Australia: Adverse weather forecast across parts of central New South Wales coastal areas through at least July 6 /update 1

Event

Heavy rainfall is forecast across parts of the central New South Wales coast, including Metropolitan Sydney, through at least July 6. As of July 4, the Australian Bureau of Meteorology (BOM) has issued a severe weather warning for heavy rainfall across parts of Metropolitan, Illawarra, and parts of Hunter and Central Tablelands forecast districts. A severe weather warning for damaging surf is in place in the coastal regions of the Metropolitan, Illawarra, and Hunter forecast districts.

A trough over the central coast is forecast to move northward through July 4 and cause moderate to possibly heavy rainfall. Drier conditions are forecast after the trough passes. Although rainfall rates have eased as of early July 4, localized heavy rainfall may lead to flash flooding over the Illawarra, Blue Mountains, Sydney Metropolitan, and parts of Hunter (including Central Coast) districts through the evening of July 4; isolated three-hourly rainfall totals of 5-7.5 cm (2-3 inches) are possible. Forecast models indicate that the rainfall over the Sydney Metropolitan and Illawarra districts is likely to ease from the afternoon of July 4, while light to moderate rainfall will probably continue across the Hunter through July 5.

As of early July 4, the following flood watches and warnings are in place:

• Moderate to Major Flood Warning: Colo, Hawkesbury, and Nepean rivers.

• Minor to Major Flood Warning: Bell, Darling, and Macquarie rivers.

• Moderate Flood Warning: Macquarie River and Saint Georges Basin.

• Minor to Moderate Flood Warning: Bokhara, Culgoa, and lower Hunter rivers, and Wollombi Brook.

• Minor Flood Warning: Bogan, Cooks, Georges, Lachlan, Paterson, Shoalhaven, and Woronora rivers and Tuggerah Lake.

• Flood Watch: Lower Hunter and Central Coast.

Officials could update and possibly extend the coverage of weather alerts over the coming days.

Authorities have issued evacuation orders and warnings for parts of the Hunter, Illawarra South Coast, and Sydney regions, affecting more than 30,000 people. Evacuation shelters are located at Canley Vale, Narellan, Gymea, Richmond, North Richmond, Castle Hill, and West Gosford. Click here for further details on evacuation orders and warnings and here for more information regarding evacuation shelters. Officials have confirmed one fatality on the Parramatta River in western Sydney due to the severe weather conditions. The Warragamba Dam in western Sydney started overflowing early July 3, exacerbating the flooding.

The Golden Highway is closed between New England Highway and Putty Road due to flooding. Train services on the Southern Highlands Line between Campbelltown and Moss Vale, T1 Western Line between Emu Plains and Penrith and between Mulgrave and Richmond, and Hunter Line between Maitland and Newcastle Interchange, are suspended due to flooding and severe weather. Other train lines are running reduced services.

F1 Manly ferry services between Circular Quay and Manly and private ferries between Cronulla and Bundeena Ferry are suspended due to large swells, while the F3 Parramatta River ferries are suspended due to the weir flooding.

Hazardous Conditions
Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed or a lack of stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall.

Transport
Floodwaters and debris flows may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around affected areas. Ponding on road surfaces could cause hazardous driving conditions on regional highways. Authorities could temporarily close some low-lying routes that become inundated by floodwaters.

Flooding could block regional rail lines; freight and passenger train delays and cancellations are likely in areas that see heavy rainfall and potential track inundation. Severe weather could also trigger flight delays and cancellations at airports in the region. Authorities may temporarily suspend port operations if strong winds and large waves trigger hazardous sea conditions.

Localized business disruptions may occur in low-lying areas; some businesses might not operate at full capacity because of flood damage to facilities, possible evacuations, and employees' inability to reach work sites. Electricity and telecommunications service disruptions are possible where significant flooding, strong winds, or landslides impact utility networks.

Advice

Monitor local media for weather updates and related advisories. Confirm all transport reservations and business appointments before travel. Allow extra time for travel in the affected area and plan alternative routes if necessary. Do not drive on flooded roads.

Resources

Australian Bureau of Meteorology