BOSTON (CBS) – If you love snow and winter storms, the current seven-day forecast is likely to put you to sleep. No prediction of the forecast in the Boston area, or most of New England, is in the offing.
I even got a few tweets from people asking if this is it. Is winter over? Honestly, I do not even know how to respond to a question in early January. I think it must be someone pulling my leg or someone not coming from New England – I mean coming. We know better. Honestly, many had made the same mistake earlier to mid-February and asked to stick a fork in the winter while Mother Nature just took a short siesta. Honestly, until the Red Sox drop the field at Fenway and the trees start flowering, it’s never safe to count the winter here. And even then, it’s not a lock.
This winter was a little weird, but is not it all? Although no two winters are ever alike, at the beginning of each winter we try to find the few large-scale factors that can steer us in one direction or another. This year was La Nina (and is still the most important factor). A fairly strong La Nina, along with some other large-scale atmospheric tips, has led most meteorologists, including us at WBZ-TV, to a milder winter than average with less snow than average. And of course, we were immediately hit by one of our biggest snowstorms in December. This storm aside, things went pretty well as planned. December averaged 1.3 degrees above average and so far January is more than 3 degrees warmer than average. Easy, right?
Well, not so fast.
Here we present another one of the geeky weather conditions, something that might throw a wrench in our winter forecast. I know you’ve all heard of the Polar Vortex. But have you heard of the grumpy neighbor of the Vortex, Sudden stratospheric warming? Let me introduce you.
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First, the stratosphere is the layer of air above the troposphere (where we live) that extends from about 6 miles to 30 miles above the earth’s surface. Although the temperature usually decreases in the troposphere, it reverses and increases with altitude in the stratosphere. A “sudden stratospheric warming” is a not uncommon event in which the winds in the stratosphere shift from their typical westerly direction to the east, causing a dramatic warming, which in many days often exceeds 50 degrees Celsius! The effects this could have on the weather all over the world can be quite dramatic.
(WBZ TV graphics)
In essence, this sudden warming causes a chain reaction in the atmosphere, starting from the top. Generally, there is a wind ribbon that revolves around the Arctic, also known as the Polar Vortex. If these winds stay strong and strong, it helps bottle the cold air around the North Pole. A sudden stratosphere warming event (SSW) causes chaotic changes in the vortex, which many times forces it to divide into several different vortices that tend to erupt southward in parts of Asia, Europe and North America.
(WBZ TV graphics)
Just as we say that no two winters are alike, we can also say that no two SSWs are alike. Just take the last few years for example. The SSW that took place in February 2018 turned an otherwise favorable winter into a historic year. In March, we had four residents who dropped nearly 2 feet of snow in Boston, causing major coastal flooding and tree damage.
In contrast, in January 2019, the SSW had the opposite effects, leading to divergent heat in parts of the US and Europe.
What effect does this year’s SSW have on the Polar Vortex and us again?
Right now is the best we can say to stay.
With the event still in its infancy, it is almost impossible to predict the wild waves that are about to happen as the dominoes of the North Pole fall northward to our latitude. Initially, at least for the next few weeks, it looks like the most dramatic consequences will be in parts of Asia and Northern Europe. It is predicted that severe cold in response to the SSW will dive into the areas, and you will probably hear reports of the news of record cold and snow from that side of the world.
When these interruptions are the worst, we can usually get a period of 30-45 days of harsh winter weather. The time frame to look at is for us the second half of January to mid-February. Can we descend into another historic cold and snow stretch? Yes. But at this point I would say that the odds are just as favorable for the worst consequences on the other side of the world, while our winter is still mainly driven by La Nina and more typical daily variations.
Either way, winter is far from over. Even in the mildest and most benign weather patterns, we are likely to experience interruptions of cold and snow here and there. The discussion above is merely a head move “that great things are happening atmospherically now. A giant bowling ball has been thrown into the atmospheric orbit, whether our pens remain standing or not remains to be seen.
The WBZ TV weather team will closely monitor the development in the coming days and keep you informed as the pattern develops. We plan to have a full update of the winter forecast early in the week of January 18th, so stay tuned!
Follow Terry on Twitter @TerryWBZ