I had a couple of days on the snow early this week…a terrific day at Sunday River and a very disappointing day split between Wildcat and Attitash.  You can add me to the list of those taking Vail to task for the manner in which they are operating their eastern resorts and I will leave it at that.  The pattern has not been for the faint of heart of late, as an upper-level trough has been energized by the co-mingling of cold air from the north and milder air to the south.  We saw an east coast blizzard last weekend and an enormous storm this week, one that prompted winter storm warnings from New Mexico to Maine on Wednesday. In my experience, that is something that I have never seen.  While the trough has benefitted resorts in the Midwest and East, the West has been sitting under a dry upper-level ridge much of the New Year and snow has been sparse.  Will that change anytime soon?  Let’s take a look. 

The eastern trough/western ridge couplet will remain in place for a while, and a look ahead to late next week’s jet stream gives me a chance to explain why by illustrating a forecast trick I learned a long time ago.  Here is a look at the jet stream for next Friday…

Clearly, there is a deep trough over the East and a ridge just offshore of the Pac NW.  But I want to focus on the trough east of Hawaii.  When an upper trough is located in that position, or southeast of Hawaii, its’ counterclockwise flow helps to pump warmth into the ridge to its north, which strengthens the ridge.  When the two features get hooked up like that, they tend to remain in place until one or the other weakens or is forced out of the region.  That combo “teleconnects” to an eastern trough, so if you are checking out jet stream features on your favorite weather site, that trough’s position relative to Hawaii can tell you a lot about the near-term weather downstream over the U.S.

So, with that in mind, let’s jump ahead another week, to the start of President’s Day weekend…

It looks like the trough will still be in control from the Plains to the east coast, and the ridge will still be just off the NW coast.  But, the trough east of Hawaii is no longer there.  As a result the ridge is weaker and the northwesterly flow on its’ eastern flank will allow some Pacific moisture to slide down from the northern Cascades to the central and southern Rockies.  That is not a blockbuster storm track, but it will support a break from the recent diet heavy on packed powder and bluebird skies.  There are some early signs of changes in the position of thunderstorms in the southwest Pacific and Indian Ocean by mid-month, and if that comes to pass, we are likely to see a trough…and significant snows…return to the West late in the month.  In the shorter term, though, most of the storm action will remain over the eastern half of the country.

Northwest U.S./Western Canada:  Only the occasional weak disturbance passing through B.C. and Washington will produce snow for the next week or two. 

Sierra:  December’s snow is holding up well, and will have to continue to do so for a while longer.

Rockies:  Only the northernmost and southernmost resorts have a shot at some snow for the foreseeable future…from the two branches of the jet stream working around the pesky offshore ridge.

Midwest:  Every few days, a Clipper system will slide southeastward through the Great Lakes, producing light snow and modest backside lake effect. 

Mid Atlantic/Southeast:   Good temps for snowmaking for the next week or so.  Expect one or two significant snow events this month.

Northeast/QB:  Sizable late week snow gets period off to fine start.  Several shots at fresh snow in the next two weeks thanks to the trough.