Service director Arona Ngari said the system was “unpredictable”, adding the chances of it developing into a tropical cyclone were “low to moderate”.
The Regional Specialised Meteorological Centre in Nadi, Fiji was scheduled to give an update on the system last night.
Ngari said the update would provide a clear indication of the location and severity of the tropical disturbance system.
He said a wet and windy weekend was on the cards for Rarotonga and the rest of the southern group islands.
Ngari said this was not related to the tropical disturbance, but was due to a high pressure system to the southeast of the group “directing a fresh to strong easterly wind flow over Southern Cooks”.
A trough of low pressure with cloud and occasional showers will also affect the group.
A strong wind warning remains in force for the land areas and waters of Rarotonga and the southern Cooks Islands.
Meanwhile, Rarotonga and the other southern Cook Islands face an elevated cyclone risk in coming months.
Earlier this year, New Zealand’s National Institute for Water and Atmospheric Research (NIWA) said there was possibility the southern group might experience two or more cyclones between November and April.
The government scientists project nine to 12 named tropical cyclones could occur during this period in the southwest Pacific basin, which includes the Cook Islands.
Four severe cyclones reaching Category 3 or higher might occur anywhere across the region, NIWA said.