VANCOUVER Few people outside public health circles knew an extreme heat alert issued by Metro Vancouver health authorities at the start of the heat wave was unprecedented, and even the authorities’ own forecasting dramatically underestimated how many people could die in the record-breaking temperatures. Internal documents obtained by CTV News Vancouver support the admission that health officials were unprepared for the scope and severity of the heat wave, which saw quadruple the number of deaths the region typically sees during that week. Health officials had expected only a fraction of that number. “According to the BCCDC historical data, the Extreme Heat Alert criteria is linked to at least a 20 per cent increase in mortality,” wrote Dr. Mark Lysyshun, Vancouver Coastal Health’s deputy chief medical health officer to hospital staff on Friday, June 26.