The medium-range forecasts are all in agreement: California is in for one hell of a storm cycle over the next 7-10 days. The High Sierra may see historically high precipitation rates.
The pattern over the next 7 days will have three major waves. The first significant precipitation will begin the morning of January 22 between 11 am-1 pm. Flakes will first fall in Tahoe and move southwest from there. Precipitation (not snowfall) accumulations of up to 0.05″ (~0.5″ of snowfall) per 3 hours are possible. The first wave of the system will move out by about noon on the 23rd. This first wave should bring a dusting of snow of about 2 inches.
The second wave should roll in around 3-6 pm on Sunday, January 24. This wave will be more substantial than the first. SWE accumulation rates may be up to about 0.1″ in 3 hours. This wave should bring up to 0.7″ total inches of SWE, or about 8.5″ of snowfall assuming 12-1 snow ratios typical for the Tahoe area.
The third and strongest wave of the storm rolls in around 10 pm on January 26. This storm will bring 3-hour snowfall rates of up to 1.5 inches of snow water equivalent, which translates to about 18 inches of snow… in just 3 hours! From 10 pm on the 26th until 10 am on the 28th, the Tahoe area could see up to 5 inches of water accumulation, or a whopping 60″ of fresh snowfall.
Good modeling accuracy ends around a week out, so I don’t like to forecast specifics beyond that range. However, there is still a significant amount of moisture and energy left upstream barreling straight down toward the Sierra Nevada. I would not be surprised if the storm total ends up close to 100 inches in regions along the Sierra Crest.
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