A 'surge' in gas fired generation cannot 'cause' a near doubling...

A 'surge' in gas fired generation cannot 'cause' a near doubling of wholesale electricity prices - Impossible and it makes no sense. Without the 'surge' in gas fired generation, prices would have been through the roof and/or there would have been load shedding.
The higher cost gas fired generation price signal to 'surge' in output is caused by reduced output from other cheaper generation and/or increased demand. Those are the 'causes' of the near doubling of electricity prices. Specifically in this case, forced outages and stockpile management at some coal fired plant, the ongoing wind 'drought' across the NEM, network constraints and hydro management, all combined with increased demand due to a colder winter.