Australia: Authorities issue tropical cyclone watch for parts of northern Western Australia and Northern Territory Feb. 24

Event

The Australian Bureau of Meteorology (BoM) has issued a tropical cyclone watch for parts of northeastern Western Australia (WA) and northwestern Northern Territory (NT) Feb. 24 due to the presence of a tropical low in the east Timor Sea, which has the potential to develop into a tropical cyclone in the coming days. The watch zone extends from Point Stuart, NT, to Kalumburu, WA, and includes Darwin, the Tiwi Islands, Wadeye, and Wyndham. Authorities are advising those in the watch zone to monitor the situation and prepare for cyclonic conditions.

The storm system is forecast to move closer to the northern coastline Feb. 26-27. Although the exact track and intensity of the storm remain uncertain at this stage, forecast models indicate it could develop into a category 2 tropical cyclone and make landfall near Daly River Mouth, NT, Feb. 27. Other models suggest the system may track either in a more eastward direction over the Top End of Northern Territory or in a more southwestward track towards Western Australia.

Gales of around 100 kph (62 mph) are expected to develop in western parts of the Tiwi Islands late Feb. 25 and may extend over the rest of the watch zone Feb. 26. Heavy rainfall is expected to develop over the Tiwi Islands and parts of Daly District, NT, Feb. 25-26, and depending on the track of the storm, could develop over Kimberley District, WA, Feb. 26.

Hazardous Conditions

The storm system will likely bring heavy rainfall, strong winds, and rough seas to coastal areas of northeastern WA and northwestern NT in the coming days. Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, rivers, and urban areas with easily overwhelmed or a lack of stormwater drainage systems. Sites located downstream of large reservoirs could experience flash flooding after relatively short periods of intense rainfall. Rain-induced landslides are possible in steeply sloped terrains; surface runoff in desert locations and along old bushfire burn scars could also result in dangerous mudslides.

Prolonged swells and storm surge generated by the system may trigger coastal flooding as the system approaches land. Abnormally high tides are likely through at least Feb. 27, which will exacerbate storm surge throughout the affected area. While surge levels will ultimately depend on the landfall timing and speed of the system, the most significant coastal flooding is likely near and to the west of where the center of circulation transits. Persistent onshore flow could make it difficult for the surge to recede and for water levels to decrease in coastal river catchments.

In addition to the heavy rain, flooding, and storm surge, the storm system will likely produce damaging wind gusts as it approaches the watch zone. Gusts in excess of 100 kph (62 mph) cannot be ruled out, especially in areas near the center of circulation. Widespread and prolonged power outages are likely due to uprooted trees and toppled utility lines.

Transport

In addition to the immediate threat to personal safety, inclement weather associated with the storm could trigger localized business, transport, and utility disruptions. Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Areal flooding in urban locations could also result in severe traffic congestion, while strong winds will pose a hazard to high-profile vehicles. Heavy rain and low visibility may trigger flight disruptions at airports in the affected area, including Darwin International Airport (DRW).

Disruptions triggered by inclement weather and resultant hazards, such as flooding could persist well after conditions have improved. If there is severe damage to infrastructure, repair or reconstruction efforts may exacerbate residual disruptions.

Advice

Activate contingency plans in areas where officials forecast tropical storm conditions. Heed all evacuation orders. Use extreme caution in low-lying coastal areas and near streams, creeks, and other waterways due to the high potential for severe flooding and storm surge. Stockpile water, batteries, and other essentials in advance. Charge battery-powered devices when electricity is available; restrict the use of cellular phones to emergencies only. Power down mobile devices when not in use. Keep important documents in waterproof containers. Observe strict food and water precautions, as municipalities could issue boil-water advisories following flooding events. Take precautions against insect- and waterborne diseases in the coming weeks. Keep any necessary medications in a waterproof container.

Plan accordingly for protracted commercial, transport, and logistics disruptions in areas in the path of the storm, especially if vital infrastructure is damaged. Seek updated information on road conditions before driving or routing shipments through areas where flooding has occurred. Confirm flights before checking out of hotels or driving to the airport; clearing passenger backlogs may take several days in some locations.

Resources

Australian Bureau of Meteorology (BoM)