this winter will be sick. it's long, but informative,
hanges in the jet stream configuration will continue during the upcoming week, and by next weekend, we will see a ridge of high pressure building over the west coast of the U.S. and Canada. The polar vortex is finally being dislodged from the pole, which will help set up a cross-polar flow by the week of the 15th. Western Canada is growing colder, and that cold is spreading eastward across the Prairie Provinces, so the air that arrives from the high latitudes won’t moderate as much as in recent weeks. The first [profanity omitted] of cold will flow into the northern Rockies and northern Plains, but low level cold air will also be pressing into the east. With an upper level trough over the Southwest, the flow aloft over the East will continue to be from the west southwest, and as that air overruns cold, dense air near the surface, the stage is set for a series of increasingly colder systems to ride along the boundary. I think that during the week of the 15th, snow cover will be laid down from north to south with time, and sleet and freezing rain will be quite common in the transition zone. One of the analog winters that is very similar to what we have seen thus far in ’06 and ’07 is ’77-’78. Folks in the Northeast, particularly in southern New England, remember the Blizzard of ’78, which paralyzed the region and dumped upwards 54” of snow (Manville, RI). What isn’t so well remembered is the ice storm that preceded the blizzard by a couple of weeks, as the reversal from a very warm December and early January got underway. It would not surprise me at all to see a significant icing event or two as we transition back to winter over the next 2 weeks or so. North of any icing zone we will find more and more snow as the month progresses, and by the 20th or so, it looks to me as though an upper level trough will be anchored over the east, and cold air will be in the region to stay for a while. As long as the southern branch of the jet, reinforced by the weakening El Nino, doesn’t get suppressed too far to the south, we could be looking at a very stormy period in late January and early February. The jet will get pressed to the south as the cold air starts to become more dominant, which will push the mean storm track further south...that means that resorts in the southern Appalachians are going to get their fair share of snow from this turnaround, as well.
Weak El Ninos typically produce back-loaded winters, and indications are that we are going to see that happen once again. The other analog years that most resemble this season, ’57-’58 and ’65-’66, also brought about a dramatic mid-winter reversal to cold that lasted through February and into March, so there is reason for optimism that once the cold air returns, it will dominate for the bulk of the remainder of the season.
In the West, the pattern change is also good news. The Pacific Northwest and far northern Rockies, where heavy snows fell much of December as the Pacific jet roared ashore, have received a good [profanity omitted] of snow in the past several days, on the order of 2-3 feet in the Cascades. More snow is falling today, along with strong winds, so avalanche danger is going to rise rapidly this weekend. The pressing of arctic air into the region during the next week will produce drier snow, but when the upper level ridge takes shape along the west coast in the next week to 10 days, the jet energy will be deflected far to the north. That will effectively [profanity omitted] of the snow for a while in that region, but they have plenty “in the bank” for any dry run that may develop. The southern branch of the jet, again, fueled to some extent by the weakening El Nino, has generated snows in the southern Rockies (and Denver), and that part of the country will continue to pick up its fair share of fresh powder as we move through the winter. It’s the I-70 corridor from Salt Lake City to Denver that worries me a bit, as they look to be too far north for southern branch snow and not far enough east to collect from the Clippers that will move down the east side of the western ridge. I expect powder days to be down north of I-70 from late January onward, but overall, the snow thus far is more than enough to sustain the resorts.
Ski areas that pick up lake effect snow (Michigan, Ohio, western PA, West Virginia, Maryland, and upstate New York) are about to cash in on an unusual mid winter bonanza. Water temperatures are in the low to mid 40’s...more like those found in early November, and very warm for January. When the seriously cold air flows over those lakes later this month, the snow squalls are going to explode, due to the extreme difference between the water surface temperatures and the air at 5,000 feet. Northern Vermont and the Eastern Townships of Quebec are included, too, as Lake Champlain is going to get in this act. We could see some obscene amounts of snow in lake effect resorts...of course, getting to that powder could be an issue to contend with, as well.
While the change to winter will not come in one [profanity omitted], and the transition promises to be a messy one in many locations, but the message I want to convey in the strongest terms possible is that the change is coming, and it is going to be dramatic to produce some fantastic skiing and riding in areas where that notion is just about unimaginable right now. The season will be a shorter one, to be sure, but we do have some terrific days on the slopes to look forward to in the not too distant future.
