In all my years of studying atmospheric dynamics, I have never seen jet stream patterns shaped the way they have been for as long as they have this winter (the better part of 3 months). Case in point; just last week there was a wind structure in place over the North Atlantic at about 20 thousand feet altitude such that if you wanted to fly an airplane from Lisbon, Portugal to Minneapolis, you’d have a tail wind of at least 50 knots the whole way. The whole way. That’s just backwards. Should be a headwind, right ? With colder air “typically” at the poles we should have westerly (not easterly) winds at high altitudes across much of the globe.

The reason why we don’t right now, and haven’t had for much of this winter, is that relatively warm air over the south has been repeatedly displaced to the north above the arctic circle and remained there for weeks at a time. Because this rearrangement of the temperature patterns has also been accompanied by the southward displacement of polar air (unfortunately this year over the highly populated regions of Europe and the Lower 48), we’ve ended up with an atmosphere whose Northern Hemisphere jet stream flow is so awkwardly configured and generally weaker than normal. Please keep in mind that the severity of our winter is intimately associated with this large-scale temperature disfiguration, and not in any way reflects a trend or discredits global warming. While the contiguous 48 states have been cold, many locations across the Northern Hemisphere (and the world for that matter), have been much above average, including Canada.

It’s unclear exactly why the atmosphere for the last few months has preferentially found this mode. The answer is probably tied to forcing mechanisms over the tropical oceans (like El Nino and the Madden-Julian Oscillation, or MJO) and their resonance with the kind of weather systems that bypass us daily. Whatever the case, there are signs that these tropical forcing mechanisms are moving in a way that could give us a break in the coming weeks. These drivers of our climate system are organizing in a way that will try to “spin up” the jet stream. One byproduct of this process, however, may lead to a more active stormy pattern across the southern states. As such, it wouldn’t surprise me if severe weather chances increase along the Gulf Coast in early March. Maybe, just maybe, Spring is not too far away after all.