There are similarities between the 6 and 18 January situations. For example, both produced high significant wave heights of about 7 m, and high magnitudes of the Extreme Forecast Index of about 0.8 to 0.9. But there are differences.
On 6 January, low pressure evolved rapidly, deepening to a value of 936 hPa. The deepening reached the stage of explosive cyclogenesis with an intensity of 36 hPa in 24 hours, while the low pressure on 18 January never exceeded 965 hPa at the center. Plus, there wasn’t any intense deepening or strong winds associated with it.
The fetch in the 6 January situation was very long - around 3000 km. In contrast, the fetch in the 18 January situation was relatively short.
The periods recorded during the 6 January situation were exceptional, 18 s. In contrast, the periods did not reach 13 s on 18 January. The shorter period waves will not increase in height nearly as much as the longer period waves when shoaling and breaking in shallow water.
The 18 January situation impacted human activities but did not result in any infrastructure damage or loss of human life.