California will be hit by another atmospheric river storm this week. But this one will be warm rather than cold, raising concerns about possible flooding and melting ice.
The incoming storm is building as a northern pressure ridge meets subtropical moisture rising from Hawaii. Such systems are sometimes referred to as Pineapple Express and have been known to drop heavy precipitation.
Thursday: The storm will move in at night, bringing rain and snow to high altitudes.
Friday: Heavy rains will fall, with the possibility of flooding in some river, mountain and foothill areas.
Thursday: The rain will begin at night.
Friday: The most intense part of the storm is expected.
Saturday: The rains will decrease.
Areas of concern
- According to the National Weather Service, rivers that could flood include the Russian River in Hopland; the Salinas River at Bradley and Spreckels; the Merced River in Stevinson; the Tuolumne River in Modesto; the Cosumnes River in Michigan Bar; the Mokelumne River at Benson’s Ferry; and Bear Creek at McKee Road.
- Nearly two dozen additional river locations across the state may rise above their “control stage,” meaning they could overflow their banks and cause minor flooding in low-lying areas. That includes multiple locations along the Sacramento and San Joaquin rivers.
- officials in ash tree and Wood Counties have issued evacuation warnings for residents in their areas, warning of potentially severe flooding from the oncoming storm. Fresno County Sheriff’s Office spokesman Tony Botti said officials are particularly concerned about flooding around Pine Flat, as well as Lake Millerton, which empties into the San Joaquin River and flows west into Mendota, Tranquility and other communities.
- At the Oroville dam, which suffered a near-catastrophic failure amid a series of atmospheric rivers in 2017, state operators said they could start releasing water from the dam’s rebuilt main spillway starting Friday.
- In the mountains of San Bernardino County, where some residents remain snowbound after historic blizzards dumped more than 100 inches of fresh powder on the area, officials warn the rain could increase the weight of snow on the mountains. structures, which could cause roofs to collapse. or other problems. Residents and authorities have already reported several roof collapses due to snow accumulation, including a grocery store providing critical supplies at Crestline last week.
- Up to 8 inches of rain is possible in the coastal foothills from north of Morro Bay, while the rest of San Luis Obispo and Santa Barbara counties could see up to 4 inches. In Ventura County, up to 2 inches of rain is possible, while the greater Los Angeles area could receive up to 1.5 inches. Temperatures in the coasts and valleys of Ventura and Los Angeles counties will be mostly in the 60s and 60s, with a chance of 70 degrees in the warmest location in the valley.