The national emergency system doesn't rely on one provider[0] or one cloud, while Pelmorex Corp (The Weather Network) is part of the chain (and a curious one) it isn't the entire system, nor is their choice of provider/hardware a government choice (but it doesn't seem poor). The network isn't down, an aspect may have endured an outage. For significant (but not total) coverage of the country the "Alert Distributors" could be covered with contacting 15 corporations (huzzah anti competitive Canada)... or less if you pick a specific channel (eg Wireless=4), which I imagine is part of alerting protocol (your cable, mobile, radio, TV, and web applications don't all send the same alert)

[0]: https://www.publicsafety.gc.ca/cnt/mrgnc-mngmnt/mrgnc-prprdn...