The North Atlantic Ocean is moving toward normal values. How will this affect weather in the Arab world?

Arab Weather - The latest climate data extracted from numerical models indicates an expected change in one of the most important climate indicators affecting weather in the Mediterranean region, the North Atlantic Oscillation (NAO), which is a key factor in medium-term weather forecasts.

From negative to positive values: Changes in the atmospheric pressure pattern affect the distribution of air masses.

Over the past ten days, the NAO has been recording negative values, leading to a retreat of the Azores High southward, allowing high-pressure systems to settle over the Maghreb countries and trigger intense heat waves, amid extremely hot and dry conditions, particularly in Algeria. However, according to the latest forecasts, the NAO is expected to rise to positive values in the coming days, which would signal a significant change in the prevailing weather patterns.

Positive values for the North Atlantic Oscillation Index indicate low atmospheric pressure in the polar regions and high at lower latitudes, allowing cold, moist air masses from the North Atlantic to push towards southern Europe and sometimes even the southern Mediterranean basin.

A strong heat dome over the Maghreb... and moderate winds begin to reach the western Mediterranean.

As a result of the change in the index, strong high pressure systems are expected to remain centered over the Maghreb countries, especially Algeria and Morocco, forming a strong heat dome over the coming days. This will lead to continued scorching, dry conditions across most of the interior regions of these countries, with temperatures potentially reaching 45°C in some areas.

In contrast, cooler, more humid northerly winds are expected to begin sweeping across northern Algeria and Tunisia, leading to a drop in temperatures on the coasts and most northern regions. These milder conditions will gradually expand during the final days of the month.

The effects of the cooler air mass are likely to gradually extend to the Levant during the last week of July, leading to a gradual drop in temperatures in Jordan, Syria, Lebanon, and Palestine, particularly in mountainous and coastal regions.

It's not unlikely that the edges of this moderate air mass will reach Iraq as well, where it's expected to lead to a gradual decline in the intense heat wave currently sweeping the country, particularly in the northern and western regions. However, the weather will remain extremely hot in the central and southern regions, albeit with less intensity than in recent days.

Arabian Peninsula: A tropical high imposes its influence, and temperatures remain high.

On the Arabian Peninsula, weather data shows the continued influence of a subtropical high pressure system on the Arabian Gulf and the Arabian Peninsula. This means extremely hot weather is expected to persist over the coming days, particularly in eastern Saudi Arabia and Kuwait. Northwesterly winds will be active toward the end of the month across several regions, causing dust storms.

For those interested and specialists: What is the North Atlantic Oscillation (NAO) and why is it important in weather forecasting?

The North Atlantic Oscillation (NAO) index is a numerical expression of the difference in atmospheric pressure at sea level between the Icelandic Low and the Azores High in the North Atlantic Ocean. This index is one of the most important climate indicators that influence weather patterns in Europe, North Africa, and West Asia, particularly during the fall and winter seasons, but it also significantly affects the behavior of the atmosphere in the summer, particularly in the Mediterranean basin.

The indicator is expressed in numerical values that may be positive or negative:

In a positive NAO, atmospheric pressure is unusually high in the Azores and deeply low in Iceland, strengthening westerly currents in the Atlantic and preventing cold air masses from advancing southward. In this situation, low-pressure systems often push toward southern Europe and North Africa, while high-pressure systems stabilize in lower latitudes (such as the Levant and North Africa), resulting in more stable weather in these regions.

In negative NAO cases, the difference in atmospheric pressure between the Azores High and the Icelandic Low is weak, which leads to weaker westerly currents and increased chances of cold masses rushing south towards central and western Europe and later towards its eastern parts, reaching the Levant.

And God knows best.