Cold upper low will make a loop to Las Vegas, then return to Southern California

Map showing storm system off the West Coast
Satellite image of a tightly wound, slow-moving cutoff low sporting an eye-like feature spinning off the the Southern California coast at 2:30 p.m. Wednesday.
(Cooperative Institute for Research in the Atmosphere & Los Angeles Times)

A cold cutoff low spinning off the Southern California coast Wednesday afternoon will head toward Las Vegas Thursday morning, then loop back to Southern California before heading east to Arizona Friday night, the National Weather Service said.

As a result, wintry scattered rain and mountain snow with below-normal temperatures will persist across the region through early Friday.

Precipitation will become more widespread as the low moves ashore Wednesday night. According to the weather service, the low will perform a complete counterclockwise loop, meandering east to Nevada, then returning to California, with a quarter-inch to three-quarters of an inch of rain likely in many areas, and heavy snow above 5,000 feet in the mountains.


Interstate 5 over the Grapevine can expect brief periods of mixed rain and snow, but no significant travel issues were anticipated.

Some areas in the eastern San Gabriel Mountains have received more than 30 inches of snow since Sunday, and could receive another 12 to 24 inches. Other mountain areas above 6,000 feet can expect another 6 to 12 inches. Meanwhile, at lower elevations, the next 36 to 48 hours are expected to be wet. Brief periods of heavy rain are likely, and thunderstorms, although not expected, could not be entirely ruled out.

Showers are expected to taper off by Friday as the stubborn low-pressure system finally heads east into Arizona.

A low-pressure system loops into Nevada and returns to Southern California before departing for Arizona.
(Paul Duginski / Los Angeles Times)