It is Friday evening, and this is Powderchaser Steve with a few updates. It is going to be very deep in the west with several waves of energy associated with an AR in the PNW. The action will be underway through Sunday night. Expect widespread snow totals of 20-30 inches or more in the Cascades and Rockies. Snow will change to rain in the PNW on Sunday or Sunday night.
Chases? PNW, Idaho, Northern and Central Rockies.
Here are a few snow totals as of 4 PM Friday from telemetry
Mt Baker- 11 inches
Stevens Pass- 6 inches
Alta 8 inches
Grand Targhee- 8 inches on telemetry, 5-6 at the base cam.
Aspen: 6 inches (Separate storm from the south Friday morning).
Below: New webcam for Beaver Mountain (We love the Beaver at the top and hope the snow hits it).
Below: Taos scored POW on the teaser that brushed Colorado and New Mexico on Friday.
PNW UPDATE
In the Cascades, heavy snowfall was underway with your deepest dumps likely along the entire spine of the Cascades from Washington to Oregon (20-30 inches). Whistler and the coastal BC resorts will all do well with this storm (8-14). Interior Washington sees colder temps and 8-12 inches for Selkirk Powder Guides in northern Idaho including Schweitzer.
Mt Baker is benefiting from SW flow initially Friday night (Will be deep on Saturday) before winds shift to the W-NW Saturday favoring central and southern areas. Convergence zones might form Saturday, circulating moisture bands around the central Cascades (Stevens, Alpental), and even south to Crystal. We would expect storm totals to be 20-25 inches in many areas, with perhaps higher totals near Baker (Favored Friday night) or Stevens (Saturday).
Warm air starts to creep up from the south Saturday morning in Oregon and southern Washington pushing snow levels up a tad, before dropping again midday Saturday. I think you will see primarily snow in most areas on Saturday especially above 4,000 feet with the brief warming in southern areas as quality deteriorates. Snow quality will be denser Saturday, and even more so on Sunday. Northern or central areas in Washington will benefit from some cooler pockets.
Below:
Snow levels rise Sunday morning, especially in the southern Cascades. Brief cooling may return snowfall (See the cold front briefly pushing in from the north below), especially to the northern Cascades near Baker late Sunday. Easterly flow will keep Stevens and Snoqualmie Pass cooler with snowfall continuing (Possible mixed precipitation at the base). The eastern Cascades including Mission Ridge and areas to the Idaho border will stay cooler on Sunday. Eventually, rain will be falling over the PNW from late Sunday night to Monday.
Below: Total snowfall through Sunday morning for the Cascades. Strong winds and a warming trend will increase avalanche danger significantly especially late Saturday to Sunday.
Whistler grabs 12-15. Moderate snow over Schweitzer and Selkirk Powder Guides including the Idaho Panhandle (Deeper). Lots of winners. Northern Montana near Whitefish will also be scoring freshies.
Announcement: Selkirk Powder Guides is opening for the season with AVY classes beginning December 15th and CAT and Snowmobile tours near XMAS. They have 6500 acres of new terrain this season (Expansion). Take advantage of a promotion from Powderchasers and get a free concierge program if you book a trip by December 15th. You can book here and mention PC for the promo.
Rockies:
The Rockies score good snowfall this weekend ending Sunday night or Monday morning. There is a decent wave noted for Idaho/Wyoming and Utah Friday night followed by a brief break on Saturday. (6-9 for the Tetons Friday night with some snow continuing Saturday). Totals in the Tetons will range from 12-20 inches.
Deeper totals in Utah will likely occur anywhere from Beaver Mountain near Logan, Northern Wasatch (Snowbasin or Powder), and the Cottonwoods. I would expect an additional 5-10 inches for these areas by Saturday morning. Higher amounts are possible with the models not able to distinguish isolated convection and some totals might exceed 10 inches in Utah. A brief break on Saturday before more snow moves in with a warm front into Sunday with intensity increasing.
For Colorado, the initial wave Friday night will favor the western corridor from Aspen to Steamboat (5-9 inches) with lighter amounts on the core of the I-70 corridor. Aspen might be a decent place to chase or Steamboat by Saturday morning. Keep reading for the deeper part of the storm is Saturday night and Sunday.
Saturday night/Sunday- Rockies getting deeper.
The warmer air noted in the PNW moves over the Rockies, especially Saturday night and Sunday. This front combined with a very saturated atmosphere will bring an even stronger wave of heavy snowfall for the Tetons, Wasatch Range, and Colorado.
The main focus in Wyoming is mid-morning Saturday to Sunday morning., moving into Utah and Colorado from Saturday PM to Sunday PM.
Storm totals will continue to rise into the expected ranges of 2-3 feet for many areas (Tetons-Wasatch) when this storm finally moves east on Monday. Colorado will likely land in the 15-20 inch range by Monday morning.
The models are pushing higher snow totals than previously expected over a wide area of the Colorado Central and N mountains. We feel really good about 12-15 inches for most mountains from Steamboat, Aspen, Irwin Lodge (CB looks deep also- but a bit of an outlier), and all of Summit and Grand Counties. This will be a storm that the core of I-70 has been waiting for.
Highest precipitation rates will be late Saturday night through Sunday evening. Berthoud Pass, Winter Park, and even Eldora will be scoring snowfall. Temps will be warming so quality will be a bit denser than on Saturday. Ride Sunday and Monday for the deepest totals.
Below: Snow totals will be higher as colder air increases the ratios (Snow water equivalent). We would not be surprised to see 12-20 inches in some of these areas by Monday morning. The peak snowfall rates will likely be late Saturday night to Sunday afternoon. (2 waves- Friday night and again late Saturday night).
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Below: Total snowfall in the west through Monday at 10:1 snow ratios. These totals will likely exceed the numbers on the map in the Rockies. There are few losers aside from some spots in southern Montana and the Sierra. NM might also miss out but Taos has 7-8 inches today. 
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Powderchaser Steve. Follow @powderchasersteve on Instagram.
Stay safe everyone as this storm is coming in upside down.
Powderchaser Steve
