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In the northern part of Queensland, Cyclone Nathan has had a spiral type of track, as can be seen below:

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Image credit: Tropical Cyclone NATHAN Forecast Track (Joint Typhoon Warning Center)

As can be seen in the diagram, it tracked in from the Coral Sea, stopped short of making landfall on the Cape York Peninsula, went back out to sea and has tracked back inland -and is expected to make landfall and cross into the Gulf of Carpentaria (where it may re-intensify).

What meteorological mechanisms would cause the spiraling track of a cyclone?

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Hurricanes backtracking and looping seem to be quite common in the Atlantic (Nadine, Jeanne, Alberto, Dennis), and West Pacific (Ernie, Nari, Fung Wong, Parma, Roke) but not so much in the East Pacific (where the tracks are way more linear, with much less latitudinal change).

In general, tropical cyclones are steered by the global wind field. The environmental wind field (winds that surround a hurricane) guides a cyclone along its path. Hurricanes are steered predominantly by winds in the upper atmosphere, especially winds from about 3000 to 10000 meters above sea level. High-pressure and low-pressure systems often cause cyclones to divert from their initially east-to-west movement. When a high- or low-pressure system is located to the west and extends far enough latitudinally, storms are blocked and a change in direction may occur.

In the case of Tropical Cyclone Nathan, there seems to have been a stationary high over southwestern Australia on 12 March 2015 that connected with another high to the north and prevented the movement of the cyclone. The presence of Tropical Cyclones Olwyn and Pam probably influenced the change in path.

three cyclones.

Nathan started to move north as Pam was moving south (13 March) and then went east without that much obstruction (14-15 March). As the high pressure to the south moved east, there was a clear path for Nathan to continue moving west (18-March).

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  • $\begingroup$ I have some problems with this answer because it appears to me that N. Atlantic hurricane tracks do not commonly loop or backtrack, although it can occur. In the related question, earthscience.stackexchange.com/questions/4438/…, I quote Australia BOM saying, "Research has shown that cyclones in the Australian region exhibit more erratic paths than cyclones in other parts of the world." The details on interactions of pressure system are appreciated. I still don't understand the prevalence of erratic paths off NE Australia. $\endgroup$
    – haresfur
    Commented Mar 19, 2015 at 1:33
  • $\begingroup$ In my answer, I posted 4 examples of North Atlantic hurricanes that looped in recent years and I know there are more as they can be seem in the cumulative tracks for the region. In the Australian region, the paths are erratic, yes, but no more than in other areas such as the North Atlantic and West Pacific. You can easily get that information by analyzing the tracks in the different regions. The only region that seems different is the East Pacific. The answer by @Fred to your question implies as much! $\endgroup$
    – arkaia
    Commented Mar 19, 2015 at 1:46
  • $\begingroup$ You can easily get that information by analyzing the tracks in the different regions (e.g., weather.unisys.com/hurricane). The only region that seems different is the East Pacific. When you look at the South Pacific, the only recent cyclone that clearly looped is Nathan $\endgroup$
    – arkaia
    Commented Mar 19, 2015 at 1:51

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