Unusual stagnation of tropical conditions in the Atlantic Ocean!

Weather of Arabia - The Atlantic hurricane season has so far been rarely calm, with not a single named storm since July 2, and this has not happened in 40 years.

Scientists believe that with climate change, the intensity of tropical storms and cyclones has become more harmful, and scientists have unanimously expected an active season for Atlantic hurricanes for 2022, so that the season will be much higher or higher than the average.

"I'm a little surprised at the lack of activity so far," said Matthew Rosenkranz, chief monsoon forecaster at the National Oceanic and Atmospheric Administration (NOAA), adding, "This calm does not line up with expectations," noting that the storm numbers I had forecast NOAA is still achievable, as the bulk of tropical storms and hurricanes typically form from late August through October.

During the past 70 years, from August 20 onwards, it accounts for 75% of all tropical cyclone activity across the Atlantic. For example, Hurricane "Andrew" developed at the end of August 1992 after an inactive season, and the hurricane devastated parts of southern Florida.

The reason for the reduced activity of the Atlantic hurricane season

Three factors to watch: the Pacific Ocean, water temperatures, and dusty winds

NOAA forecasts indicate higher-than-normal chances of an active season, noting the strength of La Niña and warmer-than-average waters in the MDR region of the Atlantic Ocean, and these factors usually portend favorable conditions for peak season hurricane formation.

While these factors remain, drastic changes have occurred in three key variables that are difficult to predict early on and explain the inactivity in August.

First: Pacific activity

The eastern Pacific experienced frequent hurricanes in July and August, which is unusual during mild La Niña. All this air rising from the storms of the eastern Pacific has to descend somewhere, mostly over the Gulf and the Caribbean.

This downward, steady flow of air from activity in the eastern Pacific has led to a much calmer situation in the Atlantic. The above-average wind shear spread throughout the Caribbean, damping off the nascent storms that would have developed.

La Niña seems to have finally won the war in the Pacific, and no hurricanes are expected in western Mexico within the next week or so.

Second, the water temperature

The eastern half of the Atlantic is still a mess. While the waters of the MDR region above which tropical conditions develop are still slightly warmer than average, a second issue is that sea surface temperatures north of the tropics have changed dramatically in the past few weeks. The subtropical ocean has cooled (20-35°N), while the mid-latitude (35-50°N) Atlantic is now experiencing record warmth.

In addition, the north-south gradient in Atlantic temperatures is much lower than normal this year, causing the jet stream to shift northward. This meant a hot summer in Europe, and made it easier for dry, stable air masses from the temperate subtropics to drift into the MDR, where the average humidity was much lower than normal last August. This also discourages the development of tropical cyclones.

Third: dust

This summer, stronger than usual easterly trade winds swept across the Sahara Desert in Africa and carried desert dust particles over the tropical Atlantic Ocean. These dust grains warm the middle atmosphere, stabilizing the already dry air mass and preventing convection.

The lack of hurricanes to hit the US so far this season has been a respite given that much of the country has had to deal with extreme heat and drought and five rainstorms that hit the country in several weeks were the strongest in 1,000 years.

(Water floods homes in Jackson, Kentucky, USA, as a result of heavy rains in late July 2022)

Expected return to activity for the hurricane season

Clusters of thunderstorms moving off Africa, known as tropical waves, need certain conditions to become more regulated, said Kim Wood, a meteorologist at Mississippi State University.

"The ocean is warm enough to support the strong thunderstorms needed for one of these waves to become a tropical storm, but these tropical waves also need rising moist air and low vertical shear winds," he added.

(On August 26, 2022, clusters of clouds associated with tropical turbulence were observed entering the Caribbean (center left), over the mid-Atlantic (centre right) and near the coast of Africa (far right). The system over the mid-Atlantic was showing significant strength. ( AccuWeather RealVue™))