Rare September rain due in Southern California, with some areas under flood watch
An unseasonable shift in weather is bringing the chance of showers and thunderstorms across Southern California, prompting some concerns about flooding as temperatures also drop well below average for mid-September.
In much of the Los Angeles area, the system is expected to bring only light rain or drizzling Thursday and Friday, but there is a possibility for pockets of thunderstorms that could bring heavier rain.
The greatest chance for thunderstorms is in the mountains, including along the Interstate 5 corridor and across the San Gabriels, according to Bryan Lewis, a National Weather Service meteorologist in Oxnard.
“We’re looking at mostly less than a tenth of an inch, maybe up to a quarter of an inch in the mountains,” Lewis said. “It could be higher if a large thunderstorm develops in a certain area.”
He called this weather pattern “somewhat abnormal” for this time of year, given that September is typically one of the drier and warmer months in Southern California.
After a prolonged stretch of record breaking heat that scorched Southern California and sparked wildfires much of the state will experience below average temperatures, rain and even early season snow this week.
The expected amount of rain is “definitely above average for what September usually brings,” Lewis said, “and we’re also quite a bit below average for temperatures.”
Much of inland Ventura and San Luis Obispo counties, as well as western Kern County and parts of Santa Barbara County, are under a flood watch Thursday. People living near the Hurricane and Apache burn scars are at particular risk, according to the National Weather Service, and should prepare for the possibilities of debris flows and flooding.
Thunderstorms in these areas of southwest California are “capable of producing heavy rainfall.... [R]ates of one-half inch per 30 minutes and one inch per hour will be possible,” the National Weather Service wrote in its flood watch.
The Apache fire in late July burned about 1,500 acres near Ojai in the Los Padres National Forest, according to local officials. The Hurricane fire grew to about 10,000 acres in mid-July, primarily burning across the Carrizo Plain National Monument in San Luis Obispo County, according to the California Department of Forestry and Fire Protection.
National Weather Service forecasters also warned that residents near the Lake fire burn scar in the Santa Barbara County mountains should be prepared for heavy rains, though that area wasn’t yet a part of the flood watch. There’s a 20% chance that thunderstorms could reach that area as well, causing flash flooding and debris flows, the weather service warned.
The National Weather Service predicts cooler temperatures and scattered showers and thunderstorms across Southern California on Sunday
The Lake fire burned almost 40,000 acres this July, igniting near Zaca Lake.
Meanwhile, parts of the Sierra Nevada are also expected to see effects from the wet, cool pattern, with a winter weather advisory issued for some of the highest peaks in Yosemite, Kings Canyon and Sequoia national parks and in Mammoth Lakes. Elevations above 9,000 feet are expected to get 2 to 5 inches of snow Thursday, the advisory said.
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