BOSTON (CBS) – If you love snow and winter storms, according to the latest forecast, you will likely go to sleep for seven days. No flake or decline in forecast in the Boston area or most of New England in sight.
I even got a couple of tweets from people asking if this is it. Is the winter over? In all honesty, I don’t even know how to answer such a question in early January. I think it either has to be someone pulling my leg or someone who is not from New England – I mean, come on. We know better. In all fairness, many made the same mistake in early to mid-February, sticking a fork in winter while Mother Nature just takes a quick siesta. In all fairness, it’s never safe to count the winter out here until the Red Sox reach the field in Fenway and the trees start to bloom. And even then, it’s not a lock.
This winter has been a little strange, but aren’t they all? While no two winters are the same, at the start of each winter we try to find the few big factors that can steer us one way or another. This year the main factor was (and is) La Nina. A fairly strong La Nina, along with some other large-scale atmospheric cues, led most forecasters, including us at WBZ-TV, to call for a milder than average winter with less than average snow. And of course we were hit by one of our biggest snowstorms in December from the start. Other than this storm, things went as well as planned. December was an average of 1.3 degrees above average and January has so far been more than 3 degrees warmer than the average. Easy-peasy, right?
Well, not that fast.
Here we introduce another of those geeky weather terms that may throw a wrench in our winter forecast. I know you have all heard of the Polar Vortex. But have you heard of the grumpy neighbor up in the Vortex? Sudden warming of the stratosphere? Well, let me introduce you.
For starters, the stratosphere is the layer of air above the troposphere (which we live in), which extends from about 6 miles to 30 miles above the surface of the earth. While temperatures in the troposphere generally decrease with altitude, they turn around and actually increase with altitude in the stratosphere. A “sudden warming of the stratosphere” is a not uncommon occurrence in which the winds in the stratosphere change from their typical westerly direction to the east and thus trigger a dramatic warming that is many times over 50 degrees Celsius in just a few days! The impact on weather around the globe can be very dramatic.
Essentially, this sudden warming is causing a chain reaction in the atmosphere, starting from above. In general, there is a band of winds swirling around the Arctic, also known as the Polar Vortex. If these winds stay dense and strong, they help keep the cold air around the North Pole bottled. A sudden stratospheric warming (SSW) event causes chaotic changes in the vortex, often forcing it to split into several different vortices that tend to travel south into parts of Asia, Europe and North America.
Similar to how we say that no two winters are the same, we can also say that no two weeks of pregnancy are the same. Take the past few years, for example. The SSW, which took place in February 2018, turned an otherwise harmless winter into a historic one. We had four Nor’easters dropping nearly 2 feet of snow in Boston in March, causing massive flooding on the coast and tree damage.
In contrast, January 2019 SSW had the opposite impact, causing abnormal warmth in parts of the US and Europe.
How will this year’s SSW affect the Polar Vortex and our weather?
Right now the best we can say is to stay tuned.
With the event still in its infancy, it is next to impossible to predict the wild waves that will occur when the dominoes fall south from the Arctic to our latitude. For the next few weeks at least, it initially appears that the most dramatic effects will occur in parts of Asia and Northern Europe. A severe cold is expected to plunge into these areas in response to the SSW and you are likely to hear reports of news of record cold and snow from this side of the world.
When these disruptions are at their worst, we can typically get 30 to 45 days of harsh winter weather. For us, the time frame is clearly the second half of January to mid-February. Could we descend into another historically cold and snow-covered route? Yes. At this point, however, I would say that the odds are equally likely to have the worst effects on the other side of the world as our winter continues to be dominated by La Nina and more typical everyday variations.
In any case, winter is far from over. Even in the mildest and mildest weather conditions, there are interruptions from cold and snow here and there. The above discussion is just a “heads up” that big things are happening atmospherically. A gigantic bowling ball was thrown into the atmospheric alley, whether our pins will stop or not remains to be seen.
The WBZ-TV weather team will closely monitor the developments in the coming days and keep you informed about the development of the pattern. We plan to release a full update to the winter forecast early in the week of January 18th. So stay up to date!
Follow Terry on Twitter @TerryWBZ