California ski resort workers attempt to clear feet of snow off roof
Workers at the Northstar California Resort in Truckee, California try and clear massive piles of snow off the roof of a building.
MAMMOTH LAKES, Calif. – Just a few weeks after the foothills of the Sierra Nevada and southern California mountains were slammed with several feet of snow, the added woes of inches of rainfall from multiple atmospheric rivers are increasing concerns for roof collapses and another dangerous event some call a "roofalanche" – large amounts of heavy, wet snow sliding off roofs.
As much as 5-10 feet of snow fell across the mountains as winter storms pummeled California at the start of March, even bringing snowfall to the foothills of Los Angeles. Towns all across the Sierra struggled to dig out after homes, businesses and roads became buried under enormous amounts of snow.
CALIFORNIA AGAIN BESIEGED BY ATMOSPHERIC RIVER'S FLOODING RAINS, TRIGGERING ‘ROOFALANCHE’ CONCERNS
"We have (extreme snow load impacts) spread all across the Sierras from Truckee to South Lake Tahoe, Mammoth Lakes and Lone Pine," said FOX Weather Meteorologist Marissa Torres.
However, more recent tropically-infused storms are pushing snow levels considerably higher, meaning it's several inches of rain instead of snow falling in those affected communities.
"We're going to be seeing rain falling at 5,000, 6,000, even 7,000 feet (elevation); areas that (previously) had snow," Torres said.
It's bringing new dangers to snow-weary communities. On a typical 2,000-square-foot roof, a foot of fluffy snow would weigh about 4.1 pounds per square foot. That weight increases to 6.2 pounds per square foot for average snow.
Extreme snow load on roofs impacts in California
FOX Weather meteorologist Marissa Torres on examining the weight of snow amid historic snowfall in the Golden State.
But a heavy, wet snow that is near freezing or melting as temperatures warm, and that average roof is now carrying snow at 12.5 pounds per square foot per 12 inches of snow depth. That's about 25,000 pounds of snow in this 12-inches-of-snow scenario or 50,000 pounds with 24 inches of snow.
CAN YOUR ROOF HANDLE RECORD-SETTING SNOW?
If you add in an inch of rain on top of all that snow, that adds another 20,000 pounds, and some areas are facing the prospect of several inches of rain on top of feet of leftover snow as a new atmospheric river arrives Monday and Tuesday.
"Snow loading concerns on structures will likely increase with the added heavy rain and snow, especially on Tuesday," NWS forecasters in Reno wrote in their Monday morning forecast discussion. "There will also be a higher risk of 'roofalanches' in these areas."
MAMMOTH LAKES, CALIFORNIA - MARCH 12: In an aerial view, snow from new and past storms covers the landscape and rooftops of homes in the Sierra Nevada mountains, in the wake of an atmospheric river event, on March 12, 2023 in Mammoth Lakes, California. (Photo by Mario Tama/Getty Images) (Getty Images)
"Roofalanches" refer to when mounds of melting, wet snow slide off roofs and come crashing to the ground below, damaging anything below and presenting a grave danger to anyone caught underneath the onslaught.
WHAT YOU SHOULD KNOW ABOUT BLOWING, DRIFTING SNOW
Already with the previous storms earlier this month, an 80-year-old woman was killed on March 1 when a "roofalanche" crashed into her porch and crushed her while she was clearing it. Other slides have triggered fires in the snow after severing natural gas and propane lines leading into homes.
