SWIRLnet observations during Tropical Cyclones Jasper (2023) and Kirrily (2024)

The 2023/24 tropical cyclone season saw two major storms make landfall on the east coast of Queensland, Tropical Cyclone (TC) Jasper and Tropical Cyclone Kirrily. TC Jasper made landfall near Wujal Wujal in North Queensland as a category 2 storm, while TC Kirrily made landfall just north of Townsville also as a category 2 storm. The Surface Weather Relay and Logging Network (SWIRLnet) was deployed for both events with wind and surface weather information recorded by the ruggedised weather stations that make up the network. Relatively low wind speeds were measured during both events, with the maximum 10-minute mean and 0.2-second gust recorded by the towers (3.2 m elevation) during TC Jasper being 12.7 m/s and 22.4 m/s, and 13.4 m/s and 29.9 m/s for TC Kirrily. Standardising these gusts to 10 m elevation, flat open terrain conditions leads to estimated peak 0.2-second gust values of 26.0 m/s for TC Jasper and 37.6 m/s for TC Kirrily. Both these values are below 55% of the regional wind speed specified in AS/NZS1170.2 for Region C. Analysing the turbulence statistics of the measured data reveals that the tendency for positive skew highlighted by recent observational and wind tunnel studies of hurricane winds in the USA are also present in these data. A close match to the measured skew of 0.5 for hurricane winds at heights and terrain similar to the SWIRLnet towers was observed. This observation suggests that standard wind engineering practice of assuming that turbulence is normally (Gaussian) distributed may be inappropriate and therefore typical peak factors may be an understimation. Noting the relatively low wind