Intense tropical cyclone (SWIO scale) | |
---|---|
Category 4 tropical cyclone (SSHWS) | |
Formed | February 9, 2012 |
Dissipated | Currently active |
Highest winds | 10-minute sustained: 185 km/h (115 mph) 1-minute sustained: 230 km/h (145 mph) |
Lowest pressure | 932 hPa (mbar); 27.52 inHg |
Fatalities | At least 2 |
Part of the 2011–12 South-West Indian Ocean cyclone season |
Intense Tropical Cyclone Giovanna
Cyclone Giovanna's origins were from the interaction of a monsoon trough and tropical wave associated with irregular convection with a clockwise circulation oriented east-west in the Mozambique Channel on 8 February. The system was forecasted to progress along the northwestern fringe of a subtropical ridge, and low-level inflow and sea-surface temperatures were conducive for development.[1] Influenced by weak vertical wind shear, a low-level circulation center formed soon thereafter, but convection remained disorganized and wavering,[2] though the circulation center swiftly coalesced. Near 2300 UTC, banding convection started to become established around the circulation center, and upper-level outflow was favorable for the formation of a tropical cyclone; the Joint Typhoon Warning Center (JTWC) subsequently issued a Tropical Cyclone Formation Alert, indicating a high chance of the system becoming a tropical cyclone.[3]
The storm was designated as Tropical Depression Nine by RSMC La Réunion at 0600 UTC on 9 February, although its organization continued to waver. It sustained the path along the subtropical ridge, but was projected to slow down as a result of a fracture in an anticyclonic belt to the south.[4] Six hours later, the JTWC also began releasing advisories on the storm, designating it 12S.[5]