A Tropical Low over the Coral Sea is undergoing the early stages of cyclogensis, and is expected to develop into a Tropical Cyclone over the next 24 hours. When this occurs it will be named 'Odette'. The system seems to be taking a little longer to gain some structure, probably due to presence of a second tropical low over the Northern Territory (see chart to the right). 

Latest computer model guidance is still indicating that this system will intensify over the weekend (to the east of Townsville) and may reach the severe category (category 3 or above). Tropical Cyclones are classified in 5 categories by the Bureau of Meteorology, based on wind speeds, which rates their destructive capacity. They are as follows:

CATEGORY 1 Negligible house damage. Damage to some crops, trees and caravans. Craft may drag moorings. A Category 1 cyclone's strongest winds are GALES with gusts to 125 km/h.

CATEGORY 2 Minor house damage. Significant damage to signs, trees and caravans. Heavy damage to some crops. Risk of power failure. Small craft may break moorings. A Category 2 cyclone's strongest winds are DESTRUCTIVE winds with gusts of 125 -170 km/h.

CATEGORY 3 Some roof and structural damage. Some caravans destroyed. Power failures likely. A Category 3 cyclone's strongest winds are VERY DESTRUCTIVE winds with gusts of 170 - 225 km/h.

CATEGORY 4 Significant roofing loss and structural damage. Many caravans destroyed and blown away. Dangerous airborne debris. Widespread power failures. A Category 4 cyclone's strongest winds are VERY DESTRUCTIVE winds with gusts of 225 - 280 km/h.

CATEGORY 5 Extremely dangerous with widespread destruction. A Category 5 cyclone's strongest winds are VERY DESTRUCTIVE winds with gusts of more than 280 km/h.

Beyond the weekend it is difficult to be completely confident of the path of Tropical Cyclone Odette, but the most likely scenario is for a southward movement early next week. One of the leading computer models is indicating that the Tropical Cyclone may be located very close to the Southeast Queensland Coast around Tuesday (see chart to the right). If this were to occur, local weather conditions could be too extreme for surfing, with very large waves and gale-force winds. 

Additionally, there may also be a risk for a 'storm surge', which could lead to severe flooding along the coastal fringe (depending on the position and the strength of the Tropical Cyclone). A storm surge occurs when strong onshore winds and large swells cause water to 'pile up' along the coastline. This would probably occur on the southern side of the Tropical Cyclone if it were to move down the coast, as this is where the strongest onshore winds and largest waves are likely to be located.

Also contributing to the rising sea levels is the low atmospheric pressure associated with a Tropical Cyclone, which exterts less pressure on the sea surface (reflected in the lower barometric pressure readings). This allows sea levels to rise further, and is known as the 'Inverse Barometer Effect', of which a 1hPa drop in barometric pressure increases the sea surface level by 1cm. Using the average Mean Sea Level Pressure across the globe of 1013hPa, this means that a Tropical Cyclone which crosses the coastline with a central pressure of 983hPa would increase sea surface levels by 30cm - in addition to the sea level increase generated by strong onshore winds and large swells.

This three-fold, storm surge affect can cause some serious damage to low lying coastal areas, especially when a naturally occurring high tide is also present. High tide for the Gold Coast Seaway on Tuesday morning is at 9.30am, and at 10am on Wednesday.

So what can we make of the Tropical Cyclone in terms of surfing prospects for next week? Early indications are that it may become located too close to the coast for any quality waves - mainly due to the likelihood of extreme winds. If the tropical system does track very close to the coast, the largest waves (potentially in the 10-15ft range) may also be confined to a small local region. In other words, the surf could be very large along the Sunshine Coast, but much smaller at Byron Bay. Therefore, if you're planning a trip up to Queensland based to score some large surf, it's probably worth holding back for a couple of days before booking flights and accomodation until there is more certainty regarding the local conditions. Residents of the Tropical Queensland Coast should pay attention to any warnings issued by the Bureau of Meteorology as the the system develops over coming days.