A deep, cold trough, associated with its parent upper-level low in the Pacific Northwest, swung through southern California on the 27th, providing the CWA with widespread moderate to locally heavy rainfall and heavy mountain snow. The dynamics were also such that thunderstorms, some with up to pea-sized hail, were also observed. The trajectory of this storm system brought the brunt of the storm through San Diego county providing areas below the snow level and west of the mountains with one-third of an inch to slightly over one inch of rain. Some minor flooding was observed in San Diego County. Orange County and the Inland Empire received less rain, coming in with amounts up to three-quarters of an inch. The snow level was very low with this cold storm, dropping to between 2000 and 2500 feet late in the day. From this level to around 3000 feet had a trace to 3 inches, 3 to 10 inches up to around 7000 feet and up to 14 inches above 7000 feet. Several vehicles slid off the roads in the San Diego County Mountains as well, though no serious injuries were reported. On the lower end of elevation, snow fell as low as 1800 feet in Ramona, however the inch of snow melted later that night. Strong, gusty winds also accompanied this system, most notably in the San Diego County Mountains and the Coachella Valley. San Diego Gas and Electric reported major impacts with this system, including rime ice accumulations on power lines and structures up to a few inches thick.

Heavy Snow in RIVERSIDE COUNTY MOUNTAINS, CALIFORNIA
From 27-FEB-12 15:00:00 to 28-FEB-12 23:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A spotter 5 miles southwest of San Jacinto Peak reported storm total snowfall of 9.5 inches with a water equivalent of 1.33 inches. Idyllwild/Pine Cove reported 14 inches of snow at 5400 feet, which is their heaviest snow for the season.

Heavy Snow in SAN DIEGO COUNTY MOUNTAINS, CALIFORNIA
From 27-FEB-12 16:00:00 to 27-FEB-12 23:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A spotter on Mt. Laguna reported storm-total snowfall of 11 inches. Spotters at Palomar Mountain and Pine Valley each reported 7 inches.
Julian schools were closed, tree damage from heavy, wet snow, and the I-8 mountain pass saw issues with 2 to 4 inches of snowfall. Widespread chain control was mandated.

Heavy Snow in SAN BERNARDINO COUNTY MOUNTAINS, CALIFORNIA
From 27-FEB-12 15:00:00 to 27-FEB-12 23:00:00 (PST-8)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Onyx Summit and Snow Summit between 8000 and 8500 feet near Big Bear received between 11 and 14 inches of storm-total snow.
Heavy snow of 4 to 8 inches in 6 hours led to CHP escorts on I-5 through the Cajon Pass (snow level 3000 feet).

Heavy Rain in SAN DIEGO, CALIFORNIA
From 27-FEB-12 20:00:00 to 28-FEB-12 05:00:00 (PST-8)
Location: BANNER
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Heavy rain caused mud to cover Highway 78, 2 miles east of Scissors Crossing.

High Wind in SAN DIEGO COUNTY MOUNTAINS, CALIFORNIA
From 27-FEB-12 22:00:00 to 28-FEB-12 04:00:00 (PST-8)
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

A mesonet station 5 miles ESE of Cuyamaca Peak measured a wind gust of 64 mph around 2250 PST on the 27th and a gust of 58 mph around 0330 PST on the 28th.
Another mesonet station 5 miles SW of Dulzura measured a wind gust of 60 mph around 2314 PST on the 27th.