While presenting the weather forecast, Sarah mispronounced the name of a town with Karl making fun of her for it.
"You did really well until the last bit. You always have to have something to get better at," he told her.
"I'm supposed to be here all week you know that right?" Sarah responded.
"Are you? We will see about that," Karl joked.
Sarah then stood up and joked, "Wow, ok see you, I'm out of here," as she walked away from the desk.
"No Sarah, come back!" Karl yelled, as she returned laughing.
Allison is back in hospital after complications from an incident she suffered while filming the show last year.
The 42-year-old was filming a watersports segment for the show on the Gold Coast in February last year when she injured her knee.
Karl revealed last Friday that Ally was "holed up" in hospital as he and his co-hosts continued reporting on the floods in Queensland and New South Wales.
"Before we go to the weather, I just wanted to say a quick good morning to you all and particularly [highlight] some lovely messages from Ally, who has passed on her thanks from home to all the State Emergency Service for doing a great job," he said.
The show shared a snap of Ally from her hospital bed, with Karl adding, "She's, unfortunately, got... that knee of hers, it's just shonky. If she could replace it I'm sure she would.
"She's holed up watching the program this morning. All our love Ally, and to a speedy recovery."
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