Spring has sprung in San Diego County, but it'll still feel like winter this week.
The region is again bracing for cold rain, gusty winds and potentially damaging floods as California is met this week by its 12th atmospheric river of the wet season, which typically lasts from October to April, according to the National Integrated Drought Information System. Atmospheric rivers are long, powerful portions of the atmosphere that carry lots of water from the tropical regions near the Earth's equator toward the poles.
This storm system could bring anywhere from 1 to 3 inches of rain along San Diego County's coast and inland valleys, while the mountains could see 4 to 7 inches of rain and/or snow. Light showers started overnight Sunday and by 5:30 a.m. Tuesday, about a tenth-of-an-inch to a quarter-inch of rain had fallen; Palomar Mountain received nearly an inch by 5:30 a.m.
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Overnight rain made for a wet morning commute. At least one crash involving several vehicles was reported on a wet westbound state Route 94 near Interstate 5, but no immediate injuries were reported. Further north, the busy SR-78 freeway was still partially closed as the rain prevented Caltrans crews from completing work on a massive sinkhole that formed last Wednesday. Westbound lanes were expected to be closed through Friday, Caltrans said.
Heavier rainfall was expected Tuesday along with a chance of thunderstorms, according to NBC 7 Meteorologist Sheena Parveen. With that much rain, it's possible the San Diego River will flood, closing roadways in the Mission Valley area -- as it frequently does.
"With all of the rainfall that will be occurring below the snow level, expect significant runoff, which could contribute to local flooding issues especially at low-water crossings and in poorly drained urban areas," the NWS said.
A flood watch was issued from Tuesday morning through Wednesday evening for San Diego's coast, valleys and mountains. Some areas that could be affected include Encinitas, Escondido, Pine Valley, La Mesa, San Marcos, San Diego, El Cajon, Poway, National City, Julian, Chula Vista, Carlsbad, Oceanside, Santee, and Vista.
The NWS said rainfall rates could be up to .7 inches an hour on the mountain slopes. More rain on already saturated soil could produce rapid runoff.
The storm will be a cold one and could bring more snow to the mountains, which could see snow at elevations above 4,500 feet by early Tuesday and 4,000 feet by Wednesday morning. A winter weather advisory was in effect from 10 p.m. Tuesday to 10 p.m. Wednesday for these areas. Temperatures are expected to be 20 to 25 degrees below average in the mountains and inland valleys.
Winds will be a factor with this storm, affecting all parts of San Diego County. A high wind warning will be in effect for the coast from 6 a.m. to 10 p.m. Tuesday, affecting areas like Oceanside, Vista, Carlsbad, Encinitas, Chula Vista, National City and San Diego. During that time, wind will average 25 to 35 mph with some gusts between 45 to 55 mph expected. The high wind warning will also be in effect for the mountains and deserts -- where gusts could reach up to 65 mph -- from 10 a.m. to 10 p.m. Tuesday. Powerful winds could knock down trees and blow away other objects during that time.
San Diego Gas & Electric said it's increasing the number of crews available to deal with any power outages that occur during the storm. The agency urges customers to have a plan in place in case of outages. They also warn residents to stay away from any downed power lines and call 911 and SDG&E to report them.
At the beaches, the storm will bring large swells Tuesday evening into Thursday. Some sets could be as high as 12 feet in the South Bay, the National Weather Service said. The conditions could add to beach erosion. A high surf advisory is in effect from 2 a.m. Wednesday to 9 p.m. Thursday.
California's wet season typically lasts from October to April and is categorized by a few significant rain events. This year has been especially wet. the National Weather Service says this storm will be the 12th atmospheric river to reach the county this season.
The rain will lighten up by Wednesday morning and, so far, it appears we'll have a sunny San Diego weekend, Parveen said.