Two storms could bring more rain to San Diego County, with the first arriving Friday night

An atmospheric river is expected to flow through Southern and Central California on Friday and Saturday.
An atmospheric river is expected to flow through Southern and Central California on Friday and Saturday.
(UC San Diego Center for Western Weather and Water Extremes)

Forecasters say it appears that a pair of atmospheric rivers from the subtropics will brush the region, with the first arriving on Friday night and the second moving in a week from Tuesday.


A 1,000-mile-wide atmospheric river that’s forming in the subtropics will brush San Diego County with light rain Friday and Saturday and bring heavy precipitation to the rest of Southern and Central California, further aiding reservoirs and muting the risk of wildfires, the National Weather Service said on Monday.

The storm is part of a major pattern change that also is expected to produce a second warm, moist atmospheric river that will flow through roughly the same areas on March 14, possibly bringing heavier rain to San Diego, which is experiencing its first wet year in three years.

“This second one could cause some action,” said Marty Ralph, director of UC San Diego’s Center for Western Weather and Water Extremes.

The atmospheric rivers will be pulled into the region by the jet stream, which is dropping farther south than usual. Scientists think Central California will take the biggest hit. But lighter, warmer rain could prove to be beneficial elsewhere because less of it runs off into the sea.

Forecasters said Friday’s system will likely drop from 0.20 inches to 0.30 inches of rain at and near the coast in San Diego County and perhaps a half-inch or more in the mountains and foothills. The region will be touched by the southern-most edge of the storm. If the system tracks a little bit further north, greater San Diego could receive very little rain.

The storm also will produce snow in Southern and Central California, but only above 8,000 feet. It won’t be cold enough to generate heavy snow. In fact, forecasters believe that the system’s rains will melt large amounts of the snow that fell in Southern California over the past 10 days, including Lake Arrowhead in the San Bernardino Mountains. The area recently got more than 100 inches of snow.

This phenomenon happens a lot, and the National Weather Service says there’s a fairly simple explanation. You can blame Point Loma.

March 3, 2023