Thursday, February 23, 2006

Tropical Weather: South Atlantic Tropical Cyclone?

By Tom Thunstrom

Off of the East Coast of South America satellite imagery is showing a potential tropical cyclone developing. The South Atlantic Ocean is the rarest place among the world's oceans, outside of the Arctic, for Tropical Cyclone development. There have been only three recorded tropical cyclones.

In 1991, one formed off of the coast of Angola in April.

In 2004, there were two. The first, in January, made landfall near Salvador, Brazil. The second, called Catarina, made landfall in the Catarina province of Brazil as a hurricane.

Now, the Naval Research Labratory is tracking and monitoring this system shown above and is carrying the tracking of Investigation 90L. If this storm can maintain itself, it might become the fourth record tropical cyclone in South Atlantic History.

Wikipedia: South Atlantic Tropical Cyclone

Friday AM Update:

This is the satellite image taken earlier Friday AM of the cyclone in the South Atlantic that appeared to be taking on tropical characteristics. The tropical characteristics appear to be diminishing from the system as it moves away from the South American coast. Sea Surface Temperatures appear to be below the magic 26 degree celsius mark (look to be 23-24 based on satellite and map observations). It is incredibly tough for any tropical development to take place in the South Atlantic Ocean because of wind shear in the South Atlantic at the upper levels, as well as the lack of a intertroipcal convergence zone, which is where many of the 'Cape Verde' Hurricanes form from in the North Atlantic. The ITCZ doesn't exist in the Southern Hemisphere and thus it is difficult to get any storms to develop. If they do, wind shear usually destroys them in short order.

The idea that a system in the South Atlantic even had the potential of becoming tropical is something quite interesting and certainly worthy of looking at because of the rarity of such of an event.