What is sudden stratospheric warming (SSW) and how can it bring cold temperatures to the east coast?

Forecasters across the northern hemisphere are warning of an upcoming stratospheric movement that could send temperature plummeting in in the coming days. Experts predict that a sudden stratospheric warning (SSW) event is about to unfold above the Arctic and send freezing weather further south.

Early next week experts predict that the stratospheric polar vortex, a region of rotating cold air at the North Pole, will become deformed. This will push a mass of cold air towards the east coast of the United States.

Axios warns that that colder-than-normal conditions may persist in the east for weeks, or even a month, as a result of the SSW.

How does an SSW affect temperatures?

Meteorologists forecast that a complex weather phenomenon will soon unfold 100,000 feet above the Arctic. Large waves in the atmosphere can disrupt the polar vortex, pushing warmer masses of air up beyond the troposphere and into the stratosphere.

This movement pushes up the temperature in the stratosphere and create a new, and often unpredictable movement, in the polar vortex.

With warm air entering into the polar vortex huge masses of cold air become displaced from their normal arctic positioning and push further south. Because this event occurs at the North Pole it is the northern hemisphere, particularly regions closest to the Arctic, that experience this SSW most keenly.

This process is brought about by an instability in the atmosphere so the fall out is notoriously difficult to predict. However temperature could well drop throughout the northern hemisphere. In the United States, current projections suggest that the east coast will bear the brunt of the freezing conditions.

What is the polar vortex?

The SSW is brought about by a polar vortex disruption, but what actually is the polar vortex? Each of the earth’s poles has a region of cold, spinning air that broadly remains there all year round. These extremities of the earth are furthest from the sun and so experience far colder temperatures than elsewhere on the planet.

The difference in temperature between polar and sub-tropical regions forms a low-pressure circulation in the atmosphere. This is typically most pronounced during the winter when temperatures at the pole are even colder than normal.

This circular motion continues and forms the polar vortex, a spinning mass of cold air. The column of rotating air spans from the troposphere (the lower region whether weather events take place) to the stratosphere (the drier layer of atmosphere that contains the ozone layer).