Extratropical cyclone turns Sahara into ephemeral lake

The Sahara Desert experiences heavy rainfall, the most recent of which was an extratropical cyclone that crossed the northwestern Sahara on 7-8 September and flooded large areas of treeless land in Morocco, Algeria, Tunisia and Libya, even though these regions rarely receive rain.

“Although moderate rainfall occurs in this region every summer, what is unique this year is the involvement of an extratropical cyclone,” said Moshe Armon, a senior lecturer at the Institute of Earth Sciences and the Hebrew University of Jerusalem. The phenomenon formed over the Atlantic Ocean and spread far south, drawing moisture from equatorial Africa to the northern Sahara, NASA said, adding that “early satellite analyses show rainfall totals ranging from several dozen to more than 200 millimeters in the affected areas, roughly equivalent to what the region receives in a year.”