2006-07 Southeast Indian Ocean extratropical cyclone season

The 2006-07 Southeast Indian Ocean cyclone season was the first Southeast Indian Ocean cyclone season on record. It was inactive, with only four extratropical depressions forming throughout the season. Of these depressions, three attained extratropical storm status and two attained minor extratropical cyclone status. The season officially began on November 1, 2006, and ended on May 15, 2007. Most cyclones in the Southeast Indian Ocean basin form between these dates. The first storm, Armand, formed on December 1, 2006, while the final storm, Clovis, dissipated on April 28, 2007. The strongest storm of the season, Moderate Extratropical Cyclone Brigitte, caused $1.8 million in damage after it made landfall near Adelaide at peak intensity.

The Southeast Indian Ocean basin is defined as the area between Australia and Antarctica that stretches from longitude 115°E to longitude 150°E. Due to its location, the vast majority of the systems that form in the basin are extratropical in nature. In the Southeast Indian Ocean basin, cyclones are classified using a modified version of the Saffir-Simpson hurricane wind scale known as the GK Weather Center (GKWC) Extratropical Cyclone wind scale. Like the Saffir-Simpson scale, the GKWC scale has seven categories, which, in order of increasing intensity, are: extratropical depression, extratropical storm, minimal extratropical cyclone, moderate extratropical cyclone, severe extratropical cyclone, extreme extratropical cyclone, and catastrophic extratropical cyclone. Extratropical depressions have maximum sustained winds of ≤30 mph (≤49 km/h). Extratropical storms have maximum sustained winds of 31–50 mph (50-80 km/h). Minimal extratropical cyclones have maximum sustained winds of 51-70 mph (51–113 km/h). Moderate extratropical cyclones have maximum sustained winds of 71-95 mph (114–153 km/h). Major extratropical cyclones have maximum sustained winds of 96–115 mph (154–185 km/h). Extreme extratropical cyclones have maximum sustained winds of 116-135 mph (186–217 km/h). Catastrophic extratropical cyclones have maximum sustained winds of ≥136 mph (≥218 km/h). Cyclones that attain minimal extratropical cyclone or moderate extratropical cyclone status are classified as minor extratropical cyclones, while cyclones that attain severe extratropical cyclone status or higher are classified as major extratropical cyclones.

On August 26, 2006, the GK Weather Center issued their first forecast for the 2006-07 Southeast Indian Ocean cyclone season. This forecast called for 7 named extratropical cyclones, 3 minor extratropical cyclones, and 1 major extratropical cyclone. On December 8, 2006, the GKWC released their mid-season forecast, which called for 4 named extratropical cyclones, 2 minor extratropical cyclones, and 0 major extratropical cyclones.