It may take weeks or longer for firefighters to fully extinguish the two most destructive fires that have ravaged parts of the Los Angeles area, fire officials warned.

The sheer sizes of those blazes, the Palisades and Eaton fires, have presented a significant challenge. They have charred almost 40,000 acres combined and are still only partly contained.

Difficult weather conditions have also hindered efforts. David Acuna, a battalion chief with Cal Fire, said the persistence of strong winds, and the fact that fires were burning through homes, which can generate intense heat, made containment impossible when the blazes first ignited.

Crews have been trying to establish a boundary around the fires, using trenches, natural barriers and other methods to prevent further spread. But Capt. Erik Scott, a spokesman for the Los Angeles Fire Department, said, “It’s going to be a slow, arduous process.”

The emergence of smaller fires over the last week has further complicated efforts. Of particular concern was the Auto fire in Ventura County, northwest of Los Angeles, which grew to more than 50 acres before being contained. Officials worried about it breaking free again in windy conditions.

These fires have required an immediate response from both air and ground crews to prevent them from growing, Mr. Acuna said, which diverts resources from the larger blazes.

Stopping the fires’ forward progress is only the first step. Firefighters must also extinguish all remaining flames inside the contained area.

Mr. Scott said this second part of the process would also take time. Among other steps, he said, firefighters need to use hand tools to scrape away brush near the burn perimeter and turn over smoldering piles to ensure nothing is hot enough to reignite.

These timelines are not unusual for large fires. In 2018, the Woolsey fire burned through nearly 100,000 acres in Los Angeles and Ventura counties, destroying over 1,600 structures. The fire ignited in early November and was not contained for two weeks. And it took until early January for the fire to be fully extinguished.

The Santa Ana winds that have repeatedly raised the fire danger over the last week have so far proven lighter than anticipated on Tuesday, but forecasters warn that wind speeds could increase on Wednesday. The region remains critically dry, with little rain expected in the near future. The combination of those elements is threatening to ignite more fires across Southern California, and could further hinder firefighters’ efforts.

Erin McCann contributed reporting.

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Top BlackRock executive Mark Wiedman is departing, in a move that disrupts the asset manager’s planning for the eventual departure of founder Larry Fink, according to four people close to the company.

Wiedman had been widely discussed as a potential successor to Fink for more than a decade and had recently been one of the $11.5tn asset manager’s most prominent public faces as the head of its client business.

BlackRock’s board described him in as a regulatory filing last year as one of three “senior leaders who we believe will play critical roles in BlackRock’s future” as it granted him a special retention package.

However, Wiedman, who led the integration and rapid growth of BlackRock’s flagship index and exchange traded fund business, has opted not to wait around. His departure is expected to be announced very shortly, the people said. He is forfeiting $8mn in stock options, according to the proxy.

Wiedman’s departure comes after the world’s largest asset manager embarked on a $28bn acquisition spree last year to bulk up its footprint in the fast-growing and lucrative alternative assets sector. The strategic moves not only put pressure on Fink, 72, to personally oversee their success, but also brought in a clutch of high-powered and high-paid executives who need to be carefully managed.

Fink, who has led BlackRock since its 1988 founding, is very popular with investors and is among the most influential figures in finance. But analysts and some within the firm have begun expressing concerns whether the slow pace of succession planning will drive the next generation of top talent to start going elsewhere. BlackRock president Rob Kapito, 67, is also a founder of the firm.

BlackRock declined to comment.

Wiedman is leaving almost exactly a year after Salim Ramji, another executive who was also once touted as a potential leader. Ramji became chief executive of Vanguard, BlackRock’s chief rival in the US and the world’s second-largest asset manager. Several other lower-ranking executives have also left in the past few years to take leadership jobs at smaller firms, including Daniel Gamba to Northern Trust and Zach Buchwald to Russell Investments.

After Ramji left, the group touted its strong stable of current leaders, including Wiedman and two other executives who also received special option grants: chief operating officer Robert Goldstein and chief financial officer Martin Small.

“BlackRock is proud to have a record of our firm’s alumni going on to lead multiple investment management companies and financial institutions,” it has previously said.

A senior Wall Street figure with knowledge of the situation said “Larry [Fink] and Rob [Kapito] are not going anywhere. They just made a major acquisition and you have to see that through, [but] Wiedman is at an age where if he doesn’t make a move, he ages out of being a CEO.”

A lawyer by training, Wiedman joined BlackRock in 2004 after stints at the US Treasury and McKinsey. He started BlackRock’s financial markets advisory consulting arm, which helped central banks and government agencies dig through the rubble of the 2008 financial crisis.

Wiedman negotiated the 2009 purchase and integration of Barclays Global Investors, the deal widely seen as the most important in BlackRock’s history. He then headed up the resulting iShares business from 2011 to 2019 as it developed into a juggernaut in index and ETFs.

Keenly interested in talent development, Wiedman recruited or promoted many of BlackRock’s top executives, including Small and Rachel Lord, who heads the international business.

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