Gusty winds, dry air to raise risk of rapid wildfire spread to end the week
Following a break from warmth, strong winds and low humidity, fire weather conditions will ramp up again in California late this week and weekend.
Wildfires have taken many lives, scorched more than 190,000 acres and destroyed over 3,500 homes and businesses in California in recent days.
Flames approach a building as smoke from a wildfire blankets the area on Monday, Oct. 9, 2017, in Napa, California. (AP Photo/Rich Pedroncelli)
More than 20 fires were currently active in California as of Thursday morning, according to Calfire.
Large wildfires can create their own wind, which can add to the challenges facing firefighters. Even a slight shift in the wind direction can play havoc when battling the blazes.
Smoke poses a serious health risk. Winds will carry the smoke for dozens of miles. Light winds at night can cause the smoke to build to unbearable levels locally. At times, smoke will be thick enough to lead to delays on the highway and at major airports, such as San Francisco.
The high pressure area responsible for kicking up the warm, gusty winds this past Sunday and Monday will move east of the Rockies for the rest of this week.
A high pressure area represents a large zone of sinking, dry air that rotates clockwise. The stronger the high pressure area, the stronger the winds can be.
"In Northern California, the air has cooled significantly, but northerly winds will still be locally quite gusty into Friday," according to AccuWeather Senior Meteorologist Ken Clark.
Any change in wind direction may cause some problems for firefighting efforts, but calm winds and high humidity can provide significant help.
"Compared to Sunday and Monday, less wind, higher humidity levels and lower temperatures may help firefighters gain more control into Thursday in Southern California," according to AccuWeather Meteorologist Evan Duffey.
However, the period of light winds and moisture from the Pacific Ocean will not last long in Southern California.
"Northerly gusts, known as Sundowner winds, are likely to kick up Thursday night in parts of Southern California," Clark said.
"Areas likely to be affected by the Sundowner winds in the mountains and north/south-facing passes into the Interstate-5 corridor are Santa Barbara, Ventura and northern Los Angeles counties."
To make matters worse, a new area of high pressure is forecast to build from the coastal Northwest states toward the Great Basin this weekend.
This high pressure area is about as strong as the high pressure area from last weekend.
"The risk of wildfire ignition and rapid spread will continue and may increase throughout California this weekend," Duffey said.
"Northeast winds will kick up and become gusty. Humidity levels will drop and warmth will build in coastal areas of California," Duffey said.
People should use extreme caution with outdoor power equipment and with open flames such as campfires and grills. Never park a vehicle over high brush as intense heat from the exhaust system can cause a fire.
The Santa Ana fire season typically ramps up in October and continues through the winter and into the early spring.
This is the time of the year when dry and strong offshore winds during a Santa Ana event can cause flames to rapidly spread toward heavily populated coastal areas.
"Abundant rain from this past winter resulted in an extra heavy growth of vegetation this spring and early summer," according to AccuWeather Meteorologist Brett Rossio.
The vegetation has had many months to dry out by this point in the year.
No rain is in the forecast through this weekend. There is a chance that rain will reach some of the fire areas of Northern California later next week.
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