Summary
A tropical low formed within the monsoon trough over the Northern Territory's Top End near Katherine on 13 February 2011. The low drifted northwest towards Darwin during 14 and 15 February and underwent a period of strong intensification during the 15 and 16 February. The low moved into the Beagle Gulf early on 16 February and was declared a tropical cyclone at 2100 UTC 15 February (0630 CST (Central Standard Time)=UTC+9.5 hours) when centred near Darwin Harbour. Tropical Cyclone Carlos remained a Category 1 cyclone as it moved very slowly southeastwards over Darwin and surrounding rural suburbs during 16 February, before it was downgraded to a tropical low at 1500 UTC 16 February near Batchelor. Ex-tropical Cyclone Carlos tracked southwards over the Northern Territory's western Top End and by 19 February the tropical low crossed the border into Western Australia near Wyndham (Figure 1).
Very heavy rainfall associated with the tropical low broke many rainfall records in the region including Darwin's wettest day with 367.6 millimetres (mm) recorded in the 24 hours to 2330 UTC 15 February. The heavy rain caused widespread flooding and damage to roads and properties in the Darwin area. Squally winds felled many hundreds of trees, powerlines, cut roads and caused damage to property. In addition, most Government Departments and Darwin International Airport was closed during the worst weather. Heavy rain from Ex-Tropical Cyclone Carlos also caused major flooding in the Daly River, which led to the community of Nauiyu to be evacuated.
The tropical low pressure system steered rapidly west across the Kimberley region and moved offshore north of Broome during the early hours of 21 February. The tropical low redeveloped into a tropical cyclone by 0000 UTC 21 February (0800 WST= UTC+8 hours) and began a generally south-westward movement. Carlos intensified to Category 2 before it crossed the Pilbara coastline close to Karratha around 0400 UTC 22 February. Carlos then turned west and moved offshore north of Mardie. The cyclone then moved south west again, parallel to the Pilbara coastline before it crossed the North West Cape and weakened slightly. Carlos then moved out over open water to the west of the state. Observations indicated that the strongest winds associated with Carlos were located in the northeast (rear-right) quadrant.
Once Carlos passed to the west of the North West Cape the tropical cyclone began to intensify. Sea surface temperature (SST) analyses showed SSTs of between 26°C and 28°C extending well south and west of the West Australian coastline. This enabled Carlos to reach a maximum 10 minute mean wind of 65 knots (kn) (120 kilometres per hour (km/h)) by 1800 UTC 24 February despite being located a long way south. As Carlos moved steadily southwards over cooler SSTs the cyclone weakened and was downgraded to below cyclone strength by 0600 UTC 26 February (refer Figure 2).
Gale and storm force winds associated with Severe TC Carlos were experienced along parts of the Pilbara coastline and offshore islands however communities reported little damage. During the afternoon of 21 February, while Carlos was off the coast near Port Hedland, a tornado associated with severe thunderstorms in one of the outer rain bands caused extensive damage in the central business district of Karratha.
For more information see the TC Carlos Report (pdf).
Track and Intensity NT
Track and Intensity WA