Crestline, CA - March 03: Crestline, CA - March 03: The heavy snowfall in Crestline caused the roof of a tire shop to collapse, as seen on Friday, March 3, 2023. (Photo by Watchara Phomicinda/MediaNews Group/The Press-Enterprise via Getty Images)
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CRESTLINE, CALIFORNIA - MARCH 03: An aerial view of residents (L) waiting in line to receive donated food outside the local grocery store (R), which was severely damaged when its roof collapsed under the weight of several feet of snow, after a series of winter storms in the San Bernardino Mountains in Southern California on March 3, 2023 in Crestline, California. Some residents have been stranded in Crestline more than a week due to heavy snowfall while the grocery store was the main hub for food purchases in town. California Governor Gavin Newsom has declared a state of emergency due to winter storms for 13 counties including San Bernardino County and the California National Guard is assisting relief efforts in the mountains. (Photo by Mario Tama/Getty Images)
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MAMMOTH LAKES, CALIFORNIA - MARCH 12: Mammoth Lakes Fire Department firefighters respond to a propane heater leak and small fire at a shuttered restaurant surrounded by snowbanks on March 12, 2023 in Mammoth Lakes, California. Snowpacks and snow drifts can bear weight on delicate gas lines which can potentially break and create a dangerous pocket of explosive gas. The eastern Sierra Nevada mountains currently hold 243 percent of its regular snowpack for this time of the year. California is bracing for another powerful atmospheric river event, bringing more snow to higher elevations and rain to lower elevations, beginning tomorrow. (Photo by Mario Tama/Getty Images)
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MAMMOTH LAKES, CALIFORNIA - MARCH 12: Mammoth Lakes Fire Department firefighters respond to a propane heater leak and small fire at a shuttered restaurant surrounded by snowbanks on March 12, 2023 in Mammoth Lakes, California. Snowpacks and snow drifts can bear weight on delicate gas lines which can potentially break and create a dangerous pocket of explosive gas. The eastern Sierra Nevada mountains currently hold 243 percent of its regular snowpack for this time of the year. California is bracing for another powerful atmospheric river event, bringing more snow to higher elevations and rain to lower elevations, beginning tomorrow. (Photo by Mario Tama/Getty Images)
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MAMMOTH LAKES, CALIFORNIA - MARCH 12: In an aerial view, snow from new and past storms covers the landscape and rooftops of homes in the Sierra Nevada mountains, in the wake of an atmospheric river event, on March 12, 2023 in Mammoth Lakes, California. Flooding washed away roads and breached a levee in parts of Northern and Central California due to runoff from the state’s 10th atmospheric river storm. The eastern Sierra Nevada currently is holding 243 percent of its regular snowpack for this time of the year. California is bracing for another powerful atmospheric river event, bringing more snow to higher elevations and rain to lower elevations, beginning tomorrow. (Photo by Mario Tama/Getty Images)
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MAMMOTH LAKES, CALIFORNIA - MARCH 12: Mammoth Lakes Fire Department firefighters use a ladder on a snowbank while responding to a propane heater leak and small fire at a shuttered restaurant surrounded by snowbanks, in the wake of an atmospheric river event, on March 12, 2023 in Mammoth Lakes, California.
(Mario Tama)
MAMMOTH LAKES, CALIFORNIA - MARCH 12: In an aerial view, snow covers roofs next to snowbanks piled up from new and past storms in the Sierra Nevada mountains, in the wake of an atmospheric river event, on March 12, 2023 in Mammoth Lakes, California. Flooding washed away roads and breached a levee in parts of Northern and Central California due to runoff from the state’s 10th atmospheric river storm. The eastern Sierra Nevada currently is holding 243 percent of its regular snowpack for this time of the year. California is bracing for another powerful atmospheric river event, bringing more snow to higher elevations and rain to lower elevations, beginning tomorrow. (Photo by Mario Tama/Getty Images)
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MAMMOTH LAKES, CALIFORNIA - MARCH 12: In an aerial view, a vehicle navigates a snowy roadway lined with snowbanks piled up from new and past storms in the Sierra Nevada mountains, in the wake of an atmospheric river event, on March 12, 2023 in Mammoth Lakes, California. Flooding washed away roads and breached a levee in parts of Northern and Central California due to runoff from the state’s 10th atmospheric river storm. The eastern Sierra Nevada currently is holding 243 percent of its regular snowpack for this time of the year. California is bracing for another powerful atmospheric river event, bringing more snow to higher elevations and rain to lower elevations, beginning tomorrow. (Photo by Mario Tama/Getty Images)
