[Australia]: Tropical Cyclone's Ilsa and John

[Owen]

NORTHERN INDIAN OCEAN, 9 DECEMBER 1999

As the 1999-2000 Australian Region Cyclone Season began, two cyclones would form simultaneously in the Indian Ocean. One would form just north-east of the Cocos (Keeling) Islands whereas the other would form south-west of the Indonesian side of the island of Timor. The one near Cocos Islands would be designated as Tropical Cyclone Ilsa and the other near Timor, Tropical Cyclone John. Ilsa would be tracking easterly but relatively slow, whereas John would begin tracking south and intensifying rapidly. The Tropical Cyclone Warning Centre in Perth, operated by the Bureau of Meterology would begin tracking these cyclones closely and issuing updated tracks as they come to hand and issuing warnings if necessary. At the moment there was a general warning for shipping traffic in the area and a Strong Marine Wind Warning for the Kimberley and Pilbara regions of Western Australia and a Gale Marine Wind Warning for Christmas Island and Cocos (Keeling) Islands. Cocos (Keeling) Islands followed by Christmas Island would begin getting lashed by Tropical Cyclone Ilsa with strong winds, heavy rainfall and abnormally hide tides and swells. Residents would begin stocking up on essential supplies but all in all it wasn't that intense, only a Category 1 and the residents of both islands were used to/prepared for this type of weather. This would similarly be the case for the Indonesian islands of Timor, Sumba, Rote and Sawu who would be getting hit by Tropical Cyclone John as a Category 1.

Tropical Cyclone Ilsa in the Indian Ocean​

 

[Owen]

Prior to Cyclone John's landfall, hundreds of people were evacuated from homes, primarily in Karratha, where two shelters were set up. In Point Samson, 500 people evacuated to shelters in Wickham, Western Australia. TCWC Perth began issuing hourly warnings for potentially affected areas beginning at 2pm on the 14th of December. As the storm made landfall, some residents of Whim Creek took refuge in a shipping container. Strong winds from the cyclone caused widespread power outages to areas in Pilbara. At Cape Lambert, winds averaged 150 km/h for five hours, with a peak wind gust of 210 km/h. Karratha suffered minor damage from John, primarily in the form of wind damage. Various trees were uprooted by strong winds, and some homes suffered minor roof damage. Palm fronds in Karratha were blown off palm trees due to strong winds. In Whim Creek, where the cyclone had made landfall, the top floor of a 113-year-old pub and hotel was destroyed. 140 windmills between Whim Creek and Newman were destroyed by the cyclone.

Offshore, 220 cattle aboard a ship died after the ship was battered by rough seas associated with Cyclone John. Production from an oil field off the coast of northwest Australia were down 38%, partly due to being shut down in preparation for Cyclone John. Rough seas from John also caused a maximum storm surge height of 2 metres, recorded in Port Hedland by the Port Hedland Authority on 15 December. Further inland, Cyclone John brought widespread rainfall and flooding. In Newman, Western Australia, 240mm of rain was recorded early on 16 December. As a result, some roads and 25 houses were flooded by the rains. By the evening of that day, the rainfall total had increased to 500mm. Todd River was flooded after 80mm of rain fell as a result of the cyclone. Overall John was responsible for no deaths and a limited amount of damage.

​

---------------------------

Tropical Cyclone Ilsa moved to the south of Christmas Island on the 13th producing a heavy swell which caused some damage. Its development was impeded by vertical windshear for a large part of its lifetime. After a long track eastwards across the Indian Ocean it eventually crossed the Western Australian coastline on the Eighty Mile Beach near the Sandfire Roadhouse during the early afternoon of the 17th of December. Apart from producing heavy rainfall, Ilsa did not produce any significant damage.