A red flag fire warning prompted by gusty Santa Ana winds and low humidity levels is in effect for much of San Diego County as a wildfire driven by similar conditions tore through Ventura County north of Los Angeles.
A high wind warning also remained in effect, with the red flag warning set to expire late Thursday night and the high wind warning expected to expire Thursday afternoon, according to the National Weather Service. But the Santa Ana winds could persist into Friday or Saturday, which would likely mean an extension of both warnings.
The National Weather Service issued the red flag warning for the San Diego County coastal area, inland valleys and mountains, including the Palomar and Descanso Ranger Districts of the Cleveland National Forest.
Tuesday and Wednesday, sustained winds are expected to be between 20 and 30 mph with gusts up to 55 or 60 mph, the NWS said. But forecasters now believe Thursday and Friday pose the most significant fire risks, with isolated gusts of 70 to 80 mph possible Thursday.
Helping somewhat to mitigate the fire danger this week will be the relatively mild weather. High temperatures Tuesday in San Diego County will be 70 to 75 degrees at the beaches, inland and in the western valleys, 61 to 66 near the foothills and 48 to 58 in the mountains.
The fire threat this week doesn’t come from high temperatures. Instead, it’s the strong winds and humidity levels expected to be in the 7 to 15 percent range Tuesday and the 5 to 15 percent range from Wednesday until Saturday.
The wildfire threat was on full display in Ventura County, where the “Thomas Fire” was being driven by Santa Ana winds and conditions similar to local conditions. That blaze erupted around 6:30 p.m. Monday and quickly spread, growing to 31,000 acres and destroying at least 150 structures.
To prepare for the potentially dangerous conditions, both the San Diego Fire-Rescue Department and San Diego Gas & Electric beefed up staffing levels this week. The fire department put several extra strike teams on alert that included 10 brush rigs, five engines, two water tenders and two helicopters. SDG&E officials staged field crews and contract firefighters in areas where winds are expected to be the strongest.
“Meteorologists at the National Weather Service have not seen models for a Santa Ana event like this in many years,” SDFD Chief Brian Fennessy said. “We are being vigilant in up-staffing to protect San Diegans and their property. We ask that residents practice their evacuation plans and be prepared in case of a wildfire.”
SDG&E — which last week lost a ruling in relation to the 2007 wildfires the company was found responsible for starting — said it may need to turn off power this week in certain areas “if weather conditions threaten the integrity of our system and create the possibility of an imminent emergency.”
Fire officials said several years of drought coupled with heavy rains last winter created significant fire fuel in the form of underbrush and grass. But the lack of recent rainfall and low humidity levels have dried out the extra fuel, making it ready to spark.
The U.S. Forest Service’s Santa Ana Wildfire Threat Index, which categorizes Santa Ana winds based on anticipated fire potential as extreme, high, moderate, marginal or no rating, predicts that Thursday the threat index will be extreme and Friday it will be high. Tuesday, the index listed the threat as marginal, while Wednesday and Saturday were listed as moderate.
On Thursday, with gusts potentially exceeding 80 mph, the Forest Service said that “upon ignition, fires will have extreme growth, will burn very intensely, and will be uncontrollable.”
San Diego officials and the weather service warned residents to “avoid activities that could spark a fire” and warned of the dangers of high winds that include power outages and damaged or toppled trees or power lines.
— City News Service
