The main impacts of tropical lows and cyclones in the Wyndham region are heavy rainfall and associated flooding. Wyndham's cyclone risk with respect to wind is much lower than at other coastal Kimberley and Pilbara towns. This is illustrated by the map showing coastal crossing points of cyclones. The reduced risk is related to several factors:
- less cyclones occur in this region (see cyclone frequency map);
- most cyclones in the area are of only category 1 intensity and there are very few at category 3 or more (severe);
- the preferred cyclone movement of systems in this region is to the southwest and the shape of the coastline results in systems moving over land and weakening on their approach to the Wyndham area; and
- being located about 50 km inland from the exposed part of the coastline Wyndham is somewhat protected from the full force of the cyclone impact.
Of the systems occurring within 100 km of Wyndham since 1910 there is only one identified system, Wilma in March 1975, that was stronger than a category one cyclone. Nevertheless there is still the risk that a severe cyclone will impact Wyndham and or neighbouring communities. The threat of a major impact lies from those systems arriving from the north. Three examples highlighting this risk are Tracy at Darwin in December 1974, Thelma in December 1998 and Ingrid in 2005. The map of coastal crossing points shows that Tracy was one of the few severe tropical cyclones to affect the top end. It just happened to hit Darwin and arguably be the most significant natural disaster in Australia's history. Although initially being steered to the southwest Tracy curved to the southeast towards Darwin. Thelma was a very intense category 5 cyclone that moved to the southwest eventually crossing the remote north Kimberley coast. Had Thelma been steered to the south or southeast over Joseph Bonaparte Gulf then Wyndham would have faced the impact of a category 4 or 5 cyclone (see track of TC Thelma). Similarly Ingrid was steered to the southwest over the Timor Sea and crossed the coast near Kalumburu as a category five cyclone (see track of TC Ingrid).
It is possible that there have been more severe cyclones off the north Kimberley that have gone undetected. Prior to the satellite era it is likely that there were many unidentified systems north of the Kimberley. A Thelma-type of system prior to the 1960s may have not have been identified or may have been analysed as a much weaker system given that it did not impact a Kimberley community. The low population of the coastal northeast Kimberley and poor historical wind observations also make it difficult to properly describe the historical cyclone risk in this region.
Cyclones that impact Wyndham typically form over warm ocean waters off Northern Territory. The typical steering of these systems is to the southwest so that systems move over land before reaching the Wyndham area. As a result most systems either weaken below cyclone intensity or are category 1 strength. A few systems take a more southerly track. Some have formed north of the Kimberley and moved to the south or southeast. There are many other lows that move westwards across the Northern Territory, and while they do not bring gale-force winds, they can produce widespread heavy rain. The more intense systems are more likely to come from the north over warm ocean waters unimpeded by the land mass.
See also the Interactive Tropical Cyclone Plotting web page to access tracks of historical tropical cyclones.
Rainfall totals in excess of 100 mm over the northeast Kimberley are common with tropical lows and cyclones. Such totals may occur even if systems that are well to the west as a result of moisture laden northwesterly monsoon winds. The amount of rainfall is not related to the intensity of the cyclone, rather to the location, size and speed of the system. Some of the largest flood events have been associated with monsoon lows below cyclone intensity, as in the case of the February 1993 and January 2000 events. Flooding is enhanced if the low is slow-moving and follows previous rainfall that has already saturated the ground and elevated river levels. Cyclone Hector in January 1986 meandered over the Kimberley for many days causing widespread floods.
Some Notable Cyclones Impacting Wyndham
|Tropical Cyclone||Rainfall (mm)||Impact Description|
|8-13 Jan. 1903||637/5 days||Floods around Wyndham, described as unprecedented, caused heavy stock losses.|
|April 1959||440/2 days||Heavy rain from a cyclone in January was followed by another in April, both passing close to Wyndham. Each event caused over 400 mm of rain. The airport was flooded.|
|Hector Jan. 1986||>200||Hector crossed the coast as a category 1 cyclone north of Wyndham on the 19th then meandered over the Kimberley for the next five days causing floods throughout the Kimberley. Two hundred people were evacuated from the Oombulgurri community northwest of Wyndham due to the flood risk.|
|Ingrid Mar. 2005||>200||Ingrid crossed the coast northeast of Kalumburu as a category five cyclone demolishing the resort of Faraway Bay then passing close to Kalumburu before heading southeast to Wyndham. Being a small-sized system, Ingrid rapidly weakened over land and was only at category one intensity when it passed close to Wyndham causing a brief period of gales on the morning of the 17th. Heavy rain (Emma Gorge 445 mm) caused some flooding cutting the Great Northern Highway but low rainfall prior to the event helped mitigate flooding.|