Tropical Cyclone Alistair formed in the Arafura Sea on the 17 April from a low which was first identified off the Irian Jaya coast on the 15th. The system tracked steadily west-southwest at around 25 km/h and brushed past the Tiwi Islands with minimal impact on the evening of 17 April. Alistair intensified to a Category 2 storm during the 18th and passed close to Troughton Island that evening with peak recorded winds of 85 km/h gusting to 110 km/h. The system continued to track west-southwest at a steady 25 km/h before taking a more westerly track for under the influence of a strong mid level ridge. The system experienced increasing shear over this period and the deep convection became displaced to the southeast of the low level centre. At this time Alistair began to slow and move in a more southerly direction.
By the 22 April the low level centre was completely exposed and convection was limited to outbursts in the southeast quadrant. The system then began to move southeast under the influence of upper north-westerly winds, indicating that the system was still being steered by mid-level winds despite having little deep convection associated with it. Convection began to rebuild on the southeast side as it moved towards the coast, crossing close to Carnarvon around 0500 WST 24 April.
For more details see the TC Alistair Report (pdf)
Track and intensity
All times in WST - subtract 8 hours to convert to UTC.