|
Severe Tropical Cyclone Rona–Frank (JTWC designations: 20P, 22P; RSMC Nadi designation: 16F) was the only tropical cyclone to threaten Queensland during the 1998–99 Australian region cyclone season. Rona-Frank originated from a low that developed on 9 February about to the northeast of Cairns. Over the next couple of days, the low slowly developed further before it was upgraded into a Category 1 cyclone on the Australian intensity scale by the Australian Bureau of Meteorology on 10 February as it started to move towards the southwest. Subsequently, Rona rapidly intensified just before making landfall near the Cape York Peninsula. While the low-level circulation became difficult to locate on 12 February, the upper-level circulation was eventually emerged onto the Coral Sea and later regenerated into Tropical Cyclone Frank. The system rapidly intensified before making landfall on New Caledonia as a Category 2 cyclone on the Saffir-Simpson Hurricane Scale in the early morning hours of 20 February. Frank was re-classified as an extratropical cyclone the next day. Seven deaths were reported from Rona and a state of disaster was declared. Over 2,000 fled their homes due to flooding and many residents were caught off-guard for the storm. Significant crop damage was reported. Overall, Rona brought $150 million (1999 USD) in damage to Queensland. Minor damage was reported in New Caledonia. After the season, the name "Rona" was retired from the list of tropical cyclone names. ==Meteorological history== On 9 February 1999, the Australian Bureau of Meteorology (BoM) started to monitor a tropical low, that had developed within the monsoon trough about to the northeast of Cairns, in Queensland, Australia. At this time strong westerly winds persisted around the northern side of the low, however, a weak pressure gradient and light winds existed to the south of the system and the monsoon trough.〔〔 This was because of a deep area of low pressure near south-eastern Queensland, had an intense pressure gradient to its south, which prevented the trade winds extending up to the monsoon trough. Throughout 9 February the tropical low moved eastwards under the influence of a middle-to upper-level trough over eastern Australia, however, over the next day the trough dissipated along with the deep area of low pressure.〔〔 As a result, an area of strong ridging developed to the south of the system, while the trade winds rapidly extended northwards to the monsoon trough.〔〔〔 The upper level pattern also became favorable for further development, with an outflow channel forming on the equator-ward side of the system.〔 The low subsequently rapidly intensified during 10 February, with atmospheric convection surrounding the system dramatically improving.〔 The system was subsequently named Rona by the BoM later that day, after it had developed into a category one tropical cyclone on the Australian tropical cyclone intensity scale.〔 At around the same time the United States Joint Typhoon Warning Center (JTWC) initiated advisories and designated the system as Tropical Cyclone 20P, after it had become equivalent to a tropical storm.〔 As it was named the system was located about to the east of the northern Queensland coast, and had started to move towards the southwest under the influence of the subtropical ridge of high pressure.〔〔 After the system had been named the system continued to intensify, and became a category 3 severe tropical cyclone on the Australian scale early on 11 February.〔〔 The system subsequently moved rapidly west-northwest towards the Queensland coast as the ridge strengthened.〔 Just before Rona made landfall the JTWC estimated that the system had peak 10-minute sustained wind speeds of , this made it equivalent to a category 1 hurricane on the Saffir–Simpson hurricane wind scale. However, during their post system analysis they lowered their estimate, to between which made it equivalent to a tropical storm.〔 The BoM subsequently estimated that the system had peak 10-minute sustained wind speeds of when it made landfall on the Queensland coast, at around 1300 UTC (2300 EST) just to the north of Cow Bay near the mouth of the Daintree River.〔〔 The system maintained its west-northwest movement as it tracked over land, and according to the BoM maintained cyclone intensity until later that day after it had become difficult to track a definite low level centre.〔 Over the next 24 hours the JTWC continued to track Rona as a tropical cyclone as it moved through the Great Dividing Range. Late on 12 February, the JTWC issued their final advisory on Rona after the system had weakened below cyclone intensity and deep convection, associated with the system had dissipated despite fair upper-level outflow. The JTWC subsequently tracked Rona's remnants into the Gulf of Carpentaria, however over the next few days the BoM tracked the systems remnant low to mid-level circulation as it moved southward.〔 During 16 February, the system's low to mid-level circulation moved off Queensland's east coast, and tracked eastwards across the Coral Sea within the monsoon trough to the south of the subtropical ridge of high pressure.〔〔 Early on February 17, the JTWC initiated advisories on the system and designated it as Tropical Cyclone 22P, while it was located about to the east-northeast of Rockhampton, Australia.〔 Later on 18 February, RSMC Nadi remarked that Tropical Depression 16F had moved east of 160°E and into their area of responsibility. Meanwhile, they also noted that 16F had intensified into a category one tropical cyclone and was thus named Frank. At the time of the upgrade, the storm was centered west-northwest of Nouméa, New Caledonia. By this time, an upper-level trough over eastern Australia moved into the Tasman Sea. The poleward outflow of Frank improved; as a result, Frank rapidly intensified over the next 24 hours.〔 Frank made landfall near the northern tip of New Caledonia at peak intensity with winds of 145 km/h (90 mph) at 0000 UTC on 20 February. Even though the JTWC operationally assessed the peak intensity at 185 km/h (115 mph), this was lowered to 175 km/h (110 mph) during post-storm analysis.〔(【引用サイトリンク】title=JTWC Best Track Data for Tropical Cyclone 22P (Frank) )〕 After making landfall on New Caledonia, Frank maintained peak intensity for 18 hours.〔 Soon afterwards, northwesterly wind shear and cooler sea surface temperatures caused Frank to weaken rapidly. During the morning of 21 February, RSMC Nadi passed warning responsibility to Meteorological Service of New Zealand Limited (TCWC Wellington) as the cyclone had moved south of 25°S.〔(【引用サイトリンク】title=Tropical Cyclone Seasonal Summary 1998-99 )〕 Roughly 18 hours later, Frank merged with a trough to form an intense extratropical cyclone,〔 which eventually made landfall on the South Island of New Zealand near Westport. TCWC Wellington stopped monitoring the system on 27 February. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cyclone Rona–Frank」の詳細全文を読む スポンサード リンク
|