An “atmospheric river” will bring nearly two days of rain to the San Diego region, with over 3 inches likely on inland mountain slopes.
The rain will be heaviest on Wednesday night through Thursday afternoon, with the coasts and valleys receiving from 1 to 3 inches over the period.
The mountain slopes could see well over 3 inches, while the deserts are expected to get .5 to 1 inch.
“A trough of low pressure extending southwestward from the Pacific Northwest into the eastern Pacific, will direct a plume of tropical moisture into southern California,” according to the National Weather Service office in San Diego.
According to the weather service, atmospheric rivers are the most impactful type of storm that occurs in California and along the West Coast, causing extreme precipitation.
A flash flood watch for the county mountains, valleys and high desert areas will be in effect from late Wednesday evening through Thursday evening.
The San Diego River is likely to flood during the period, with street closures around Fashion Valley Mall possible.
Showers are expected to begin Wednesday afternoon and continue into the weekend, with a cold front arriving on Saturday night.
#AtmosphericRiver has become a term that translates to “rain in California”. We’re expecting one to hit Wed & Thur. If you want to know more about this unique atmospheric event and its potential effects check out the link and graphic below! https://t.co/zdScOY0XdF #CAwx pic.twitter.com/MZfeYIXuvY
— NWS San Diego (@NWSSanDiego) February 12, 2019