While the western states were having fun in November and early December with over 100” of snow, east coasters were sitting around hoping for a little sign that winter is an equal-opportunity season. That sign came over the last few days, as a large atmospheric “block” forced winter to show up east of the Mississippi with cold air and BIG snow totals. So, what’s an atmospheric “block” and why should you care? Read on snow addict…
Three-day snow totals of 33” at Wisp (Maryland), 27” at Jay Peak (Vermont), and even 24” at Ski Beech (North Carolina) did not occur due to snow dances and sacrificial campfires in the woods, despite what you’ve been taught or what you practice. The deep snow was, however, a result of the atmosphere getting “blocked” up over the Atlantic Ocean.
Think of an atmospheric “block” just like a partial clog in a drain; a little water can make it through, but the flow basically stops and leaves you with a tub full of stagnate water. In the atmosphere’s case, though, this tub of stagnate water was really a ton of cold air and snow that was stuck over New England and the mid-Atlantic.
Usually, the storm that hit the east coast late this past weekend would move through and leave sunny skies in its wake. With the block in place over the Atlantic, though, the storm actually retrograded – or headed back west – since it couldn’t go east. This ensured that a strong and moist wind from the northwest would slam into the Appalachians and drop its bounty for several days.
Now before you go pulling out Global Warming to explain this “strange” weather, rest assured that atmospheric “blocking” is a very normal occurrence even though it doesn’t happen every day. Blocking can occur in many different regions of the world and over varying time periods, and was actually responsible for the record heat in Russia this summer (the atmospheric pipes clogged up and kept the hot weather pattern over Russia for weeks).
How long will this block last? Probably for another week or so, through the middle of December. While it won’t be snowing and cold for the entire 7-10 days between now and then, it looks like at least one or two more storms will get stopped up by the block and provide additional snow for the east coast. Toward the end of December, the blocking pattern will likely let up, but hey – that’s 2-3 weeks away, and long-range forecasts aren’t very reliable. Let’s take it one storm at a time, and celebrate the powder accordingly!
Meteorologist Joel Gratz is the creator of http://www.ColoradoPowderForecast.com and is based in Boulder, CO.