The winds are expected to continue to subside this week, but for a while in southern California, which has been hit by wildfires.
The risk of another major fire outbreak in Los Angeles and Ventura counties is increasing starting early next week.
This article is provided free of charge to help keep our community safe and supported during these devastating fires.
But more than winds, the region faces dangers from extreme dryness and lack of rain.
Southern California is experiencing the start of its driest winter on record. Many parts of the region have received just 5% or less of the average precipitation for this point in the water year, which began Oct. 1, said Alex Tardy, a meteorologist with the National Weather Service in San Diego. Orange County and the Inland Empire.
Downtown Los Angeles has received just 0.16 inches of rain since October 1st. This is 3% of the average rainfall of 5.56 inches at this point in the season.
According to data shared by Tardy, the lowest recorded water in downtown Los Angeles during this three-and-a-half month period was a water year that began on October 1, 1903, with only trace amounts of rain detected until January 13, 1904. It wasn’t done.
The early part of the 1962–1963 water year was also very dry, with only 0.16 inches of rain falling in downtown Los Angeles by January 13, 1963.
The average annual precipitation in downtown Los Angeles is 14.25 inches.
In many other parts of Southern California, “this is the driest start of the water year and we’re seeing extreme fire activity with ignition,” Tardy said.
In San Diego, only 0.14 inches of rain fell between October 1st and January 14th. This is the start of the driest water year in 174 years on record. The previous record for the same period was 0.35 inches of rain, which fell from October 1, 1962 to January 14, 1963, said Miguel Miller, a forecaster with the National Weather Service in San Diego.
Further exacerbating fire weather conditions is that January brings with it strong Santa Ana winds, which occur when high pressure over Nevada and Utah sends cold air screaming toward low-pressure areas off the California coast. This is the peak month for the wind.
The air that flows from the high deserts to the northeast over California’s mountains and down the slopes through canyons dries, compresses, and heats up, drying out plants as they blow through.
Citing research from the U.S. Forest Service and the Scripps Institution of Oceanography, Tardy said Santa Ana winds are typically strongest in January.
“Santa Anas are very common in December and January, and that’s when we usually see the strongest, largest and most damaging Santa Anas. But we don’t usually have conditions this dry,” Tardi said. Said.
“In my career, I have never seen such a severe event in Santa Ana overwhelm a normal winter rainy season,” said retired climate scientist Bill Patzert.
The National reports that the most concerning days at this point are Monday and Tuesday, when Los Angeles and Ventura counties have a 70% chance of a red flag warning, which means a serious fire if it ignites. This indicates that there is a high possibility that this will occur. weather service.
“The big news is it looks like it’s going to be very dry all week next week, increasing the risk of a red flag warning being issued,” said Ryan Kittel, a meteorologist with the Oxnard National Weather Service office. Ta.
Relative humidity could drop below 10% next week, meaning plants will be particularly dry and vulnerable.
“It’s like off the charts,” Kittel said.
As for the winds, there is growing confidence that a mild Santa Ana will develop. As of Wednesday, forecasters estimated a 70% chance of moderate winds in Santa Ana on Monday and Tuesday. The day before, the probability was predicted to be 40%.
There is also a small chance of strong winds in Santa Ana.
Next week’s wind direction is expected to be influenced by an “inside slider.” An inside slider is a type of low pressure system that is expected to descend from Canada into interior California and Nevada, bringing winds from high pressure over the Great Basin. Much needed rain.
The system is called an “inside slider” because “it just slides on the inside, never over the water and never allows for rain to fall,” Kittel said. he said.
The high pressure system that will send cold, dry air into Southern California next week is also influenced by frigid air that is expected to move from the Arctic into the northeastern United States, Tardy said. “We’re going to be on the windy, dry side of that cold air.”
It’s “just going back to the same, same pattern,” he says.
“It really is a broken record. It’s normal to have Santa Ana winds this time of year, but it’s not normal for it to be this dry,” Tardy said. “Normally, in a normal year, we would have at least some rain and a Pacific storm between us and Santa Anas, but we haven’t even seen anything like that.”
After devastating fires that flattened large areas in and around Altadena and the Pacific Palisades, there will be a welcome respite from severe fire weather for a few days before winds pick up next week.
“The moral of the story is that thankfully we get a break from all of this this weekend, but unfortunately it won’t last long,” Kittel said of the dangerous fire weather.
Forecasters currently do not plan to issue any extreme red flag warnings, known as “particularly dangerous conditions,” next week.
“But that’s still something we’ll continue to look at,” Kittel said.
As for this week, “particularly dangerous conditions” due to extreme red flag fires in the San Fernando Valley, throughout Ventura County, and on the Grapevine section of Interstate 5 peaked around noon Wednesday and ended at 3 p.m.
Early Wednesday afternoon, wind gusts in excess of 30 mph were observed along the traditional Santa Ana wind corridor that stretches southwest through places such as Palmdale, Santa Clarita, Ventura, Oxnard, Simi Valley and Thousand Oaks. Ta.
Wednesday’s winds were about as expected, but Tuesday’s winds were not as strong as expected that day. One possible reason, Kittel said, is that the pressure difference between the ocean and the desert was not as strong as the computer predicted.
Another possible reason is that a rotating low-pressure system off the coast of Santa Ana with westward winds swung a little further north than expected, Kittel said.
That low pressure system that is separated from the prevailing jet stream is called a “cutoff low,” meaning it wobbles and is less predictable than if it were connected to the jet stream.
Kittel said the cut-off minimum temperature is so notorious among forecasters that it’s called the “forecaster’s disaster.”
The red flag warning for parts of Southern California was largely lifted by 6 p.m. Wednesday, affecting Los Angeles, San Diego, Orange, Riverside, San Bernardino and Ventura counties, as well as the mountains of Santa Barbara and San Luis Obispo counties.
A red flag warning will remain in place until 3 p.m. Thursday for parts of Los Angeles and Ventura counties, including the Grapevine section of Interstate 5, the western San Gabriel Mountains and the Santa Susana Mountains.
Dry air continues into Thursday, with relative humidity levels of 8% to 20% fairly common in and around Los Angeles and Ventura counties. Temperatures will remain well below normal, with Friday’s high, the coldest in the coming days, reaching just 58 degrees in Redondo Beach, Thousand Oaks and Oxnard. 59 in Downtown Los Angeles, Long Beach and Covina. 60 at Canoga Park. In Santa Clarita, 61 people.
“The upside to weather concerns is that humidity will continue to rise, especially [Thursday]It also reduces fire weather concerns,” Kittel said. Fire weather concerns should be fairly minimal Friday and Saturday as humidity increases, but localized wind gusts of 25 to 40 mph are possible from the northwest.
A low-pressure system off the coast of Southern California will move, but there is little chance of rain Saturday night through Sunday, Kittel said.
“It’s going to make landfall eventually, and all predictions are that it’s going to be well south of Los Angeles County,” Kittel said. “Therefore, the chance of rain is very low.”
Unless we get a lot of rain, Southern California won’t be very safe from wildfires. Forecasters say the chance of rain is still low until January 25th.
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