Summary:
The trend for powder is still active with the PNW scoring Monday/Tuesday with leftovers aimed at Idaho and Wyoming. The long term forecast shows some glimmer of hope for the Southern Rockies for XMAS Day, and a possibly colder and more active pattern for the end of December. The PNW will likely stay fairly active with generally warmer temps. You can chase from the PNW, to the Rockies and then back up to Canada Wednesday. Stay at Logden Lodge where we stayed if you end up chasing to Whitewater near Nelson BC (Christmas availability).
Sunday was a great powder day in the Tetons, where up to 11 inches of medium-density snow fell, primarily during the early morning hours. I chased to Targhee and had endless laps of Wyoming Powder. The coverage was decent, but you still had to be on guard and choose northern aspects (Overall coverage is good). Reports from JHMR, are that more terrain is opening and conditions are improving (9/13 lifts are spinning). Westerly flow on Monday/Tuesday and the upcoming storm will likely favor Teton Pass and JHMR slightly. This will help the Tetons and especially JHMR which has the steeper and rockier terrain.
The next 24 hours will provide ample opportunity to chase to Oregon, Idaho, and Wyoming. From there, the chase might include interior BC where a northern impulse brings 5-11 inches to the interior regions.
PNW
Below: Strong system moving over Oregon Monday/Tuesday taking a northern path in the Rockies.
Below: Total snowfall through Tuesday morning in the Cascades will be plentiful, especially in the central regions of Oregon towards Bachelor where 12-28 inches might land. Slightly lower totals are noted to the north especially as you get into the central and northern areas of Washington and BC.
Projected totals: Bachelor: 10-20 inches, Mt Hood: 18-25 inches, White Pass: 9-14 inches, Crystal: 5-11 inches, Stevens Pass: 3-5 inches. These totals are through Tuesday morning. Significant moisture and warming move in Tuesday/Wednesday with higher totals at the summits as snow levels skyrocket bringing rain to most ski areas.
Below: Total snow through Wednesday morning for the PNW. Spoiler Alert: Warming will occur as early as early Tuesday for Oregon and midday for Washington. Snow levels will climb significantly from Tuesday night to Wednesday with rain likely below 6,000 feet Tuesday night. Snow levels drop slightly on Wednesday and rise to 7,000 feet by Thursday (All rain). Bottom Line: Get the Powder NOW. 7-9 inches have already fallen in many of the Oregon resorts Monday morning (Storm Ski) with lighter totals in Washington with snow increasing. I would chase to Oregon now.
Sponsor Alert: Please check out Selkirk Powder in the northern area of Idaho. Cat Skiing with 6200 acres of new terrain this season stretched across 3 peaks reaching 6700 feet! They will score some powder from the next few storms. Cat Skiing begins on January 4th.
Below: Warm front pushing into Oregon early Tuesday morning and just advancing into Washington. Easterly flow over the Washington Cascades will keep most of Washington in the cooler sector until mid-morning Tuesday as the warmer air advances north. Snow levels in Oregon rise to nearly 5000 feet initially. Slightly cooler temps are noted for the interior and northern areas.
Sierra
Below: Total moisture for the Sierra ranges through due Monday. General totals for areas around Lake Tahoe are 1/4 to 1/2 inch of liquid which would result in 3-6 inches of snow. There is nearly 1.5 inches noted north near Mt Shasta where significant totals are likely on Monday.
Rockies and Idaho:
Wrung-out leftovers will bring 7-14 inches to many areas in central Idaho and the Tetons Monday to Tuesday. Snow density will be slightly higher than the last storm, but still respectable. Some areas in the Tetons might see higher totals near Teton pass or JHMR that is slightly favored with West, SW wind direction. The northern most area of Utah near Logan (Beaver Mountain) may also see some snow from this next system. Beaver is still closed.
Below: Total snowfall through Tuesday afternoon for the west. You can see the narrow band of heavier totals from the PNW (Oregon primarily Monday before warming Tuesday) extending east into central Idaho (McCall, Stanley, Sun Valley (Wildcard), Bogus Basin, etc. That moisture will be over the Tetons as early as 2 PM on Monday. Utah gets scraps, primarily in the northern regions with Colorado also too far north of the action (Steamboat could see 1-3).
Canada
Snow is likely by Wednesday as another low skirts north Tuesday night. Colder temps are noted in the interior for the best quality, however western areas will be deeper up high.
Below: Wednesday- Snow has overspread BC with some decent totals for Whistler (Warming) and 9-14 inches in the interior of BC (Colder). Consider chasing to Canada for Wednesday!
Let's dig into the extended forecast below
Extended
The overall trend is for high pressure for the Rockies until perhaps December 23-25 when a storm might take a southern route over the Rockies and 4 corners. The PNW shows better hope as a ridge buckles slightly in the next week. I am not seeing any blockbuster storms. The end of December looks very active with multiple systems possible, and hopefully breaking down the ridge. Colder air is also noted for the end of the month.
Below: Wednesday, December 18 to Friday, December 20. You can see the fast-moving low over BC skirt east by Thursday (Date in upper right of map). High pressure has overspread the Rockies and Sierra.
Below: Saturday (December 21) to Monday (December 23). The ridge is buckling in the PNW as moisture streams north into the western Cascades and Canada. Most of this moisture will likely not make it into the Rockies. The PNW should remain unsettled (no blockbuster storm). Temps are also fairly warm with snow levels in the 4,000-foot range (Fluctuates down slightly with moisture). This period might offer some chases in the PNW or Canada.
Below: Upper atmosphere- Santa Week! December 24 (XMAS eve) shows a quick-moving storm possibly favoring the southern Sierra range and moving into the 4 corners by Xmas day. This would increase the odds of a white Xmas for much of CA, Utah, and Colorado as moisture streams north of low (NM and AZ are just south of the main action, but that could change).
Below: The upper atmosphere for late December shows a lineup of storms entering the west that might take a more southerly route. This period is too far out to forecast with confidence. (December 29-30 shown below).
Below: In looking for colder temperatures there is some hope towards the end of December (Colder air settling over the PNW and Sierra). Hopefully, combined with the low pressure noted above this brings us some decent blower dumps.
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