Southern California Santa Ana winds bring fire hazard with gusts in excess of 80 miles per hour

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Wildfire risk has returned to Southern California with the arrival of the strongest Santa Ana wind event of the season. Just a week ago, a strong winter storm dropped several inches of rain across the region, part of a cold, wet pattern that appeared to be bringing the fire season safely to an end. But the sky cleared quickly and the weather changed in an instant.

Los Angeles’ National Weather Service warns of impending wind damage, power outages and wildfires as roaring, dry winds descend on Santa Ana on Wednesday.

“If [a] If a fire is ignited, rapid spread of wildfire could result, resulting in a threat to life and property,” they wrote.

While last week’s rain should help limit the spread of the fire, the strength of the winds combined with bone-dry air is worrying forecasters.

Peak gusts of 60 to 75 mph are expected on Wednesday, with isolated gusts of up to 95 mph in very high terrain. Early Wednesday morning, a wind sensor along the Magic Mountain Truck Trail, 23 miles north of Los Angeles at an altitude of over 4,500 feet, reported one Gust of 102 km/h.

Rich Thompson, a fire weather forecaster with the Los Angeles National Weather Service, said in a tweet that winds are dangerous in Santa Ana this week, despite the recent rain.

“At this time of year my mantra ‘wind beats all’ still applies,” he wrote, referring to the danger of wildfires. “Be ready.”

Winds will blow “offshore” from the north and northeast as a strong high-pressure center over Nevada and Utah pushes air towards lower pressures off the California coast. The difference in surface pressure between Los Angeles and Daggett, a city about 100 miles northeast, is used to estimate potential wind strength. This difference is expected to be “well above the 97th percentile for this time of year and would be one of the stronger offshore gradients we’ve seen in quite some time,” the Los Angeles Weather Service wrote.

Ventura County and the western portions of Los Angeles County are on a high fire risk red flag warning through 7 p.m. Wednesday.

“The whole area is very wind prone — you should see some pretty strong winds through Wednesday,” said Ryan Kittell, a weather forecaster with the National Weather Service in Los Angeles.

That region also had less rain from the most recent storm — less than an inch for much of Ventura County — and has generally missed storms this fall that have drenched other parts of Southern California.

“Typically 5 inches anywhere is a starting point for rain that kills fire season,” Kittell said. “We’re close in some areas, but not quite.”

More time and more rain are needed to mitigate the risk of fire in winter, he said.

“The plants that are still alive — they really haven’t had much time to absorb moisture from the soil,” he said. Meanwhile, leaves and other dead plant debris on the ground are drying up quickly from last week’s storm.

This trend is set to continue with another Santa Ana event expected this weekend.

South and east of Los Angeles County, recent rains have significantly reduced the risk of fire, particularly in the inland mountainous areas. However, the landscape is not yet as verdant as it will be later in the winter, and coastal parts of San Diego and Orange counties are still facing an “elevated” fire weather threat on Wednesday.

“We have potential for some fire growth if there is ignition in the right sensitive area,” said Alex Tardy, meteorologist for alert coordination at the National Weather Service’s San Diego office. “We have another Santa Ana over the weekend, so we have to account for the significant dry-out of fuel that will occur after Wednesday.”

La Niña typically brings long breaks between storms in Southern California, as well as an increased jet stream that can lead to windy weather patterns like this week’s, he said. As the core winter months are expected to be drier than normal, there could be a forest fire risk during the cold season.

“We’re not out of fire season, although last week’s event was much wetter than most November storms and was widespread,” Tardy said.

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