Sahara desert hit by extraordinary rainfall event — suggested link to ‘subdued’ hurricane season

A clue may be that ‘the ITCZ [Intertropical Convergence Zone] has shifted north this year, over the northern Sahara’, but uncertainty remains. The unexpectedly low activity of this hurricane season (Talkshop post here) has put a spanner in the works for many climate pundits, now hunting for possible reasons.
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An unusual deluge of rain is hitting the Sahara, one of the driest regions on Earth, says LiveScience.

It’s unclear exactly why the desert is experiencing so much rain, but it could be connected to an especially quiet Atlantic hurricane season, scientists say.

The rain is so heavy that some usually dry regions of North Africa are now experiencing monsoons and flooding, with parts of the Sahara predicted to see five times their average September rainfall.

Precipitation in the Sahara overall is not completely uncommon — the region is huge and diverse, and some parts often receive small amounts of rain, Moshe Armon, an atmospheric scientist at the Federal Technical University (ETH) Zürich, told Live Science.

But now larger portions of the Sahara are being inundated, including areas further north where it’s usually drier, Armon added.

Some scientists suggest this is part of Earth’s natural climate fluctuation, while others say it’s a product of human-induced climate change. “The answer is probably somewhere in between,” Armon said. [Talkshop comment – just an opinion].

This climatic shift in the Sahara may be connected to a weaker Atlantic hurricane season. This year’s hurricane season has been quiet so far, despite predictions early in the summer of severe hurricane activity due to high ocean temperatures.

Meteorologists noted this was the first Labor Day weekend in 27 years without a named storm forming in the Atlantic.

Over half of named storms and 80% to 85% of major hurricanes in the Atlantic each year usually come from the region just south of the Sahara, Jason Dunion, a meteorologist at the National Oceanic and Atmospheric Administration (NOAA), told Live Science in an email.

During a typical hurricane season, atmospheric waves move off the western coast of Africa and into the North Atlantic Ocean, along what’s called the Intertropical Convergence Zone (ITCZ) — a belt circling close to the equator, where air from the Northern and Southern hemispheres meets.

The ITCZ belt can carry clouds, rain and storms. The atmospheric waves carried west along the ITCZ over the Atlantic, combined with warm Atlantic waters, develop into tropical storms and hurricanes.

But part of the ITCZ has shifted north this year, over the northern Sahara. Scientists are not completely clear why this is happening now, although climate models have previously predicted the ITCZ will move north due to ocean warming, and warmer air temperatures, as carbon emissions heat the Northern Hemisphere faster than the Southern Hemisphere.

The effect of the current northward shift is that the ITCZ pushes rain further north in Africa than usual — across the Sahara — while those atmospheric waves from Africa are also displaced north of their usual path. Without ITCZ moisture moving over the warm Atlantic, the ingredients aren’t all there for severe storms to develop.

Full article here.
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Image: Sahara desert from space [credit: NASA]

Source: https://tallbloke.wordpress.com/2024/09/14/sahara-desert-hit-by-extraordinary-rainfall-event-suggested-link-to-subdued-hurricane-season/