80” (or More) of Snow Forecast in California This Week
The Sierra Nevada Mountains in California are about to make up for a dry, fire-inducing stretch of weather in a hurry with anywhere from 3 to 7 feet or more of snow forecast to fall this week.
Here’s the technical setup of the forecast. An active jet stream will help generate multiple storms that impact the Southwest U.S. this week. One round comes late Sunday through Monday, before a more prolonged and more significant period of heavy (valley) rain and mountain snow develops. An atmospheric river, a very wet flow of air often originating in the tropics, will focus a stream of deep moisture from the Pacific Ocean toward the southwest US beginning Tuesday lasting through Friday. Like a firehose, this stream of moisture will result in heavy rain for lower elevations while in the colder mountain tops, epic amounts of snow will drop.
The green “plume” streaming into the Southwest Tues-Fri indicates the #atmosphericriver, ushering in anomalously high moisture content. This results in flooding valley rain and intense mtn snow in CA pic.twitter.com/y8h1YdBxuu— Kerrin Jeromin (@KerrinJeromin) January 24, 2021
As the moisture flows generally southwest to northeast, it runs into the mountains in California, which are generally oriented northwest to southeast. This cross-mountain flow will cause the moisture-laden flow to hit the mountains, and be forced to rise, cooling and causing precipitation to develop, much of which will fall as snow in the colder, higher elevation.
While we’re focusing on the snow here at SnoCountry, the rain shouldn’t be understated with many hazards including flooding and potential for landslides. Even in the snow zones, travel will be severely impacted, as well as increase the risk of avalanches.
The forecast from the Weather Prediction Center shows a widespread total 4-7” of liquid moisture to fall from this event in California, with localized amounts near 10”. Here's the liquid forecast below from Sunday January 24 through Saturday January 30.
A typical snow to liquid ratio is around 10 to 1, meaning for every 1 inch of rain, 10 inches of snow would fall if cold enough. Assuming a 10 to 1 ratio, that would bring 40-70” of snow, with locally 100” in the central Sierra Nevadas. However, with colder air at highest elevations, snow ratios will likely be even higher, which could mean some areas could get more than 100" of snow in this event.
Here’s the forecast from the local National Weather Service office in California for snow Tuesday to Friday (not including a quick hit of snow late Sunday-Monday prior to this prolonged event).
Needless to say, ski areas "in the snow zone" are excited for what’s ahead, and so are we! Be safe and have a blast!
Calling all powder hounds! 12"-18" of fresh snow has fallen and now the skies are clearing so get up here for one of the best days of the season. pic.twitter.com/WQHluQHsrr— Mountain High (@mthigh) January 24, 2021
Above the clouds today up at 8260' as we get ready for serious snowfall this week! pic.twitter.com/ggjnacl8so— MtRoseSkiTahoe (@MtRoseSkiTahoe) January 24, 2021