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MAMMOTH LAKES, CALIFORNIA - MARCH 12: In an aerial view, a person shovels on a snowy roadway lined with snowbanks piled up from new and past storms in the Sierra Nevada mountains, in the wake of an atmospheric river event, on March 12, 2023 in Mammoth Lakes, California. The eastern Sierra Nevada currently is holding 243 percent of its regular snowpack for this time of the year. California is bracing for another powerful atmospheric river event, bringing more snow to higher elevations and rain to lower elevations, beginning tomorrow. (Photo by Mario Tama/Getty Images)
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MAMMOTH LAKES, CALIFORNIA - MARCH 12: In an aerial view, a vehicle and people navigate a snowy roadway lined with snowbanks piled up from new and past storms in the Sierra Nevada mountains, in the wake of an atmospheric river event, on March 12, 2023 in Mammoth Lakes, California. The eastern Sierra Nevada currently is holding 243 percent of its regular snowpack for this time of the year. California is bracing for another powerful atmospheric river event, bringing more snow to higher elevations and rain to lower elevations, beginning tomorrow. (Photo by Mario Tama/Getty Images)
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MAMMOTH LAKES, CALIFORNIA - MARCH 12: People watch as Mammoth Lakes Fire Department firefighters respond to a propane heater leak and small fire at a shuttered restaurant surrounded by snowbanks, in the wake of an atmospheric river event, on March 12, 2023 in Mammoth Lakes, California. Snowpacks and snow drifts can bear weight on delicate gas lines which can potentially break and create a dangerous pocket of explosive gas. The eastern Sierra Nevada mountains currently hold 243 percent of its regular snowpack for this time of the year. California is bracing for another powerful atmospheric river event, bringing more snow to higher elevations and rain to lower elevations, beginning tomorrow. (Photo by Mario Tama/Getty Images)
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Mammoth Mountain California March 7, 2023-A vehicle makes its way along Lakeview Blvd. in Mammoth Mountain Tuesday. Over 550 inches of snow has fallen at the main lodge as residents try to dig out. (Wally Skalij/(Los Angeles Times via Getty Images)
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Mammoth Mountain California March 8, 2023-A cabin its buried in snow at Tamarack Lodge in MammothWednesday. The lodge at 8,600 feet is expecting another 100 inches of snow this coming week. (Wally Skalij/(Los Angeles Times via Getty Images)
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A house with a caved in roof in Crestline, California, US, on Tuesday, March 7, 2023. The San Bernardino Mountains received more than 100 inches of snow over the past several days, stranding an unknown number of residents in the mountain communities, reports the Los Angeles Times. Photographer: Kyle Grillot/Bloomberg via Getty Images
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CRESTLINE, CALIFORNIA - MARCH 03: An aerial view of residents (LOWER C) waiting in line to receive donated food outside the local grocery store, which was severely damaged when its roof collapsed under the weight of several feet of snow, after a series of winter storms in the San Bernardino Mountains in Southern California on March 3, 2023 in Crestline, California. Some residents have been trapped in Crestline more than a week due to heavy snowfall while the grocery store was the main hub for food purchases in town. California Governor Gavin Newsom has declared a state of emergency due to winter storms for 13 counties including San Bernardino County and the California National Guard is assisting relief efforts in the mountains. (Photo by Mario Tama/Getty Images)
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"This is why it’s important to take those necessary precautions as we go ahead and navigate the next couple of days because that added weight is just going to put so much pressure on people’s roofs," Torres said.
Tips to stay safe while clearing snow from a roof
FEMA and other emergency officials have important tips for those who need to clear snow from their roofs:
- Look for signs of roof collapse before climbing atop. Look for sagging trusses or sounds of popping or creaking.
- Always have someone below to act as a spotter and to keep people away from walking underneath where you're clearing snow.
- Use a snow rake or broom to remove snow. Avoid using metal that could conduct electricity from nearby power lines.
- Be careful of removing icicles, and always wear headgear or goggles when removing snow.
- Watch for skylights.
- Keep storm drains and gutters clear to allow drainage of melting snow.
How much does snow weigh and can your roof handle it?
Heavy snowfall can pose a serious risk to homes, causing roof drainage concerns, damage or even failure.