From Top L, clockwise: Pacific Trough, Arctic High, Alaskan Ridge, Arctic Low – Simon Lee
Winter weather patterns in North America are dictated by changes to the polar vortex winds high in the atmosphere, but the most significant cold snaps are more likely influenced by the tropics, scientists have found…
It is already well established that the vortex wind strength influences weather in Europe and Asia, and the study revealed it also has a strong effect on three out of the four main winter weather patterns in North America, giving forecasters an additional tool to understand potentially high-impact weather during winter.
The study, published in Geophysical Research Letters, also revealed that, unlike in Europe, the most extreme cold snaps affecting the whole of North America are not most likely to occur after a weak vortex. Instead, the shape of the vortex and conditions in the tropics were identified as stronger influences of these conditions…
(Researchers) found widespread extreme cold is more common when an area of high pressure extends up to Alaska, and the polar vortex stretches down towards North America – pushing cold Arctic air southward in the lower atmosphere.
The scientists say the influence of the stratosphere on weather patterns, as well as how this interacts with long-term weather patterns in the tropics like El Niño, should be studied further and incorporated into forecasts to improve their accuracy.
Still, awfully complex. Certainly requiring a CPU stronger than my little gray cells. But, my confidence in forecasters incorporating more into their offerings isn’t diminished. Technology keeps on rocking, capabilities continue to grow and expand.