A cyclone threatening Australia’s southeast coast has taken a long and meandering path over the past week, challenging forecasters seeking to provide residents in the storm’s path with certainty on its track.

The issue stems from where the system has developed. Storms that form in the Coral Sea off Queensland can take “erratic and variable paths” because competing high and low pressure systems steer them in different directions, said Dean Narramore, a senior meteorologist at Australia’s weather bureau.