LOS ANGELES, Feb 5 (Reuters) - The National Weather Service issued flood watches and warned of potential mudslides on Thursday in Northern California foothills already ravaged by wildfires and drought, saying an "atmospheric river" could bring up to 10 inches (25 cm) of rain to some areas.
The storm is the result of a ribbon of moist air from the tropics, sometimes known as a "Pineapple Express" that has churned across the Pacific Ocean to take aim at the West Coast, National Weather Service meteorologist Brooke Bingaman said.
Bingaman said rain had already began to fall on Thursday afternoon in the northeastern-most corner of California and was expected to move inland throughout the evening and overnight.
She said the Sacramento metro area would likely get hit with up to several inches (cm) of rain on Friday but coastal communities such as redding could be deluged with up to 10 inches (25 cm).
"We do have flood watches in effect across much of Northern California. We foresee flooding near small streams and in some urban areas, especially where they have poor drainage," Bingaman said.
Authorities were also keeping a close eye on hillsides left barren by wildfires, where mud and debris can be brought down by heavy rain.
Southern California was also expected to get several inches (cm) of rain, but forecasters were not expecting major flooding or mudslides.
California has been in the grip of a record-shattering, multi-year drought that has forced officials to sharply reduce water supplies to farms and prompted drastic conservation measures statewide.
Bingaman said the storm would provide a small measure of relief to the water-starved state but cautioned that the tropical rainstorm would be too warm to add much to the state's snow pack, which is critical for providing run-off in the dry spring and summer months. (Reporting by Dan Whitcomb; Editing by Sandra Maler)