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Summary – 12/1/2017 . AM report
Yesterday I mentioned that the Rockies were back in the game! Models are coming close to agreement for heavy mountain snow in the Cascades to transition east this weekend combining with very cold air from Canada bringing decent snows to the northern Rockies. Highlights will include most of the Cascades Friday PM through Sunday, north/central Idaho, western Montana, Wyoming, and isolated spots of northern Utah and Colorado. A teaser hit the Tetons last night with 4 inches being reported at Grand Targhee .
Short Term Forecast
Snow intensifies during the day in the northern Cascades (Baker) before transitioning south by afternoon into the central and southern regions of Washington. The highest amounts will be found near Mount Baker (They scored another foot yesterday) followed by areas around Stevens and Snowqualmie Pass later in the day or tonight. Crystal is my wildcard pick. It will be snowing at Crystal tonight however it may not intensify until later Saturday/Sunday as heavier moisture moves in. Some spots of the northern Cascades of Washington will see an additional 12-18 inches through Sunday morning. Oregon gets into the action Saturday PM through Sunday (Heaviest amounts). “Pay attention to the web cams in WA as NOAA has the highest amounts over Crystal through Saturday.” Its possible that the heaviest moisture stays further north until the late Saturday/Sunday timeframe for the southern Cascades (Chase north to south this weekend).
Image: Low pressure over the northern Rockies edging a cold front south Sunday morning
The Rockies earn respectable amounts in central Idaho (Northern Sawtooth ranges near Stanley will see the highest amounts) edging into Ketchum (Sun Valley) late Saturday night (lower amounts). Moderate amounts will be falling near Schweitzer especially into Sunday morning where 5-10 inches is likely. Montana edges out moderate amounts up north (Whitefish) with lighter amounts to the south (Big Sky- Bridger). Snow quality will be good with cold temps and lighter densities!
Moderate snow moves into the Tetons late Saturday that continues into Sunday night. Snowfall rates will be on the low side adding up slowly over a 24-30 hour period (No single double digit dump wake up call) where it’s likely 5-12 inches will fall through Monday morning. Best days to ride will be Sunday and Monday. The highest amounts will be found on the northern areas of Teton National Park. Jackson may be favored with SW flow Saturday night however winds edge more west/northwest Sunday favoring Targhee later in the period.
Utah was a wildcard yesterday. Models still have some discrepancy. It’s likely that Sunday PM through Monday nabs moderate snowfall (4-6) for most of the Wasatch range (Including Park City), with heavier amounts downwind of the Great Salt Lake (Cottonwoods). Amounts near Alta could exceed 10 inches if everything pans out (Wildcard). NW flow can either be your best friend (Unexpected dumps) or skunk you but it’s unlikely the skunk appears this weekend. Orographic snow showers continue into Monday morning in the higher terrain of the Wasatch with NW flow (Thats what will put the Cottonwoods in the double digit range). Let it snow!
Colorado will get light to moderate leftovers in the northern mountains. I am still forecasting a wide area of 2-5 inches in most mountain locations along I-70 and north (Some light snow will be falling as far south as Telluride). Most snow will be falling late Sunday into Monday. Higher amounts are likely near Steamboat where perhaps 5-10 inches falls (Wildcard pick) as well as some isolated 3-7 inch amounts near the northern Divide (Winter Park). Vail can also benefit from NW flow orographics and the colder air so its on my list for higher amounts if we are lucky.
Below: Total snowfall through Monday night across the west
The extended pattern looks dry for at least December 9th in the West with a more active pattern setting up for the east (Thursday brings a warm system with rain/snow followed by all snow late in the storm period for New England). Models show a chance the ridge in the west will break down as we approach the middle of month but’s its impossible to predict this far out. There may even be some systems that edge into Colorado around the 11th of December pushing a system through the eastern edge of the Rockies?
Image: Thursday next week – High pressure in the west with low pressure in the east.
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