Summary: We are in a very active period with snowfall returning to the Sierra this weekend as cold air and an Atmospheric River merge with the "Bomb Cyclone" spinning off the Pacific. Significant snow totals will be found in the Sierra Saturday/Sunday. Moisture spreads north initially through the Cascades (3-7) and Idaho (Decent totals) into northern Montana. Phase 1 of moisture brings light or moderate snow to the Rockies late this weekend. New England is also grabbing some teases with up to 16 inches reported in the Catskills. More snow is headed to New England this weekend.
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Phase 2 of the cycle that provides 2-3 feet to the Sierra will move over the Rockies by mid next week producing double digits, especially in Utah and Colorado.
Powder Forecast:
Temps are warm on Friday morning in CA, after one departing storm in the Sierra landed 2 feet in the northernmost mountains near Mt Shasta and up to 15 inches at the higher elevations of the ranges closest to I-80 (Donner Summit). Areas south of Palisades saw lower totals (4-8) as forecasted. The northern Crest picked up 8-15 inches.
Below: Telemetry stations show warm temps at 7200 feet in the Sierra (40F), and it is hard to find any elevations below freezing, aside from some summits at 9-10K. Some resorts are opening with rain.
Below: Rain is approaching the Sierra on Friday morning and will overspread many ski areas by 9 AM. Photo: OpenSnow Maps
The good news is that colder air will usher in on Saturday and, combined with the AR and the low pressure from the "Bomb Cyclone," will create some very deep totals for the entire Sierra Range (North and south).
Below: Snowfall overspreads Tahoe from late Friday night through Saturday.
Totals could exceed 20-30 inches at mid or summits with 9-11 at the bases. Colder air on Saturday will drive snow levels to the base and lake level. Caveat: Powerful winds are on the models for Friday night and will slowly decrease on Saturday. Upper elevations might not spin lifts on Saturday. However, the wind speeds gradually migrate down during the day, especially on Sunday. Snow quality at the summits will be wind-impacted on Friday night.
Below: A cold front is approaching the Sierra by Saturday morning (the Date and time in Zulu time are in the upper right). This will drive the snow levels to lake level on Saturday.
As of Friday morning, moisture is also focused on the Cascade ranges, with Crystal Mountain opening (6 new overnight). Temps are warming in the Cascades, with some surf snow expected through Saturday/Sunday, primarily focussed on the interior from Mission Ridge to Spokane. Schweitzer and Selkirk Powder Guides in Northern Idaho will likely nab decent totals through Sunday (9-13) and slightly cooler temps being inland.
Below is the total snowfall for WA and northern Idaho from Friday to Saturday night (November 24). Northern Idaho extending into southern BC could fare well this weekend, albeit with slowly warming temperatures.
Below: The total snowfall for Idaho from Friday to Sunday shows decent amounts for many areas. Unfortunately, the models downtrended for Sun Valley based on my last forecast. Another deep spot to watch will be Whitefish in northern Montana as moisture streams east of the northern Panhandle of Idaho. Selkirk Powder Guides should once again score some deep snowfall.
Quick shout out to New England
New England received light to moderate snowfall on Friday morning. The Catskills of New York received the highest totals (12-16 inches), and many ski areas reported 2-4 inches further north into Vermont and less towards New Hampshire.
Below: Short-term NAM-12 (Saturday AM to Sunday PM) showing snow picking up again this weekend, focusing on the northern ranges of Vermont and, to a better extent, far northern New Hampshire and Maine. The likely results will be highest in the ranges north of Conway, extending to the Maine border. Perhaps Sugarloaf will do okay. Vermont could grab decent totals toward Stowe to the Canadian border (5-11).
EXTENDED POW
The active pattern in the Sierra shifts east with an initial wave of light or moderate snow likely for much of the Rockies as early as Sunday/Monday. This teaser comes with warmer temps, followed by a cold front and more significant snowfall for the Tuesday/Wednesday period. Signficant totals of 1-2 feet are likely for much of Utah and Colorado, with the Tetons just north of the peak action. There is model discrepancy on the exact track that we will discuss below.
WAVE #1
Below: This map shows snowfall from Friday afternoon through Monday. Snow will initially arrive in the Sierra this weekend (2-3 feet) and extend into the Cascades and Idaho (9-11) before reaching Wyoming and Utah by Sunday (Light or moderate amounts initially). The Cottonwoods may grab higher amounts (4-8). You can see snow overspreading many regions of the west primarily under the warm front with the exception of the colder air over the Sierra this weekend.
The cold front and more significant moisture from California streams east over the Rockies Tuesday-Wednesday. This is the storm to watch aside from the Sierra snow this weekend.
Below: Per the European solution below, total snowfall is plentiful for much of the Teton Range, Utah, and Colorado from Tuesday to Wednesday and extends into southern Montana (Left map). The GFS (not shown) brings less moisture north of Utah and decreases the totals for the Tetons and southern Montana (The exact track is still unknown).
The highest confidence for double digits is in Utah and Colorado, with less further north (Moderate totals).
Below: University of Utah ensembles show the first wave to hit Alta late Saturday (5 inches) and another more prominent bump Tuesday-Wednesday (Additional 10-12). This is a reasonable forecast. However, the amounts could be higher with the colder NW flow for Utah.
Colorado has high confidence of double digits, primarily from Tuesday through Wednesday night. Temps will be warm initially, pushing snow levels near 8,000 feet, which will lower significantly by Wednesday (Dense snow initially followed by blower). Models diverge on how far south this system digs. I propose that the central and southern mountains see the highest totals. Winds initially from the SW will favor the southern mountains; however, a distinct switch to the NW will feed moisture north into most of northern Colorado. NW winds and a slight south trajectory can often pull some big numbers up for Highlands, Snowmass, and Telluride (Like NW flow). Monarch can also score in this regime. There will likely be no losers in this storm!
Below: Winds from the SW will initially favor the southern mountains of Colorado on Tuesday (Warm initial phase of the storm). You can see a distinct shift to the NW by Wednesday, with colder temps overspreading much of Colorado (Snowfall increases early Wednesday from Telluride and north through I-70 and the northern mountains).
Below: The European model showing 12-15 inch totals for Colorado -Tuesday/Wednesday evening storm (November 26-27 PM). This model shows a northern track into southern Wyoming. Higher totals will likely land along or west of the Divide on this storm. There won't be any losers!
Below: The American GFS is slightly less bullish for the northern mountains (9-11) and depicts higher totals for the southern mountains (10-20) in Colorado. This might provide a better chance of snow pushing to the northern New Mexico mountains.
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