The Difference Between East and West Is Remarkable.

Over the past few weeks, I have shared with you some of my winter forecasting tricks of the trade but now it is time to get down to business and do some actual forecasting. 

The pattern change that was foretold a couple of weeks ago by the re-curvature of a typhoon east of Japan is well underway (The “Typhoon Rule”). By this weekend an unseasonably cold upper trough will cover the eastern half of the country.  The air that the trough delivers will be of arctic origin, and, although it travels over ground that is not yet covered with snow, it will still be cold enough for some productive snowmaking in the taller mountains of the Northeast and as far south as resorts in the central Appalachians. 

Better yet, the cold air will rush in on the heels of a low pressure system that will generate a swath of snow from the Great Lakes eastward to the interior Northeast.  Lake effect snow will kick in downwind of Erie and Ontario for a short time, but because the system will be progressive, that backside snow won’t last very long.  This looks like a three- to six- inch event from the Adirondacks eastward through the Greens and Whites and on into the mountains of Maine.  That may not seem like much, but that first inch of machine made snow is laid down a lot faster when it lands on crystals and not leaves and dirt.  The cold temps this weekend will help to chill the soil, too.

On a broader scale, the developing pattern will be one of the “haves” and the “have nots” with respect to cold weather and prospects for snow.  Here is what the jet stream pattern is likely to resemble late next week

The deep trough will cover much of the eastern half of the country, with a strong ridge covering the waters of the eastern Pacific.  Clockwise flow around the ridge will combine with counterclockwise flow around the trough to tap into air masses from far to the north. This setup is ideal for the delivery of cold to the Midwest and East.  This next map shows the expected temperature anomalies at the five thousand foot level in a week from now. That altitude level is a proxy for forecasting surface temps.

The purple shading tells me that the air will be plenty cold for snowmaking and natural snow opportunities from the upper Midwest through the Northeast.  That takes us to the middle of the month, but my sense is that the same general pattern will persist until after the 20th or so, and perhaps close to Thanksgiving.  From time to time, smaller scale disturbances embedded in the flow around the trough will spin through the Lakes and into the East, and those systems will represent the best shots at natural snow over the next couple of weeks.

That is the good news.  While eastern North America will be unseasonably cold for the foreseeable future, thanks to the trough, the not-so-good news is that the ridge over the Pacific will keep temps above normal for the most part from the Continental Divide westward, as the temperature anomaly map suggests. 

Some snowmaking will be possible at times in the higher elevations of the West, but natural snow will be hard to come by in this pattern.  In the heart of winter, there is enough cold air around for both the West and the East to be cold simultaneously, but we are still six weeks away from the START of winter, so we are playing the game of “haves” and “have nots”.  For now, it is “advantage Midwest and East”.           

One Comment

  1. After an unusually wet September in the Pacific NW, (fall arrived a full month early), the rain just … went away. We haven’t had rain for more than two weeks and October is traditionally our wettest month, often setting up weather patterns for the coming ski season. Sigh.

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