Another in a series of storms is about to unwind over Southern California, and winter storm warnings of more than 10 inches of mountain snow were issued for mid-morning Monday.
At about 8 p.m. Sunday, the National Weather Service issued a storm warning to take effect Monday morning, and said heavy rain and snow will fall through Tuesday. Between 10-13 inches of snow were forecast to fall above the 5,000 foot level of the eastern San Gabriel Mountains.
According to the National Weather Service, there is a 90 percent chance of rain Monday, with the day's high to reach 61 degrees in Glendora.
In Orange County, rain that is heavy at times is forecast for the morning commute and is expected to continue into the afternoon.
And the storm was expected to drop snow, possibly heavily at times, on Interstate 5 over the Grapevine, the Antelope Valley (14) Freeway near Acton, and Interstate 15 at Cajon pass, north of Riverside. The snow level was
predicted to drop to the 3,000-foot level Monday night.
A Sunday midafternoon reassessment of weather models showed that the incoming “cut-off low pressure system'' was stronger and colder than first thought, one meteorologist said. A cut-off low is the weatherman's woe, “and we are doing a lot of crying right now,'' National Weather Service forecaster David Sweet said.
Such a description defines the weather pattern that deposits a spinning storm system over Southern California, cut off from the high-altitude jet stream winds that generally sweep from west to east across this continent.
The latest cut-off low storm should bring rain and snow, starting late Sunday or early Monday. Snow could first affect travel along the Grapevine section of Interstate 5 Monday afternoon, said Sweet in an interview with City
By late tonight or early Monday, heavy snow is expected at elevations of about 5,000 feet and higher, lowering to about 3,000 feet by the time the weather system moves east later Monday.
The two major freeway passes into and out of Southern California -- Cajon Pass near San Bernardino and the Grapevine's Tejon Summit -- both top out at more than 4,000 feet.
“By Monday afternoon we could be looking at some snowflakes falling on the Grapevine, and then by Monday night there is a chance for some significant accumulations,” Sweet told CNS.
The Antelope Valley (14) Freeway over 3,258-foot-high Escondido Summit
at Acton may see snow, according to the NWS. But in the high country, as much
as 13 inches of snow could fall.
Thanks to a couple of early season rains, the Los Angeles is ahead of its seasonal rainfall norm so far, with about 2.75 cumulative inches at the USC weather station since July 1. The basin historically averages about 15 inches of rain per year.