Large-scale cloud features referred to as cloudbands are known to be related to widespread and heavy rain via the transport of tropical heat and moisture into higher latitudes. The Australian Northwest Cloudband (NWCB) is a such a feature that has been identified in fairly simple searches and with limited interrogation of the synoptic features to support these heavy rain events. An accurate, long-term climatology of NWCBs is key to fully assessing these events. A sophisticated search algorithm has been developed that is guided by the presence and orientation of the subtropical jet stream. This jet stream is the large-scale atmospheric feature that is strongly linked to NWCB events. A manual comparison of this new search algorithm for NWCBs in 2016 has positive results for its ability to capture real events and limit false event detection. Using this new search algorithm, composite synoptic conditions over the period 1979-2018 have been assessed to further develop our understanding of the link between NWCBs and heavy rain events in Australia. Composites of vertically integrated water vapor transport (IVT) centered around the jet maximum during NWCB events reveal a distinct Atmospheric River that supplies the necessary tropical moisture for the associated heavy rain. A suite of other diagnostic indices including 500-hPa height anomalies, velocity potential, wave number, wave activity flux, sea surface temperature anomalies, and thermal wind, are investigated using a Monte Carlo analysis to determine the unique synoptic conditions present during NWCB events. A long control run of the ACCESS-D model is assessed for its ability to represent NWCB events and their associated rainfall.