After snowy start to week, heavy rain headed to Lake Tahoe
Service warns rain could add to snow load leading to structural collapses
SOUTH LAKE TAHOE, Calif. — From a dumping of snow to a dousing of rain, Lake Tahoe is getting it all this week.
Snow showers will continue through Wednesday before a major pattern change takes place Thursday into the weekend, including a warmer atmospheric river event that is packing heavy moisture, weather officials said.
The National Weather Service in Reno said a break in the snowy weather is expected Tuesday morning before snow showers begin again in the mid afternoon and more energetic showers are expected early Wednesday morning before tapering off mid-to-late afternoon.
“Between today and Wednesday, expect up to 2 feet of new snow accumulation on the Sierra crest generally north of U.S. Highway 50, 4-8 inches in the Tahoe Basin, 2-6 inches in northeast California, and up to 2 inches of more spotty accumulations for western Nevada,” the service said.
Even light snow can impact mountain travel and chain controls are already in effect throughout the basin, except for US-50 from Meyers through South Lake Tahoe.
The storm remains wide open on Thursday into the weekend with the first atmospheric river arriving in the afternoon bringing wind, rain and snow impacts.
Winds are expected to gradually increase in the afternoon into Friday with 100 mph gusts possible along Sierra ridges. The service said precipitation may dampen the winds a bit and added there is a 60-70% chance for gusts between 40-50 mph in the basin.
The winds will be transporting “impressive moisture for this time of year,” the service said. From Thursday into Saturday there is a 100% chance for 1 inch of moisture and 80-90% chance for 2 inches and 70-80% chance for 3 inches and lower chances for up to 5 inches.
Snow levels are trending high, the service said, but will start out lower Thursday (5-6,000 feet) and are expected to rise quickly through the evening as the snow transitions to rain.
The service said that above the snowline, snow will again be measured in feet. There is a likelihood of at least 8 inches of snow along the crests at Lake Tahoe, but only a 40-50% chance of a foot or more.
Snow levels will be between 7,000-9,000 feet by Friday morning with a 10% chance that snow levels could exceed 9,000.
The service said areas with a large snowpack, like Tahoe, may act more like a sponge and retain the water.
“Rain combined with strong winds and high humidity will add considerable energy into our record-to-near-record deep regional snowpack at mid to lower elevations,“ the service said. “While higher elevation and deepest snowpacks will continue to accumulate snow and water
equivalent, deep mid-elevations snowpacks are expected to retain most of the projected rain. Some of these areas may begin to develop preferential pathways for melt and start releasing rainfall after prolonged periods of rain, but are unlikely to contribute significant snowmelt to the runoff.”
The service said areas with a relatively shallow snowpack may have significant melt and flooding issues.
The issue facing Tahoe homeowners more urgently may be the snow load on roofs.
The service said locations that are already buried under a deep snowpack should prepare to avoid snow load on structures, “as rain absorbing into the snowpack may contribute additional weight and lead to structural collapses.”
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