L.A. winter storms: Officials prepare for mudslides, debris flows

Glendora officials are bracing for possible mudslides and debris flows from the Colby fire burn area as two much-needed winter storms are expected to douse the region with rain Wednesday through Friday.

“We’re definitely concerned about that,” Scott Sukup, a meteorologist with the National Weather Service, said of the potential for flooding in storm drains and in the foothill areas burned in the fire above Glendora and Azusa.

Some fire stations are already offering free sand bags ahead of what could be the wettest storm system L.A. has seen in two years. The last time the region saw so much rain was March 25, 2012, when downtown measured 0.91 inches.

The first storm is expected to arrive Wednesday and could drop from 0.25 to 0.75 inches across coastal and valley areas.

But the big show is expected Friday, when a more powerful system is forecast to drop rain heavily in the late morning and afternoon before turning to showers by nightfall Saturday. The National Weather Service says from 1 to 2 inches could hit the coastal and valley areas, and 2 to 4 inches could fall in the foothills and mountains.

In Glendora, it’s the second storm that is of most concern.

“The second storm which is forecast to arrive on Friday will have much more rain and could include thunderstorms. This is the storm that has us concerned at this point,” Glendora City Manager Chris Jeffers said.

Glendora knows all too well the dangers of heavy rainfall. Fire in the hills above the city in 1968 led to deadly debris and mudflows the following year.

“More damage was incurred to property as a result of the 1969 mudflows than the fire itself,” Jeffers said.

Dozens of people were killed in mudslides, floods and other debris flows across Los Angeles County that year.

Jeffers said city officials have been working closely with the same agencies since the Colby fire to asses the damage and develop plans to address any potential problems from the rain.

City officials have organized visits to about 60 residents to tell them they may need assistance in the event of a crisis.

They also visited about 150 homes since the Colby fire, advising residents on flood protection measures, and have held community meetings, Jeffers said.

So far, dry, summer-like weather has gripped Los Angeles during what is supposed to be its rainy season. L.A. has received only about 1.2 inches of rain since July 1, while the average is about 10.45 inches by this time of year.

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ari.bloomekatz@latimes.com