page_title: Cyclone Ernie
section_title: Meteorological history
hierarchical_section_title: Cyclone Ernie / Meteorological history
caption_attribution_description: English: An image of the precursor tropical low to Severe Tropical Cyclone Ernie (26U) at 06:10 UTC on 6 April 2017 (about 6 hours before developing into a cyclone). Image taken by NASA's 'Aqua' satellite.
context_page_description: Severe Tropical Cyclone Ernie was one of the quickest strengthening tropical cyclones on
  record. Ernie was the first Category 5 severe tropical cyclone in the Australian region since Cyclone Marcia in 2015, and also the strongest tropical cyclone in the Australian region since Cyclone Ita in 2014. Ernie developed from a tropical low into a cyclone south of Indonesia in the northeast Indian Ocean on 6 April 2017, and proceeded to intensify extremely rapidly to a Category 5 severe tropical cyclone. A few days later, on 10 April, the system was downgraded below cyclone intensity following a period of rapid weakening, located southwest of its original position. Ernie had no known impacts on any land areas.
context_section_description: On 5 April 2017, the Australian Bureau of Meteorology began monitoring a developing tropical low located in the northeast Indian Ocean, approximately 710 km (440 mi) east of Christmas Island. The system had been tracking in a generally westwards direction during the previous few days as a weak area of low pressure, but had not been significant enough to warrant the issuance of tropical cyclone warnings. The tropical low tracked south-westwards throughout the day of 5 April, before adopting a course to the south-southwest during the night. On the morning of 6 April, sustained gale-force winds developed on the western side of the system. Despite the existence of these cyclone-strength winds, the Bureau of Meteorology still classified the storm as a tropical low because they did not extend more than halfway around the system.
  The storm continued its trend of steady intensification, and was upgraded to a Category 1 cyclone on the Australian tropical cyclone intensity scale by 12:00 UTC on 6 April. The storm was assigned the name Ernie – the seventh tropical cyclone and sixth named storm of the 2016-17 Australian region cyclone season. This intensification to Category 1 status marked the beginning of a period of explosive intensification lasting about 24–30 hours, which concluded with Ernie being upgraded to a Category 5 severe tropical cyclone at about 12:00 UTC on 7 April. Upon strengthening to Category 5 intensity, the cyclone had 10-minute sustained winds of 205 km/h (125 mph), gusting to 285 km/h (180 mph). Aided by favourable environmental conditions, including sea surface temperatures of 29-30 °C (84-86 °F), the cyclone maintained its Category 5 intensity for more than 12 hours, while still tracking to the south-southwest. Ernie continued to intensify gradually during this time, peaking with 10-minute sustained winds of 220 km/h (140 mph), gusts to 315 km/h (195 mph), and a central pressure of 922 hPa (27.23 inHg). Its maximum one-minute sustained wind speed of 260 km/h (160 mph) at this time made the storm the equivalent of a lower-end Category 5 major hurricane on the Saffir–Simpson Hurricane Wind Scale (SSHWS).
  Soon afterwards, the system turned to the west-southwest and encountered an unfavorable environment of increased wind shear, dryer air, and cooler sea surface temperatures, which caused Ernie to weaken. The storm was downgraded to Category 3 status by 12:00 UTC on 8 April, about one day after it reached Category 5 intensity. Ernie's decline in strength was paused, though, when the system began to re-intensify a few hours later, on the morning of 9 April, local time. The renewed period of strengthening proved short-lived and meager, however, as Ernie began weakening again on the afternoon of the same day, before it could reattain Category 4 status. The cyclone was downgraded below severe tropical cyclone status to Category 2 intensity by 12:00 UTC on 9 April, and then further to Category 1 intensity by 00:00 UTC on the following day. Ernie weakened below tropical cyclone intensity by 06:00 UTC on 10 April, ending its short but significant 90-hour existence as a cyclone. Gales persisted in the southern quadrants of the system for a number of hours despite its declassification, due to the steep pressure gradient caused by a high pressure ridge to the south. Ex-Tropical Cyclone Ernie continued to track to the west-southwest, and later in a more southerly direction, until the remnants of the system dissipated four days later.
caption: Ernie shortly before being named on 6 April
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