Australia: Adverse weather forecast across most of New South Wales through at least early Sept. 23 /update 1

Event

Heavy rainfall is forecast across most of New South Wales through at least early Sept. 23. A low-pressure system over northern New South Wales is forecast to bring heavy rainfall and thunderstorms across northeastern NSW. Rainfall is forecast over the rest of the state through early Sept. 23. The Australian Bureau of Meteorology (BOM) has issued a severe weather warning for heavy rainfall across parts of the Northern Rivers and Mid North Coast forecast districts. Six-hourly rainfall totals of 6-8 cm (2.4-3.1 inches) are possible across the warning area, and the downpours could trigger flash flooding in some areas.

Due to the threat of flooding, the following warnings have been issued by the BOM across NSW:

• Minor to Major Flood Warning: Birrie, Bokhara, Culgoa, Lachlan, Macquarie, Namoi, Narran, and Peel rivers

• Minor to Moderate Flood Warning: Barwon, Bogan, Darling, Edward, and Murray rivers

• Minor Flood Warning: Castlereagh, Gwydir, Macintyre, Murrumbidgee, Orara, Paroo, and Warrego rivers

• Flood Watch: Northern Rivers, Mid North Coast, and Hunter districts

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

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
At least 40 flights at Sydney Kingsford Smith International Airport (SYD) were canceled early Sept. 22 following warnings that severe weather could result in just a single operational runway. Officials have also instructed those with scheduled domestic flights to arrive at least two hours prior to the flight and international passengers to arrive three hours prior. Residual disruptions are likely as officials clear the backlog once the situation normalizes.

Officials have requested residents avoid all non-essential travel. 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 additional flight delays and cancellations at airports in the region, including but not limited to Sydney Kingsford Smith International Airport (SYD) and Coffs Harbour Airport (CFS).

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
New South Wales State Emergency Service