LA CAÑADA FLINTRIDGE, Calif. — The rain had slowed to a mere pitter-patter on the windshield as Sgt. Tracy Stewart began surveying the area early Tuesday morning. Tiny streams of water were running speedily though the gutters and drain basins meant to protect the homes from floods and to ease the risk of mudslides like the ones that crashed through this Los Angeles suburb earlier this year.  But as the nonstop rain battered Southern California into the afternoon, officials and local residents were warily looking toward the barren foothills, wondering if, when and where they might come tumbling down again.  The rain pummeled much of the Southwest on Tuesday, with Zion National Park in Utah shutting down because of the storm. In at least one town near there, officials declared a state of emergency and warned residents to evacuate, concerned that a dam could be overwhelmed. In northwestern Arizona, four homes were swept away, The Associated Press reported. Potential flooding at the Beaver Dam prompted officials to declare a state of emergency, with residents warned that they might need to evacuate.  In the La Cañada area Tuesday evening, evacuations orders were issued for about 200 houses.  Just blocks from Sergeant Stewart’s post at the Los Angeles County Sheriff’s Department, there were still scars from the last major storm, 10 months ago. Entire homes were filled to the roof with mud then after wildfires wiped out most of the trees in the neighboring mountains, leaving the area north of Los Angeles vulnerable to major mudslides.  It fell to Sergeant Stewart to fan the area near the San Gabriel Mountains northeast of Los Angeles, looking for any sign that the most recent storm was about to wreak further havoc on the neighborhood.  “Maybe we’ll get lucky this time,” she said. “So far, we’re much better off than we were then. But it can get really wet really fast.”  The most severe rains were expected to hit Tuesday evening and continue through early Wednesday. But the record rains throughout the state have already caused major damage, prompting evacuations in some areas and shutting down busy freeways. Forecasters predict that this December is likely to become the wettest on record for the region. In less than a week, downtown Los Angeles has already had a third of its average annual rainfall.  Officials were bracing for problems here, where dozens of homes sit directly in the path of mud and debris coming down the hills nearby.  “We weren’t prepared the last time around,” Sergeant Stewart said. This time, her office has set up a command station to keep track of any problems. She pointed to a white board with columns laid out to track evacuations and mudslides. “All of this is because of the lessons we learned,” she said.  At the end of one cul-de-sac that has been particularly bruised by the mudslides over the last couple of years, Sergeant Stewart looked up at a pile of wet rocks and trees. “See how close it is?” she asked an inspector from the Department of Public Works. “If something there breaks, that’s it, it will be a huge mess.”  Standing outside his home a few yards away, Skeet McAuley recalled the February storm, when his Dodge Caravan quickly slid down the hill after the water and mud rose to more than two feet. The concrete barriers in the street — known as K-rails — were not secured to the ground then, and scattered like dominoes. Now, they are pinned to the street, and residents have decorated a few with twinkling Christmas lights.  “You can’t help but feel at least a little anxious, given what has happened, and now that we’ve seen how bad it can be,” Mr. McAuley said.  Over the last year or so, Mr. McAuley has been evacuated seven times because of potential mudslides. Most of the time, he has obeyed, but other times he stayed put. He said he was planning to stay home working this week, too.  “As long as I can get in and out of the street by walking, I’m fine,” he said.  Some other residents were a lot more nervous, and as Sergeant Stewart’s morning shift neared its end, she almost laughed at the dire predictions herself, noticing how much more water was streaming in the gutters — and with a distinctly muddy tinge — where there had been just a trickle a couple hours before.  Ian Lovett contributed reporting from Los Angeles.
A cycle of powerful storms has inundated the region with as much as 14 inches of rain, flooding freeways, causing power outages and forcing evacuations.