A northwest Queensland town is waiting for its worst-ever floods to peak, with multiple communities and outlying cattle properties isolated and severe thunderstorms putting the state’s west and south at risk of flash floods.

The Albert River at Burketown has already surpassed the record 6.78-metre flood of 2011, and the Bureau of Meteorology says waters in the Gulf of Carpentaria community will likely reach their highest on Sunday.

About 90 locals still in town were told to pack a grab bag on Friday night after 25 elderly and sick people, along with 18 children accompanied by one of their parents, were airlifted out. Weeks of torrential rain have overwhelmed the region’s rivers, leaving dozens of communities such as Doomadgee, Normanton and Karumba stranded on islands amid a vast inland sea.

Those towns as well as more isolated settlements and outlying cattle stations are relying on food and other supplies being sent by air and on barges.

The danger of the late-season monsoon has moved south, and a flood watch has been declared for a giant chevron stretching from Julia Creek to the NSW border and back up to Bundaberg.

The BoM says more rain is forecast this weekend following widespread falls of 35-80 millimetres and isolated downpours of 130mm on Friday.

“Severe thunderstorms with heavy rainfall that may lead to flash flooding are possible around broad parts of western and southern Queensland, including #SEQld,” the forecaster said on Twitter on Friday. Seqwater said releases from the Somerset Dam into the Wivenhoe Dam on the Upper Brisbane River were possible due to forecast rainfall.

“The Seqwater Flood Operations Centre has moved to the alert activation level due to the weather forecast,” the dam operator said.

“If you are downstream of the dam, stay away from fast-flowing or deep water near waterways and floodplains.”

Source: AAP