The first Pacific system was expected to come ashore in the northern portions of the state Wednesday morning and move down the central coast, reaching southern areas by afternoon. A bigger storm will reach the north by early Friday and also head south.
"Most areas of the state will see significant precipitation," said Alex Tardy, warning coordination meteorologist at the NWS office in San Diego.
After 2013 ended as the state's driest year on record, all that predicted rain and snow should be nothing but good news. But residents of cities such as Glendora and Azusa at the foot of the steep San Gabriel Mountains east of Los Angeles face the prospect of debris flows and mudslides from nearly 2,000 acres of barren slopes burned by a wildfire in January.
Glendora, a city of 50,000, raised its local alert level from green to yellow, and work was underway on clearing drainages and sandbagging properties.
"We want to be on the front side of this as opposed to reacting," Steve Wittenberg told KABC-TV. "But aesthetically, you know, it's not going to look the best but you've got to do what you've got to do to protect the homes.
Iris Whiting's home was defended by a barrier four sandbags high.
"The mud and the rocks and the debris is going to come down the street and since I'm kind of at the end, the bottom of the street ... it may come into my yard, the pool area," Whiting explained to KABC.
The National Weather Service also noted the potential for mud and debris flows from the burn area of the May 2013 Springs Fire, which scorched nearly 38 square miles of the Santa Monica Mountains as it burned from the edges of suburban homes down to the beach about 50 miles west of downtown Los Angeles.
Numerous other wildfires statewide left scarred landscapes over the past year, including a 400-square-mile area devastated by last summer's forest fire in and adjacent to Yosemite National Park in the Sierra Nevada.
A so-called Pineapple Express storm brought rain and snow to California earlier this month, and when it departed the Sierra Nevada snowpack had grown but was still only 29 percent of normal.
"The big difference between the storm earlier in the month in California and the coming two storms is in the area it will effect," Ken Clark, an Accuweather meteorologist, said in an email. "Much of the rain that occurred with the storms early in the month was in the northern half of the state with only very small amounts getting down into the Los Angeles and San Diego area.
The second of the two storms will bring by far the heaviest of rain to Southern California, he wrote. "In fact as much, or more rain, may fall in parts of Southern California than fall, let's say, around the (San Francisco) Bay Area when all is said and done."
Downtown San Francisco is close to its February average of 3.86 inches of rain to date, but is 11.62 inches below normal for the rain year that began on July 1.
Downtown Los Angeles has recorded only .23 inch of rain this month, 3.05 inches below normal to date. The location has received only 1.23 inches since July 1, a deficit of 9.52 inches.