Climate reading: Polar vortex splitting and major consequences for weather around the world

Arab Weather - Weather specialists at Arab Weather are following the latest readings of advanced computer maps, which specialize in studying weather systems over the Arctic region, scientifically known as the polar vortex. This is an upper-level weather system that is the main source of cold and very cold air masses around the world, and the resulting severe cold waves or low-pressure systems, whether rainy or snowy, depending on the path and characteristics of these air masses.

According to the latest readings, forecasts indicate that there will be splits or several splits in the polar vortex during the coming period, specifically during the first quarter of February, and this is attributed to what is scientifically known as Sudden Stratospheric Warming (SSW).

What is sudden stratospheric warming and what are its effects?

The sudden stratospheric warming is characterized by a large and rapid rise in temperatures in the stratosphere layer above the North Pole, which leads to the formation of several strong high-pressure systems over the polar region, significantly weakening the polar vortex and causing it to lose its natural cohesion.

Paradoxically, under normal circumstances, the polar vortex is cohesive and centered over the North Pole, with cold arms extending towards various regions of the Northern Hemisphere. However, in the event of this warming, high-pressure systems form over the pole, causing the polar vortex to break apart and fragment, allowing cold air masses to surge southward towards the mid-latitudes.

The North Pole Index (AO) and its trend towards sharp negativity

Readings indicate that the Arctic Oscillation (AO) index is trending towards sharply negative values, reaching around (-5), which is an indicator that measures the nature of the distribution of atmospheric pressure over the Arctic.

When the values of this coefficient are positive, it indicates the presence of deep atmospheric depressions over the polar circle and the coherence of the polar vortex, which is the normal and expected situation during this time of year.

Its tendency towards extreme negativity reflects the formation of high-pressure systems over the North Pole and the occurrence of significant weakness and splitting in the polar vortex, leading to the disintegration of the polar vortex and the occurrence of multiple splits in it, which produces a large ripple in the polar jet stream.

The North Atlantic Oscillation (NAO) is also trending negative.

Numerical models also show a clear trend of the North Atlantic Oscillation (NAO) index towards negative values, an indicator used to measure the strength and activity of Atlantic storms.

The negative reading on this indicator points to an increase in Atlantic storm activity compared to normal rates, which is one of the direct reflections of the splitting of the polar vortex and the disruption of air currents in the upper latitudes.

This climate event has widespread global repercussions around the world.

These developments are expected to have a global impact on weather through:

• More severe cold waves and strong, successive snowstorms are expected across large parts of the United States.
• East Asia, including Japan and neighboring countries, was affected by extremely cold air masses and heavy snowfall.
• Higher than usual activity for Atlantic storms, with successive low-pressure systems moving towards the west of the European continent, accompanied by strong winds, very heavy rain, high sea waves, and snowfall in the highlands.

What about the weather in the Arab world?

Up to this point, it is not possible to definitively determine the nature of the direct effects on the Arab region, because the effects usually occur many weeks after the occurrence of this climatic event, due to the complexity of the atmospheric interactions resulting from the splitting of the polar vortex.

However, short- and medium-term computer simulations indicate that the Maghreb countries may have the largest share of these effects, as the passage of low-pressure systems and cold fronts is expected to be concentrated towards those regions, due to their proximity to the paths of Atlantic storms coming from Western Europe, which increases the chances of rain, wind, and a drop in temperatures.

As for the Levant and the Arabian Peninsula, the near-term effects are likely to manifest as an early clash between air forces, with the region experiencing:

• Periods during which temperatures rise above their usual climatic averages, sometimes reaching levels of twenty or more, especially in parts of the Arabian Peninsula.
• Other periods are colder.
• Scattered chances of rain.

And God knows best.