LA wildfires at risk of 'explosive' growth as Santa Ana winds to return

2 days ago 3
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Firefighters try to extinguish a burning bush at the Palisades Fire.Image source, Reuters

Matt Taylor

Lead Weather Presenter

After the extreme winds and deadly fires last week, lighter winds over the last few days have helped firefighters tackle the remaining blazes raging around Los Angeles.

However, with Santa Ana winds set to strengthen again this week, the National Weather Service in Los Angeles are warning of the potential for further "explosive fire growth".

How strong will the winds get?

We are entering another crucial period for containing the fires that continue to burn in California.

With high pressure building over the Great Basin (an area around Nevada, Utah and Idaho), Santa Ana winds are set to strengthen again over the next few days. Winds blowing in from the east or north-east, are set to peak on Tuesday, with gusts up to 70mph (112km/h) possible.

But the strongest winds will be to the north and east of Los Angeles, including the counties of Ventura and Los Angeles. However, the wind will not reach the Palisades and Eaton fires, which are more than 40 miles (64 km) away.

The areas threatened by those two fires are facing winds closer to 30mph (48km/h) with gusts up to 50 (56km/h), which one local fire chief called "normal".

Last week, winds in excess of 100mph (160km/h) were recorded and the presence of a deep area of low pressure centred on the border with Mexico, boosted the strength of the Santa Ana wind. That area of low pressure has now moved away and the winds won't be quite as fierce this week.

Image caption,

Santa Ana winds will peak again on Tuesday

What impact could the wind have on fires?

Even though winds are lighter than last week, their dry and gusty nature means they are still capable of causing explosive fire growth.

The Santa Ana wind is very dry. With humidity levels remaining low, further moisture will be stripped from vegetation making it easier to catch alight and more likely for the fires to spread rapidly.

The US National Weather Service has various red flag warnings in force across southern California. Red flag warnings mean that "warm temperatures coupled with very low humidity and strong winds are expected to combine, bringing a greater risk of fire danger".

Strong winds may help to spread these fires extremely quickly and their gusty nature adds to the unpredictability around their direction and speed of movement.

How long will the Santa Ana winds last?

There is some good news here. Lighter winds are forecast to develop after Wednesday bringing a longer window than we've seen so far, for fire fighters to contain the remaining blazes.

Rain would also help the situation by returning some moisture to the ground and surrounding vegetation. However, the weather forecast still shows very little rainfall on the horizon.

The lack of rain during what should be California's wet season, has been a key reason behind why the fires took such a firm grip and spread so rapidly.

Parts of southern California have barely seen any rain in recent months.

And in contrast, the wet conditions we've seen here over the last two years have encouraged the growth of vegetation meaning there is a lot more of it to burn right now.

The ongoing dry weather means that even if fires are extinguished, the area will still be ripe for more to develop.

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