Rain accelerates snowmelt in the mountains of Southern California
- US News
- March 17, 2023
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Recent rainstorms in the San Bernardino Mountains brought both relief, melting much of the snow that had stranded some residents for weeks, and new problems, sparking minor flooding and rockfalls.
In Lake Arrowhead, Linda Knorr and her husband were trapped in their home for about a week and had to shovel several feet of snow off their property.
They were among the many snowed in by a series of snowstorms earlier this month that left some mountain residents without reliable access to food, supplies and medicine.
Plowing the steep highways and roads that wind through the communities of Crestline and Lake Arrowhead was arduous work. Some residents were effectively buried in their homes due to impassable roads or towering snow banks blocking their driveways.
The Knorrs’ road was once plowed during winter snowstorms, she said. Then rain from this week’s atmospheric river storm quickly melted much of what was left.
“We got several inches of rain,” said Knorr, 54. “Although more is coming next week and maybe some snow.”
As much as 4.3 inches of rain had fallen on the slopes of the San Bernardino County mountains as of Wednesday morning, according to the National Weather Service, and the storm had mostly settled by Thursday. Officials said there are no major problems from the rains, despite concerns much of the snowpack is melting under the new rains.
San Bernardino County firefighters responded to two calls late Tuesday and early Wednesday regarding minor flooding at homes in Crestline and Twin Peaks, but neither required an evacuation, department spokesman Eric Sherwin said.
Some roads were hit by rockfalls, Sherwin said, but most of the fallen rocks were quickly cleared by crews without completely closing the roads. The largest slides were along Highway 18 near Waterman Canyon Road, he said, although all were typical of storm conditions.
The runoff slowed somewhat on Thursday, he said, adding that although much snow was still melting, officials did not see any unusual accumulation of water in the mountains.
Ahead of the storms, residents were told to “prepare for flood conditions,” and county employees were working to clear culverts and provide sandbags, county chief executive Leonard Hernandez said at Tuesday’s board meeting.
Crews worked to ensure that “150 high-priority culverts were clear,” a task complicated by the fact that “many were obscured by massive snow berms,” forcing crews to use mapping technology and old photos To find many of them, county officials said a Wednesday storm response update.
Officials will continue to clear drainage routes and prepare for another storm expected next week.
In Crestline, resident Aaron Creighton said there was almost a “small river flowing down the street” Wednesday, although much of the drainage infrastructure has recently been upgraded and appeared to be holding up. Water was still flowing through the street on Thursday, he said, but not as much.
“It melts so much so quickly,” he said. “A few days ago I had 5 feet of snow left on my deck and I have about 6 inches left now.”
Creighton’s first floor began flooding Wednesday, remaining under about an inch of water, he said, but it took more than 24 hours for a plumber to respond because so many people were struggling with damage from the winter storms. The plumber found his flooding was caused by a pipe bursting from the cold.
“I can’t pump it out fast enough with my little Shopvac,” said Creighton, publisher and editor of Crestline’s local Alpine Mountaineer News. “It’s completely underwater.”
Downstream from the mountains, snowmelt, compounded by this week’s rain, swelled the waterways and turned the Santa Ana River into a dangerously fast-moving current.
At its peak Wednesday afternoon, about 11,500 cubic feet of water per second flowed through the river. In the days leading up to the storms, the river’s flow rate was below 1,000 cubic feet per second.
At the same time, the river’s water level peaked at nearly 6.5 feet, about 4 feet from the stage at which officials should have taken mitigation measures, according to the National Weather Service.
Riverside City Fire Department responded to two adults — a man and a woman — who became stuck on a sandbar near the Van Buren Boulevard Bridge over the Santa Ana River in Riverside around 10:30 a.m. Wednesday, according to Battalion Chief Bruce Vanderhorst.
Firefighters conducted a water rescue and got the two people, who were unharmed, out of the area.
Vanderhorst said the people had no shelter and they offered to put them through to their homeless solutions team, but they declined and went back to the river bottom and set up a new camp.
With most mountain roads reopened and a brief respite before another atmospheric river storm – the 12th of the rainy season – is expected early next week, ski resorts and towns are bracing for a rush of visitors this weekend.
Knorr, a Lake Arrowhead resident, said she was surprised when Caltrans District 8 announced this week that all routes except portions of Highway 18 had reopened to all drivers.
“If we have a small amount of snow, people come and they’re not prepared — they don’t have the right tires, vehicles or tracks,” she said. “They park at the edge of the freeway and sled. It’s hard for our highway patrol and emergency services to deal with the amount of people coming up here.”
At Big Bear Mountain Resort, staff were preparing for crowds to return to the slopes after the mountains were cut off to non-residents following snow storms in recent weeks.
“We expect visitor numbers to return to normal levels at this time of year,” resort spokesman Justin Canton said Thursday morning. “Looking out my window, the Snow Summit upper parking lot is pretty full.”
The resort expected clear skies over the weekend with a low chance of showers Sunday afternoon, Canton said.
“In terms of conditions, it’s still fantastic,” he added. “We’ve lost a bit of snow the past few days due to the rain, but we’re still in the 75-100 inch range, which is phenomenal at this time of year. Normally at this time of year we are looking at the 1 to 3 foot range.”