0.00K
Reported by: Fire Department/Rescue

The Lilac Fire began on the 7th near Interstate 15, and spread rapidly through the San Luis Rey River Basin near Bonsall. The fire consumed 4,100 acres, destroyed 157 structures and damaged 64. Over 100,000 residents were forced to or advised to evacuate and 20,000 people lost power. The fire was fanned by sub 10% relative humidity values and wind gusts over 50 mph. The fire was 100% contained on December 16th, but the majority of damage occurred in the first 48 hours. Damage value is an estimate.

High Wind in SANTA ANA MOUNTAINS AND FOOTHILLS, CALIFORNIA
From 04-DEC-17 20:51:00 to 05-DEC-17 09:51:00 (PST-8)
Magnitude: 70.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Fremont Canyon reported wind gusts over 70 mph for 13 hours, with sustained winds over 40 mph. A peak gust of 80 mph occurred 0751 PST and 0951 PST. Winds gusts over 70 mph were also reported at Pleasants Peak.

High Wind in ORANGE COUNTY INLAND, CALIFORNIA
From 04-DEC-17 20:00:00 to 05-DEC-17 04:00:00 (PST-8)
Magnitude: 52.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Mesonet

Report of a large tree downed by strong winds in Orange, CA. Tree damage, minor roof damage, and an exploding transformer were also occurred in Santa Ana.