Rain possible Saturday, with dangerous Santa Ana winds to follow
A storm system moved into Southern California on Friday night, bringing with it a chance of rain through midday Saturday before giving way to strong Santa Ana winds that will elevate the threat of wildfires across the region through Tuesday.
In Los Angeles and Ventura counties, there is a 30 percent chance of showers before 11 a.m. Saturday, the National Weather Service said, with winds of 5 to 10 mph in the morning.
In Orange County, showers are likely with thunderstorms possible before 11 a.m. Saturday. The chance of rain is 60 percent, with an accumulation of less than a tenth of an inch unless there are thunderstorms, the weather service said.
In the Inland Empire, there is a 70 percent chance of rain during the day Saturday with winds up to 25 mph. The chance of rain at night is 40 percent.
Despite the potential for rain, the threat of quickly spreading wildfires will increase, particularly in Los Angeles and Ventura counties, fire officials said.
Strong Santa Ana winds are expected across Southern California starting Sunday night and continuing into Tuesday. The strongest winds will be Monday with sustained speeds of 20 to 40 mph. Humidity levels will drop into the 8 to 15 mph range with almost no increase overnight Monday.
“At this time, we think rainfall amounts will be light enough to where the anticipated Santa Ana winds will greatly elevate the fire threat across the area,” Tom Rolinski, a U.S. Forest Service meteorologist, said in a fire weather statement Friday. Significant rain would reduce the danger, he added.
The weather service has issued a fire weather watch, which means that critical fire weather conditions are forecast to occur.
Santa Anas are created when high-pressure systems form in Nevada and Utah, and the air is heated through compression. That air blows east to west, and combined with low humidity in vegetation, creates dangerous wildfire conditions.
The Santa Ana Wildfire Threat Index lists “moderate” risk in Los Angeles and Ventura counties for Monday, which means fires will spread rapidly and will be difficult to control. Northeast winds of 20 to 30 mph are expected.
“Recent rains have moderated fuel conditions slightly, but not enough to prevent significant fires from occurring in the more wind-prone areas,” the threat index website advises.
The threat index for the Inland Empire and Orange County on Monday and Tuesday is listed as “marginal,” which means fires may grow rapidly. Northeast winds of 20 to 30 mph are forecast. The same threat is listed for Tuesday for Los Angeles and Ventura counties.
Fire officials urge residents to have an emergency preparedness kit and an evacuation plan prepared. More information is available on ReadyForWildfire.org.