Polar Vortex Strengthens, Bringing Cold Wave to US, Temperatures Drop to 50 Below Zero

Arab Weather - The latest analyses of weather maps from what is called computer simulation, which show the distribution of air masses in the Arctic region, indicate significant activity in the stratospheric polar vortex during these days and the coming days. Where zonal wind speeds are recorded above average, meaning the presence of strength in the polar vortex and an increase in its activity during the coming period, which means the availability of opportunities for several regions to be exposed to cold waves, especially North America and Canada, all the way to Greenland.

How is the strength of the polar vortex measured and what does strong winds in the polar vortex mean?

The strength of the Arctic vortex is determined by several key factors, and its strength is usually measured by the strength of the winds within and around it. This is done by measuring the speeds of zonal winds (moving from west to east) around the Arctic Circle at 60 degrees latitude. One of the most important factors affecting the strength of the polar vortex is the "polar jet stream," a stream of fast winds that forms at high altitudes and surrounds the vortex.

When winds in the jet stream are strong, they strengthen the polar vortex, which helps trap cold air within the polar region. In this case, the vortex remains stationary and stable, which means cold weather stays confined to northern regions. But when the jet stream weakens, the vortex becomes distorted, allowing cold air to rush south toward warmer regions, causing temperatures to drop in parts of Europe, North America and Asia.

Scientists measure the strength of the polar vortex using an index called the Arctic Oscillation (AO), a numerical indicator that helps describe atmospheric pressure and weather patterns over the North Pole. When the AO is in its positive phase, the polar vortex is strong and cohesive, keeping cold air trapped in the north. When it is in its negative phase, the vortex is weaker, allowing cold air to rush south.

Arctic Oscillation (AO) coefficient is trending towards neutral values.

A neutral mode in the context of climate oscillations such as the Arctic Oscillation (AO) or the North Atlantic Oscillation (NAO) refers to a situation where the oscillation is neither clearly positive nor negative. In other words, in a neutral mode, weather conditions are mild, and the large changes that occur in the positive or negative cases do not occur, as there is no significant difference in pressure between these regions, meaning that cold polar winds are not confined as strongly to the polar region as in a negative mode, nor are they pushed northward as in a positive mode.

Arctic neutrality is reflected in a decrease in the polar vortex and a break in the jet stream in North America, Canada and Greenland.

The polar vortex is rushing towards North America, including Canada and Greenland, in the form of a very cold and large air mass coming directly from the North Pole towards the North American continent and the mentioned areas, causing very cold winter weather, as temperatures in some areas drop to about 40-50 degrees Celsius below zero, which means a severe wave of severe cold, with widespread snowfall in several states, especially the northeastern states, and the occurrence of a severe state of freezing in large areas.

At the same time, large areas of Europe remain under the influence of a strong high pressure system in all layers of the atmosphere, and temperatures are warmer than average for this time of year, while the western parts are in the range of Atlantic storms in the coming days, accompanied by strong winds or very heavy rain.

And God knows best.