Slow-moving storm could drop 2 feet of snow on Palomar by late Thursday

A Gulf of Alaska storm is drenching San Diego County

A Gulf of Alaska storm is drenching San Diego County

(NWS )

A super-cold storm out of the Gulf of Alaska slow-waltzed into San Diego County Wednesday, producing soaking rains from Oceanside to San Ysidro, stinging hail in Poway and Carmel Valley, lightning in Del Mar and snow that could be two feet deep by the time the system fades Thursday.

(Rainfall totals below)

“We’ll continue to get an assembly line of rain cells and hail and maybe some lightning,” said Mark Moede, a forecaster at the National Weather Service. “And this is going to be a very big snow-maker.”

The system moved ashore 10 days before the start of spring, canceling in-person classes in at least three school districts and leading to a rare snow day at Julian High School, a community also whipped by 30-mph winds. The temperature never got above 38.

Forecasters say that some coastal areas could receive an inch of rain by late Thursday while areas east of Interstate 15 get soaked with 1.5 inches or more of precipitation in what has been a very dry winter.

Wednesday's storm produced a rainbow over Carmel Mountain Ranch

Wednesday’s storm produced a rainbow over Carmel Mountain Ranch

(Kirk Kenney / The San Diego Union-Tribune )

More lightning and hail is expected. The air temperature over Southern California was about 5 degrees at 20,000 feet before the storm arrived. On Thursday, it will fall to minus 24 degrees, which also will keep the snow falling in the mountains. The snow level will drop to 3,500 feet.

Palomar Mountain had received at least 5.5 inches of snow by Wednesday evening. Sunrise Highway was still passable at 4 p.m. on Wednesday, but snow was falling steadily. Motorists will be required to use chains in the mountains. Driving also will continue to be hazardous on Interstate 8, east of Alpine.

The system unfolded largely as forecast, bringing widespread showers before dawn Wednesday, then becoming intermittently stronger. Pine Valley got an inch of rain, Henshaw Dam got 0.84 inches, and San Ysidro got 0.83 inches through 7 p.m. Campo got 0.82 inches, Descanso got 0.80 inches, Vista got 0.59 inches and Fashion Valley got 0.42 inches.

The storm only brushed downtown San Diego, allowing operations to continue at the COVID-19 vaccination site near Petco Park. But managers were keeping an eye on the radar as unstable air moved in. A similar storm on March 3 produced lightning that briefly forced the station to close.

Three school districts in the backcountry announced plans to provide distance learning for all students Wednesday because of the storm. Schools in the Julian Union Elementary School District, Mountain Empire Unified School District and Warner Unified School District won’t have any in-person instruction Wednesday, the county Office of Education said.

The storm could produce showers into Friday, which would give the region the kind of slow soaking that helps reduce the risk of wildfires. But the county’s seasonal rainfall remains way below average. San Diego International Airport has recorded only 3.78 inches of rain since October 1. That’s close to 4.5 inches below normal.

Forecasters say it’s possible that a significant storm will move into California early next week, and another system could follow. But it’s too early to estimate rainfall.

Sample of rainfall totals through 8 p.m. Wednesday:

Pine Valley: 1.02 inches
Cameron: 0.98 inches
Henshaw Dam: 0.84 inches
Lake Cuyamaca: 0.84 inches
San Ysidro: 0.83 inches
Campo: 0.82 inches
Descanso: 0.80 inches
Mesa Grande: 0.80 inches
Alpine: 0.79 inches
Julian: 0.79 inches
Big Black Mountain: 0.74 inches
Santa Ysabel: 0.71 inches
Volcan Mountain: 0.64 inches
Brown Field: 0.62 inches
Tierra Del Sol: 0.61 inches
Vista: 0.59 inches
Warner Springs: 0.47 inches
Oceanside: 0.46 inches
Fashion Valley: 0.42 inches
San Diego University Heights: 0.42 inches
Chula Vista: 0.35 inches
Ranchita: 0.32 inches
Del Mar: 0.28 inches
Encinitas: 0.27 inches
Tijuana Estuary: 0.26 inches
Point Loma: 0.26 inches
San Marcos: 0.25 inches
San Diego SeaWorld: 0.24 inches
Mission Beach: 0.21 inches
San Diego International Airport: 0.18 inches

Union-Tribune reporter Karen Kucher contributed to this story.