Western US weather expert

Major fires torching Southern California; Santa Ana winds continue through the week

By Jordan Root, AccuWeather meteorologist
12/05/2017, 5:59:21 PM

Several major fires continue to roar across sections of Southern California as strong Santa Ana winds continue to fan the flames.

Three major fires are currently burning across two counties, Ventura and Los Angeles.

modis fire image

Three major smoke plumes from fires can be seen by a satellite passing over Southern California Tuesday afternoon.

The Thomas fire began Monday night just north of Santa Paula and rapidly spread westward into Ventura. So far, the fire has burned 50,000 acres and continues to threaten structures in the Ventura area. Evacuation information can be viewed HERE.

Two new fires ignited today (Tuesday). The Rye fire started just west of Valencia and the Creek fire started just north of Lake View Terrace. Both fires continue to spread rapidly with 0 percent containment. Evacuations for the Creek fire have been ordered in some areas and information can be viewed HERE.

There are several weather factors that are driving these fires. A Santa Ana wind event is currently underway. A strong area of high pressure over the Great Basin is producing a strong offshore flow across Southern California.

high pressure dec 5 santa ana WPC

A strong area of high pressure (1042 mb) is over the Great Basin. This is driving a strong offshore flow across California.

The air is accelerated and dried out as it descends from the mountains to the valleys resulting in gusty and dry winds. Many places experienced wind gusts between 40 and 60 mph over the past 24 hours as show in below.

gusts santa ana dec 5

Observed wind gusts over the past 24-hours.

Relative humidity values have dropped into the single digits in many places as well, showing how dry the air is.

So the big question going forward is how long will this Santa Ana wind event continue? As I mentioned in my previous blog post, we expect gusty winds to continue through the rest of the week. High pressure will remain over the Great Basin through the week and even into the weekend resulting in some kind of offshore flow that can bring wind gusts of 40 to 50 mph in the canyons and mountains.

feature gusty winds dec 5

However, the time that is most concerning appears to be Wednesday night into Thursday morning as models show some of the strongest winds during this time, similar to Monday night.

The pressure gradient looks to tighten a bit more during this time which would lead to some of the strongest gusts. Frequent gusts of 40 to 60 mph in the foothills and canyons will be possible with higher gusts up to 80 mph in the mountains.

gusty winds again santa ana

Models show the pressure gradient becoming stronger Wednesday night into Thursday which would result in another strong Santa Ana wind event, similar to Monday night.

With dry and gusty winds remaining persistent through the week, the threat for fire ignition and growth will remain high. Fire weather conditions will present a dangerous situation for lives and property through this weekend.

Follow more coverage of the fires:
Reports: Thousands flee as Thomas Fire explodes to 50,000 acres near Ventura, California
Explosive fire growth threatens Southern California as strongest Santa Ana winds of season howl
VIDEO: Wildfire explodes in size, forces thousands to evacuate in Southern California

The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com


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Western US weather expert