Meteo Twitter buzzing for weeks about prospects for a sudden stratospheric warming event that could now be developing over the north pole region. These events are not rare, but do not happen every year, and they are often associated with extremes as the polar vortex can become weakened and lead to arctic outbursts.
These arctic intrusions have become more frequent in recent years, according to scientists I have interviewed (see bottom of page). Still somewhat unclear on the concept, but sharing here what I know.
Weather geeks weigh in.
What is a sudden stratospheric warming?
A sudden stratospheric warming refers to a rapid warming in the stratosphere between 10km to 50km above the Earth’s surface. In some years, the winds in the polar vortex can temporarily weaken or even reverse in direction – so instead of flowing west to east they flow east to west. Air descends into the vortex and warms rapidly as it is compressed.
In the most extreme sudden stratospheric warmings, the temperatures in the stratosphere can rise by up to 50 to 60 °C in just a few days – so the temperatures in the winter over the poles can go from around -50 °C to zero or maybe slightly above in a matter of days, even in the depths of winter when the Arctic is receiving no sunlight. Knock-on effects on the jet stream in the troposphere can follow a few weeks later and this can affect the weather we experience down on the ground.
Scientists can reliably predict individual sudden stratospheric warmings about 1-2 weeks in advance. This means there is time to see how they develop and how they may impact our weather in the future. A sudden stratospheric warming typically takes a few weeks to have maximum impact on our weather, but its influence can last for up to 2 months.
It was one of these events that foreshadowed the infamous Texas freeze of 2021.
The image on the right shows a relatively low temperature anomaly for February 2021 of 0.67°C, with some very cold areas showing up over North America and Russia.
As acknowledged by the WMO, the Sudden Atmospheric Warming event did contribute to more extreme weather with some very low temperatures temporarily showing up in some areas in February 2021.
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The image below illustrates the severity of the Sudden Stratospheric Warming event.
Once again, posting Martha Shulski, Nebraska State Climatologist, and Judah Cohen of MIT, on arctic outbreaks in central North America.
Some interesting details.
Sent from my iPhone
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