Category Archives: Other Basins

Other TCs

Iba Develops Into Rare South Atlantic Tropical Storm

Tropical Storm Iba developed into a rare South Atlantic Tropical Storm on Sunday.  At 8:00 p.m. EDT on Sunday the center of Tropical Storm Iba was located at latitude 19.2°S and longitude 36.0°S which put it about 260 miles (420 km) east of Linhares, Brazil.  Iba was moving toward the south at 3 m.p.h. (5 km/h).  The maximum sustained wind speed was 50 m.p.h. (80 km/h) and there were wind gusts to 65 m.p.h. (105 km/h).  The minimum surface pressure was 1000 mb.

More thunderstorms developed near the center of a low pressure system off the east coast of Brazil and the Instituto Nacional de Meteorologia designated the system as Tropical Storm Iba.  The circulation around Tropical Storm Iba was still organizing.  Bands of showers and thunderstorms were developing and starting to revolve around the center of circulation.  Storms near the center of circulation were beginning to generate upper level divergence which was pumping mass away from the tropical storm.

Tropical Storm Iba will be in an environment favorable for intensification during the next 24 to 36 hours.  Iba will move over water where the Sea Surface Temperature is near 28°C.  It will move under the narrow eastern end of an upper level ridge.  The upper level winds right over Tropical Storm Iba will be relatively weak and there will not be significant wind shear.  Iba will likely strengthen during the next 24 to 36 hours.  There is a chance that Tropical Storm Iba could strengthen into a hurricane.

Tropical Storm Iba is in an area where the steering winds are weak.  Iba may drift slowly toward the south during the next day or so.  On its anticipated track Tropical Cyclone Iba will stay just off the coast of Brazil during the next 48 hours.

Tropical Cyclone-like Low Forms Over the Mediterranean Sea

A small circular symmetric low pressure system developed over the southern Mediterranean Sea on Friday.  The low had an eye-like feature in its center and spiral bands of convection which made its structure look somewhat similar to a tropical cyclone.  The low brought wind gusts to 64 m.p.h. and a pressure of 986 mb to Malta.  At 3:00 p.m. the center of the low was near 32°N and longitude 15°E which put it about 300 miles south of Syracuse on the island of Sicily.  The low was moving toward the east-northeast and it was passing just south of the island of Sicily.

There have been other low pressure systems over the Mediterranean Sea that were similar to the current system and they often start debates about how they should be classified.  Some aspects of their structure (i.e. an eye-like feature in the center and spiral bands of clouds) are similar in structure to tropical cyclones.  The strongest winds are usually found close to the center of circulation and the pressure falls rapidly near the center, which are characteristics also seen in tropical cyclones.  The convection in the Mediterranean lows is usually not as deep as the convection in tropical cyclones and it is difficult to determine if they have a warm core in the middle and upper troposphere, which is part of the definition of a tropical cyclone.  Some of the lows are very similar to tropical cyclones from other parts of the world while other Mediterranean lows appear less like tropical cyclones of the deep tropics and more like subtropical cyclones or some other type of hybrid mesoscale low pressure system.  In any case they do bring winds which are strong enough to cause damage and they can produce heavy rainfall, especially when the cross mountainous regions.