The periodically heavy rain that spread across San Diego County on Tuesday afternoon will give way to a far more powerful and potentially damaging storm late Wednesday night, packing snow and rain that will last into late Thursday, with a third drenching possible late Sunday, the National Weather Service said.
Collectively, the three storms could drop more than 1.5 inches of precipitation at the coast, twice as much inland, and 2 to 4 inches of snow above the 4,000-foot level, mostly on Thursday, when temperatures will be about 10 degrees below average throughout much of the region.
Forecasters said torrential rain could hit spots from the coast to the mountains from 3 a.m. to 9 a.m. on Thursday, with 0.75 inches or more of rain falling within an hour in isolated places — a rate that could cause lots of street flooding, including during the morning rush hour. A flood watch will go into effect throughout the county at 10 p.m. Wednesday and last until 6 p.m. on Thursday.
“The San Diego River at Fashion Valley will reach monitor stage at 7.5 (feet) by noon on Thursday the 13th, peaking that afternoon and evening around 8.5 (feet),” the weather service said in a statement.
A winter storm watch will be in effect east of Interstate 15 starting before dawn Thursday and might last into Friday.
“Roads, and especially bridges and overpasses, will likely become slick and hazardous,” the weather service said. “Visibilities may drop below 1/4 mile due to falling and blowing snow. Plan on slippery road conditions. The hazardous conditions could impact the Thursday evening and Friday morning commutes. Strong winds could cause tree damage.”
Forecasters say the winds could reach 60 to 70 mph in East County, 35 mph in San Diego and 33 mph in Oceanside.
The air will be very unstable during that period, which also raises the possibility that thunderstorms will develop. The weather service also warned offshore boaters that water spouts might develop.
Forecast models suggest that the third storm could arrive in the county on Sunday night and peak on Monday. Many areas could get at least a quarter of an inch of precipitation.
