Except The West Coast.

Last week I discussed the role of upper level troughs as they relate to our insatiable appetite for fresh snow, both natural and machine made. Most of the time, troughs are indeed our friends but that doesn’t necessarily mean that upper level ridges are the enemy. The influence of ridge is just like the old cliche about real estate: location, location, location. Troughs often look like the letter “U” on a map while ridges tend to take on the shape of the Greek letter Omega. I have used a jet stream forecast map for Sunday the 22nd to illustrate this common configuration.

Now, in order to take on the Omega shape, you can see that the two ends of the line are wrapped around adjacent troughs, and that is where the location piece comes into the equation. You see, ridges are areas where overall, the air is sinking. Sinking air limits cloud cover and precip, and it also warms up as it sinks, consistent with the laws of physics. So, if you find your favorite resort under a ridge, your odds of seeing snow are greatly reduced. But, if that same ridge is off to the west of the resort by several hundred miles or more, the clockwise flow around the ridge will work together with the counterclockwise flow around a downstream trough to the east to tap cold air from the north. At that point, the ridge becomes your ally. As I have expressed in earlier posts, I am confident that a western ridge/eastern trough couplet is going to be the favored setup as we head through this winter, but in the shorter run, the ridge is going to spread out and cover much of the eastern two thirds of the country as we head through the holidays. Overall, Pacific systems will bring seasonable cold and some snow to the west while it is milder than normal east of the Mississippi.

Here Are The Regional Details.      

Northwest U.S./Western Canada: A very juicy storm will be in progress into this weekend. Whistler finally gets tagged. Cascades get healthier trail counts. Pattern more benign next week.

Cascades and Sierra:  The same storm will nail the Cascades. Snow levels will be rising through the storm, so only count on “all snow” above 6K feet. Amounts will be 2-3 feet WA and OR. CA Sierra pick up moderate snow Sunday. The pattern will turn quieter through most of Christmas Week.  

Rockies: The coastal storm will slow coming inland due to the spreading of the upper ridge further east, so any snow that makes it out of the Cascades will be spotty and light late this weekend/early next week. No big storms next week by the looks.

Midwest: Late week lake effect will help set up this weekend. Milder temps develop into next week, which limits snowmaking windows. The good news is, it looks rather dry, under the ridge, Christmas week.   Colder air returns after the 29th or so.

Northeast: Late week shot of Arctic air will allow snowmakers to get busy 24/7 in most spots. It will turn milder next week and snowmaking will be feasible in the mountains. The lower elevation areas should have some windows, too. With the ridge axis fairly far to the west next week, some colder air will filter into the region at times. No significant snow events appear to be in the cards through the end of next week.  

Overall, after a major “Cascade Cement” storm in the NW at the outset, the holiday period looks rather dull from a forecaster’s perspective. Some lighter snow will fall in the west…the milder temps will keep it comfortable on the slopes for skiers and riders in the Midwest and East.       

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