The beginning of February marked the official halfway point of winter. With spring a little over a month away, winter still hasn’t arrived in full force in many areas. This has many of you calling, emailing, and commenting on our site, wanting to know what gives.
The last two winters were dominated by a pattern known as the North Atlantic Oscillation, a big block in the upper levels of the atmosphere over Greenland. When that block is in place, very cold air over the polar region gets diverted southward and brings frigid air into the United States and southern Canada. This blocking pattern also allows storms moving up from the south to slow down, intensify, and dump a lot of snow. We saw this all too well over the last two years, with the Snowmageddon of 2010, the crippling Groundhog Day Storm of 2011, and plenty of other big snow events.
Ironically, when this happens, that very cold air is almost absent in the usually icy regions across central and northern Canada and Alaska, causing winters in these far-northern locales to be unusually mild.
Unlike the last two winters, though, this winter has seen a near total absence of NAO. That means the very frigid air has been pinned up across the northern parts of North America, while farther south, there has been very little penetration of cold air at all this winter. Alaska, for instance, is experiencing its seventh coldest winter on record. With no blocking pattern, most of the southern storms have been racing rapidly along, unable to intensify much, and depositing little in the way of substantial snowfall.
Obviously, because of the lack of an Arctic Oscillation that was so prevalent the last two winters, this winter has been considerably milder than what most forecasts had indicated. However, in the coming weeks, we’ll be seeing more in the way of unsettled and even stormy weather conditions. There are signs that the NAO will try to make a comeback in the coming weeks, but we’re not 100% sure that it will. With the mild air still in place, the likelihood is that we’ll be looking at more rain than snow. All you need, though, is a properly positioned storm to develop relative to a wave of cold air and you can receive a significant snowfall.
March can be a pretty wild month, so if you’re a winter weather lover, don’t give up the ship just yet! Our long-range outlook suggests an active weather pattern in February and March, so we’ll just have to wait and see what happens!