Forecasters say they are running late because there is not enough moisture in the air and will most likely hit near Gympie and move out to Rainbow Bay.

They could still contain large hail, heavy rain and strong winds, the Bureau of Meteorology said on Tuesday afternoon.

But the severe weather was predicted to hit north of Brisbane - near Gympie - and south of Brisbane, in the Border Ranges - before slowly moving north.

At 2pm on Tuesday the BOM issued a severe thunderstorm warning for a line of thunderstorms north of Brisbane, based on its computer modelling.

"Severe thunderstorms are likely to produce damaging winds, heavy rainfall that may lead to flash flooding and large hailstones in the warning area over the next several hours," the warning read.

"Locations which may be affected include Toolara Forestry."

Toolara Forestry is between Gympie and Tin Can Bay.

Hail was still predicted after 4pm when the storm band appears, meteorologist Andrew Bufalino said.

"It has been a little bit slower development than we originally thought," he said.

"And that is because there is a lot less moisture than we were anticipating across south-east Queensland."

The Bureau is now predicting heavy falls north of Brisbane.

"North of the Sunshine Coast, we now expect," he said.

"The latest trough is still trying to push its way across south-east Queensland."

Mr Bufalino said the BOM's Monday prediction that storms would begin to form along a line from Toowoomba to Maroochydore and move eastwards had pushed further north.

"You can see some storms beginning to form on the Gympie radar right now," he said.

"That should be the focal point this afternoon. That is where most of the storm activity is likely to be."

Mr Bufalino said the weather conditions had settled on Tuesday morning to create a "cap" on the storms.

"But once that ???cap' breaks, you get the ???explosive' nature of thunderstorms," he said.

"But as I said before we are just lacking a bit of the moisture we were expecting.

"But when that happens, you get a bust and that is what we are expecting this afternoon."

At 2pm, the bureau's radar showed some moderate storms around Gympie, near Kandanga and on the coast at Rainbow Bay.

Some relatively heavy falls were shown over the Hinze Dam and Springbrook in the Gold Coast Hinterland.

These warnings are issued during heavy thunderstorms

• Move your car under cover or away from trees.
• Secure loose outdoor items.
• Never drive, walk or ride through flood waters.
• Seek shelter, preferably indoors and never under trees.
• Avoid using the telephone during a thunderstorm.
• Beware of fallen trees and power lines.
• For emergency assistance contact the SES on 132 500.