"Western Canada's most powerful radio station"? Well, at least they didn't say "Western Canada's first 50,000 watt radio station".
They were, in fact, #4. CBK-540 in Watrous, Saskatchewan, came on the air in 1939 as a new non-directional 50,000 watts meant to serve the entire province. In 1948, the other two Prairie Provinces got 50,000 watt CBC stations: CBX-1010 in Lacombe, with a figure 8 directional pattern day and night to better serve Edmonton and Calgary (but it still wasn't good enough); and non-directional CBW-990 in Winnipeg at the same time as the call letters were changed from CKY, just months after the CBC bought CKY from Manitoba Government Telephones.
From everything I can see, CKWX was indeed the first non-CBC station in Western Canada to go to 50,000 watts.
Ironically, CFCN Calgary may have been the first Western Canadian (non-CBC) station to apply for 50,000 watts, as there is a report of them being turned down in 1946. The irony: two years later, the CBC moved them off of their Canada/Mexico clear channel of 1010 KHz, to make way for the new CBX Lacombe. It was not until 1966 that CFCN was granted 50,000 watts on the frequency that the CBC forced them to: 1060.
Other early 50,000 watt Western Canada stations include CFRN-1260 Edmonton in 1961, and CKY-580 Winnipeg in 1960.
