Bureau of Meteorology forecaster Adam Blazak said there was still disagreement about which path the storm will take, but there was a possibility it could make landfall at the weekend.
He said while south-east Queensland may not get the direct impact of the system, winds could start picking up.
The BoM is warning of strong winds, high tides and swells along the coast, and potential heavy rainfall regardless of Oma's direction.
Hazardous surf warnings remain in place for Queensland as well as severe weather warning for abnormally high tides for people in parts of Wide Bay, Burnett, Gold Coast, Maroochydore, Moreton Island, Noosa Heads, Caloundra and Rainbow Beach.
Surf lifesavers say the building swell is likely to force the closure of beaches on the Gold and Sunshine coasts.
After that, its behaviour is less predictable.
"The current severe weather watch also covers a slow-moving front affecting southwestern parts of the South Island, with heavy rain possible until the early hours of Friday morning".
"We're going to see gale-force winds developing tomorrow, and not only gale-force winds but conditions along the beach are going to be quite risky".
BoM forecaster Sam Campbell told the ABC that there is a possibility it will cross over the coast "over the weekend", in an area anywhere from Central Queensland to the QLD-NSW border.
'That's likely to increase in the next couple of days'.
Weather warning continues for areas right from the New South Wales Border to the Fraser Coast.
On Thursday afternoon, the category-two system was already whipping up unsafe surf conditions, closing all Gold Coast beaches and most on the Sunshine Coast, but was not expected to make landfall.
'These conditions are then expected to extend south over the remaining southeastern Queensland coast during this evening and Friday.
It comes after the Weather Bureau issued its first Cyclone Watch, in it's 11.07am update of the system's tracking.