Although it sounds complicated, the stratospheric polar vortex is, quite simply, the Earth’s large system of cold air and low pressure. One to the north and one to the south, rotating around the poles, acting as a barrier that keeps the frigid air away from the temperate zones of the planet.
And that’s exactly what happened in November. A sudden warming of the Arctic stratosphere (rises of up to 30 degrees in a few days) caused a huge mass of air to enter the troposphere and, in response, the westerly winds plummeted from strong values to almost 0 meters per second. El vórtice se paró.
Something extremely rare at the end of November. And it’s not just a scientific curiosity; but it entails a brutal redistribution of air masses. However, the vortex did not break completely: it was a quick and strong blow that left the system in stand-by, but it started again relatively quickly.
That’s why, the spectacular consequences that were expected
So? While it is true that the warming was “historical”, “very rare” for the dates on which it occurred and “very abrupt”, it must be understood (above all) as a warning that the atmosphere is very unstable this winter.
Like a wake-up call: something we have to monitor.
What the models say. As explained by MeteoVigothe models indicate that the strength of the stratospheric winds (the “muscle” of the vortex) will decrease again in the coming days; But facing the last days of December (around the 26th) the vortex will tend to recover a more circular shape and an intensity close to the climatic average.
And what does all this mean? For Europe (and specifically for Spain), the vortex is something important: determines the probability of cold winters, anticyclonic blockages in high latitudes and trains of Atlantic storms. That is to say, if the vortex strengthens heading into December there will be less probability of extreme arctic irruptions and, possibly, a greater weight of storms.
However, all scenarios are open: the models continue to draw the busiest winter of the time.
In Xataka | The last hope of winter in Spain is desperate, but increasingly possible: the breaking of the polar vortex
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