TROPICAL CYCLONE NANCY, 27 JANUARY - 4 FEBRUARY The depression that was to become Tropical Cyclone Nancy formed over the Coral Sea on the 26th of January. Prior to this the South Pacific Convergence Zone (SPCZ) and the northeast Australian monsoon trough had been unusually inactive for the first part of the 1989/1990 cyclone season. During the last weeks of January these became significantly more active which resulted in the formation of two tropical cyclones (Nancy and Ofa). Although the system was in the Nadi Tropical Cyclone Warning Centre (TCWC) area of responsibility for only about 24 hours, it reached tropical cyclone status during this period and was thus named by the Nadi TCWC. At peak intensity, at approximately 0600 UTC on the 2nd of February, Nancy had maximum winds estimated at 55 knots with gusts to 70 knots near the centre. At this time the cyclone was moving southwest towards the Queensland coast. However as the cyclone neared the coast it began to move erratically and weakened only slightly. After completing a clockwise loop near Brisbane it then tracked southward along the New South Wales coast. Rain associated with Tropical Cyclone Nancy caused major flooding along the southern Queensland and New South Wales coasts. Five lives were lost in these floods due to drowning. History A surge in the northeast trade winds north of the equator and the southern-hemisphere northwest monsoon during the last week of January led to the South Pacific Convergence Zone (SPCZ) and the northeast Australian monsoon trough becoming active after a prolonged period of dormancy, spawning two tropical depressions. The first, over the Coral Sea, was to become tropical cyclone Nancy, while the second became tropical cyclone Ofa. Winds around the Coral Sea depression quickly increased and gales were evident in the southwest quadrant by 1500 UTC on the 27th of January. At this time the depression was moving slowly southwest towards Australia. Shortly afterwards the system began to be influenced by unfavourable conditions in the upper atmosphere and intensification was halted. It then began to weaken and became slow-moving. Winds remained below gale force for several days until a trough in the upper troposphere approached the depression from the west on the 29th, providing favourable conditions for development. The combination of upper northwesterly steering flow and ridging over the Tasman Sea steered the system steadily east southeast as it re-developed and winds once again increased to gale force. The depression gained tropical cyclone characteristics some 36 hours later and was named Nancy at 0000 UTC on the 31st of January. At about this time Nancy began to be steered around the southern extension of the upper trough, changing its path to south, and then southwestward as the cyclone became embedded in the northeast flow on the equatorward side of the ridge. The southwest track continued for some 12 to 18 hours as the cyclone approached the Australian coast. However landfall was not made, and Nancy slowed down and its track became erratic as the cyclone came within 30 miles of the coast. The change in motion was accompanied by a marked reduction in convection about the cyclone. However there was no associated decrease in wind intensity as Nancy maintained a strong low level circulation. After moving first southeast, then southwest, and then completing a small clockwise loop near Brisbane, Nancy moved southward following the warm water of the East Australian current. Warnings International marine warnings for tropical cyclone Nancy were initiated by the Brisbane TCWC at 1630 UTC on February the 27th. At this time gale force winds were forecast to develop in the next 12 hours and a gale warning for a developing tropical depression was issued. Shortly afterwards, the depression, which had been moving slowly southwest, became slowmoving and further development was temporarily arrested. Subsequently, the gale warning was cancelled at 2100 UTC on the 27th. Brisbane recommenced issuing warnings for this system at 0600 UTC on the 29th of January when it became evident that intensification was recurring. The Nadi TCWC began issuing tropical disturbance advisories at 2100 UTC on the 30th of January. At this time the depression was approaching the 160 east meridian, which marks the boundary between the Brisbane and Nadi areas of responsibility for issuing maritime warnings, and was continuing to intensify. At 0100 UTC on the 31st of January the system was named tropical cyclone Nancy by the Nadi TCWC. A total of 7 marine international warnings were issued by the Nadi TCWC before the system curved south, then southwest, and re-entered the Brisbane TCWC area of responsibility. The warning was upgraded to storm status with the issue of the 0000 UTC warning on the 1st of February. A variety of information relating to tropical cyclone Nancy was also issued by several U.S. agencies. The Joint Typhoon Warning Centre (JTWC) at Guam issued warnings for the system and the Satellite Meteorology Centre at Honolulu issued a number of bulletins with Dvorak intensity estimates. Unfortunately advisories and warnings from these centres ceased to be received at the Nadi TCWC from about 0600 UTC on February the 2nd. As the remains of Nancy travelled down the East Australian coast, warnings were also issued by the New South Wales Regional Forecasting Centre (RFC). Effects Tropical cyclone Nancy spent its formative and mature stages over the open ocean and did not affect any land areas during this period. As Nancy approached Australia during the latter stages of its life it caused widespread heavy rain over coastal regions of Queensland and New South Wales. The resulting floods led to 5 deaths due to drowning and caused significant damage to roads and bridges. There was no significant damage reported which was attributable to winds associated with tropical cyclone Nancy.