METEOROLOGISTS said Friday they were observ-ing an unprecedented early disruption of the polar vortex, raising the risk of cold snaps across the Northern Hemisphere, though there remains sig-nificant uncertainty.
The polar vortex is a vast region of cold, low-pressure air that normally circulates from west to east high above the Arctic.
It generally strength-ens through autumn and peaks around January. It can weaken in the second half of winter, typically be-tween January and March, sending bitterly cold air spilling south into Europe, North America and Asia.But scientists say the vortex is already weaken-ing in early November.Scientists report an unprecedentedly early disruption of the polar stratospheric vortex, ex-pected to break down fully by 20 November.
Caused by upward-surging Rossby waves triggering sudden stratospheric warming (SSW), this rare event — occurring only three times in November since the 1950s—can split the vortex and push cold air toward populated regions in the US, Europe, and East Asia.Experts suggest an exceptionally strong El Niño may be amplifying these atmospheric waves, though MIT climatolo-gist Judah Cohen notes a record high-pressure system over Scandinavia and northwestern Russia — plus speculative climate-change-driven temperature contrasts — could also be driving it.Despite the historic timing, the severity of po-tential winter cold snaps remains uncertain.
Because Arctic and Siberian temperatures are not yet at their mid-winter lows, and because El Niño typ-ically brings milder win-ters, the resulting cold outbreaks could be mod-erated rather than severe.
AFP
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